Reproductive Isolation

Postzygotic Isolation prevents reproduction after a zygote is formed. Examples include hybrid inviability and hybrid sterility.

Prezygotic barriers prevent the formation of a zygote.

Prezygotic barriers include temporal isolation, where species breed at different times, and behavioral isolation, where differences in mating rituals prevent interbreeding.

Gene flow: The movement of alleles from one population to another

• Can cause a population to evolve

Genetic drift

• The change in allele frequency due to chance

• Can lead to significant evolutionary changes, particularly in small populations where random events can have a larger impact on the overall genetic makeup.

Types of Genetic drift include:

• Bottleneck effect - Drastically reduces the size of a population.

• The founder effect occurs when a small group of individuals establishes a new population, leading to reduced genetic diversity compared to the original population.

Sexual selection

• Selection in which having certain traits increases an organism’s chance of finding a mate and reproducing. Example: Male peacocks have elaborate tales made of long, colorful feathers that are more attractive to females.

  Intrasexual selection

• It involves competition between male members to have the right to mate. Male elk, deer, and rams fight each other to have the right to mate with females

  Courtship selection

• It refers to behaviors and displays that attract potential mates, often involving elaborate rituals or displays. For instance, birds may perform intricate dances or songs to impress females, thereby increasing their chances of successful mating.

  Intersexual -

• Males display certain traits that attract females.

• Often brightly colored, larger features or other characteristics