Speciation Geographic isolation of populations Can lead to Reproductive isolation of population New Species (unable to breed when together)
Pre-zygotic Barriers Habitat isolation Land garter snake Water garter snake
Geographic Isolation Members of a population may become isolated from one another by geographic boundaries like mountains, rivers or even oceans
Behavioral Isolation Firefly flash pattern is species specific. A mutation which changes the pattern will isolate that population.
Temporal Isolation Rainbow Trout Brown Trout
Gametic Isolation
Mechanical Isolation
Post Zygotic Barriers Reduced hybrid viability
Reproductive Isolation
Reduced Hybrid Fertility Mules – hybrid horse and donkey
Hybrid Breakdown F2 generation shows mortality or infertility
Modes of Speciation Allopatric speciation
Grand Canyon Barrier
Sympatric Speciation
Genetic Mutation Speciation
Evolutionary Rates
Gradualism
Convergent Evolution
Divergent Evolution
Macro-Evolution
Micro-Evolution Small changes; change in gene frequencies, appearance of subspecies
One gene can have many effects When a mutation in one gene can cause multiple phenotypic effects. Selection for tameness (low adrenaline production) in the silver fox led to changes in coat color, ear shape and behavior Pet foxes?