| module | units of body construction |
| heterochromy | comparing different species, an alternation in the timing of developmental events, leading to different results in adults |
| developmental plasticity | the capacity of an organism to alter it's pattern of development in response to environmental conditions. |
| parallel phenotypic evolution | repeated evolutionary patterns of change that occur independently in multiple lineages |
| differential survival | those individuals in a population that are the most fit can survive. |
| population | any group of organisms coexisting at the same time and in the same place and capable of interbreeding with one another |
| adaptation | a paticular structure , physiological process or behavior that makes an organism better able to survive and reproduce |
| gene pool | all the different alleles of all the genes existing in all individuals of a population |
| population bottlenect | a stressful period during which only a few individuals of a population survive |
| gene flow | exchange of genes btwn diff species (extreme refers to hybridization) or btwn different populations of the same species caused by migration followoed by breeding. |
| founder effect | random changes in allele frequencies resulting from establishment of a population by a very small number of individuals |
| artificial selection | selection by plant and animal breeders of individuals with certain desireable traits |
| natural selection | differential contribution of offspring to the next generation by various genertic types belonging to the same population |
| stabilizing selection | selection against the extreme phenotypes in a population so that the intermediate types are favored |
| directional selection | selection in which phenotypes at one extreme of the population distribution are favored |
| disruptive selection | selection in which phenotypes at both extremes of the population distribution are favored |
| sexual selection | selection by one sex of chracteristics in individuals of the opposite sex. also the favoring of characteristis in one sex as a result of competition among individuals of that sex for mates. |