speciation

Question 1

What causes natural selection

Answer 1

Competition for resources

Disease

Predators

Question 2

How does variation in a pop occur

Answer 2

Wide range of variation in phenotype due to both genetic and environmental factors

Question 3

What are the sources of genetic variation

Answer 3

mutation, meiosis and random fusion

Question 4

How does predation etc cause natural selection.

Answer 4

Selective pressure

Those with phenotypes have selective advantages are more likely to survive

Likely to produce more offspring and pass on favourable alleles to next gen

Causes change in alleles frequency

Question 5

What is differential reproductive success

Answer 5

Not all individuals are likely to reproduce — changes in allele frequency within a gene pool

Question 6

What is disruptive selection

Answer 6

When individuals which contain alleles coding for either extreme trait are more likely to survive and pass on alleles

Causes allele frequency to change and more individuals posses allele for extreme trait and middling trait allele becomes less frequent

Continued disruptive selection ca ultimately lead to speciation

Question 7

What is speciation

Answer 7

The process that results in the creation of a new species

Question 8

When does speciation occur

Answer 8

When one orig pop of same species become reproductively isolated — two pops of same species that can’t breed together

Over time will accumulate differences in their gene pools to extent over many gens are unable to interbreed and make fertile offspring

Question 9

What are the two ways that pops can become reproductively isolated

Answer 9

Geographically (allopatric speciation)

Due to changes of reproductive mechanisms (sympatric speciation)

Question 10

What is allopatric speciation

Answer 10

Pop could become geographically isolated by new mountain range or body of water which separates original pop

Question 11

What is sympatric speciation

Answer 11

Pops can become reproductively isolated due to differences in behaviour — may not be separated geographically but still unable to reproduce

Random mutation could impact reproductive behaviour (diff courtship ritual or fertile at different times of the year)

Means won’t reproduce and will be no gene flow between pops overtime accum diff mutations etc

Question 12

What is genetic drift

Answer 12

The change in the allele frequency within a population between generations (always genetic differences between parents and offspring)

Will always be genetic drift between gens but substantial genetic drift results in evolution

Question 13

What size pop is better for genetic drift

Answer 13

The smaller the pop the bigger the impact allele freq changes have proportionally and this is why evolution occurs more rapidly in smaller pops