| A | B |
|---|
| homologous structure | structures that have the same embryological origin, but different functions; examples are the arm ones of humans, birds, and bats |
| vestigial structure | a structure that has decreased size or function; appendix, whale pelvis and leg bones |
| analogous structure | structures that have the same function, but are not evolutionarily related; insect wing and bird wing |
| embryo | the beginning stages of an organixms development, after the zygote has formed |
| fitness | a measure of the success of an individual bsed on their phenotype and how well they can survive in an environment |
| mimicry | when one species evolves to resemble another species; usually one or both are toxic or poisonous |
| camouflage | when an organism blends in with its environment |
| Hard-Weinberg Principle | A principle, that when all 5 conditions are met, results in no evolultion for the population: 1. no gene flow; 2. no natural selection; 3. random mating; 4. large population; 5. no mutation |
| genetic drift | a random change in the gene pool |
| founder effect | a random change in a gene pool that happens when a small group leaves a larger group |
| allopatric speciation | occurs when a popuplation divided by a geographic barrier evolves into 2 or more populations unable to interbreed |
| sympatric speciation | occurs when a species evolves into a new species in an area without a geographic barriers |
| convergent evolution | unrelated species evolve similar adaptations due to similar environment; shark & dolphin, mara & rabbit |
| fossil | evidence through rock strata, preserved organixms, and differences seen over millions of years in geological time |
| evolution | change in a population over time |
| natural selection | the process by evolution occurs, via the success of populations based on phenotypes & how well they can survive in their environments |
| artificial selection | when an organism's mate is chosen for them; example, when a farmer breeds his plants & animals for specific traits |
| endosymbiont theory/ endosymbiotic theory | the theory that complex organelles (like mitochondria & chloroplasts) evolve from mutualistic symbiotic relationships between bacteria |
| bottleneck effect | geneticd drift resulting from a drastic reduction inpopulation size, often caused by a natural disaster |
| stabilizing selection | natural selection that favors intermediate phenotypes rather than the extreme phenotypes; example, birthweight |
| directional selection | natural selection that favors one end of a phenotypic spectrum & acts against another; example is if light brown snails were once favored, but now dark brown snails have better success |
| disruptive selection | natural selection that favors the extreme phenotypes & selects against the intermediate phenotypes, process usually results in speciation (creation of 2 new species from one) |
| behavioral isolation | a pre-zygotic barrier that happens when organisms are not attracted sexually to members of another species due to traits like mating dances or calls |
| prezygotic isolation | isolation before sex; temporal isolation; geographic isolation; behavioral isolation; ecological isolation |
| postzygotic isolation | isolation after sex; hybrid sterility; donkey + horse mate= mule (sterile) |
| adaptive radiation | the emergence of many species from one common ancestor; Darwin's fincher |
| gradualism | theory that evolution occurs in small gradual steps over time |
| punctuated equilibrium | theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability |
