mechanisms of evoltuion

Question 1

gene pool

Answer 1

the collection of genes (traits) found in a population

Question 2

5 mechanisms of evolution exist:

Answer 2

• natural selection
• mutation
• gene flow (migration)
• genetic drift (founder effect and bottle neck effect)
• sexual selection

Question 3

types of natural selection (patterns)

Answer 3

• stabilizing
• directional
• disruptive

Question 4

stabilizing selection

Answer 4

moderate trait selected for (favoured) in a population, for example finches with medium sized beaks

Question 5

directional selection

Answer 5

extreme trait selected for (favoured) in a population, for example thick beak in finches

Question 6

disruptive/diversifying selection

Answer 6

both extreme traits selected for (favoured) in a population, for example thin and thick beaks in finches

Question 7

mutation

Answer 7

• a change in DNA structure which changes the genotypes and one types of a population
• mutations introduce brand new alleles into a population
• this causes changes to their genotype and phenotype
• mutations are the original source of variation which leads to changes in traits

Question 8

gene flow (migration)

Answer 8

-changes to the gene pool (alleles) of a population due to migration

Question 9

genetic drift

Answer 9

• change in alleles due to chance
• changes are more pronounced in small populations
• usually results in the decrease of genetic variation
• two types: bottleneck and founder effects

Question 10

bottleneck effect

Answer 10

• a severe event (ie natural disaster) decreases a population
• only a small sample of alleles remain in the population
• by chance certain genes (traits) may then be represented more frequently than others among the survivor
• creates random genetic change without regard to adaptation
• severe genetic bottleneck occurred in northern elephant seals from fur hunting

Question 11

founder effect

Answer 11

• when a few new individuals find a new location
• the founders will carry some, but not all, of the alleles from the original populations gene pool
• the founder effect occurs frequently on islands
• example: unusually high frequency of polydactylism (6 fingers or toes) in pennsylvania amish country
• interbreeding contributes to small gene pool which reduces variation
• low fertility, deformities and genetic diseases are commune when the gene pool shrinks

Question 12

the effect of genetic drift is inversely related to population size

Answer 12

large populations=small effects

small populations=large effects

Question 13

non random mating (sexual selection)

Answer 13

• mating based on sexual characteristics and behaviours
• sexual selection-favours selection of traits deemed desirable by females (or traits that have outcompeted other male competitors)
• ex blister beetles are more likely to mate with partners of the same size
• ex male cardinals, male peacock, male mandrill

Question 14

is survival of the fittest always true

Answer 14

no because genetic drift is change by chance