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132 Cards in this Set
- Front
- Back
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Genetic Divergence what is it? How does it occur? What counters it?
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Gradual accumulation of differences in the gene pools of populations
Natural selection, genetic drift, and mutation can contribute to divergence Gene flow counters divergence |
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Morphology and Species the effects and things that it can't effect
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Morphological traits may not be useful in distinguishing species
Members of same species may appear different because of environmental conditions Morphology can vary with age and sex Different species can appear identical |
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What is a species?
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Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.
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The 7 isolating mechanisms are:
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mechanical isolation, temporal isolation, behavioral isolation, ecological isolation, gamete mortality, hybrid inviability, and hybrid sterility
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mechanical isolation
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In mechanical isolation individuals cannot mate or pollinate because of physical incompatibilities
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temporal isolation
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individuals of different species reproduce at different times
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behavioral isolation
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individuals of different species ignore or don’t get the required cues for sex
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ecological isolation
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individuals of different species live in different places and never meet up
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gamete mortality
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gametes of different species are incompatible so no fertilization occurs
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hybrid inviability
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hybrid embryos die early or the new individuals die before they can reproduce
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hybrid sterility
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because hybrid individuals cannot make functional gametes
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What are the 3 methods of speciation?
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Allopatric speciation
Sympatric speciation Parapatric speciation |
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Allopatric speciation what happens?
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Speciation in geographically isolated populations
Some sort of barrier arises and prevents gene flow Effectiveness of barrier varies with species |
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Extensive Divergence Prevents Inbreeding how?
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Species separated by geographic barriers will diverge genetically
If divergence is great enough it will prevent inbreeding even if the barrier later disappears |
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Archipelagos what are they and how do they effect speciation?
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Island chains some distance from continents
Galapagos Islands Hawaiian Islands Colonization of islands followed by genetic divergence sets the stage for speciation |
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sympatric speciation
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Species forms within the home range of the parent species
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parapatric speciation
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Adjacent populations evolve into distinct species while maintaining contact along a common border
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Sympatric Speciation in African Cichlids
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Studied fish species in two lakes
Species in each lake are most likely descended from single ancestor No barriers within either lake Some ecological separation but species in each lake breed in sympatry |
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speciation by polyploidy how does this cause speciation
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Change in chromosome number (3n, 4n, etc.)
Offspring with altered chromosome number cannot breed with parent population Common mechanism of speciation in flowering plants |
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hybrid sterility
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because hybrid individuals cannot make functional gametes
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2 types of Patterns of Change in a lineage
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anagenesis
Cladogenesis |
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What are the 3 methods of speciation?
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Allopatric speciation
Sympatric speciation Parapatric speciation |
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Allopatric speciation what happens?
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Speciation in geographically isolated populations
Some sort of barrier arises and prevents gene flow Effectiveness of barrier varies with species |
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Extensive Divergence Prevents Inbreeding how?
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Species separated by geographic barriers will diverge genetically
If divergence is great enough it will prevent inbreeding even if the barrier later disappears |
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Archipelagos what are they and how do they effect speciation?
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Island chains some distance from continents
Galapagos Islands Hawaiian Islands Colonization of islands followed by genetic divergence sets the stage for speciation |
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sympatric speciation
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Species forms within the home range of the parent species
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parapatric speciation
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Adjacent populations evolve into distinct species while maintaining contact along a common border
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Sympatric Speciation in African Cichlids
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Studied fish species in two lakes
Species in each lake are most likely descended from single ancestor No barriers within either lake Some ecological separation but species in each lake breed in sympatry |
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speciation by polyploidy how does this cause speciation
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Change in chromosome number (3n, 4n, etc.)
Offspring with altered chromosome number cannot breed with parent population Common mechanism of speciation in flowering plants |
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2 types of Patterns of Change in a lineage
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anagenesis
Cladogenesis |
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Cladogenesis
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Branching pattern
Lineage splits, isolated populations diverge |
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Anagenesis
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No branching
Changes occur within single lineage Gene flow throughout process |
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What is the gradual model? Is it a good model or not?
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Speciation model in which species emerge through many small morphological changes that accumulate over a long time period
Fits well with evidence from certain lineages in fossil record |
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what is the Punctuation model? Is it a good model or not?
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Speciation model in which most changes in morphology are compressed into brief period near onset of divergence
Supported by fossil evidence in some lineages |
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Adaptive radiation causes?
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Burst of divergence
Single lineage gives rise to many new species New species fill vacant adaptive zone Adaptive zone is “way of life” |
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Extinction how have they affected us sp far?
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Irrevocable loss of a species
Mass extinctions have played a major role in evolutionary history Fossil record shows 20 or more large-scale extinctions Reduced diversity is followed by adaptive radiation |
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who survives an extinction?
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Species survival is to some extent random
Asteroids have repeatedly struck Earth, destroying many lineages Changes in global temperature favor lineages that are widely distributed |
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Taxonomy
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Field of biology concerned with identifying, naming, and classifying species
Somewhat subjective Information about species can be interpreted differently |
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Binomial system what is it and who developed it?
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Devised by Carl von Linne
Each species has a two-part Latin name First part is generic Second part is specific name |
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higher taxa
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Kingdom
Phylum Class Order Family |
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Phylogely what is it and what are its practical applications?
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The scientific study of evolutionary relationships among species
Practical applications Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another |
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Five-Kingdom Scheme
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Monera
Protista Fungi Plantae Animalia |
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Are we related? How so or why not?
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All species are related by descent
Share genetic connections that extend back in time to the prototypical cell |
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genetic disconnect
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end of the line for a species. Mass extinctions are catastrophic events in which major groups abruptly and simultaneously are lost
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genetic divergence
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basis of life's diverstiy, as brought about by adaptive shifts, branching, and radiations. Rates and times of change varied within and between lineages
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Genetic persistence
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the basis of unity of life. The biochemical and molecular basis of inheritance extends from the origin of first cells through all subsequent lines of descent.
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The big bang theory
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12-15 billion years ago all matter was compressed into a space the size of our sun
Sudden instantaneous distribution of matter and energy throughout the known universe |
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Archaeon and earlier... Origin of earth was? Crust was formed when? What kind of evolution was occuring? What kind of cells developed?
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4,600 mya: Origin of Earth
4,600 - 3,800 mya Formation of Earth’s crust, atmosphere Chemical and molecular evolution First cells (anaerobic bacteria) |
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Earth forms
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About 4.6 and 4.5 billion years ago
Minerals and ice orbiting the sun started clumping together Heavy metals moved to Earth’s interior, lighter ones floated to surface Produced outer crust and inner mantle |
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why is earth ideal for life?
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Smaller in diameter, gravity would not be great enough to hold onto atmosphere
Closer to sun, water would have evaporated Farther from sun, water would have been locked up as ice |
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What was the first atmosphere made up of?
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Hydrogen gas
Nitrogen Carbon monoxide Carbon dioxide No gaseous oxygen |
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Origin of organic compounds
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Amino acids, other organic compounds can form spontaneously under conditions like those on early Earth
Clay may have served as template for complex compounds Compounds may have formed near hydrothermal vents |
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chemical evolution
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Spontaneous formation of porphyrin rings from formaldehyde
Components of chlorophylls and cytochromes |
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Discuss RNA and it's origin and the origin of life
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DNA is genetic material now
DNA-to-RNA-to-protein system is complicated RNA may have been first genetic material RNA can assemble spontaneously How switch from RNA to DNA might have occurred is not known |
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Proto cells
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Microscopic spheres of proteins or lipids can self assemble
Tiny sacs like cell membranes can form under laboratory conditions that simulate conditions in evaporating tidepools Nanobes may resemble proto-cells |
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Proterzoic eon what happens in the formation of the earth?
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Origin of photosynthetic Eubacteria
Noncyclic pathway first Cyclic pathway next Oxygen accumulates in atmosphere Origin of aerobic respiration |
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The first cells
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Originated in Archeon Eon
Were prokaryotic heterotrophs Secured energy through anaerobic pathways No oxygen present Relied on glycolysis and fermentation |
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What are the advantages of organelles
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Nuclear envelope may have helped to protect genes from competition with foreign DNA
ER channels may have protected vital proteins |
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Theory of endosymbiosis
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Lynn Margulis
Mitochondria and chloroplasts are the descendents of free-living prokaryotic organisms Prokaryotes were engulfed by early eukaryotes and became permanent internal symbionts |
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Community
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All the populations that live together in a habitat
Type of habitat shapes a community’s structure |
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6 factors that shape community structure
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Climate and topography
Available foods and resources Adaptations of species in community Species interactions Arrival and disappearance of species Physical disturbances |
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Niche
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Sum of activities and relationships in which a species engages to secure and use resources necessary for survival and reproduction
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Realized and Fundamental niches
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Fundamental niche
Theoretical niche occupied in the absence of any competing species Realized niche Niche a species actually occupies Realized niche is some fraction of the fundamental niche |
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Species interactions discuss commensalism and mutualism
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Most interactions are neutral; have no effect on either species
Commensalism helps one species and has no effect on the other Mutualism helps both species |
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species interactions discuss interspecific competition and predation and parasitism
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Interspecific competition has a negative effect on both species
Predation and parasitism both benefit one species at a cost to another |
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symbiosis
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Living together for at least some part of the life cycle
Commensalism, mutualism, and parasitism are forms of symbiosis |
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Mutualism
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Both species benefit
Some are obligatory; partners depend upon each other Yucca plants and yucca moth Mycorrhizal fungi and plants |
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yucca and yucca moth
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Example of an obligatory mutualism
Each species of yucca is pollinated only by one species of moth Moth larvae can grow only in that one species of yucca |
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mycorrhyzia
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Obligatory mutualism between fungus and plant root
Fungus supplies mineral ions to root Root supplies sugars to fungus |
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3 types of comeptition
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Interspecific - between species
Intraspecific - between members of the same species Intraspecific competition is most intense |
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forms of competition
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Competitors may have equal access to a resource; compete to exploit resource more effectively
One competitor may be able to control access to a resource, to exclude others |
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competitive exclusion principle
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When two species compete for identical resources, one will be more successful and will eventually eliminate the other
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Hairston's experiment
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Two salamanders species overlap in parts of their ranges
Removed one species or the other in test plots Control plots unaltered 5 years later, salamander populations were growing in test plot |
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resource partitioning
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Apparent competitors may have slightly different niches
May use resources in a different way or time Minimizes competition and allows coexistence |
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predation
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Predators are animals that feed on other living organisms
Predators are free-living; they do not take up residence on their prey |
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coevolution
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Joint evolution of two or more species that exert selection pressure on each other as an outcome of close ecological interaction
As snail shells have thickened, claws of snail-eating crabs have become more massive |
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3 types of predator prey models and the different appearances of each
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Type I model: Each individual predator will consume a constant number of prey individuals over time
Type II model: Consumption of prey by each predator increases, but not as fast as increases in prey density Type III model: Predator response is lowest when prey density is lowest |
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variation in prey cycles
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An association in predator and prey abundance does not always indicate a cause and effect relationship
Variations in food supply and additional predators may also influence changes in prey abundance |
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4 prey defenses
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Camouflage
Warning coloration Mimicry Moment-of-truth defenses |
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predator responses
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Any adaptation that protects prey may select for predators that can overcome that adaptation
Prey adaptations include stealth, camouflage, and ways to avoid chemical repellents |
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parasitism
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Parasites drain nutrients from their hosts and live on or in their bodies
Natural selection favors parasites that do not kill their host too quickly |
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4 kinds of parasites
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Microparasites
Macroparasites Social parasites Parasitoids |
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parasitoids
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Insect larvae live inside and consume all of the soft tissues of the host
Used as agents of biological control Can act as selective pressure on host |
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ecological succession
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Change in the composition of species over time
Classical model describes a predictable sequence with a stable climax community |
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2 types of succession and what each does
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Primary succession - new environments
Secondary succession - communities were destroyed or displaced |
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pioneer species
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Species that colonize barren habitats
Lichens, small plants with brief life cycles Improve conditions for other species who then replace them |
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climax community
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Stable array of species that persists relatively unchanged over time
Succession does not always move predictably toward a specific climax community; other stable communities may persist |
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cyclical changes
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Cyclic, nondirectional changes also shape community structure
Tree falls cause local patchiness in tropical forests Fires periodically destroy underbrush in sequoia forests |
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restoration ecology
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Natural restoration of a damaged community can take a very long time
Active restoration is an attempt to reestablish biodiversity in an area Ecologists are actively working to restore reefs, grasslands, and wetlands |
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community instability
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Disturbances can cause a community to change in ways that persist even if the change is reversed
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Keystone species
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A species that can dictate community structure
Removal of a keystone species can cause drastic changes in a community; can increase or decrease diversity |
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species introductions
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Introduction of a nonindigenous species can decimate a community
No natural enemies or controls Can outcompete native species |
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exotic species
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Species that has left its home range and become established elsewhere
Becomes part of its new community Can have beneficial, neutral, or harmful effects on a community |
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endangered species
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A species that is extremely vulnerable to extinction
Close to 70 percent of endangered species have been negatively affected by exotic competitors |
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rabbits in austraillia
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Rabbits were introduced for food and hunting
Without predators, their numbers soared Attempts at control using fences or viruses have thus far been unsuccessful |
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where in the world is more diversity and where is les?
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Diversity of most groups is greatest in tropics; declines toward poles
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why are tropical species rich?
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Resources are plentiful and reliable
Species diversity is self-reinforcing Rates of speciation are highest in the tropics |
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distance effect on speciation
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The farther an island is from a mainland, the fewer species
Closer islands receive more immigrants Species that reach islands far from mainland are adapted for long-distance dispersal and can move on |
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area effect
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Larger islands tend to support more species than smaller islands
More habitats Bigger targets Larger populations decrease extinction risks |
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Ecosystem
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An association of organisms and their physical environment, interconnected by ongoing flow of energy and a cycling of materials
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Autotrophs modes of nutrition
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Capture sunlight or chemical energy
Producers |
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Heterotrophs Modes of nutrition
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Extract energy from other organisms or organic wastes
Consumers, decomposers, detritivores |
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Consumer levels
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Herbivores
Carnivores Parasites Omnivores Decomposers Detritivores |
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Trophic levels
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All the organisms at a trophic level are the same number of steps away from the energy input into the system
Producers are closest to the energy input and are the first trophic level |
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Food Chain
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A straight-line sequence of who eats whom
Simple food chains are rare in nature |
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Energy losses
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Energy transfers are never 100 percent efficient
Some energy is lost at each step Limits the number of trophic levels in an ecosystem |
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Biological magnification
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A nondegradable or slowly degradable substance becomes more and more concentrated in the tissues of organisms at higher trophic levels of a food web
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DDT and its effects
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Synthetic pesticide banned in United States since the 1970s
Birds that are carnivores accumulate DDT in their tissues, produce brittle egg shells |
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Primary productivity Gross and net
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Gross primary productivity is ecosystem’s total rate of photosynthesis
Net primary productivity is rate at which producers store energy in tissues in excess of their aerobic respiration |
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primary productivity varies how and why?
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Seasonal variation
Variation by habitat The harsher the environment, the slower plant growth, the lower the primary productivity |
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Ecological pyramids
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Primary producers form a base
Successive tiers of consumer above them Can be used to visualize: Biomass Dryweight of all the ecosystems organisms at each tier Energy Illustrates the transfer of energy through an ecosystem Sunlight is captured at base and declines through successive levels |
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What happens to energy as it is used?
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At each trophic level, the bulk of the energy received from the previous level is used in metabolism
This energy is released as heat energy and lost to the ecosystem Eventually all energy is released as heat |
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biogeochemical cycle
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The flow of a nutrient from the environment to living organisms and back to the environment
Main reservoir for the nutrient is in the environment |
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3 types of biogeochemical cycles and what each deals with
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Hydrologic cycle
Water Atmospheric cycles Nitrogen and carbon Sedimentary cycles Phosphorus and sulfur |
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watersheds
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Any region where precipitation flows into a single stream or river
Water seeps into soil or joins surface runoff Water moves nutrients into and out of the surrounding ecosystem |
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Hubbard Brook Experiment
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A watershed was experimentally stripped of vegetation
All surface water draining from watershed was measured Removal of vegetation caused a six-fold increase in the calcium content of the runoff water |
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water use and scarcity
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Most of Earth’s water is too salty for human consumption
Desalinization is expensive and requires large energy inputs Irrigation of crops is the main use of freshwater |
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negative effects of irrigation
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Salinization, mineral buildup in soil
Elevation of the water table and waterlogging Depletion of aquifers |
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Carbon cycle atmospheric cycle
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Carbon moves through the atmosphere and food webs on its way to and from the ocean, sediments, and rocks
Sediments and rocks are the main reservoir |
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Carbon in atmosphere what kind? How is it added? How is it removed?
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Atmospheric carbon is mainly carbon dioxide
Carbon dioxide is added to atmosphere Aerobic respiration, volcanic action, burning fossil fuels Removed by photosynthesis |
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carbon in the ocean
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Most carbon in the ocean is dissolved carbonate and bicarbonate
Ocean currents carry dissolved carbon |
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Greenhouse gasses
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Greenhouse gases impede the escape of heat from Earth’s surface
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Global Warming
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Long-term increase in the temperature of Earth’s lower atmosphere
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Carbon Dioxide increase
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Carbon dioxide levels fluctuate seasonally
The average level is steadily increasing Burning of fossil fuels and deforestation are contributing to the increase |
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Other greenhouse gasses and where they come from
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CFCs - synthetic gases used in plastics and in refrigeration
Methane - produced by termites and bacteria Nitrous oxide - released by bacteria, fertilizers, and animal wastes |
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Nitrogen cycle nitrogen atmospheric cycle
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Nitrogen is used in amino acids and nucleic acids
Main reservoir is nitrogen gas in the atmosphere |
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Nitrogen fixation
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Plants cannot use nitrogen gas
Nitrogen-fixing bacteria convert nitrogen gas into ammonia (NH3) Ammonia and ammonium can be taken up by plants |
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Ammonification and nitrification how it occurs
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Bacteria and fungi carry out ammonification
conversion of nitrogenous wastes to ammonia Nitrifying bacteria convert ammonium to nitrites and nitrates |
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Nitrogen loss
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Nitrogen is often a limiting factor in ecosystems
Nitrogen is lost from soils via leaching and runoff Denitrifying bacteria convert nitrates and nitrites to nitrogen gas |
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How humans increase and decrease the amount of nitrogen in the air
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Humans increase rate of nitrogen loss by clearing forests and grasslands
Humans increase nitrogen in water and air by using fertilizers and by burning fossil fuels Too much or too little nitrogen can compromise plant health |
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Phosphorous cycle or sedimentary cycle
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Phosphorus is part of phospholipids and all nucleotides
It is the most prevalent limiting factor in ecosystems Main reservoir is Earth’s crust; no gaseous phase |
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human effects on phosphorus
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In tropical countries, clearing lands for agriculture may deplete phosphorus-poor soils
In developed countries, phosphorus runoff is causing eutrophication of waterways |
