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169 Cards in this Set
- Front
- Back
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define micro-evolutionary forces
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causes changes in allele and genotype frequencies within populations
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Five Micro-evolutionary forces
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1. mutation
2. sexual selection/non-random mating 3. natural selection 4. gene flow 5. genetic drift |
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What is the Hardy-Weinberg Equilibrium Theory?
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a mathematical theory that allows us to predict genotype frequencies from observed allele frequences
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What are the assumptions of the H-W Equilibrium Theory?
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There are no micro-evolutionary forces operating; mating is random
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Frequency Dependent Selection
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the fitness of a particular genotype depends on its frequency in the population
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Adaptive Radiation; give examples
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when one species evolves into many species in a short time period, usually in response to open ecological niches
ex. anolis lizards, galapagos finches; hawaiian honey creepers |
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Gene flow
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the movement of individuals from one population to another with mating.
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Migration (not the same as gene flow)
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seasonal movements of populations from one geographic locality to another
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What happens with lots of gene flow?
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prevents populations from becoming genetically different; therefore it prevents speciation
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What happens with no gene flow?
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populations become genetically different. can cause speciation
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Genetic Drift
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sampling error in the production of zygotes from a gene pool; allele frequencies are more stable in large populations
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Characteristics of genetic drift
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1. not adaptive
2. decreases the frequency of heterozygotes, increases frequency of homozygotes 3. reduces genetic variation 4. big problem in small populations |
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Population Bottlenecks
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severe reduction in population size with loss of genetic variation
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Founder effects
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-when a small # of individuals starts a new population
-genetic variation is small compared to original poplation |
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Why is inbreeding bad?
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There is a reduction in fitness associated with the increased expression of harmful recessive alleles
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Effective Population Size
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The average number of individuals in a population that contribute genes equally in the next reproduction . Usually smaller than the actual population size
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Neutral Theory of Molecular Evolution
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-beneficial mutations are very rare
-Most mutations have little or no effect on fitness (3rd codon position) -the frequency of a neutral allele in a population is determined by genetic drift only |
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Molecular clock
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if most mutations are neutral then the rate of molecular evolution should be roughly constant over time, ticking along like a clock.
-can use to predict time since divergence |
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Macro-evolution
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-the evolution of species and higher groups.
-evolution above the level of populations. -micro-evolution over very long time periods |
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Phyletic gradualism
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species evolve by the accumulation of many small changes over a long time period
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punctuated equilibrium
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speciation is rapid and is followed by long periods of stasis (no change)
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Ecology
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how organisms interact with each other and the environment
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Community
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different species living in the same geographic area at the same time
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habitat
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the place where an organism lives
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niche
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an organism's functional role in a habitat or community
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fundamental niche
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all of the places that a species could live if there were no competitors
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realized niche
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where that species is actually found. limited by competition
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Allen's Rule
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mammals living in the cold have shorter faces and limbs than mammals living in warmer areas
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Bergmann's Rule
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mammals that live in cold areas are bigger than those that live in warm areas
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Gloger's Rule
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dark pigments are more common in organisms living in warm, humid environments than in cool, dry ones
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Commensalism. Give examples
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an interaction that benefits one speices, but has no affect on the other
ex. bird's nest; epiphyte |
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Mutualism. Give examples
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an interaction that benefits both speices
ex. cleaner shrimp; humming bird-flowers; leaf-cutter ants |
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What is the oldest mututalism on Earth?
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Eukaryotic Cell
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Competition
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nobody benefits
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Intra-specific competition
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competition between individuals of the same species
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What is the affect of intra-specific competition on population size?
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limits population size
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Inter-specific competition
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competition between different species
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Character Displacement
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species evolve non-overlapping traits so they don't have to compete for the same food
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Resource Partitioning
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when species divide resources so they don't compete for the same food
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Competitive exclusion
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one species excludes another through competition
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Herbivory
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-one species benefits, the other harmed
-eats plants; sometimes herbivory kills the plant, sometimes not. |
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Grazing
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eating the whole plant (above ground part)
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Browsing
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eating only part of the plant
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Why are some plants poisonous?
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for defense against herbivores
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Inducible defenses
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only make your poison if you are attacked first
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parasitism
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-one organism feeds on the living tissues or another organism.
-parasite doesn't always kill the host |
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parasitoid
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usually eats its host while the host is still alive
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Predation
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one organism benefits, the other dies
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Cryptic coloration
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for hiding
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aposematic coloration
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warns of poison
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Mullerian mimicry
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poisonous prey species all evolve bright warning colors (red, blue, orange)
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Deceptive patterns or behaviors
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to distract or fool potential predators
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Batesian mimicry
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when a harmless species mimics a harmful species (viceroy mimics monarch)
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Do communities change over time?
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Yes
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Ecological Succession. examples
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the chronological colonization of a habitat by a series of ...
ex. annual plants, perennial plants & grasses, shrubs |
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Macro-Evolution
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-the evolution of species and higher groups
-evolution above the level of populations -micro-evolution over very long time periods |
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Phyletic Gradualism
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species evolve by the accumulation of many small changes over a long time period
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Punctuated equilibrium
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speciation is rapid and is followed by long periods of stasis (no change)
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Anagenesis
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change within a lineage;
1 species to start and a different speices at finish |
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Cladogenesis
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change within a lineage; 1 species to start and 2 different species at finish
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**Biological Species Concept**
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"species are groups of interbreeding natural populations that are reproductively isolate from other such groups." --Ernst Mayr
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Reproductive isolation
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-when populations of organisms cannot interbreed and produce infertile or inviable offspring
-arises as a byproduct of genetic change |
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Pre-zygotic isolation
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mating or zygote formation is prevented
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Temporal
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species do not breed at the same time
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Behavioral
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different mating behaviors prevent different species from mating
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Ecological/Habitat
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if species live in different environments, they never meet
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Mechanical
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sometimes the parts just don't fit together
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Post-zygotic Isolation
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mating occurs, but offspring are sterile or inviable
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Allopatric Speciation
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-ranges do not touch or overlap significantly
-no gene flow between populations -probably the most common speication mechanism |
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Parapatric Speciation
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-ranges touch, but do not overlap significantly
-hybrid zone forms where ranges meet -gene flow is usually small |
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Sympatric Speciation
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-ranges overlap significantly
-geography does not prevent gene flow -not common |
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Speciation by polyploidy
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new species formed when chromosome number in hybrids doubles, allowing hybrids to mate with other similar hybrids, but not with either parent species; thus, creating a new hybrid species that is reproductively isolated from either parent species
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Extinction
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a. fossil record show at least 20 large scale extinction events
b. loss of species diveristy c. reduced diversity followed by adaptive radiation |
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Permian-Triassic Extinction
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-about 250 mya.
-the biggest. -probably a comet or asteroid impact. -around 95% of all species extinct |
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Cretaceous-Tertiary Extinction
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-about 65 mya
-caused by asteroid impact in the Gulf of Mexico. -Extinction of the dinosaurs |
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What are the primary causes of extinction?
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extraterrestrial impacts & changes in ecology
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Which strikes the Earth more frequently, Asteroids or Comets?
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Asteriods
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Linnaean Hierarchical Classification System
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organisms in the same group are more closely related to each other than to organisms in different groups
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Phylogeny (cladogram)
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a tree showing evolutionary relationships & history of a group of organisms
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What is the idea behind the phylogeny?
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close branches mean close evolutionary relationships
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Homology. examples
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organisms are similar because they are closely related;
ex. blue jar, stellar's jay, scrub jay |
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convergent evolution (analogy)
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organisms are similar because they evolved the same characteristics independently via natural selection as adaptations to the same selective forces.
ex. stork & turkey vulture; friggon vulture & fish eagles |
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Co-evolution
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a change in allele frequencies of one species in response to a change in allele frequencies in another species
ex. predator-prey co-evolution; flower-pollinator co-evolution |
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Vestigal structures
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structures that have lost their original function
ex. your appendix; leg bones in fossil whales; leg bones in pythons |
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What are atavisms?
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"throwbacks"--genes present but normally turned off;
ex. horses w/ extra toe; hind limbs in dolphins; supernumary nipples |
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What are some examples of rapid evolutionary change?
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antibiotic resistance/pesticide resistance
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ingroup
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the group of closesly related species you are studying
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outgroup
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the closely related species that is not part of the ingroup
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ancestral character
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a character found in the ingroup and in the outgroup or can be found in the outgroup only
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shared derived character
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a character that is shared by two or more members of the ingroup, but not with the outgroup
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Apomorphy
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a character found in only one species
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What does each tick mark on the "tree" represent?
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evolutionary transitions from one state to a new state
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Explain the Principle of parsimony
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the simplest explanation is the best explanation
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Mammals evolved from primitive reptiles called
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Therapsids
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What are some important characteristics of mammals?
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1. warm blooded
2. mammary glands and milk 3. hair made of keratin 4. four-chambered heart 5. well developed brain 6. specialized teeth 7. neocortex region of the brain 8. sweat glands 9. 3 middle ear bones used in hearing |
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What are the three main lineages of mammals?
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1. monotremes; platypus and echidnas
2. marsupials 3. placental |
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Montremes; platypus and echidnas
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only living mammals that lay eggs
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Marsupials
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young develop in a marsupium (pouch)
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Placental (Eutherian)
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developing embryo nourished by a placenta inside mother's uterus.
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The greatest diversity of marsupials is found on what island continent?
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Australia
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What are some characterisitcs of the primates?
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1. all primates (except humans) have a big toe separated from other toes
2. thumb is separate from fingers 3. binocular (sterioscopic) 3D vision 4. large brains & short jaws 5. flat nails on fingers & toes; no claws |
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Two groups of primates
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Prosimians & anthropoids
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Prosimians
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lemurs, lorises, pottos, tarsiers of Asia, Africa & Madagascar
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Anthropoids
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monkeys, apes & Humans of both new and old worlds
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Three main groups of anthropoids
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1. new world monkeys
2. old world monkeys 3. great apes |
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New world monkeys
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-prehensile tail
-all species arboreal -nostrils open to the side |
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Old world monkeys
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-no prehensile tail
-arboreal and terrestrial species -nostrils open downward |
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Great Apes
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-no tail
-arboreal and terrestrial species -large body size -nostrils open downward |
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What prosimian is most closely related to the anthropoid primates?
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tarsiers
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Which anthropoid primate is most closely related to humans?
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Australopithecus
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Which group of Monkeys is most closely related to the great apes and humans, NW monkeys or OW monkeys?
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Old world monkeys
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what does this tell us about the geographic origin of modern humans?
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humans originated from Africa
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The entire history of the primates goes back how many millions of years?
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65 million years ago
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How long ago did humans and chimpanzees diverge on different evolutionary branches?
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6 million years ago
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Ardipithecus ramidus
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-4.4 million years old
-small brain -walked upright -big toe still separated from other toes |
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Australopithecus afarensis- (Lucy)
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-live in Africa 3.5 mya
-75% smaller than human skull -walked upright -about 4 ft tall -Laetoli footprints |
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Homo habilis
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-lived in Africa from 2.2 - 1.6 mya
-used primitive stone tools |
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Homo erectus
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-migrated out of Africa & colonized asia & europe
-lived from about 1.8 mya to 200,000 ya |
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Peking man (homo erectus)
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lived in asia 500,000 years ago
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Homo neanderthalensis
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-Lived in europe & asia
-from 130,000 -30,000 years ago -did not interbreed with homo sapiens |
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homo sapiens
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-arose about 200,000 years ago in Africa
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Cro-magnon man
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-40,000 - 10,000 years ago
-name for earliest modern humans that lived in Europe |
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Behavior
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-what an animal does and how it does it
-influenced by both genetic and environmental factors -influences an organisms survival and reproduction -should be shaped by natural selection |
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innate behavior (instinctive)
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developmentally fixed and not modified by environmental factors.
-no opportunities for learning |
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Fixed Action Pattern
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a sequence of innate behaviors that is unchangeable and once initiated, is carried to completion.
ex. egg rolling |
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super-normal stimulus
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when organisms prefer an excessive stimulus to the normal stimulus.
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Learning
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the modification of behavior resulting from specific experiences
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Imprinting
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the recognition, repsonse and attachment of young to a particular adult or object.
-usually irreversible. (ducks & geese) |
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Habituation
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the loss of responsiveness to unimportant stimuli.
"crying wolf" effect |
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Associative learning (classical conditioning)
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associative learning is the ability of many animals to learn to associate one stimulus with another
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opreant conditioning
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-trial & error learning.
-an animal learns to associate one of its own behaviors with reward or punishment |
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insight learning
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reasoning. formulating a course of action by understanding the relationships between the parts of the problem. common only in primates, especialy in humans
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Why do animals play?
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playing may facilitate social development, practice certain behaviors and develop coordination and skills that may be important later during the adult life
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what is a population?
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individuals of the same species present together in the same area at the same time
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What is population ecology?
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study of populations in relation to the environment
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Population size
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how many individuals
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population density
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how many individuals per unit area
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population dispersion
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the pattern of spacing among individuals
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clumped
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organisms together in patches, herds, flocks, etc.
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Uniform
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equal spacing among individuals
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random
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no pattern
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Which dispersion pattern is the most common?
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clumped
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life table
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age specific summary of the survival of individuals in a population
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Survivorship
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proportion of individuals alive during a given time interval
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Type 1
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high survivorshp through early and middle ages
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Type II
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relatively constant survivorship throughout life
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Type III
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low survivorship early in life
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Do males and females of the same species have the same survivorship curves?
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no, females tend to live longer than males
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Fertility/Fecundity
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age-specific summary of the reproductive rates in a population
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why is it important in conservation biology to know which age class produces the most offspring?
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you need to preserve age classes that are most productive
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Life history
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the traits that affect an organisms schedule of survival and reproduction
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What are some examples of life history traits?
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-how long to live?
-when to reproduce? -how many eggs to make? -how much parental care? |
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Semelparity
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large numbers of offspring produced in a single reproductive bout
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iteroparity
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small numbers of offspring produced in each of several reproductive bouts
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life history tradeoffs
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a. survival and reproduction
b. offspring quality versus quantity |
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Exponential population growth
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maximum growth rate under ideal conditions
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logistic population growth
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population growth is limited by carrying capacity (k)
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What is carrying capacity?
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the maximum population size an environment can support
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Factors controlling population size
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-disease
-competition -parasites -predators -territoriality -accumulation of wastes |
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Density-dependent factors
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these factors become more intense as population size increase
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What is the allele effect?
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Individuals in a population may have a hard time surviving or reproducing if population size is too small or too large
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Density-independent factors
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-population size affected by natural disasters & climate changes.
-these factors may affect large and small populations equally |
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Which hypothesis does the molecular and skeletal data support?
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Replacement Hypothesis
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Replacement hypothesis
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1. homo erectus leaves Africa 1-2mya and colonizes europe, asia, and australia
2. Homo sapiens leaves africa 100,000 years ago and replaces (out competes) all homo erectus populations |
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Multiregional Hypothesis
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1. homo erectus leaves Africa 1-2 mya colonizes europe, asia and australia
2. by 100,000 y.a all homo erectus populations evolve into homo sapiens at the same time 3. lots of gene flow between populations |
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Biological evolution
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change in the frequency of an inherited character from one generation to the next
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Natural selection
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differential survival and reproduction of individuals based upon genotypes and phenotypes
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fitness
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the ability to survive and reproduce
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Adaptation
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characterisitcs or trait of an organism that is or has been under the influence of nautral selction
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