chapter 10: evolution and natural selection Flashcards
population
group of organisms of the same species living in the same geographical region
evolution
a change in allele frequencies of a population
ideas influencing Darwin
- earth is very old
- species go extinct
- species may change
- earth’s features change
traits
physical characteristics
4 processes that can change evolution
mutation, genetic drift, mutation, natural selection
mutation
alteration of base-pair sequence in DNA of an individuals gamete-producing cells that changes an alleles frequency
1. we cannot predict which individuals will have which mutations
2. cannot predict whether the mutation will be helpful, harmful, neutral
genetic drift
random change in allele frequencies, unrelated to any allele’s influence on reproductive success
gene flow (migration)
change in allele frequencies caused by individuals moving into/out of a population
natural selection
change in allele frequencies that occurs when individuals with 1 version of veritable trait have greater reproductive success than individuals with different alleles
fixation
when results of allele are 100% frequency in a population
founder effect
isolation of small subgroups of larger population leading to changes in allele frequencies of the isolated group
population bottleneck effect
sudden reduction in population size that can lead to changes in allele frequencies of the isolated population
when does natural selection occur
- there is variation for a trait
- heritability
- differential reproductive success
differential reproductive success
some individuals have greater reproductive success
sexual selection
traits have greater reproductive success because they make an individual more attractive
hardy-weinberg law
alleles must add up to 100%
fitness
measure of amount of reproduction of an individual with particular phenotype relative to reproductive output of individuals of same species with alternative phenotypes
adaption
process organisms become better matched to their environment and to the specific feature that makes an organism more fit
artificial selection
differential reproduction success determined by humans
- typically goal oriented
directional selection
(for a trait) increases fitness at one extreme of phenotype and reduces fitness at other
stabilizing selection
selection that produces greatest fitness at intermediate point of phenotype range
disruptive selection
increases fitness at both ends of phenotype distribution and reduces fitness at middle value
fossil
remains of an organism, usually hard parts, that have been naturally preserved
radiometric dating
method of determining both relative and absolute age of object by measuring the radioactive isotopes they contain and their decay points
