Name:_Answer Key_
Population and Diversity
Genetic Drift
Type a 100-200 word summary about genetic drift and its impact on genetic diversity
Rapid changes in gene frequencies totally independent of mutation, recombination, and natural
selection. These changes are due solely to chance factors. The smaller the population, the
more susceptible it is to such random changes. This phenomenon is known as genetic drift.
This kind of deviation from the expected outcome with small samples also occurs in genetic
inheritance when breeding populations are very small. The net effect of genetic drift on a small
population's gene pool can be rapid evolution
Founder Principle
Type a 100-200 word summary about the Founder Principle and its impact on genetic diversity
This occurs when a small amount of people have many descendants surviving after a number of
generations. The result for a population is often high frequencies of specific genetic traits
inherited from the few common ancestors who first had them.
Bottleneck Effect
Type a 100-200 word summary about the bottleneck effect and its impact on genetic diversity
In many species, there have been catastrophic periods caused by rapid dramatic changes in
natural selection, during which most individuals died without passing on their genes. The few
survivors of these evolutionary "bottlenecks" then were reproductively very successful, resulting
in large populations in subsequent generations. The consequence of this bottleneck effect is
the extraordinary reduction in genetic diversity of a species since most variability is lost at the
time of the bottleneck
Quiz
1. Rapid random changes in gene pool frequencies occurring in a small population
are likely due to:
a) genetic drift
b) founder principle
2. Which of the following statements about genetic drift is true?
greatest effect on gene pool frequencies in large populations.
c) bottleneck effect
a) It has its
b) It occurs
independently of mutation and recombination.
natural selection.
c) It is due to mutation rather than
3. In which of the following types of societies would genetic drift have the least
likelihood of causing rapid evolution?
a) a band of 12 isolated humans living
70,000 years ago in Southern Africa
b) Japan today
c) a community of 40
members of a religious sect who have had nothing to do with their neighbors in
Pennsylvania for 8 generations
4. High frequencies of rare genetically inherited traits in people who share a
common ancestor is most likely the result of:
founder principle
c) genetic drift
a) natural selection
b) the
d) Huntington's disease
5. The fact that South and Central American Indians are nearly 100% type O for the
ABO blood system is best explained as being the result of:
b) natural selection
a) genetic drift
c) the founder principle
6. Which of the following is true of genetic bottlenecks?
a) They occur when there
are major environmental changes that alter natural selection so that most members of a
species die before reproducing.
b) The result is usually increased genetic diversity in
a population following a genetic bottleneck.
survivors.
c) They reduce the fertility of the