Mechanisms of Evolution Crossword

states the allelic frequencies in populations stay the same unless they are affected by a factor that causes change.
random change in allelic frequencies in a population.
random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations.
process in which a large population declines in number, then rebounds.
the most common form of natural selection in which organisms with extreme expressions of a trait are removed.
shift of a population toward an extreme version of a beneficial trait.
process in which individuals with average traits are removed.
change in the frequency of a trait based on competition for a mate.
factor that prevents individuals from different species from mating; operates before fertilization.
factor that prevents a hybrid zygote from developing, or prevents hybrid offspring from reproducing; operates after fertilization.
occurs when a population divided by a geographic barrier evolves into two or more populations unable to interbreed.
occurs when a species evolves into a new species in an area without a geographic barrier.
diversification of a species into a number of different species.
theory that evolution occurs in small, gradual steps over time.
theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability.