Topic 7.10 - Speciation 𖦹⋆｡°✩ Flashcards
when does speciation occur
when populations are reproductively isolated from one another
what is the definition of species that is provided by the biological species concept
a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring
what is speciation and what is it a result of
the creation of new species as a result of diversity of life forms
what biological barriers separate members of two species
༻ interbreeding
༻ producing fertile offspring
what reproductive barriers prevent gene flow between populations
༻ prezygotic barriers - prevent production of a fertilized egg
༻ postzygotic barriers - prevent a zygote from developing into a viable, fertile offspring
what are the 5 prezygotic barriers and explain each
༻ habitat isolation
༻ temporal isolation
༻ behavioral isolation
༻ mechanical isolation
༻ gamete isolation
what are the 3 postzygotic barriers
༻ hybrid inviability
༻ hybrid sterility
༻ hybrid breakdown
what is allopatric speciation
the evolution of new species due to individuals from the same population being geographically isolated over a long period time
what are the consequences for allopatric speciation
༻ no gene flow
༻ separation may expose populations to different selection pressures
what is sympatric speciation
the evolution of a new species due to individuals being reproductively isolated from a surviving ancestral population
what are the conditions for sympatric speciation
༻ no geographical barrier
༻ can result from genetic mutation
༻ can result from habitat differentiation
༻ can result from sexual selection
what are the 2 models that represent the rate of evolutioin
༻ punctuated equilibrium - evolution occurs rapidly after a long period of stasis; species may experience no change for long periods of time
༻ gradualism - evolution occurs slowly over millions of years; ecological conditions change gradually over a long period of time
what is the stimulus of evolution according to the punctuated equilibrium theory
changing ecological conditions are the stimulus for evolution
when does divergent evolution occur
occurs when adaptation to new habitats results in phenotypic diversification
when are speciation rates rapid
during times of adaptive radiation as new habitats become available
