Chapter 14 Flashcards
Speciation
The process by which one species splits into two or more species.
Biological Species Concept
Defines a species as a group of populations whose members have the potential to interbreed in nature and produce fertile offspring.
Morphological Species Concept
Defines a species based on physical traits (Morph: form).
Ecological Species Concept
Identifies species in terms of their ecological niches, focusing on unique adaptations to particular roles in a biological community.
Phylogenetic Species Concept
Defines a species as the smallest group of individuals that share a common ancestor and thus form one branch on the tree of life.
Prezygotic Barrier
Prevents mating or fertilization between species.
Postzygotic Barrier
Operates after hybrid zygotes have formed.
Habitat Isolation
Lack of opportunities to encounter each other. (land vs water snakes). (Prezygotic).
Temporal Isolation
Breeding at different times or seasons. (Prezygotic).
Behavioral Isolation
Failure to send or receive appropriate signals. Different courtship rituals. (Prezygotic)
Mechanical Isolation
Physical incompatibility of reproductive parts. (Plants that can only be pollinated by long curved-bill humming birds vs short straight ones.) (Prezygotic).
Gametic Isolation
Molecular incompatibility of eggs and sperm or pollen and stigma. (Prezygotic).
Reduced Hybrid Viability
Interaction of parents genes impairs the hybrid’s development or survival. (some salamanders can hybridize but offspring are frail and won’t survive). (Postzygotic).
Reduced Hybrid Fertility
Hybrids are vigorous but cannot produce viable offspring. (Horse x Donkey = Mule but it is sterile). (Postzygotic).
Hybrid Breakdown
Hybrids are viable and fertile, but their offspring are feeble or sterile. (Hybrids of rice can produce a next gen rice plant but it is sterile). (Postzygotic).
Allopatric Speciation
The formation of new species in populations that are geographically isolated from one another.
Sympatric Speciation
The formation of a new species within the same geographic area as its parent species.
Polyploid
A cell that has more than 2 complete sets of chromosomes.
Adaptive Radiation
The evolution of many diverse species from a common ancestor.
Hybrid Zones
Regions in which members of different species meet and mate, producing at least some hybrid offspring.
Punctuated Equilibria
In the fossil record, long periods in which a species undergoes little or no morphological change (Equilibria) interrupted (punctuated) by relatively brief periods of sudden change.
Punctuated Equilibria Model
States that species change the most as they arise from an ancestral species and then change relatively little for the rest of their existence.
