Processes that drive evolution and speciation

Natural selection

Genetic variation, overproduction of offspring, struggle for existence, differential survival and reproduction

Coevolution

Ex: predator and prey evolve to deal with each other

Stabilizing selection

Natural selection favors the average or intermediate phenotypes while selecting against both extremes

disruptive selection

natural selection favors both extremes of a trait while selecting against the average or intermediate formsd

directional selection

Natural selection favors one extreme of a trait’s range

Sexual selection

Traits that enhance an organism’s chance to mate are another key driver to evolution. Signals that the mate is more fit for survival or reproduction.

genetic drift

reduction in the gene pool due to chance

Founder effect

When a small group of individuals becomes isolated from a large population.

Bottleneck effect

When a population with reduced genetic diversity forms due to a catastrophic event and only a few members survive.

Consequences of reduced variation

Disadvantaged genes become homozygous (inbreeding), fewer and less viable offspring, low survivorship, increased chance of extinction sp

Species

a group of organisms with similar morphological,physiological, biochemical, and behavioral characteristics which can interbreed to produce fertile offspring

Genomics

A way to test species without breeding. This will give the entire DNA of an individual.

Allopatric speciation

Separated by some physical barrier

Parapatric speciation

Partial separation of species.

Sympatric speciation

no separation but something causes a division of species.