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population whose members can interbreed in nature to produce viable, fertile offspring with each other, but not with members of other populations
biological species concept
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defining species by measurable anatomical criteria
morphological species concept
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based on morpholgical differences known only from the fossil record
paleontological species concept
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defining species in terms of ecological roles
ecological species concept
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a set of organisms with a unique genetic history- that is, as one branch on the tree of life
phylogenetic species concept
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what type of bird was hybridized
oriole
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accumulation of heritable changes alters the typical phenotype for the species over generations
anagenesis
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branching evolution leads to new species
cladogenesis
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evolutionary adaptations that prevent hybridiation before fertilization
prezygotic barriers
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biological accidents that can result in decreased or zero fitness
postzygotic barriers
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Examples of prezygotic barriers
habitat, temporal, behavioral, mechanical, gametic isolation
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examples of postzygotic barries
reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
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Different habitats minimize contact
habitat isolation
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active at different times of day,year, breeding season
temporal isolation
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distinct body color and courtship display can prevent hybridization
behavioral isolation
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structural differences in genitalia may prevent accidental sperm transfer(plants,insects,spiders)
mechanical isolation
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inability of sperm to fuse with ovum of other species (chemical barrier in sea urchins)
gametic isolation
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Hybrid offspring does not develop properly
reduced hybrid viability
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offspring may be healthy but cannot reproduce as easily as their parents
reduced hybrid fertility (mule)
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future generation are less viable
hybrid breakdown
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ancestral population segregated by geographic barrier (divided into two or more geographically isolated populations)
allopatric specaiation
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radical change in genome of subpopulation reproductively isolates in from the parent population
sympatric speciation
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Describe the paleozoic period
251 million years ago, when the earths crust was in its pangaea form
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Describe the mesozoic period
135 myo, was the period after pangaea and the crust was in two pieces: laurasia, gondwana
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Describe the cenozoic period
65.5 myo, the period before the earths current form. North america, south america, antarctica, australia, india, madagascar, africa, eurasia,
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emergency of numerous species from a common ancestor introduced into an environment that presents a diversity of new opprotunities and problems
adaptive radiaiton
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Mutational change (meiotic failure resulting in diploid gametes) may produce an offspring with more than two sets of chromosomes, all derived from a single species
polyploidy
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variation in the relative rates of growth of various parts of the body, which helps shape the organism
allometric growth (chimp/human fetus skull size to adult size)
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evolutionary change in the timing or rate of an organism's development
heterochrony
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control overall body plan by controlling the developmental fate of groups of cells
homeotic genes
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retention of juvenile characteristics in a mature organism
neoteny
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