6.2 speciation Flashcards
what is speciation?
speciation is the splitting of a genetically similar population into two or more populations leading to genetic differentiation and is no longer able to interbreed and produce fertile offspring
what is formed when speciation occurs?
a new species is formed when speciation occurs
what are sub-species?
sub-species are populations which are different but are still able to interbreed
what changes leads to a new species being formed?
sufficient genetic, behavioural and physiological changes in the population so they can no longer interbreed produces a new species
what are the two main types of isolation mechanisms?
the two main types of isolating mechanisms are geographical isolation and reproductive isolation
when does geographical isolation occur?
geographical isolation occurs when physical barriers divide a population
what are examples of physical barriers that lead to geographical isolation?
examples of physical barriers that lead to geographical isolation include lakes, rivers, oceans and mountains
what may the genetic changes be a result of when geographical isolation occurs?
genetic changes may be a result of mutation, selection and genetic drift
what type of speciation is geographical isolation?
geographical isolation is a type of speciation called allopatric speciation
what does allopatric mean?
allopatric means in different countries
what is an example of a population that has undergone allotropic speciation?
finches have undergone allotropic speciation where the head shape of some species are different
what is reproductive isolation?
reproductive isolation is where changes in the population prevents interbreeding
what changes may cause reproductive isolation?
changes which may cause reproductive isolation include biological, behavioural and genetic changes
what is an example of a behavioural change which may lead to reproductive isolation?
some organisms of a population may change their foraging behaviour and become active at dawn, dusk or at night than during the day then they are unlikely to interbreed with members of the other populations
what is example of a genetic change that can also need to reproductive isolation?
an example of a genetic change that can also lead to reproductive isolation is a change in the chromosome number
what may a change in the chromosome number of a population lead to?
a change in the chromosome number may:
- prevent gamete fusion
- make the zygotes less visitor, so they fail to develop
- lead to infertile hybrid offspring with an odd number of chromosomes, so that chromosomes pairing during meiosis cannot occur
what may the mating between members of the reproductively isolated population also be prevented by?
the mating between members of the reproductively isolated populations may also be prevented by mutations
what do mutations lead to changes in?
mutations may lead to changes in:
- courtship behaviour
- animal genitalia or plant flower structure
what is speciation resulting from reproductive isolation called?
speciation resulting from reproductive isolation is called sympatric speciation
what does sympatric mean?
sympatric means in the same country
