population. Regular gene flow between two populations will prevent the two populations from diverging
from one another through different selection pressures or genetic drift. Thus gene flow can be a
conservative force slowing down population differentiation and evolutionary divergence and homogenizing
the genetic composition of populations.
In wide ranging species, population in different parts of the geographical range are inevitably faced with
varying ecological circumstances. Different selection pressures in different parts of a species’ range give
rise to genetic differentiation among populations. Genetic differentiation among populations can
also arise thought the process of genetic drift, especially in species that occur in small populations.
The study of geographical variation began with C. Darwin and A. Wallace. Many evolutionary hypotheses
are tested by examining variation patterns in living organisms. Evolutionary biologists use varying levels
of differentiation among population, races, sub-species, and species to infer the course of evolutionary
change. Observations of this type indicate that evolution is generally a gradual process with differences
among populations of a species ranging from small to large.
Microclimates- south facing slope receives more sun (can have adaptation differences)
Selection is driving those populations to be different
If there is not random mating, then genetic drift will drive them to be different
Selection and drift is driving them apart
Eventually if there is enough isolation then you will see new species
Start at 0.5
Random sampling of alleles every generation
Eventually one particular allele gets fixed or lost
If a population gets split, one population could fix Big A allele and one loses it
Population can accumulate difference just by drift