Chapter 4: From Variant to Species Flashcards
founder effect
the potentially biased sampling of the genetic variation in a species due to the isolation of a small number of its members
variants
individuals within populations having different expressions of a trait
variability
the tendency for members of a population to exhibit different versions of a particular trait
variation
the expression of differences for a characteristic among members of a population
population genetics
a science concerned with variation in gene frequencies within the populations and the forces that modify them over time
Hardy-Weinberg (H-W) Equilibrium
a model specifying the conditions under which the frequency of alleles or phenotypes in a natural population remain in equilibrium unless acted on by one or more evolutionary forces
heterosis
also known as heterozygote advantage; the tendency for offspring of genetically distinct individuals to have increased vigour as they are less likely to express deleterious recessive alleles, which increase in frequency when males and females with similar genetic background mate
epigenetic
mechanisms acting during mitosis (development) to modify gene expression without modifying the actual DNA sequence; may result in heritable variation
speciation
the formation of new species from pre-existing forms
evo-devo
evolutionary developmental biology; a branch of evolutionary theory that invokes a prominent role for embryonic development and epigenetic mechanisms in the ontogeny and phylogeny of phenotypes
phenotypic plasticity
a potential for individuals to modify their phenotype in response to variation in external conditions in order to maintain homeostasis and function
transgenerational epigenetic inheritance
the transmission of novel phenotypic features from parent to offspring acquired without recourse to modification in DNA base sequences
demes
local breeding populations; a deme is a subset of a species within which most members find a mate
biogeography
the study of the geographic distribution of organisms, habitats, and evolutionary history as it relates to landscape and ecology
sympatric
refers to species that coexist in the same geographic region
allopatric
refers to species that “live apart” and do not occupy the same geographic locale; allopatric species are presumed to exist in genetic isolation
parapatric
refers to species whose ranges are contiguous but not overlapping; gene flow is possible
hybrid zones
ecological regions in which closely related species overlap in occurrence, allowing for interbreeding to occur, producing hybrid offspring
recognition species concept (RSC)
a concept of the species as a group whose members, according to particular cues, identify potential mates with whom they might successfully interbreed (in contract, the BSC emphasizes an absence of breeding potential)
conspecific
belonging to the same species