The Evolution Of Populations Flashcards
List the conditions a population must meet in order to maintain Hardy-Weinberg equilibrium.
- No mutation
- Random mating
- No gene flow
- Infinite population size
- No selection
Give the cause of nearly all genetic variations in a population (in other words, define genetic drift, gene flow, mutation, nonrandom mating and natural selection that can cause changes (variations) to a population).
Genetic drift: the random loss of individuals and the alleles they posses.
Gene flow: concept of migration, movement of alleles from one population to another.
Mutation: a change in the nucleotide sequence in an organism’s DNA.
Non-random mating: a system in which some individuals are more likely to mate with certain individuals than others.
Natural selection: a mechanism of evolution that explains how inherited traits in a population of organisms change over generation.
Distinguish between the bottleneck effect and the founder effect.
The bottleneck effect occurs when a population dramatically decreases due natural disasters or human affect.
The founder affect occurs when a new population is created by a small amount of individuals from a different population.
Distinguish among stabilizing selection, directional selection and disruptive selection.
Stabilizing selection removes extreme variants from the population and preserves immediate types.
Directional selection shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution.
Disruptive selection favors variants at each end of the distribution.
In what ways does artificial selection by humans differ from natural selection in nature?
Artificial selection requires two criteria, variation in population, and traits must be heritable. Natural selection requires three criteria variation in population, traits must be heritable, and there must be limits on population growth.
Explain the concept of relative fitness.
Relative fitness describes the number of offspring an organism has compared to the average number of offspring in a population.
In a population at Hardy–Weinberg equilibrium in which the frequency of A alleles (p) is 0.3, the expected frequency of Aa individuals is
AA =0.09 Aa=0.42 aa=0.49
In a particular region of the coast, limpets (a type of mollusc) live on near shore habitats that are uniformly made up of brown sandstone rock. The principle predators of these limpets are shorebirds. The limpets occur in two morphs, one with a light-colored shell and one with a dark-colored shell. The shorebirds hunt by sight and are able to see the light ones on the dark sandstone easier than the dark ones.
The hardy-weinberg equation law being broken is “no selection takes place” because the dark mollusk will outlive the light mollusk.
In Chen caerulescens (a species of goose), the white body form, the snow goose and the blue body form, the blue goose, occasionally coexist. In these areas of contact, whiteby-white and blue-by-blue matings are much more common than white-by-blue matings.
The hardy-weinberg law being broken is “no random mating”
Prior to the Mongolian invasions which occurred between the 6th and 16th centuries, the frequency of blood type B across Europe was close to zero. The frequency of blood type B among the Mongols was relatively high. Today, it is possible to see fairly high frequencies of blood type B in the Eastern European countries and a gradual decrease in the frequency of blood type B as one moves from the Eastern European countries to the Western European countries, such as France and England.
The law being broken is no genes are transferred to and from other sources.
