Unit 7, Topic 4 Flashcards
A change in a gene or chromosome.
Mutation
A group of individuals that belong to the same species and live in the same area
population
Combined genetic information of all the members of a particular population
gene pool
refers to an allele for which all members of a population are homozygous
fixed
A change in the gene pool of a population due to chance
genetic drift
Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.
bottleneck effect
Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.
founder effect
movement of alleles from one population to another
gene flow
ie: migration
Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
directional selection
Natural selection that favors intermediate variants by acting against extreme phenotypes
stabilizing selection
ie: the peppered moth
favors individuals at both extremes of the phenotypic range
disruptive selection
when individuals select mates based on heritable traits
sexual selection
What factors contribute to phenotypic variation in a population?
Mutations, genetic drift, migration/gene flow, natural selection
What does the phrase “non-selective pressures” mean?
Natural disasters (floods, famine, fires, hurricanes) and human activity like hunting
This is directly linked to the bottleneck effect.
Why is genetic variation important to survival?
It allows natural selection to increase or decrease frequency of alleles already in the population; enables some individuals to adapt to the environment while maintaining the survival of the population.
Research the bottleneck effect on cheetahs.
a. What has happened to their population?
b. How has this affected their genetic diversity?
c. If a new disease were to be introduced into the
cheetah population, what effect could it have? Why?
Be specific.
In this bottleneck the cheetahs of North America and Europe went extinct, leaving extant only the species’ Asian and African populations b. As large mammals died out across the world, the number of surviving cheetahs dwindled, which caused extreme inbreeding. c. The cheetah species is more likely to become extinct because alleles would begin to die out allowing few to survive.
True or false: mutations can lead to new alleles.
true
How is sexual selection similar to directional selection?
The response to sexual selection will depend on genetic variation in trait expression, more precisely on how much genetic variation there is in the direction of selection. The less the genetic variation aligns with the direction of sexual selection, the higher the genetic constraints for trait evolution
