AP Bio Chapter 23 Part 8 Flashcards
Successful reproduction=
Production of fertile offspring
Species barriers
Various mechanisms (barriers) exist that prevent successful interspecies reproduction
How can we split these barriers?
When they occur in relation to fertilization
Prezygotic barriers
Barriers prior to fertilization
Postzygotic barriers
Barriers after fertilization
What are the prezygotic barriers
Habitat Temporal Behavioral Mechanism Gametic
Habitat isolation
The species live in different areas
Temporal isolation
The species breed during different times of day, different seasons, or different years
Behavioral isolation
Unique behavioral patterns and rituals isolate species. Identifies, attracts members of species (mating dances)
Mechanical isolation
Reproductive anatomy from one species does not fit with the anatomy of another species
Gametic isolation
Proteins on the surface of gametes does not allow fusion of eggs
What are the postzygotic fertilization
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
Reduced hybrid viability
Hybrid is weak
Reduced hybrid fertility
Hybrid is sterile
Hybrid breakdown
Offspring of hybrid loses hybrid genetic combinations over succeeding generations
What is the rate of speciation
A debate
Whether it happens gradually or rapidly
Gradualism
Old thinking : Charles Darwin, Charles Lyell
A gradual divergence over long spans of time
Big changes occur as the accumulation of many small ones
Punctuated Equilibrium
New thinking: Stephen Jay Gould, Niles Eldredge
Rate of speciation is not constant
Rapid bursts of change, followed by long periods of little or no change
Species undergo rapid change when they first evolve from parent population
