The Nature of Natural Selection Flashcards
How does the environment affect fitness in terms of allele frequencies?
Allele frequencies may increase or decrease, and in some locations and not others. They are only determined by immediate conditions so cannot ‘predict the future’ or have goals.
Give an example of a trait that is good for a species and not for an individual.
Genes that cause high mutation rates (could save a species from extinction but will likely be eliminated due to individual harm).
What is pleiotropy? Does it always confer advantages?
The production by a single gene of two or more apparently unrelated effects.
No, can be advantageous, disadvantageous or both.
Do genes that are advantageous necessarily stay so throughout an organisms life?
No, genes can be expressed at different life stages, and can be advantageous or not at some times and not others.
What is group selection? Give an example.
Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the more conventional level of the individual. E.g. social insects like ants.
What is an r-selected species and example, what is a K-selected species and example?
r-selected species - produce many offspring, low probability of survival
K-selected species - produce few offspring, high probability of survival
What is kin selection?
Natural selection in favor of behavior by individuals that may decrease their chance of survival but increases that of their kin (who share a proportion of their genes). E.g. honeybees
What is Hamilton’s rule?
Kin selection causes genes to increase in frequency when
rB>C
r is relatedness (proportion of shared genes), B is benefit (number of offspring produced), C is cost to altruist
How is the fitness of an allele determined?
Its effect on phenotype, its interaction with the environment, and by the rest of the genotype in which its embedded.
Selection acts on _____ while evolution happens on ______
Phenotypes, gene frequencies
