Ch 2: Isolation

Species

Group of organisms that can breed in nature and produce fertile offspring

Reproductive barriers

Keep species separate so they can’t reproduce

Hybrid

Offspring from 2 different species

Hybrid Zone

Geographic area where interbreeding occurs and hybrids are created

Zygote

Fertilized egg

Prezygotic barrier

Prevents mating or fertilization (nothing is born)

Postzygotic barrier

Prevents growing, fertile offspring

Habitat/geographic isolation

Populations live in different areas so they don’t/can’t mate

Behavioral Isolation

Mating or courtship behaviors differ (prefer different calls or colors)

Temporal isolation

Breed at different times (different time of day or different seasons)

Mechanical isolation

(Reproductive) Body parts don’t fit together to mate

Gametic Isolation

Gametes (egg and sperm or pollen) don’t join because sperm is not attracted to egg or sperm cannot survive in the reproductive tract of the female

Zygote mortality

Zygote (fertilized egg) cannot grow so embryo is never born

Hybrid sterility

Hybrids survived but are sterile (can’t reproduce)