Biology Speciation Flashcards Mr.Loughman WCHS

____ is a change in allelic frequencies in a population that is due to chance

Genetic drift

____ removes individuals with average trait values, creating two populations with extreme traits

Disruptive Selection

The most common form of selection, ____, removes organisms with extreme expressions of a trait

Stabilizing Selection

When a small sample of the main population settles in a location separated from the main population, the ____ can occur

Founder Effect

In ____, a species evolves into a new species without any barriers that separate the populations

Sympatric Speciation

____ will shift populations toward a beneficial but extreme trait value

Directional Selection

In ____, a population is divided by a barrier, each population evolves separately, and eventually the two populations cannot successfully interbreed

Allopatric Speciation

____ is a change in the size or frequency of a trait based on competition for mates

Sexual Selection

One species will sometimes diversify in a relatively short time into a number of different species in a pattern called ____

Adaptive Radiation

The idea that evolution occurred in small steps over millions of years in a speciation model is currently known as ____

Gradualism