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232 Cards in this Set
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What is class Cestoda? Lifestyle? Adult and larval forms? Sexual/asexual? Different body parts? Sexual reproduction? Digestive tract? |
Tapeworms: -endoparasites built to produce eggs and sperm and not much else- in intermediary host: larval forms develop; may reproduce asexually - in definite host: adults develop; reproduce sexually - anterior scolex: has hooks and suckers for attachment to host gut - posterior to scolex: long ribbon of hermaphroditic proglottids - several proglottids produced per day - 50,000 eggs, 1,000 testes in every proglottid - proglottids break off after fertilization - no digestive tract; absorb food predigested by host |
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4 facts about Tapeworms: |
-can be > 20 m long
- can cause intestinal blockage - can cause nutritional deficiency - leave host’s body with feces |
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What is phylum Mollusca? Habitat? Segmented? Coelomate? |
-very large and diverse phylum (>150,000described species) → generalizations difficult - marine,freshwater,terrestrial - coelomatous and unsegmented |
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What are the 4 features used to identify Phlum Mollusca? Exaplain. |
muscular foot→ usually for movement
• visceral mass -contains internal organs -gill and anus open into mantle cavity • mantle - secretes shell: calcium carbonate in protein matrix - drapes over and protects the visceral mass -creates the mantle cavity, a water-filled chamber housing thegills, anus, and excretory pores • radula: toothed scraping tool |
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What are the classes and main characteristics of Phylum Mollusca? |
Poluplacophora, Gastropoda, Bivalvia, Cephalopoda |
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What is class Polyplacophora? What is characteristic of them? Shape, movement, eating, etc. |
Chitons! • marine • oval shape; eight overlapping dorsal plates • reduced head • large foot • grips rock • animal can move slowly or maintain position by suction– important in intertidal zone • radula scrapes algae off rock |
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What is class Gastropoda? Habitats? Eating lifestyle? General features? Unique fact? |
-Snails, slugs - > 40,000 living species - marine, freshwater, terrestrial -snails, slugs, nudibranchs only molluscs to have invaded land - grazers or predators - most: protected by single, spiraled shell - many: distinct head, eyes at tips of tentacles |
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What is torsion? |
- 180° rotation of the visceral mass in class gastropoda - anus and mantle cavity placed above head in adult • torsion IS NOT formation of coiled shell (independentdevelopmentalprocess) |
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What is class Bivalvia? Habitats? Examples? Movement? |
-marine and freshwater
• clams, mussels, scallops, oysters • usually sedentary |
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What are class Bivalvia shells like? |
-flattened
• divided into two halves • hinge at mid-dorsal line • powerful adductor muscles draw two halvestightly together |
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What about head and radula? |
Reduced head, lack of radula! |
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What type of eaters are Bivalvia? How do they eat? |
-paired gills; collect both O2 and food particles
-suspension-feeders - mantle forms siphons • flow of water: incurrent siphon→ gills→ excurrent siphon |
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How does this class Bivalvia get about? |
- sessile mussels secrete strong threads that tether them to rocks, docks,boats, and the shells of other animals
- cockles can ‘somersault’ - clams can pull themselves into the sand or mud, using the muscular foot as an anchor - scallops can swim in short bursts by flapping their shells and jettingwater out their mantle cavity |
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What is class Cephalopoda? Habitat? Look? Shell? Radula? |
-Marine -head surrounded by grasping tentacles, usually with suckers shell • external (nautilus) • reduced and internal (squid, cuttlefish) • absent(octopus) - with or without radula |
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How do cephalopods get around? |
locomotion by jet propulsion: forceful ejection of water through siphon
• rapid, directed movement |
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What kind of eating habits do they have? |
PREDATORS! |
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Do they have a nervous system? |
• well developed • complex brain and sense organs |
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What is very unique and important to know about Cephalopoda in comparison to other classes in Phylum Mollusca? |
• only molluscs with closed circulatory system! |
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What is Phylum Annelida? |
• ~16,500 species • segmented worms • terrestrial, freshwater, marine (earthworms, leeches, marine annelids) |
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Do annelids have a coelom? |
Yes and it's partitioned by septae! |
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Are annelids segmented? |
Yes. organ systems repeated in each segment: digestive, circulatory, nervous, and excretory systems |
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What is annelids digestive system? |
digestive system: pharynx, esophagus, crop (food storage), gizzard (food grindingand fragmentation), intestine (digestion and absorption) |
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What is annelids excretory system? |
excretory system = metanephridia remove wastes from blood and coelomic fluid discharge waste through pores |
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Do annelids have a circulatory system? |
closed circulatory system
- network of vessels - dorsal, ventral, and segmental vessels - blood with O2-carrying hemoglobin |
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How is O2 absorbed? |
O2 absorbed across skin, which is highly vascularized
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What is annelids nervous system? |
Cerebral ganglia pair of fused ventral nerve cords with segmental, fused ganglia
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What kind of muscles do they have? |
circular and longitudinal muscle |
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What are the classes and characteristics of Phylum Annelida? |
Oligochaeta and Polychaeta
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What is class Oligochaeta? |
Earthworms and their aquatic relatives! (including leeches) |
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What's the deal with Earthworms? Feeding? Locomotion? Reproduction? |
deposit feeders • ingest soil, extract nutrients, and leave behind castings • improve soil structure and aeration locomotion • alternating contraction of circular and longitudinal muscles • contractions coordinated among segments →peristaltic motion • chaetae (bristles) provide traction reproduction • hermaphroditic: mutual exchange of gametes • embryos develop in cocoon secreted by clitellum • asexual reproduction by fragmentation |
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What is the deal with Leeches? (Hirudinea) |
-mostly freshwater
• parasites, predators, and scavengers parasites • bloodsuckers • secrete anaesthetic • secrete hirudin (prevents bloodclotting)
• body flattened • reduced coelom and segmentation • chaetae absent • suckers at anterior and posterior end |
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What are class polychaeta? |
• marine • sedentary polychaetes stay put in burrows or tubes of cemented materials • errant polychaetes are mobile • each segment has: • chaetae • pair of parapodia (‘almostfeet’) - function in locomotion -can be vascularized for gas exchange→ act asgills • reproduction: all are dioecious (separate sexes) |
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What phylums belong to Lophotrochozoans? |
Phylums: Platyhelminthes Mollusca Annelida |
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What is phylum Nematoda? |
(roundworms)
nonsegmented pseudocoelomates • free-living and parasitic • aquatic, wetsoil, tissues of plants and animals • <1 mm to > 1m |
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What are nematoda bodies like? Digestive tract? Circulatory system? |
-bodies are cylindrical and covered by tough exoskeleton (cuticle)
-cuticle needs to be shed(ecdysis) by growing worms • complete digestive tract • nocirculatorysystem |
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What kind of muscle do nematodes have? What lifestyl do they live? |
muscle all longitudinal→ thrashing motion • free-living or parasitic on plants or animals |
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What is an example of a free-living nematode and where do they inhabit? |
• live in moist soil or decomposing organic matter (e.g. compost piles, bottom of lakes and oceans) •
e.g. Caenorhabditis elegans |
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What are some examples of parasitic nematodes and who do they bother? |
- some are important agricultural pests that invade plant roots
• some have animal hosts, e.g. -Trichinella - hookworms[intestinal parasite, teeth-like projections] • dog heartworm, transmittedthrough infected mosquitos |
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What is Caenorhabditis elegans? |
Caenorhabditis elegans: one of the best understoodanimals
• model organism for developmental genetics • complete lineages known from zygote to adult • genomesequenced |
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What is phylum arthropoda? |
-most successful of all animal phyla
- nearly a million arthropod species have been described - world arthropod population may be a billion billion (1018) individuals represented in nearly all habitats in the biosphere - great diversity |
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What is an overview of Arthropods? Segmentation? Exoskeleton? Jointed Appendages? Cephalization? Circulation? Gas exchange? |
-Segmentation• Exoskeleton• Jointed appendages• Cephalization• Open circulation• Various gas exchange strategies
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What is arthropoda's segmentation and what is tagmosis/tagmatization? |
metamerism (serial repetition of parts along the length of the body axis in bilaterally symmetrical animals) tagmosis/tagmatization: segments differ in form and function - division of labour among regions - diversification |
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What is the exoskeleton, and how does it function? |
Exoskeleton (cuticle) made of chitin and protein
-strong thin, flexible at the joints • low permeability to water enabled colonization of terrestrialenvironments --->functions: • protection • muscle anchorage • structural support (important on land) • prevention of desiccation (important on land) requires molting (ecdysis) for growth to occur • energetically costly • temporary vulnerability |
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What are the jointed appendages of arthropods? |
Jointed appendages
• variable in number among arthropod groups • joints formed by thin, flexible exoskeleton • movement of articles controlled by antagonistic muscle bands functions: -locomotion (walking, swimming) • feeding • sensory reception • copulation • defense • different forms and uses in different groups |
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What are the cephalization of arthropoda? |
Cephalization
• Senseorgans - photoreceptors: eyes -chemoreceptors: smell and taste -mechanoreceptors • Nervous system -dorsal, anterior brain -pair of ventral nerve cords (fused) -segmental ganglia (can be fused) |
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Tell me abour Arthropods circulation. |
Open Circulation
-hemolymph propelled by heart through arteries and then into sinuses surrounding tissues and organs - body sinuses: hemocoel hemo lymph returns to heart through pores (usually have valves) |
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What are arthropods gas exchange strategies? |
Gas Exchange Strategies:
-organs must allow diffusion of respiratory gases in spite of exoskeleton - in aquatic species: gills with feathery extensions - in terrestrial species: specialized internal surfaces, e.g.trachea(branched air ducts) in insects |
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Subphylum within Phylum Arthropoda and characteristics? |
Cheliceriformes, myriapoda, hexapoda, crustacea. |
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What is subphylum Cheliceriformes? |
• chelicerae: claw-like feeding appendages
• no antennae • marine (e.g. horseshoe crabs) and terrestrial • most modern chelicerates belong to the Arachnida |
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In Cheliceriformes, what is class Arachnida? |
-six pairs of appendages • chelicerae, can be equipped with poison glands• four pairs of walking legs • e.g. spiders, scorpions, ticks, mites |
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What is subphylum myriapoda? |
-terrestrial
• two tagmata: head and trunk • head - one pair of antennae -mouth parts include mandibles • trunk - uniramous (unbranched) appendages |
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What are two classes with Subphylum Myriapoda? |
Class Diplopoda (millipedes) • herbivorous • trunk: two pairs of walking legs per segment Class Chilopoda (centipedes) • carnivorous • trunk: one pair of walking legs per segment |
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In subphylum Hexapoda, what is class insecta? |
• three tagmata: head, thorax and abdomen • one pair of antennae • uniramous appendages • mouthparts modified for chewing, sucking, or lapping include mandible • usually three pairs of legs • usually two pairs of wings • mostly terrestrial • many undergo metamorphosis |
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Insect development and metamorphosis in winged insects vs. wingless insects? |
Wingless Insects: - direct development • metamorphosis absent (ametabolous) e.g. silverfish, bristletails WInged Insects: -indirect development • metamorphosis present - incomplete = hemimetabolous• e.g. crickets, damselflies - complete = holometabolous• e.g. butterflies, moths |
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Incomplete vs. complete metamorphosis? |
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What is subphylum Crustacea? |
- tagmata: two or three
- two pairs of antennae - chewing mouthparts include mandible - biramous (branched) appendages - three or more pairs of legs - mostly marine e.g. crabs, lobsters, crayfish, shrimp |
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What phyla make up Ecdysozoans? |
Nematoda and Arthropoda |
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What is phylum Echinodermata? |
~7000 species - marine e.g. seastars, brittlestars, sea urchins, sanddollars, sea cucumbers |
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What are the key features of echinodermata? |
• eucoelomate deuterostomes • secondary radial symmetry • bilateral larva, radial adult • hard calcareous endoskeleton • water vascular system: network of hydrauliccanals branching into extensions (= tube feet) -TUBE FEET used for: • locomotion • feeding• gas exchange |
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What are the classes within Echinodermata? |
Asteroidea, Holothuroidea, Ophiuroidea, Echinoidea, Crinoidea |
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What is class Asteroidea? |
Sea stars! • five arms (sometimes more) • tube feet: act like suction disks; coordinate for movement • water is pumped into the foot by contraction of the ampulla • foot extends hydraulically • foot grips • foot retracts by contraction of the longitudinal muscles • some species can autotomize (sever) an arm to escape apredator |
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What is Asteroidea's feeding? |
• smaller prey can be digested whole
FOR larger prey, e.g. bivalves • sea star grips shells and pulls • everts its stomach • inserts stomach between shells of bivalve • secretes digestive enzymes into the bivalve |
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What is Asteroidea's reproduction? |
• capable of regeneration (some can regrow entire body from single arm) • sexual reproduction • separate sexes • broadcasters (release gametes into seawater) |
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What are class Echinoidea? |
Sea urchins and sand dollars. |
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How do Sea Urchins live? |
-rocky substrates • locomotion: spines and tube feet • feeding: scrape algae from rocks (Aristotle’s Lantern) • shred kelp • capture drift algae with tube feet |
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How do Sand Dollars live? |
sand/mud substrates • locomotion: spines only • deposit feeding: tube feet |
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What is class Holothuroidea? |
Sea cucumbers! -shape: no arms, elongation along oral-aboral axis• feeding: suspension or deposit feeding • have buccalpodia • internalmadreporite |
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What is clade ophuiroidea? |
brittle star (cladeOphuiroidea).
- distinct central disc and long,flexible arms - suspension feeders -predators andscavengers |
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WHat is clade crinoidea? |
A feather star (cladeCrinoidea).
• suspension feeders -mouth directed upward |
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What is phylum Chordata? |
2 invertebrate subphyla plus all vertebrates |
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four chordate features (present in at least one stage of life cycle of all chordates): |
1. notochord
2. dorsal, hollow nervecord 3. pharyngeal slits 4. muscular, postanal tail |
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WHat is the notochord? |
-skeletal structure located between the digestive tube and thenerve cord - elastic rod – flexes laterally - composed of large, fluid-filled cells encased in fairly stiff, fibrous tissue - in most vertebrates - present in embryo only - in adults only remnants present (e.g. disks between vertebrae) - development of more complex, jointed skeleton |
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What is the dorsal hollow nerve cord? |
- tube dorsal to notochord develops from ectoderm - develops into brain and spinal cord - solid, ventral nerve cord of other phyla |
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What are pharyngeal slits? |
-slits or holes in the pharynx (posterior to mouth) allow water entered through mouth to exit without passingthrough entire digestive tract - suspension-feeding devices in invertebrate chordates - slits and supporting structures modified for gas exchange (in aquatic vertebrates), jaw support, and hearing |
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What is the muscular postanal tail? |
-contains skeletal elements and muscles - provides propulsive force (in aquatic species) - most non-chordates: digestive tract extends nearly wholelength of body |
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What is subphylum Cephalochordata? |
• lancelets
-blade-like shape - small (few cm long) - globally rare - chordate characteristics persist into adulthood • larvae - planktonic and feeding • adults -can swim but prefer to burrow in sand - swimming: coordinated contraction of serial muscle blocks - serial musculature (evidence of segmentation) - muscle segments develop from somites (blocks of mesoderm) • pharyngealslits: involved in filter feeding • gas exchange:mainly across external body surface |
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WHAT is subphylum Urochordata? |
(tunicates) -marine, may be solitary or colonial - planktonic larvae, sessile adults |
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What are tunicate larvae? |
- short-lived, non-feeding function in dispersal: can sense light and gravity; settle and attach in dark spot - during metamorphosis into adult most chordate characteristics disappear |
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What are tunicate adults? |
-scarcely resemble chordate: no notochord, nerve cord, or tail - pharyngeal slits: involved in filter feeding; mucus traps food particles, cilia movethem into esophagus - water movement: incurrent siphon → over pharyngeal slits → atrium →excurrent siphon - filtered water and wastes exit through excurrent siphon - covered by tunic (cellulose-like carbohydrate and protein) |
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What are the clades of chordates in order? And what derived characteristic separated them? |
Chordates, Craniates, Vertebrates, Gnasthostomes, Tetrapods, Amniotes |
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What are craniates? What is characteristic of them? Habitat? Lifestyle? What do they lack? How are they supported? What unique feature do they possess? |
Craniates can be hagfishes and vertebrates, while chordates include invertebrate chordates and some craniates. - jawless (agnathans) - marine - bottom scavengers - lack bone (skeleton = cartilage) support • main axial support: notochord • lack vertebrae -lack scales and paired fins - possess slime glands |
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What are Vertebrates? What is characteristic of them? Habitat? Larval and Adult lifestyles? What do they lack? What is their support? |
Includes lampreys and gnathostomes.
- jawless (agnathans) - marine and freshwater - larval lampreys: suspension feeders - many adult lampreys: parasites(suck blood from living hosts) - lack bone support • main axial support: notochord • notochord surrounded by cartilaginous rod • pairs of cartilaginous projections partially enclosing nervecord - lack scales and paired fins |
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What are vertebrates gnathostomes? |
-jaws
• may have evolved from two pairs of skeletal rods that supported anterior pharyngeal slits -endoskeleton: axial and appendicular skeleton • mineralized bones and teeth • vertebrate axial skeleton ( main support structure for axis, or central trunk, of body) • vertebrate appendicular skeleton (supports two pairs of appendages (fins, legs, or arms) - duplication of genome, including Hox genes • enlarged forebrain • aquatic gnathostsomes: lateral line • fishes and tetrapods |
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How many groups of gnasthostomes do we need to know? |
Fishes, cartilaginous fishes, and bony fishes. |
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What are the Gnasthostomes: Fishes group? |
-earliest recognizable vertebrates= fish, and fish have beenvery successful • jaws ---->exploitation of food supplies • paired fins-----> accurate maneuvering ----> active predation |
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What are the Gnasthostomes: Cartilaginous fishes? |
Chondrichthyes (sharks, rays, and their relatives)
• jaws and acute senses → big advantage for hunting • predators and suspension feeders • mostly marine, some freshwater • endoskeleton: cartilage -can be strengthened by minerals -lack bones through secondary loss • nourishing the young -oviparous: egg hatches outside mother, embryo nourished by egg nutrients -ovoviparous: egg hatches inside uterus, embryo nourished by egg nutrients -viviparous: young born live. Embryo nourished via placenta |
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What are the Gnasthostomes: Bony fishes? |
-swim bladder allows the fish to adjust buoyancy Actinopterygii (Ray-finned fishes ) • marine and freshwater • e.g.bass, trout, tuna, herring, perch Lobe-finned fishes • Actinistia (Coelocanths) • marine • one extant genus Dipnoi (Lungfishes) • freshwater (stagnant ponds and swamps) • have lungs and gills • e.g. South American loalach |
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What are the 3 groups within bony fishes? |
Actinopterygii (Ray Fins), Actinista (Lobe Fins), Dipnoi (Lungfishes). |
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What class/groups do we need to know of Tetrapods? |
Amphibia and Amniotes |
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What is class Amphibia? |
(Gr. amphibios, living a double life): metamorphosis of manyfrogs from an aquatic stage, the tadpole, to the terrestrial adult RELATIONSHIP TO WATER: -eggs shell-less - dehydrate quickly, must be laid in wet/moist place - some aquatic and terrestrial need moist skin for gas exchange |
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What are characteristics of the amniotes eggs? |
- eggs of most amniotes have a shell that retains water and can be laid in a dry place - bird eggs are calcareous, hard, and inflexible -reptile eggs are leathery and flexible |
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What are the parts of the amniotic egg? |
amnion: protection allantois: waste disposal chorion (together with allantois): gas exchange yolk sac: covers yolk (nutrients) |
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The phylogeny of amniotes and what we need to know! |
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What are Amniotes: Reptilia characteristics? |
• young are born in shelled eggs, or live • dry skin– keratinized scales • ectothermy and endothermy (e.g.birds) |
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What are the extant reptiles? (Still surviving) |
-turtles: branched off the reptilian line very early and have changed very little since -lizards and snakes: largest and most diverse order - crocodilians (alligators and crocodiles): largest living reptiles - birds |
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What are reptiles: Turtles? |
-hard shell is an adaptation that protects against predators - some species of soft-shelled turtles - turtles that returned to water during their evolution crawl ashore tolay their eggs |
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What are reptiles: Lizards and snakes? |
-lizards are the most numerous and diverse reptiles alive today - most are relatively small, except the Komodo Dragon (> 10 feet long) |
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What are reptiles: Crocodiles and Alligators |
-alligators and crocodiles are among the largest living reptiles - spend most of their time in water, breathing air through upturnednostrils |
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Tell me about Birds endothermy? |
- insulation (feathers, fat) - four-chambered heart - unidirectional ventilation oflungs |
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Tell me about Reptiles: Birds adaptations for flight? |
-wings and feathers - light skull - beak, no teeth - tail with small number of vertebrae - large flight muscles - sternum with a keel for the attachment of flight muscles - acute vision |
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What else to know about Reptiles: Birds? |
-large brains - complex behaviours - diverse beak and foot structures |
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What is characteristic of Amniotes: Class Mammalia? |
-hair • mammary glands • endothermy • teeth with specialized functions • improved hearing |
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What are the three groups of mammals? |
• Monotremata: egg-laying mammals • Marsupialia: mammals with pouches • Eutheria: placental mammals |
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What is order monotremata? examples? |
Class Mammalia - have hair and produce milk • lay eggs; no nipples– baby sucks milk from fur of mother • duck-billed platypus and echidna |
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What is order Marsupialia? |
Class Mammalia - young nourished in utero by placenta (lining of uterus and extraembryonic membranes) - born early and complete their development in apouch (marsupium) e.g. opossums, kangaroos, koalas |
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What are Eutherians? |
Eutherians: placental mammals • placenta • more complex than in marsupials • provides long-lasting association betweenmother and developing young • includes all other orders of mammals |
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Overview of all of the Chordates-onward that we need to know. |
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What cells in sponges suggest an evolutionary affinity with choanoflagellates? |
Choanocytes. (collar cells) |
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What are the functions of the following molluscan structures? a) foot; b) mantle cavity; c) mantle; d) radula.
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A) locomotion, attachment, burrowing B) location of gills, anus; modified to a lung in terrestrial gastropods C) protection; secretion of calcium carbonate shell D) scraping food from rocks or drilling the shells of other organisms |
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How does the arrangement and contraction of muscles in an earthworm generate movement?
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Each segment contains both circular and longitudinal muscles. When the circular musclescontract and the longitudinal muscles relax, the segment lengthens – moves forward. Bristles(chaetae) anchor the segment at the new spot. When the circular muscles relax and thelongitudinal muscles contract, the rest of the worm’s body is dragged up to the new spot. |
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What are the functions of the hard arthropod exoskeleton?
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• protection• muscle anchorage• structural support (important on land)• prevention of desiccation (important on land)
In marine arthropods, muscle anchorage and protection. In terrestrial arthropods, the abovetwo functions, as well as prevention of water loss and support against gravity. |
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Why are arthropod appendages striking examples of evolutionary homology?
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The arthropod appendage is a very flexible instrument (evolutionarily speaking) that hasassumed many different forms and functions: walking, sensing, feeding (mandibles), defense,capture of food, sexual reproduction. Also, different arthropods have different numbers ofappendages. |
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The bodies of many sponges contain finely branched channels through which water ispropelled. What is the advantage of this branching? |
Increased surface area means more likely to get food. The fine channels are lined with choanocytes, which absorb food particles; the greater thenumber of channels, the greater the number of choanocytes available for phagocytosis. Also,the water slows down as it branches, giving the choanocytes more opportunity to absorb foodparticles. |
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Jellyfish are diploblastic animals, and consequently lack mesoderm and true muscle. And yetjellyfish can move in the water. How do they do it?
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Jellyfish have elongated contractile cells in the epidermis or gastrodermis that are anchoredin the mesoglea. Contractions of these cells distort the body and provide movement. Strictlyspeaking, the cells cannot be considered muscle tissue, however, since they are not derivedfrom mesoderm. |
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Planarians are negatively phototactic. What does this mean, and why is this ability anadvantage?
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This means that if they sense a decrease in lighting, they are signalled to flee because it may indicate a large predator swimming overhead. A negatively phototactic animal can sense light and move away from it. It probably helps theanimal hide from visual predators. |
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Tapeworms do not have a gut or gastrovascular cavity. How do they live without one?
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All members of this group are endoparasitic and are able to absorb, across their body wall,nutrients digested by the host.
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The penis fencing contests in which some flatworms engage – contests which sometimesresult in the death of one of the combatants – would not appear to be in the best interests ofthe species. How, then, could such behaviour have evolved?
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Behaviour, structures and processes that appear by natural selection are not favoured byvirtue of being good for the species as a whole (whatever that might mean). All that mattersis that the genetic variants in question allow their possessor to thrive and reproduce. If thewinner of one of these contests produces a lot of offspring as a result, and perhaps lives toinseminate another partner, the aggressive behaviour will have selective value. |
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Why is Caenorhabditis elegans a good model for developmental genetics?
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It is small (959 somatic cells); it has a rapid generation time; the lineage of every cell in theadult organism is known.
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Hemoglobin is found in members of Chordata and Annelida. What other characteristicrelated to the circulatory system do they share?
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Closed circulatory system. |
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What important attribute does the sea star have in common with a) a cnidarian; b) amonkey?
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a) radial symmetry in adulthood; b) deuterostome development |
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What is the difference, structurally, between a notochord and a vertebral column? |
A notochord is a solid, continuous structure; a vertebral column is composed of chunks of either cartilage or bone. |
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Which living invertebrate group is most closely related to vertebrates? |
Hagfishes (Myxini) |
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What advantage does a notochord confer to larval forms that have one? |
The notochord permits whole-body swimming motions, which allow the larva to grow muchbigger than a larva propelled by cilia. |
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Which extant fishes and fishlike forms have retained a cartilaginous skeleton as an ancestralcondition, and which have acquired it after the secondary loss of a bony skeleton?
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Ancestral: hagfishes. Secondary loss: lampreys (probably), Clade Chondrichthyes, somebony fishes (such as sturgeons and some lungfishes)
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How do you think the size of an amphibian might relate to its ability to take up oxygenthrough its skin?
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The larger an animal, the lower its surface/volume ratio, and the less efficient would beacquisition of oxygen through its skin. Amphibians that get all their oxygen by diffusionthrough the skin, such as some salamanders, are limited in the size they can attain.
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What adaptations liberated reptiles from the dependence on moist habitats that restricts therange of amphibians?
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The hard-shelled egg with extraembryonic membranes that protect the embryos, and dry skinwith keratinized scales.
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What is the relationship between endothermy and body insulation?
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Endothermy, especially in temperate climates, is helped by insulating layers of fat, feathersor fur; heat generated metabolically is retained better than in a non-insulated animal. For anectotherm, insulation would be a disadvantage, because it would thwart the absorption ofheat from the surroundings.
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Much about the structure and metabolism of birds is explained by the demands of flight.What are these adaptations?
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Endothermy; a light skeleton; toothless beaks (saves weight); the four-chambered heart; theair sacs that direct a constant flow of fresh air over the lungs unidirectionally, whether thebird is inhaling or exhaling; a keel on the sternum for attachment of large flight muscles;acute vision; feathers, especially asymmetric flight feathers. |
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What are the distinguishing features of mammals?
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Hair; a four-chambered heart (a trait shared with birds); mammary glands that nourish theyoung with milk; differentiation of teeth (meaning that not all teeth in the mouth of themammal look alike); the incorporation of a couple of jaw bones into the inner ear. |
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What are the differences between monotremes, marsupials, and placental mammals?
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Monotremes lay eggs and the females have no nipples to nurse the young (although they doproduce milk, which infants lick from the mother’s fur). Marsupials are born before theirdevelopment is complete; later stages of development occur in a pouch. Placental mammalscomplete their development in the uterus, nourished by a placenta, which transfers nutrientsfrom the mother’s blood to the young.
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A sponge's structural materials (spicules, spongin) are manufactured by the: A) pore cells. B) epidermal cells. C) choanocytes. D) amoebocytes. E) neoblast tissue |
D) Amoebocytes |
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Against which hard structure do the circular and longitudinal muscles of annelids work?
A. bristles B. cuticle C. shell D. endoskeleton E. hydrostaticskeleton |
E. Hydrostatic skeleton |
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What would be the most effective method of reducing the incidence of blood flukes in a humanpopulation? A) reduce the mosquito population B) reduce the freshwater snail population C) purify all drinking water D) avoid contact with rodent droppings E) carefully wash all raw fruits and vegetables |
B) reduce the freshwater snail population |
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In a tide pool, a student encounters an organism with a hard outer covering that contains muchcalcium carbonate, an open circulatory system, and gills. The organism could potentially be acrab, a shrimp, a barnacle, or a bivalve. The presence of which of the following structures wouldallow for the most certain identification of the organism?
A. a mantle B. aheart C. a body cavity D. a filter-feeding apparatus E. eyes |
A) Mantle |
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Which structure do nudibranchs use to feed on their prey?
A) nematocysts B) a sharp beak C) an incurrent siphon D) a radula E) a mantle cavity |
D) A radula |
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Arrange these terms from most inclusive (most general) to least inclusive (most specific).
1. lobe-fins, 2. amphibians, 3. gnathostomes, 4. osteichthyans, 5. tetrapods. A) 4, 3, 1, 5, 2 B) 4, 3, 2, 5, 1 C) 4, 2, 3, 5, 1 D) 3, 4, 1, 5, 2 E) 3, 4, 5, 1, 2 |
D) 3,4,1,5,2 |
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What is agnatha? |
No jaws. |
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What is Eumetazoa? |
Eumetazoa is a eukaryote clade in Kingdom Animalia containing all major animal groups except sponges, placozoa and several other animals groups about which little is known. The differentiating haracteristics of eumetazoans include true tissues organized into germ layers, and an embryo that goes through a gastrula stage.
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What is osteichthyes? |
Bony fishes
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What is Parazoa? |
Subkingdom includes Porifera. |
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What are the subphylums and classes in Phylum Arthropoda? |
Subphylum Cheliceriformes -Class Arachnida Subphylum Myriapoda -Class Diplopoda -Class Chilopoda Subphylum Hexapoda -Class Insecta Subphylum Crustacea |
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What about Phylum Nematoda? |
No sub-phyla or classes. Just Nematodes! |
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What are the classes of Phylum Annelida? |
Class Polychaeta Class Oligochaeta |
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What are the classes of Phylum Mollusca? |
Class Polyplacophora Class Gastropoda Class Bivalvia Class Cephalopoda |
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What are the classes of Platyhelminthes? |
Class Turbellaria Class Trematoda Class Cestoda |
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What are the classes of Phylum Cnidaria? |
Class Hydrozoa Class Scyphozoa Class Cubozoa Class Anthozoa |
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What about Phylum Porifera? |
No classes, or sub-phylums! Just Porifera. |
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What are the classes of Phylum Echinodermata? |
Class Asteroidea Class Ophiuroidea Class Holothuroidea Class Echinoidea |
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What are the subphylum and classes of Phylum Chordata? |
Subphylum Cephalochordata Subphylum Urochordata Subphylum Craniata -Class Myxini -Class Petromyzontida -Class Chondrichthyes -Class Actinopterygii -Class Actinistia -Class Dipnoi -Class Amphibia -Class Reptilia -Class Mammalia |
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What does biological evolution consist of? |
1. change in a population or species over time due to inherited factors
2. diversification of lineages, or common descent |
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In biology, there are two kinds of "why" questions we can ask? |
Why in terms of functions? and Why in terms of history? Why do birds have feathers? Flight, thermal regulation.Feathers may also be an evolutionary adaptation. |
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What are two levels of change? |
macroevolution - large scale evolutionary change; long time scale
microevolution - small scale; change within a population or a group ofpopulations over short periods of time |
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What are two basic issues in evolutionary biology? |
Two basic issues in evolutionary biology :
1. how species change and adapt over time (usually by natural selection) 2. how new species arise (called speciation) |
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What is meant by evolutionary THEORY? |
Not a hypothesis. Evolutionary theory attempts to explain WHY things evolve the way they do. Not debating whether evolution happened or not, the debates are about WHY it happened. |
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What evidence is there for evolution? (5 things) |
Natural populations of organisms have genetic variability. Some of thisvariability results in differences in adaptation, survival and reproduction. Example: Populations of lady bugs not having uniform markings.
Artificial selection, the intentional breeding of plants and animals bypeople for our use, shows that selective forces can alter organisms overtime. Some species have enormous latent genetic variation. Evolutionary change can be observed directly in nature. Systematics – associations of traits in nested systems of biologicalclassification are explainable by common descent and proximity ofrelationship. Biogeography – the geographical distribution of organisms showspatterns that are explainable by migration of organisms to new areas,followed by speciation and diversification. |
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What other ways have we found evidence for evolution? |
Fossil record-- Fossil organisms form a temporal sequence that makes sense interms of evolutionary transition. Comparative anatomy-- Structures and processes in different organisms show similaritybeyond functional necessity. Functionally unnecessary similarityarises from common descent. |
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What is comparitive embryology? |
Embryos of different species have similar structures that areexplainable by common descent – homologies, in other words. Theembryos of vertebrates are good examples. |
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What are vestigial structures and why are they important for the study of evolution? |
The fact that many biological structures appear to have a rudimentaryfunction, or no function at all, suggests that they descended from astructure with a more elaborate and important role. Some vestigial structures are morphological. Whale embryo with hindlimb buds, they don’t develop any further. They became suppressed.Dandelions are apomicts (asexual flower), this means dandelions can set seed without fertilization or pollination. They do not need their yellow pigment to attract animals to grab pollen.Pollen is produced, but is not functional. It’s actually STERILE! |
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There are also nonfunctional remnants of genes that are vestigial,such as the GLO gene in primates. Explain.
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GLO gene is needed to make vitamin C, vitamin C is needed for Collagen.
Most animals can make vitamin C on their own and don’t need to consume it.But primates have a pseudogene GLO but we don’t produce the enzyme. So we needto get vitamin C in our diet. The GLO pseudogenes in these primates have the same deletion mutation that renders them non-functional.Our common ancestor was probably eating tons of fruit and are getting lots of vitamin C in the diet.So deletion happened, and animal didn’t suffer because they were consuming lots in diet. Genetic drift causes deletion to go across many animals.The differences in sequence in the rest of the gene correlate with relationship as inferred from otherevidence, such as morphology. Guinea pigs also have a GLO pseudogene, but it has been renderednon-functional by a different mutation from the primate one. |
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How has molecular biology and genomics contributed to evidence of evolution? |
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A gene can exist...... |
in several versions, or alleles. |
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What is the difference between character and traits? |
Alleles of a given gene affect the same character (eg. flower colour), butcan specify different traits of that character (eg. purple flowers, whiteflowers). A character is like flower colour, purple and white flowers would be traits of thatcharacter. |
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Where are alleles of a given gene found? |
Alleles of a given gene are found at the same position on differenthomologues of a chromosome. A diploid cell will have two homologues perchromosome, and therefore two alleles per gene.
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What is the difference between genotype and phenotype? |
The specific alleles in an individual (the genotype) help determine theappearance and properties of that individual (the phenotype). |
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What do the transmission of alleles depend on? |
The transmission of alleles (and the traits they encode) from onegeneration to another depend upon events in meiosis and fertilization. |
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What happens to an allelic pair during meiosis I? Fertilization? What does each gamete carry? |
Members of an allelic pair segregate during meiosis I, and cometogether at fertilization. Each gamete carries one allele of each allelic pair. This is aconsequence of the position of alleles on homologues, and theseparation of homologues at anaphase I of meiosis.
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What is the character? Traits? Alleles? |
In this example, thecharacter is flower colour; the two traits are purpleflowers and white flowers; the two alleles are P and p.
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What changes are made to the allele? |
Alleles usually remain unchanged during passage through manygenerations, although rarely an allele can be converted to a different oneby mutation.
Even when an allele seems to disappear, it isn’t actually harmed. It comes back withoutany problem or damage to it. |
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What is a given character affected by? |
A given character might be affected by many genes, and by theenvironment. There are a lot of very interesting inherited features from interaction of many genes,but environment can effect expression.Many experiences in childhood can influence how tall you will grow. (When I was in the womb my mother smoked with me.) |
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What is gene expression? |
The information in genes is extracted from the genome and put intoeffect by the process of gene expression.
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What does mating frequencies depend on? |
In a real-world population in which mating is random, pairs of genotypesmate with frequencies that depend upon their proportions in thepopulation.
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If we use scientific terminology correctly, what is “theoretical” about evolution? |
The idea that evolution is caused by natural selection, genetic drift, geneflow and a few other things would be part of evolutionary theory. In otherwords, evolutionary theory tries to explain why evolutionary changehappens.
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Why do the bones of the mammalian forelimbs pictured in Fig. 22.15 ofthe text suggest evolutionary relatedness?
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The forelimbs in the figure are homologous, which means that they areall descended from a common structure in a common ancestor. But how dowe recognize evolutionary homology when we see it? Homology can berecognized as similarity beyond functional necessity. Now look at thecolour-coded bones in each forelimb. Each forelimb has a purple humerus(your upper arm bone), an orange radius, a tan-coloured ulna, yellowcarpals, green metacarpals and blue phalanges (the bones of your fingers).The sizes and shapes of the bones vary among organisms but theiridentities, positions and articulation remain the same. There is nofunctional reason why the similarity should be so close among thesespecies. The human arm is used for grasping and carrying, the cat leg forrunning and fighting, the whale fin for swimming, the bat wing for flying.The same underlying bone structure could not be optimal in a design sensefor all these different activities The similarity can only be understood in thelight of common inheritance.
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If the GLO gene in primates is non-functional, why has it not beeneliminated by natural selection?
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There are two possibilities. One, although the gene does not confer anyadvantage, replicating it every generation represents only a miniscule costto the organism, and an individual in whom the gene was deleted entirelydoes not have an advantage over the individuals that retain it. Two, maybethe gene does have some function no one has discovered yet – a functionnot related to the synthesis of ascorbic acid.
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Continental islands – islands that are part of continental land masses,like our own Vancouver Island – have fewer species unique to them than dovolcanic islands, like the Galapagos Islands or the Hawaiian Islands. Whyis this?
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Volcanic islands, such as the Hawaiian Islands and the GalapagosIslands, are distant from continents, and colonizers have more time forspeciation without gene flow from new colonizers from the continent.Continental islands, by contrast, can receive regular colonizers from thecontinent, which will keep the populations part of the same gene pool andmembers of the same species.
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What does a population consist of? |
A population consists of members of the same species in the samelocation that are interbreeding.
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Is it populations or individuals who evolve? |
It is populations that evolve, not individuals.Individuals develop and senesce.
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What is a gene pool? |
Gene pool: the collection of all the alleles in a population. We can restrict the gene pool to a studyable entity by focusing on one or two genes. Gene poolsin regard to a single gene. |
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What is the genetic structure of a population? |
the frequencies of alleles andgenotypes in a population. Example: Population - AA AA aa Aa AA aa aa Aa aa AA We write down five quantities that represent frequencies in this population. f(AA) = 4/10 = 0.4 f(Aa) = 2/10 = 0.2 f(aa) = 4/10 = 0.4
f(A) = 10/20 = 0.5 f(a) = 10/20 = 0.5 |
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What is the Hardy-Weinberg equilibrium? |
The Hardy-Weinberg equilibrium describes the genetic structure of asexually-reproducing population, over generational time, when noevolution is taking place.
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What are the implications of the Hardy-Weinberg equilibrium? |
Genotype frequencies will reach equilibrium values in a non-evolvingpopulation after one generation of random mating.
Dominance and recessiveness do not by themselves result inevolution. |
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What is the f(CR) and f(CW) of this population? f(CRCR) = 400/500 = 0.80 f(CRCW) = 60/500 = 0.12 f(CWCW) = 40/500 = 0.08 |
f(CRCR) = 400/500 = 0.80
f(CRCW) = 60/500 = 0.12 f(CWCW) = 40/500 = 0.08 f(CR) = ((400x2) + 60)/1000 = 0.86 f(CW) = ((40x2) + 60)/1000 = 0.14 |
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What are the predicted genotype frequencies for this population? f(p) = f(p)2 f(q) = f(q)2 f(pq) = 2f(pq) Compare back to the previous flashcard. Is this population evolving or not? |
f(CRCR) = f(CR)2 = (0.86)2 = 0.74
f(CRCW) = 2xf(CR)xf(CW) = 2(0.86)(0.14) = 0.24 f(CWCW) = f(CW)2 = (0.14)2 = 0.02 |
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T/F: Sexual reproduction causes evolutionary change. |
Sexual reproduction does not by itself cause evolutionary change. A population that is not in Hardy-Weinberg equilibrium is being actedupon by one or more causes of evolutionary change.
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Can a population be evolving in some genetic areas but not others? |
Within a population these assumptions might all be true orapproximately true for some genes, but not for others. In other words, a population at a given moment in its history might beevolving at some genetic loci but not at others.
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What is genetic drift? |
Evolution due to random fluctuations (sampling error).The smaller the population, the more likely sampling error is to occur. |
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What is the bottleneck effect? |
One type of genetic drift is the bottleneck effect. A populationexperiences a bottleneck when there are small population numbers forone or more generations.
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What is another type of genetic drift? |
Another type of genetic drift: the founder effect, which is thecolonization of a new territory by a few individuals.
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Why can genetic drift be maladaptive? |
Because it narrows genetic diversity, meaning fewer options to fight challenges. |
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What is gene flow? What happens? Is it adaptive? GENE FLOW IS.... |
Gene flow is a change in the genetic structure of a population due toimmigration and emigration. -Allelic frequencies will probably change.
-Alleles may be lost from the population due to emigration. -Alleles may be introduced due to immigration. -Gene flow can be adaptive, maladaptive or neutral. ...MOVEMENT THROUGH SPACE! |
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What is mutation? |
Mutation – any kind of genetic change
-One important kind of mutation is the change of one allele into another allele. - Mutations are not usually important in changing the genetic structureof a population, unless they introduce new alleles. However, mutations are very important in introducing new geneticvariants on which natural selection and other causes of evolutionarychange can act. - Mutations can be adaptive, maladaptive or neutral. |
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What is natural selection? |
Natural selection is the differential transmission of genotypes to the nextgeneration due to the phenotypes determined by those genotypes. |
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What was Darwin's argument for natural selection? |
Natural selection was the primary mechanism of evolutionary changeproposed by Darwin. His argument:
Natural populations have potential fertility that exceeds resources. Therefore there is competition, a struggle for existence. Individuals in a population vary in their ability to compete; some ofthis variability is heritable. Individuals with inherited traits that help them in the struggle forexistence will be more successful in transmitting those inherited traitsto the next generation. |
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WHat is genetic variation to evolution? |
Genetic variation is evolution's raw material. No genetic variation, no evolution. |
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WHat are 5 manifestations of genetic variation? |
Manifestations of genetic variation – how do we know it exists?
1. polymorphism of discrete characters: two or more character types (morphs) are common in a population 2. continuous variation of quantitative characters 3. the appearance in a population of rare mutations 4. clines – genetic variation that correlates with changes in geography 5. molecular analysis of alleles |
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How is genetic variation created? |
by mutation by recombination in meiosis I (crossing over, independentassortment) and by sexual reproduction |
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How genetic variation preserved? |
- diploidy: recessive alleles are hidden from selection in heterozygotes - clines - balanced polymorphism: no single morph can gain a persistentadvantage |
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What is Darwinian fitness? |
Darwinian fitness is the contribution a genotype makes to the nextgeneration's gene pool. |
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What is adaptive fitness and Darwinian fitness? |
Natural selection acts by translating adaptive fitness (the ability to thrivein the environment) into Darwinian fitness.
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Selection could be: |
directional
disruptive stabilizing |
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What is sexual selection and what are the types? |
Sexual selection is a form of natural selection based on the ability toattract or acquire a mate.
intrasexual – selection due to direct competition within a sex intersexual – selection due to mate choice |
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What are 4 conclusions from evolution selection that we can understand? |
-Selection need not be intense to be important in evolution over longperiods of time.
- Favourable adaptations may disappear due to genetic drift. -Not every helpful adaptation that we can imagine will appear. - Traits that are adaptive in one environment may be maladaptive inanother. |
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What important implications does the Hardy-Weinberg Theorem have for the nature of evolutionary change?
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The Hardy-Weinberg Theorem shows that genotype and allelicfrequencies in a population will remain stable over time unless thepopulation is acted upon by one of the factors we mentioned: genetic drift,gene flow, mutation, nonrandom mating and natural selection. This impliesthat meiosis and sexual reproduction by themselves are not causes ofevolutionary change. It also implies that dominant and recessiverelationships among alleles don’t affect the genetic structure of apopulation, because the equation makes no assumptions about whichallele is dominant and which is recessive.
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You are hired as a plant breeder, and you are first assigned to increaseleaf area in a line of corn by selective breeding. You observe that there isvariability in leaf area from plant to plant, so from each generation youselect for breeding only those individuals possessing larger leaf areas.Over many generations you succeed! Your line of corn increases inaverage leaf area per plant, a boon to your company, the farmer, andsociety in general. You are promoted to the wheat division. Same assignment. Sameobservation. Same methods. But this time your selective crossing of larger-leafed wheat plants does not result in any increase in the average leaf areaper plant, even after many generations. Why did you succeed the first time but fail the second time?
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Selection, whether artificial or natural, can work only if the variationamong organisms is at least partly inherited. Evidently some of thevariation in leaf area from corn plant to corn plant was genetic in origin; butamong the wheat plants, all of the variation was due to differentenvironmental influences acting on identical genotypes. The wheat was notresponsive to selection because you were making your selections from apopulation of genetically identical plants (with respect to leaf area-determining genes) every year.
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Suppose that there is a population of a diploid annual plant speciesgrowing on the slopes of a mountain in the Rockies. Assume that the plantis cross-pollinated by a species of insect. What mechanisms ofevolutionary change might act on this plant under the followingcircumstances?
a) predation by a herbivore that occupies the area continuously b) arrival of seeds of a subspecies of the same plant from a different mountain, carried inadvertently by hikers c) infection by a plant virus that almost wipes the population out d) gradual warming of the environment from year to year e) arrival of a new species of insect pollinator that has a different morphology and different foraging habits than the pre-existing pollinator species f) increase in ultraviolet radiation reaching the plant due to ozonedepletion in the atmosphere. |
If more than one answer is given for each circumstance, the answers arenot mutually exclusive.
a) Natural selection – some possibilities: selection for less palatable orspiny leaves that the herbivore would not want to eat, or toward rapidgrowth that would replace the leaf material lost, or toward tasty andnutritious fruit that the herbivore would want to eat (a way for the plant todisperse its seeds). Genetic drift – could occur if the herbivore took many of the plants eachseason, leaving behind only the few it could not find.Gene flow – is a possibility if the herbivore deposits, in its manure, seedsfrom a neighboring population of the same plant species. b) Gene flow c) Genetic drift – looks like the bottleneck effect could occur here.Natural selection – the survivors of the disease might have survived byvirtue of inherited resistance factors. d) Natural selection – favoring plants better adapted to highertemperatures, longer growing seasons, drier soil, and the altered biologicalcommunity (insects, other plants etc.) the higher temperatures wouldproduce. e) Nonrandom mating – the new insect may have a stricter preference inthe flowering timing or colour or morphology it prefers, and may visit onlythose variants. This would enforce a like-pollinating-like effect that theplants may not have experienced with the previous pollinating species.Natural selection – there may be selection pressure pushing floweringparameters in the direction of accommodating this new pollinatingopportunity. f) Mutation – UV light is a mutagen.Natural selection – the enhanced UV levels might have a damaging effecton more than just the genes of this plant; UV can break apart many organicmolecules. Therefore the plant may develop pigments or morphologicaladaptations that protect against the higher UV levels. |
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How do the following phenomena create genetic variation?
a) mutation b) genetic recombination c) fertilization |
a) Mutation creates new alleles (new genetic variants).
b) Genetic recombination creates new combinations of alleles in thehaploid genomes of the meiotic products. (In some cases, geneticrecombination can also create new alleles.) c) Fertilization brings together two genetically unique gametes to producea diploid individual that would be genetically distinct too, and which wouldhave novel combinations of alleles. |
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How do the following phenomena help preserve genetic variation in apopulation?
a) diploidy b) balanced polymorphism |
a) Diploidy allows recessive alleles to hide out, so to speak, inheterozygotes, rather than being constantly exposed to selection as theywould be in haploids.
b) Balanced polymorphism is a situation in which neither type of individualcan gain a persistent advantage in the population. Both variants in thepopulation are retained over a long period of time. |
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What type of natural selection is acting in each of these cases?
a) selection among a population of frogs for increased body size b) selection in a species of plant for flowering to occur in August, rather than earlier or later c) selection in favor of flowering in the same species of plant during either July or September, owing to unfavorable climatic conditions in August d) selection in favor of a particularly fetching courting display among a species of birds |
a) directional selection;
b) stabilizing selection; c) disruptive selection;note that, in this case, sympatric speciation might occur; d) sexualselection |
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Why are reproductively isolated populations called independentevolutionary units?
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They do not exchange genes, and therefore the forces that producechanges in population genetic structure will act differently on each isolatedpopulation.
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A rather alarming observation among some animal species is that if amale acquires a new mate who is taking care of offspring fathered by adifferent male, the new male will kill those offspring. If this behaviour is atleast partly determined genetically, can you explain it in Darwinian terms?
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Any gene that led to this sort of behaviour would help get itself into thenext generation, because the new male would be forcing the female tospend all her future resources raising his offspring (which would alsopossess this gene) instead of the offspring of her previous mate. On theother hand, a new male who allowed the offspring of the previous male tosurvive, owing to a nice-guy gene causing him to do this, would be lesssuccessful in passing this gene to the next generation.
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How are species defined? |
"Species are groups of actually or potentially interbreeding naturalpopulations which are reproductively isolated from other suchgroups." – Ernst Mayr By this definition, species are genetically integrated, independentevolutionary units. As long as they can interbreed, they are the same species. |
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What are the problems with the biological species concept? So what do we do? |
The concept does not apply to fossils or asexual organisms. Reproductive isolation in nature can be difficult to determine. There is occasional hybridization between groups that normally do notinterbreed. WE DO THIS: Species are therefore distinguished in different ways in different groupsof organisms. |
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What is successful reproduction? |
successful reproduction = production of viable, fertile offspring
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What are the pre-zygotic barriers? |
-geographic separation: Spatial separation. Two different species of squirrels separated by the grand canyon.
-habitat differences: Different habitats perhaps within the same area, one snake lives in water, one lives in soil.They never interact because of this. -behavioural differences: Different mating calls, known to their species but not to other species. -temporal differences: Timing differences, such as bishop pine releases pollen in summer, while monterey pine releases in early spring. -anatomical or mechanical differences: A couple of snails with shells that wind in different directions, making it impossible for them toreach eachother’s genitals. -failure of gamete recognition |
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What are post-zygotic barriers? |
inviability of hybrids
infertility of hybrids |
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What is allopatric speciation? |
is evolutionary divergence of two populationsseparated by a geographic barrier.
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What is the result of allopatric speciation? |
Each population becomes an independent gene pool, resulting inmicroevolutionary divergence. |
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A small population, at the extreme edge of the species' range, is separated off.
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Evolutionary divergence of the two populations will be more rapid if oneof the separated populations is a small peripheral isolate. |
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T/F: Spatial separation by itself is enought to define a species difference. |
False! Spatial separation by itself is not enough to define a species difference,but if enough microevolutionary divergence occurs and the two groupsbecome reproductively incompatible, even if brought together again, theywill then be considered separate species.
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What is a hybrid zone? |
If the two species intermingle before they are fully incompatible inreproductive terms, a hybrid zone might develop – a zone where someinterspecific hybrids are produced.
If the hybrids in the hybrid zone are better adapted to conditions therethan either parent species, the zone will be stable. |
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What is sympatric speciation? |
arises from the reproductive isolation of twopopulations living in the same place. |
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What can it result from? |
Sympatric speciation can result from the formation of polyploidindividuals which are fertile with each other but not with their parentalspecies.
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What can polyploids form from? |
Polyploids can form from one parental species (autopolyploids) or twoparental species (allopolyploids).
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How can sympatric speciation occur? |
Sympatric speciation can also occur by the appearance of assortedbarriers previously mentioned: behavioural, temporal, mechanical, gametic. |
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Some mutations result in large differences in the appearance of an organism, but they are not necessarily large genetic changes. How so?
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Changes in developmental pattern can occur as the result of changes ina few key genes that control development.
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Why are hybrids between two species often infertile?
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Such hybrids may thrive, but when it comes time to create gametes thepairing of homologous chromosomes in meiosis I is faulty, and gameteswith the correct chromosome complement do not result.
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Why is it thought that peripheral isolates are the sort of population fromwhich new species usually develop?
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Peripheral isolates tend to have few members, and are subject to morerapid change in genetic structure than the parent population – throughgenetic drift, for example. Also, peripheral isolates are located at the edgeof a species’ range, and encounter conditions (and selective pressures)which make them unrepresentative, genetically, of the species as a whole –so there is a certain genetic distance between the isolate and the parentpopulation to begin with.
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Tell me more about peripheral isolates? |
A peripheral isolate is a small subpopulation on the edge of the mainpopulation’s range that becomes isolated due to migration,formation of a geographic barrier, or some other means. Genetic drifteffects are more common in these isolates. |
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WHat is adaptive radiation? |
Adaptive radiation is the rapid speciationof a species that moves a new area, orcomes up with a new innovation such asa wing or a notochord. |
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What is polyploidy? |
A species that originates from an accident during cell division that results in extra sets of chromosomes. |
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What is an autopolyploid? |
An individual that has more than two chromosome sets that are all derived from a single species. |
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What is an allopolyploid? |
Occurs when two different species interbreed and produce hybrid offspring. In subsequent generations of of hybrid offspring production, various mechanisms can change a sterile hybrid into a fertile polyploid. THis is rare. |
