LIFESCI 1 Lecture Notes - Lecture 6: Chromosome, Main Source, Reproductive Isolation
Document Summary
Hybrid offspring produced can have reduced fertility and viability. Occurs because speciation is a slow and gradual process: allopatric speciation = different place (most common) More than location must be taken into account, however; size and ecology matters. But the same highway will not affect birds geographically. Genetic divergence is so gradual that there are often allopatric populations that have yet to evolve even partial reproductive isolation but have accumulated a few population-specific traits. Genetic distinctness (despite no speciation yet) = subspecies. Allopatric-ness can be caused in 2 ways: 1) dispersal = individuals colonize an island far away from main source of population: peripatric speciation : a few species break off from mainland population to a new location and evolve separately, can be intentional or accidental (ex. Island population = classically small and in slightly different environment. Change accumulates faster in peripheral isolates, more than in mainland population. Genetic drift is more pronounced in small populations.
