Biology Notes

Biology Notes
Biology: Dr. Hensley / Mrs. Ingram
Genetic Equilibrium – Allele frequencies remain constant. (this doesn’t really
happen in nature, just used as a comparison to see how populations change.
Hardy-Weinberg Equilibrium – There will be genetic equilibrium if
of the following conditions are true:
Random Mating
Large Population
No Migration (leaving an area) and No Immigration (entering an area)
No Mutations
No Natural Selection
Species – Organisms that can reproduce and produce fertile offspring.
Speciation – Making new species
Reproductive Isolation - Preventing species that could mate from doing
Caused by the following:
 Behavioral – When behavior changes (usually in animals) causing absence
of mating. Example: Mating songs changed between the Eastern and
Western Meadowlark preventing mating from taking place.
 Geographic – Physical barrier comes between individuals and preventing
mating such as mountains, oceans, rivers, canyons, etc.
 Temporal – When timing is off for mating such as the season (spring,
summer, fall, winter) or time of day (daytime, night time) the organisms like
to mate.