EQ: What are the types of isolation that lead to speciation?

TYPES OF ISOLATION Reproductive isolating mechanisms Prezygotic isolating mechanisms Geographic isolation Ecological isolation Behavioral isolation Temporal isolation Mechanical isolation Prevention of gamete fusion Reproductive isolation Postzygotic isolating mechanisms Hybrid inviability or infertility

Geographic isolation- involves physical barriers that divide a population into two or more groups Isthmus of Panama formed 3 million years ago Ex: snapping shrimp on each side will not mate with one another they snap at each other instead

Grand Canyon speciation of squirrels due to geographic isolation

Populations can become isolated in several ways. Behavioral isolation- is caused by differences in courtship or mating behaviors Changes in chemical scents, mating dances, songs or signals can prevent mating Ex: Fireflies produce patterns of flashes that attract their mates. Over 2000 species of FF are isolated based on the patterns of flashes

Ecological isolation Ecological isolation. Individuals mate in their preferred habitat, and therefore do not meet individuals of other species with different ecological preferences.

Behavioral isolation Blue-fotted boobies select mates after an elaborate courtship display Will not mate with other boobies

Temporal isolation- when timing prevents mating/reproduction between populations Ex: The Monterey Pine and the Bishop pine have different pollination periods. (February/April) Bishop pine

Field crickets’ reproductive isolation due to temporal isolation

Mechanical isolation Structure of the male and female copulatory organs may be incompatible Bees may carry the pollen of one species on a certain place on their bodies; if this area does not come into contact with the receptive structures of the flowers of another plant species, the pollen is not transferred

Prevention of gamete fusion In animals that shed gametes directly into water, the eggs and sperm derived from different species may not attract or fuse with one another In plants, the growth of pollen tubes may be impeded in hybrids between different species

Reproductive isolation occurs when members of different populations can no longer mate successfully with one another It is the final step of becoming separate species

♀ ♂ Hybrid inviability or infertility sterile x = Male donkey crossed with female horse = sterile mule. Male horse crossed with female mule = sterile hinny. sterile