Selection/speciation

Question 1

process of natural selection

Answer 1

mutations take place
some are better adapted for survival
more likely to reproduce and pass on alleles
over time frequency of advantageous alleles increases in population

Question 2

define disruptive selection

Answer 2

favours individuals at both extremes of the mean

those nearer mean are selected against

Question 3

define directional selection

Answer 3

when there is an environmental change
selective pressures for species to change in response to it
favours individuals that are different
individuals at one extreme are selected for
individuals at other extreme are selected against
mean shifts

Question 4

define stabilising selection

Answer 4

when there is no change in the environment
it remains stable
phenotypes closest to mean are favoured
individuals with extreme phenotypes are selected against
distribution curve becomes narrower

Question 5

define speciation

Answer 5

evolution of a new species from an existing one

Question 6

what causes speciation

Answer 6

geographical isolation (allopatric isolation)
sympatric isolation (reproductively separated in the same area

Question 7

process of speciation

Answer 7

2 gene pools cannot mix
different selection pressures
selection for specific alleles
allelic frequency changes
eventually become s different they are different species and cannot interbreed

Question 8

define gene pool

Answer 8

all the alleles in a population

Question 9

define species

Answer 9

a group of individuals with similar genes that are able to breed with each other to produce fertile offspring