Bio 1 : Chapter 22

Prezygotic isolating mechanisms prevent the formation of what

Zygotes

Postzygotic isolating mechanisms

hybrid inviability or infertility

geographic isolation can accelerate speciation because

it restricts gene flow

allopatric speciation is thought to occur when

populations are geographically isolated and diverge because of natural selection and random processes

what would happen when two populations that have evolved complete reproductive isolation come into contact

the two populations will remain distinct species

how do prezygotic isolating mechanisms prevent successful interspecies hybridization

Although fertilization is successful, the resulting hybrid is unable to to develop or reproduce

when members of a population do not mate with each other or cannot produce fertile offspring, they are

reproductively isolated

what process can promote speciation through random changes between isolated populations

genetic drift

which processes can lead to speciation in natural populations

genetic drift natural selection

Prezygotic isolating mechanisms

Ecological isolation Behavioral isolation Temporal isolation Mechanical isolation Prevention of gamete fusion

2 main types of reproductive isolating mechanisms based on when they act relative to the production of a zygote

Prezygotic isolating mechanisms postzygotic isolating mechanisms

how can natural selection play a role in speciation

as a species adapt to different environments, they can accumulate differences that lead to speciation

which form of isolation occurs when differences in mating rituals, courtship songs, or chemical and electric communication prevent members of two different species from interbreeding

behavioral

according to the _____ species concept, species are distinguished by whether gene flow occurs between population

biological

the ___ species concept defines a species as group of individuals that is able to interbreed, producing viable and fertile offspring

biological

gene flow

decreases differences between populations

reinforcement

increases differences between populations

mechanisms that prevent genetic exchange between members of different species are termed reproductive _______ mechanisms and often play a role in plant and animal speciation

isolating

limitations of biological species concept

it is difficult codetermine whether geographically isolated species would interbreed in nature as they do In artificial settings interspecies hybridization occurs in nature more often than was thought reproductive isolation cannot explain speciation in organisms that reproduce asexually

a Prezygotic isolating mechanism that physically prevents mating due to structure differences of reproductive organs ______ isolation

mechanical

A category of reproductive isolating mechanisms called _ isolating mechanisms block the development of a viable and fertile individual after fertilization has taken place.

postzygotic

incomplete reproductive isolation may become completely effective over time when natural selection act upon less fit hybrid individuals, this process is called

reinforcement

how does ecological isolation prevent successful interspecies hybridization

the parent species do not come in contact with one another

if two species that have evolved over time to be completely reproductively isolated suddenly come in contact with one another

they will remain distinct species