20 terms

Chapter 3: The Modern Synthesis

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modern synthesis
the change in allele frequencies over time; unification of Mendelian genetics and Darwinian evolution
natural selection
differential survival and reproductive success of individuals (or genotypes) with different heritable characteristics; acts on phenotypes and causes evolution
evolution
change in allele frequencies from one generation to the next
mutation
heritable change in DNA's molecular structure; can be good, bad, or neutral
gene flow
movement of alleles into or out of populations based on migratory patterns and interbreeding; a force of evolution
genetic drift
random changes in allele frequencies due to chance; accelerated in smaller populations; force of evolution
fixation
this occurs when an allele is lost in a population
founder effect
when there is a high incidence of a particularly rare allele because two individuals with the same allele have offspring who express the phenotype; phenotype becomes more prevalent within smaller populations
bottlenecking
severely reducing the population size and genetic diversity of a species; occurs in species that are often hunted by humans
hidden variation
when many loci affect a single trait, only a fraction of genetic variation is expressed in the phenotype
correlated characters
when individuals with a certain variant of one trait also have a certain variant of another trait
polygenic trait
many genes that contribute to a single trait
pleiotropy
one gene that codes for many traits
population genetics
branch of biology that deals with the processes that change the genetic composition of populations through time
genotypic frequency
the fraction of individuals in a population that have a particular
mate guarding
a form of mating in which the male defends his mate after copulation to prevent other mates from mating with her; males increase their reproductive success, but also cannot find a new mate while protecting
positively correlated
a statistical relationship in which larger values of one variable tend to co-occur with large values of the other variable
negatively correlated
a statistical relationship in which larger values of one variable tend to co-occur with smaller values of the other variable
sampling variation
the variation in the composition of small samples drawn from a large population
development
the process by which the single-celled zygote is transformed into a multi-cellular adult
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