Chapter 14: Origin Of Species Flashcards
Reproductive Barrier
A biological feature of the organism itself to prevent individuals of closely related species from interbreeding when their ranges overlap
Temporal Isolation
Occurs when species breed at different times
Habitat Isolation
2 species live in the same general area but not in the same kinds of places
Behavioral Isolation
Little to no sexual attraction between males and female of different species
Mechanical Isolation
Male and female sex organs are not compatible
Genetic Isolation
The make and female copulante but the hamsters do not form a zygote
Pre-Zygotic Barriers:
Prevent mating or fertilization between species
Post-Zygotic Barriers:
Prevents the hybrid from being fertile
Reduced Hybrid Viability
Hybrids fail to develop
Reduced Hybrid Fertility
Hybrids fail to produce functional gametes
Hybrid Breakdown
Offspring of hybrids are weak or infertile
Allopathic Speciation
The initial block to gene flow seems to have been a geographic barrier that isolated a population
Sympatric Speciation
A new species arises within the same geographic area as a parent species
Hybrid Zone
Regions in which species meet and mate, producing hybrids
Possible outcomes for a hybrid zone over time
Reinforcement
Fusion
Stability
Reinforcement
When hybrids are less fit than members of both parent species, we expect natural selection to reinforce reproductive barriers, thus reducing formation of unfit hybrids
Fusion
When the reproductive barriers between the two species are not strong. So much gene flow may occur that the Speciation process reverses, causing the two hybridizing species to fuse into one
Stability
Many hybrid zones turn out to be stable in the sense that hybrids continue to be produced. The two hybridizing species also maintain their integrity
Adaptive Radiation
Evolution of many diverse species from a common ancestor
