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15 Cards in this Set
- Front
- Back
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Natural Selection |
process whereby organisms that possess certain beneficial traits are more likely to survive and reproduce that those with less desirable traits.
a given population will change over subsequent generations
Will affect an individual's survival but individuals cannot survive |
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evolutionary adaptation |
increase in the frequency of traits that are beneficial to the reproductive success of organisms in a given environment. |
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evidence of evolution |
certain structures have the same composition but serve different functions. Structures of ancestors were modified to take on different functions in different species over time. |
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vestigal structures |
some homologous structures can be found in organisms that do not serve any function in the organism but resemble structures found in presumed ancestors
Provide evidence of a decent with modification |
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Genetic diversity in sexually reproducing organisms |
independent assortment of chromosomes, random fertilization, and crossing over |
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Population |
smallest unit of evolution |
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Macroevolution |
includes the origin of new species origin of evolutionary novelty explosive diversification following some evolutionary breakthroughs |
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Speciation |
formation of new species- occurs when one species evolves into two or more species |
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nonbranching evolution |
a population changes by adapting to their environment, but the adapted organisms do not result in the formation of a new species.
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branching evolution |
a species experiences significant changes whereby the original species evolves into two or more species, thereby creating a new species. |
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Postzygotic barriers |
are barriers that operate after a zygote forms when species interbreed. Postzygotic barriers result in either reduced hybrid viability (offspring die before reaching reproductive maturity), reduced hybrid fertility (offspring are sterile), or hybrid breakdown (hybrids are viable as well as fertile, but second generation offspring are sterile or feeble). |
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Prezygotic barriers |
which prevents mating or fertilization. Several prezygotic barriers exist,(temporal isolation, behavioral isolation, habitat isolation, mechanical isolation, gametic isolation) |
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allopatric speciation |
a physical barrier blocks the subpopulation from the parent population, and a new species evolves. Allopatric speciation can be the result of a geologic process like the formation of a mountain range, or it can occur when organisms colonize a remote, new area which is what occurred on the Galapagos Islands. |
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sympatric speciation |
a new species forms even though the population lives in the same location during the same time as the parent population. subgroups of a population may exploit resources in a different habitat, or preferences in selection of mates can result in the formation of new species. A third mechanism of sympatric speciation includes genetic changes that occur in a single generation of a species that arise through accidents during cell division. |
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punctuated equlibria |
the species seemed to appear very suddenly, and then remain unchanged until it became extinct. |
