bio chapter 24

allopatry

populations that are geographically separated

allopatric separation

speciation that begins with geographic isolation

2 ways to start allopatric speciation

1. dispersal- movement of individuals from one place to another

2. vicariance- physical splitting of habitat

biogeography

study of how species and populations are distributed geographically

how does gene flow affect genetic divergence?

gene flow reduces the divergence of populations

the condition in which two or more populations live in the same geographic area, or close enough to permit interbreeding

sympatry

what is sympatric speciation

speciation occurs even though populations live within same geographic area

niche

describes the range of ecological resources that a species can use and the range of conditions it can tolerate

polyploidy

condition of processing more than two complete sets of chromosomes, caused by massive error in mitosis or meiosis

2 types of pilyploids

1. autopolyploid- when mutation results in doubling of chromosome number and the chromosomes all come from same species

2. allopolyploid- when parents of different species mate and an error in mitosis occues . results in nonsterile offspring w two sets of chromosomes

reinforcement

hybrid zone

what splitting event results from a two step process

speciation

• genetic isolation occurs when a theres a barrier to gene flow that isolates two populations within a species. absence of gene flow means that allleles are no longer exchanged

• genetic divergance occurs when mutation, natural selection, and genetic drift occur in each othe the isolated populations- if isolated populations diverge sufficently, distinct species form

species

• how do you identify species? 3

evolutionarily independent population or group of populations

• biological species concept

• morphospecies concept

• phylogenetic species concept

biological species concept

• uses reproductive isolation to identify a species

prezygotic

prevents individuals of different species from mating successfully

post zygotic

hybrid offspring of matings between members of different species either dont survive or dont reproduce

hybrid sterility

• post or pre zygotic isolation ?

• post zygotic isolation

• hybrid offspring mature but are sterile as adutls

• like horses and donkeys can mate and make mules but they arent sterile

hybrid iviability

• post or pre zygotic ?

post zygotic

• hybrid offspring do not develop normally and die at some point during early development

• when ring necked cloves mate with rock cloves, less than 6 percent of egss hatch

gametic barrier

• mating fails bexause eggs and sperm are incompatible

• differentce in the bind in protein determine