Theme 4C

Question 1

What is genetic drift

Answer 1

Changes in allele frequencies due to chance

Question 2

What are the two types of genetic drift

Answer 2

Bottleneck and founder effect

Question 3

What is a bottleneck

Answer 3

Temporary reduction is population causes drift, reduces genetic variation and causes genetic differences between populations

Question 4

What is the founder effect

Answer 4

Reduction in genetic variation that results when a small part of a large population is used to establish a new colony

Question 5

What is interbreeding

Answer 5

Mating with relatives, non random

Question 6

Why are small populations more susceptible to genetic drift and interbreeding

Answer 6

Alleles are more likely to go extinct with a small sample size (genetic drift) and interbreeding is caused by small populations, also can lead to interbreeding depression

Question 7

What is directional selection

Answer 7

Individuals of one extreme phenotype are favoured

Question 8

What is stabilizing selection

Answer 8

Individuals with intermediate phenotype favoured

Question 9

What is disruptive selection

Answer 9

Both extreme phenotypes favoured

Question 10

What is sexual selection

Answer 10

Favours individuals with specific traits that enhance their ability to mate with individuals of the other sex
Males have low energy required gametes - sperm
Females have high energy required gametes - eggs

Question 11

What is sexual dismorphism

Answer 11

Males and females of the same species look different, traits produced often diminish survival
Reproductive success = fecundity + mating sucess

Question 12

What is intrasexual selection

Answer 12

Competition between sexes for mating opportunities

Question 13

What is intersexual selection

Answer 13

Preferential mating (mate choice)

Question 14

What is reproductive isolation

Answer 14

Two similar species that have evolved to be unable to reproduce

Question 15

What are the prezygotic mechanisms of reproductive isolation

Answer 15

Prevent mating or fertilization
Habitat, behaviour, temporal, mechanical, or gametic isolation

Question 16

What are postzygotic mechanisms for reproductive isolation

Answer 16

Prevent zygote development or reproduction
Reduce hybrid viability, reduced hybrid fertility or hybrid breakdown

Question 17

What is speciation

Answer 17

Process by which new species arise

Question 18

What is allopathic speciation

Answer 18

Physical barrier that divides geographical range (vicarience event)

Question 19

What is Sympatric speciation

Answer 19

NO geographical barrier
Polymorphism affects fitness and mating is discouraged —> polyploidization

Question 20

What is ployploidization

Answer 20

Meiosis fails and an organism produces 2n gametes

Question 21

What is an autopolyploid

Answer 21

Occurs when a 2n gamete is fertilized with another 2n gamete
Forms 2 diploid gametes instead of 4 haploid ones
Can only mate with other autoploids

Question 22

What is alloploidization

Answer 22

Similar to autopolyploidization but first involves the mating between two closely related species

Question 23

What is the biological species concept

Answer 23

Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other groups

Question 24

What is the morphological species concept

Answer 24

Species are discrete types of organisms defined by unique reliable morphological characters

Question 25

What is outbreeding

Answer 25

Mating with individuals more distantly related (non-relatives)

Question 26

What is assorative mating

Answer 26

Individuals with similar genotypes and/or phenotypes mate with each other more frequently than would be expected under random mating pattern (eg body size)

Question 27

Does inbreeding affect genotype and alleles frequencies

Answer 27

It effects genotype frequencies but not alleles frequencies (by itself at least)

Question 28

What is inbreeding depression

Answer 28

Rare deleterious alleles are more likely to combine in homozygotes (expression of homozygous recessive)

Question 29

What is hybrid breakdown

Answer 29

Hybrids can mate, but offspring have reduced fitness

Question 30

What is a vicariance event

Answer 30

Splitting of a population so that the two “new” populations evolve separately

Question 31

What is the phylogenetic species concept

Answer 31

Shared evolutionary history

Question 32

What species concept did Leneus use

Answer 32

Morphological species concept

Question 33

What is gene flow

Answer 33

Shifts alleles and genotypes away from HWE Exchange of alleles between populations increases genetic diversity

Question 34

What are the 5 types of mutations in DNA

Answer 34

1) point mutation/substitution 2) insertion 3) deletion 4) inversion 5) duplication

Question 35

What is balancing selection

Answer 35

More then one allele is actively maintained in a population 1) heterozygotes have higher relative fitness 2) when different alleles are favoured in different environments 3) when the rarity of a phenotype provides a selective advantage

Question 36

What is the phylogenetic species concept

Answer 36

Uses both morphological and genetic sequence data

Question 37

What is a phylogenetic species

Answer 37

A cluster of populations that emerge from the same branch

Question 38

What is a ring species

Answer 38

Species that have a ring shaped geographical surrounds uninhabitable terrain

Question 39

What is clinical variation

Answer 39

A smooth pattern of variation across a geographical gradient when a species is distributed over a large, environmentally diverse area Eg. Species in colder environments often have larger bodies and shorter limbs

Question 40

What is a species cluster

Answer 40

A group dog closely related species recently descended from a common ancestor (can evolve quickly)

Question 41

What is secondary contact and what can it tell us

Answer 41

Contact after a period of geographical isolation Provides a test of whether the genes in the populations have diverged enough to make them reproductively isolated (allopathic speciation)

Question 42

What is the banding pattern in animals

Answer 42

Patterns in DNA used to identify how closely related 2 species are