Chapters 7-12 Flashcards
what is broad sense heritability
the proportion of the total phenotypic variance of a trait that is attributible to genetic variance, where variance is represented in its entirety as a single value
what is narrow sense heritability
the proportion of the totoal phenotypic variance of a trait attributile to the additive effects of alleles. the component of variance that causes offspring to resemble their parents
what is directional selection
favors individuals at one end of a trait distribution, ie. animals with a smaller body size
what is stabilizing selection
favors individuals with a trait near the population mean
what is disruptive selection
favor individuals at either end of the distribution
what is artificial selection
results from human activity; when breeders nonrandomly choose individuals with economically favorable traits to use as breeding stock
what is gene flow
the movement, or migration of alleles from one population to another
what is aposematism
an antipredator strategy used by a potential prey item to isgnal danger or a lack of palatability. eg. coloration, the coloration of prey that are potentially dangerous can act as a deterrent to potential predators
what are extended phenotypes
structures constructed by organisms that can influence their performance or success. ex. nests constructed by birds
what is genetic linkage
the physical proximity of alleles at different loci
what is a selective sweep
describes the situation in which strong selection can “sweep” a favorable allele to fixation within a population so fast that there is little opportunity for recombination
what is an ortholog
homologous genes separated by a speciation event
what is coalescence
the process by which looking back through time, the genealogy of any pair of homologous genes merges in a common ancestor
what are paralogs
homologous genes that arise by gene duplication, paralogs together form a gene family
what is a gene tree
refers to the branched genealogical lineage of homologus alleles that traces their evolution back to an ancestral allele
what is maximum parsimony
a statistical method for reconstructing phylogenies that identifies the tree topology that minimizes the amount the change
what is purifying selection (or negative selection)
removes deleterious alleles from a population, form of stabilizing selection
every phylogenetic tree is a _______
hypotheiss
what are synonymous substitutions
substitutions that do not alter the amino acid sequence of a protein
what are non-synonymous substituions
substitutions that alter the amino acid sequence of a portien
what is a molecular clock
a method used to determine time based on base-pair substitutions
what is the neutral theory
desribes the pattern of nucleotide sequence evolution under the forces of mutation and genetic drift and in the abscence of selection.
it predicts that neutral mutations will yield nucleotide substituions at a rate equivalent to the rate of mutation, regardless of size population
what are novel traits
traits that are not inherited by an ancestor
what is antagonistic pleiotropy
the condition that occurs when a mutation with beneficial effects for one trait also causes detrimental effects on another trait
what is parallel evolution
refers the the independent evolution of simialr straits, starting from a similar ancestral condition
what is deep homology
condition that occurs when the growth and development of traits in different lineages result from underlying genetic mechanisms
what are hermaphrodites
individuals that produce both male and female gameteds
what is the twofold cost of sex
the disadvantages of being a sexual rather than an asexual organism
what are two advantages and disadvantages of sex
advantages: -combining beneficial mutations -faster evolution -clearance of deleterious mutations -generation of novel genotypes disadvantages: -males themselves cannot produce offspring -males and females must locate each other in order to mate -reduce relatedness -risk of stds
what is mullers ratchet
describes the process by which the genomes of an asexual population accumulate deleterious mutations in an irreversable manner
what is the red queen effect
decribes a phenomenon seen in coevolving populations- to maintain relative fitness, each population must constatnly adapt to one anothe
what is anisogany
refers to sexual reproduction involving the fusion of two disimilar gametes; individuals producing the larger gamete (egg) are defined as female and the smaller as male
what is fecundity
the reproductive capacity of an individual, ex. number and quality of eggs or sperm
what is an operational sex ratio
the raio of male to female individuals who are available for reproducing at any given time
what is intersexual selection
occurs when members of the limiting sex (generally females) actively discriminate among suitors of the less limited sex
what is intrasexual selection
members of the less limiting sex (usually males) compete with each other over reproductive access to the limiting sex
what is sexual dimorphism
a difference in form between males and females of a species, including colour, body size, etc
what is a direct benefit
benefits that affect a particular female directly, such as food, nest sites, or protection
what are indirect benefits
benefits that affect the genetic quality of a particular females offspring
what is monogamy
a mating system in which one male pairs with one female
what is polygyny
a mating system where males mate with multiple females
what is polyandry
a mating system where females with multiple males
what is cryptic female choice
a form of sexual selection that arises after mating, when females store and separate sperm and bias which sperm they will use to fertilize their eggs
what is sexual conflict
the evolution of phenotypic characteristics that confer a fitness benefit to one sex but a cost to the other sex
which sex generally benefits more from parental care of offspring
females
what is genomic imprinting
occurs when genes inherited from one parent are silenced due to methylation
what is senescence
refers to hte deterioration in the biological function of an organsim as it ages
