ch 24 Flashcards
(20 cards)
members of a biological species are ___
reproductively compatible
cannot interbreed with other populations
speciation
origin of new species
evolutionary theory must explain how new species originate and how populations evolve
forms of prezygotic barriers
reproductive isolation
temporal isolation
habitat isolation
behavoral isolation
mechanical isolation
gametic isolation
reproductive isolation
existence of biological factors that impede two species from producting viable fertile hybrid
temporal isolation
species that breed at different times of day, different seasons, or different years cannot breed together
habitat isolation
two species encounter each other rarely
behavioral isolation
courtship rituals and other behaviors unique to a species are effective barriers
mechanical isolation
morphological differences can prevent successful mating
gametic isolation
sperm of one species may not be able to fertilize egg of another species
forms of postzygotic barriers
reduced hybrid viability
reduced hybrid fertility
hybrid breakdown
reduced hybrid viability
genes of the different parent species may interact and impair the hybrid’s development
reduced hybrid fertility
even if hybrids are vigorous/survive, they may be steriile
hybrid breakdown
some first gen hybrids are fertile, but when they mate the offspring of next gen are feevle or sterole
how can speciation occur
allopatric speciation
sympatric speciation
allopatric speciation
different locations
gene flow is interupted or reduced when a population is divided into geographically isolated subpopulations
one or both populations may undergo evolutionary changes and may not mate again when introduced
how to determine if allopatric speciation has occured
determine if populations have changed enough that they no longer have potential to interbreed and produce fertile offspring
sympatric speciation
speciation takes place in geographically overlapping populations
mechanisms for speciation include chromosomal change and nonrandom mating that reduces gene flow
how can sympatric speciation occur
from the appearance of new ecological niches
isolation can allow subpopulations to use resources not used by parent population
summary of difference of allopatric and sympatric
allopatric = a new species forms while geographically isolated from its parent population
sympatric = a reproductive barrier isolates a subset of a population without geographic separation
adaptive radiation
evolutionary process in which the original species gives rise to many new species, each of which is adapted to a new habitat and a new way of life
