ch 17 Flashcards
biological species concept (BSC)
population or group of populations within which genes are actually or potentially exchanged by interbreeding, and which are reproductively isolated from other such groups
coadapted
alleles at different loci within the same population have presumably been selected to form harmonious combinations
conspecific
belonging to same species
Dobzhandsky-Muller (DM) imcopatibility
reduction in the fitness of a hybrid because of interaction between certain alleles in one parent population with specific alleles at other loci in the other parent population
ecological isolation
mechanism that reduce the opportunities for closely related sympatric species to meet and mate
Haldane’s rule
generaliztion that when only one sex manifests sterility or inviability in hybrids between species, it is the heterogametic sex ( with two different sex chromosomes) that does so
hybrid zone (primary, secondary)
region in which genetically distinct populations come into contact and produce at least some offspring of mixed ancestry
hybridization
production of offspring by interbreeding between members of genetically distinct populaiton
introgression
movement of genes from one species or population into another by hybridization and backcrossing; carries the implication that some genes in a genome undergo such movement, but others do not
isolating barriers
genetically determined difference between populations that restricts or prevents gene flow between them. The term does not include spatial segregation by extrinsic geographic or topographic barriers
lineage sorting
process by which each of several descendant species, carrying several gene lineages inherited from a common ancestral species, acquires a single gene lineage; hence, the derivation of a monophyletic gene tree, in each species, from the paraphyletic gene tree inherited from their common ancestor
phylogenetic species concept (PSC)
species conceived as groups of populations that are distinguishable form other such groups
postzygotic barriers
occurring after union of the nuclei or uniting gametes; usually refers to inviability or sterility that confers reproductive isolation
premating barriers
occurring before union of nuclei of uniting gametes; usually refers to events in the reproductive isolation, including those that occur before mating
prezygotic barriers
occurring before union of nuclei of uniting gametes; usually refers to events in the reproductive isolation, including those that occur before mating
reproductive isolation
reduction of gene exchange between populations by any several possible factors, usually those arising form biological differences between population
secondary contact
contact and potential interbreeding between formerly allopatric populations, owing to range expansion
semispecies
one of several groups of population that are partially but not entirely isolated from one another by biological factors
sexual isolation
reduction of gene exchange between populations because of aversion to mating with members of the other population
sibling species
species that are difficult or impossible to distinguish by morphological characters, but may be discerned by differences in ecology, behavior, chromosomes, genetic markers, or other such features
sister species
two species with an immediate common ancestor
