An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have bro
ader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? A) directional selection
B) disruptive selection
C) a founder event
D) a genetic bottleneck
Genetic bottleneck refers to the sudden reduction in the population size due to some adverse climatic factors such as natural calamities. It changes the allele frequencies since the survivor population mostly have different allele frequencies than the original population.
In the given example, an earthquake kills 98% of the squirrels. The survivor population exhibits different allele frequencies for the gene responsible for the thickness of stripes. Therefore, it represents a genetic bottleneck.
Changes in the environment may leave individuals less well adapted to compete successfully for resources such as food, water and mates. Sometimes an entire species may become unable to compete successfully and reproduce. These problems can lead to extinction.
