Animal Diversity

Front 1

Animals are monophyletic with three synapomorphies

Back 1

Multicellularity, heterotrophy, and they moved under their own power at some point in their life cycle.

*All animals except sponges have neurons and muscle cells.

Front 2

Animal's Body Plan

Back 2

1. Type of embryonic tissue
2. Body symmetry, NS, degree of cephalization
3. Presence or absence of coelom
4. Nature of embryonic development

Front 3

Body Plan (type of embryonic tissue):
Diploblast vs. Triploblast

Back 3

Diploblast: ectoderm and endoderm (Cnidarians and Ctenophores).
Triploblast: ecto-, meso-, and endoderm (all animals except for Cnidarians, Ctenophores, and sponges),

Front 4

Body Plan: Nervous system, body symmetry, and cephalization

Back 4

Sponges: no neurons, asymmetrical, no head.
Cnidarians/Ctenophores: nerve net (prey and stimuli from any direction), radial symmetry, no head.
Triploblasts (all other): bilateral symmetry (allowed cephalization/head region) and CNS with ganglia (b/c tend to move in one direction and encounter stimuli at one end

Front 5

Body Plan: Evolution of body cavity

Back 5

Purpose: hydrostatic skeleton that facilitates movement in animals without limbs (e.g. roundworms).
Acoelomates: Porifera, Cnidaria, Ctenophora, Acoelomorpha, and Platyhelminthes.
Pseudocoelom: Rotifera and Nematoda
Coelomate: Annelida, Arthropoda, Echinodermata, and Chordata

Front 6

Body Plan (nature of embryonic development): Deuterostome vs. Protostome

Back 6

Deut: radial cleavage, anus first/mouth second, coelom forms when mesoderm pockets pinch off gut.
Proto: spiral cleavage, mouth first/anus second, blocks of mesoderm splits to form coelom.

Front 7

Porifera (sponges) shared characteristics with choanoflagellates (sister taxa of animals)

Back 7

Both are sessile as adults and sponges feed using choanocytes, which are similar to choanoflagellate cells.

*However, choanoflagellates are unicellular protists and sponges are multicellular.

Front 8

Porifera Characteristics

Ex. sponges

Back 8

Most are asymmetrical, no germ layers but a few have epithelial cells, spicules providing structural support, adults are sessile, feed using choanocytes.

Front 9

Cnidaria Characteristics

Ex. jellyfish, corals, anemones, hydra

Back 9

Synapomorphy: nematocysts used to feed, most are radially symmetric diploblasts, gastrovascular cavity with one opening, ectoderm and endoderm surround mesoglea

*Sister group to Acoelomorphs and Bilaterians

Front 10

Ctenophora Characteristics

Ex. comb jellies

Back 10

Diploblasts, predators that catch using various methods (mucus, tentacles, or whole digestion), move by beating cilia.

*Sister group to Acoelomorphs and Bilaterians

Front 11

Protostomes split into what two groups? Define each group and their differences.

Back 11

Lophotrochozoa (ex. Rotifera, Platyhelminthes, Annelida, Mollusca): grow by extending size of skeletons. Some have lophophore (structure used for suspense feeding) and trochophores (free-swimming larva)
Ecdysozoans (ex. Nematoda, Arthropoda): grow by molting/shedding outer skeletons

Front 12

Subgroups of Arthropoda

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1. Arachnida (spiders and mites)
2. Trilobitomorpha (500-400 mya; now extinct)
3 .Crustacea (crabs, shrimp, lobster
4. Myriopoda (millipedes and centipedes)
5. Insecta

Front 13

Segmentation

Back 13

Evolved several times independently (annelids, arthropods, and chordata), which suggests segmentation has adaptive advantages (e.g. movement).

Front 14

Four phyla of Deuterostome

Back 14

1. Echinodermata: sea stars and sea urchins
2. Chordata: vertebrates
3. Hemichordata: burrowing, deopsit- or suspension-feeding acorn worms
4. Xenoturbellida: two recently discovered worm-like creatures

Front 15

Echinodermata "spiny-skins" Characteristics

Ex. sea stars and sea urchins

Back 15

Deuterostome, bilateral larvae but penta-radially symmetric adults (5-sided radial symmetry), have tube feet, marine, endoskeleton, and has water vascular system.

Front 16

Four synapomorphies of Chordata

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1. Pharyngeal gill slits (opening into throat)
2. Dorsal hollow nerve cord runs through length of body
3. Notochord: supportive, flexible rod that runs through length of body
4. Muscular post-anal tail at some point

Front 17

Three major lineages of Chordata and their body plans

Back 17

1. Cephalochordates (lancelets/amphioxus): small, mobile suspension feeders that resemble fish. Notochord functions as endoskeleton in adults.
2. Urochordates (sea squirts or tunicates): gill slits in both adults and larvae; other 3 traits only in larvae (tail, dorsal nerve cord and notochord).
3. Vertebrates

Front 18

Two synapomorphies of monophyletic group Vertebrates

Back 18

1. Vertebrae: column of cartilaginous or bony structure protecting spinal cord
2. Cranium: skull that protects the brain

Front 19

Vertebrate Fossil Record

Back 19

Fossils of both echinoderms and vertebrates present in Burgess Shale that formed during Cambrian explosion. Earliest vertebrates lived in oceans ~540 mya.

Front 20

Key innovations in Vertebrates

Back 20

1. Bony exoskeleton (Ordovician ~443.7-488 mya)
2. Jaws (Silurian ~ 416-443.7 mya)
3. Bony endoskeleton (Devonian ~359.2-416 mya)
4. Limbs capable of moving on land (Devonian)
5. Amniotic egg (Carboniferous ~299-359.2 mya)

Front 21

Vertebrate Evolutionary Innovation: Jaw

Back 21

Most likely evolved from cartilage in anterior-most gill arch. Suggested by similar bony or cartilaginous morphology of jaws and gill arches, muscles that move both structures have same embryonic origin, and both derived from neural crest cells

Front 22

Vertebrate Evolutionary Innovation: Tetrapod Limb

Back 22

Lungfish is closest living relative to tetrapods suggested by fossils. Through mutation and natural selection, fins evolved into limbs.

Front 23

Vertebrate Evolutionary Innovation: Amniotic Egg

Back 23

Laid on land by reptiles, birds and other egg-laying mammals. Egg has an external membrane and three internal membranes. Egg has watertight shell or case enclosing membrane-bound food/water supply and waste repository.

Front 24

Vertebrate Evolutionary Innovation: Placenta

Back 24

Viviparous mammals (species that give birth) have placenta that is rich in blood vessels and facilitates flow of oxygen and nutrients from mother to embryo.

Front 25

DII Gene and Experiment

Back 25

Hypothesis: animal appendages have some genetic homology because all derived from appendages present in common ancestor. Research shows DII gene involved in limb formation in diverse species.
Experiment: Add stain that would attach to DII to developing embryos of various species to see where the DII proteins end up.
Results: In Ecdysozoa and Lophotrochozoaspecies, DII localized where appendages forming

Front 26

Mammal Synapomorphies

Back 26

Hair/fur. Expanded brain case. Three ear bones. Jaw contains only one bone. Complex teeth. Milk. Limited growth (stops at adulthood). Constant temperature.

Front 27

Three major groups of living mammals (Therians)

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1. Monotremes: egg-laying e.g. Echidna.
2. Marsupials: pouched mammals e.g. sugar glider.
3. Placentals: mammals with placenta e.g. flying squirrel.

* CONVERGENT EVOLUTION in marsupials and placental mammals.

Front 28

Primate Characteristics

Back 28

Hands/feet for grasping, flattened nails and not claws, relatively large brains, complex social behavior, extensive parental care of offspring, forward-facing eyes.

Front 29

When did the first groups of primates evolved?

Back 29

~55 mya

Front 30

During primate evolution...

Back 30

Changes in skeleton associated with locomotion, increase in brain size, shift towards smaller, fewer, and less specialized teeth, evolution of stereoscopic vision, grasping hand with opposable thumb.

Front 31

Two main primate groups

Back 31

1. Prosimians "before-monkeys": most are small, nocturnal, and arboreal (living in trees). Ex. lemurs
2. Anthropoids "human-like": include New and Old World monkeys, gibbons, and Hominidae or Great Apes.

Front 32

Primates: Prosimians

Back 32

Abundant ~33-50 mya. Small as mouse or big as cat. Arboreal, most are nocturnal, large, forwardly directed eyes, and have 5 digits on each hand and foot with either claws or nails. In tropical regions e.g. Africa and Madagascar.

Front 33

Primates--> Anthropoids: Old World Monkeys

Back 33

First anthropoids. Lived in Africa ~35 mya. Fewer teeth, larger brain, and more forward eyes than prosimians. Arboreal, diurnal, and vegetarian. Africa and Asia.

Front 34

Primates-->Anthropoids: New World Monkeys

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Appeared ~30 mya. In South America

Front 35

Primates-->Anthropoids: Hominidae or Great Apes

Back 35

First appeared ~20-30 mya in Africa and Asia during dropped sea level that allowed land bridge migration.
* ~8-9 mya: knuckle-walking ape lineage split into gorilla clade and hominin/chimp/bonobo clade

Front 36

Great Apes/Hominids' Characteristics

Back 36

Relatively large bodies with long arms, short legs, and no tails. Distinct ways of walking: orangutans primarily arboreal but fist walk when on ground, gorillas and chimps knuckle walk, and humans walk upright on legs.

Front 37

Hominins

Back 37

Monophyletic group comprising of Homo sapiens and >12 extinct-bipedal relatives. Synapomorphy: bipedalism.

Front 38

When did humans and chimps diverged from their common ancestors? How old is the oldest hominin fossil?

Back 38

1) ~7 mya
2) 6-7 million years old found in Chad

Front 39

Four groups of Hominins

Back 39

1. Australopithecus
2. Paranthropus
3. Early Homo
3. Recent Homo

Front 40

Hominin: Australopithecus

Back 40

Composed of four species of small apes called gracile ("slender") australopithecines.

Front 41

Hominin: Paranthropus

Back 41

Composed of 3 species of robust australopithecines. 3 species had massive cheek teeth, jaw, and cheekbones. Also had sagittal crest at top of skull. Hypothesized that group became extinct during human evolution.

Front 42

Hominin: Early Homo

Back 42

Composed of first humans. Flatter and narrower faces, smaller jaw and teeth, larger brain cases. Toolmaking was hallmark.

Front 43

Hominin: Recent Homo:

Back 43

~1.2 mya to present. Includes Homo sapiens (which includes Cro-Magnons and Neanderthals). Evidence present that suggest Cro-Magnons and Neanderthals had art and buried dead in organized manner.

Front 44

Things to note about Hominins

Back 44

1. Different combinations of brain size, tooth size, ad posture found in different Hominin species.
2. All but four most recent species found in Africa suggesting African origin.
3. Throughout last 4 my and as recently as last 30,000 years, 2+ species of hominin co-existed suggesting sympatric evolution (speciation occurred in same area).

Front 45

Misconceptions about human evolution

Back 45

1. Humans evolved from chimps. **Chimps are relatives of humans and we share common ancestor.
2. Human evolution is a series of step leading to Homo sapiens. **Homos sapiens is a twig on the phylogenetic tree and a distinct species that happened to survive.
3. Human traits of walking upright and brains evolved together. **Extinct lineages display combination of these traits.

Front 46

Human Evolution

Back 46

Homo erectus left Africa ~2 mya and migrated throughout Europe and Asia. Evidence suggest recent wave of emigration out of Africa ~200,000 years ago so variations is relatively recent. Evidence that increase tool and language use triggered natural selection for ability to reason and communicate, resulting in humans with large brains.

Front 47

Human Evolution: Out-of-Africa Hypothesis

Back 47

Fossils of Homo sapiens, erectus, and neanderthalensis are present in different locations during same period suggesting migration (160,000-100,000 years ago). Fossils found concentrated in Africa and dating suggest origin in Africa.