Pack 20 - Natural Selection and Speciation

Question 1

what is natural selection?

Answer 1

that some individuals are more likely to reproduce then others
they show different reproductive success

Question 2

what is directional selection?

Answer 2

one extreme of an organisms phenotype is selected and the other is acted against

Question 3

what is stabilizing selection?

Answer 3

when the intermediate phenotype is selected and both extremes of the phenotype are acted against

Question 4

what is disruptive selection?

Answer 4

both extreme are selected

Question 5

what is a species defined as?

Answer 5

group of organisms that can reproduce naturally and produce a fertile offspring

Question 6

what are the stages that lead to allopatric speciation?

Answer 6

geographical isolation
no interbreeding occurs
different variations may occur in each of the new populations which results in new beneficial alleles
the two populations then under go different selection pressures
different features and alleles will be an advantage in the different environments
in each population the organisms with the beneficial alleles will reproduce and pass on the alleles increasing the allele frequency
if the two populations come into contact again they wouldn’t be able to produce fertile offspring

Question 7

how is sympatric speciation similar to allopatric and how is it different?

Answer 7

the same processes occur into creating a new species
the two populations are isolated reproductively within the same area - through a mutation that doesn’t allow the two populations to create fertile offspring with each other