24 Speciation Flashcards
Species
an evolutionary independent population or group of populations; generally distinct from other species in appearance, behaviour, habitat, ecology, genetic characteristics etc.
What are the four criteria for identifying species?
(1) biological species concept (2) morphospecies concept (3) ecological species concept (4) phylogenetic species concept
Biological species concept
a species as a population or group of populations that are reproductively isolated from other groups (no gene flow occurs between them); members of a species can potentially interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species
Prezygotic isolation
prevents individuals of different species from mating successfully
Postzygotic isolation
the hybrid offspring of matings between members of different species either do not survive or cannot reproduce
What are the mechanisms of prezygotic isolation?
temporal, habitat, behavioural, gametic barrier, and mechanical
Temporal mechanism
populations are isolated because they breed at different times
Habitat mechanism
populations are isolated because they breed in different habitats
Behavioural mechanism
populations do not interbreed because their courtship displays differ
Gametic barrier
matings fail because eggs and sperm are incompatible
Mechanical mechanism
matings fail because male and female reproductive structures are incompatible
What are the mechanisms of postzygotic isolation?
hybrid viability and hybrid sterility
Hybrid viability
hybrid offspring do not develop normally and die as embryos
Hybrid sterility
hybrid offspring mature but are sterile as adults
Morphospecies “form species” concept
a species as a population or group of populations that have measurably different anatomical features from other groups
Ecological species concept
a species as a set of organisms exploiting a single set of resources, having the same range of environmental tolerances, and facing the same predators and parasites