Mechanisms of Evolution

Question 1

Biological Species

Answer 1

Group of populations all of whose members actually or potentially interbreed and produce fertile offspring. Potentially form a single gene pool.

Question 2

Population Genetics

Answer 2

Study of evolution within a biological species

Question 3

Units of Evolution

Answer 3

Individuals do not evolve, they develop. Alleles move freely through a population in time-can be natural selection OR random processes.

Question 4

Evolution

Answer 4

Change in allele frequency within a population

Question 5

Populations

Answer 5

Species are groups of these. Populations are units of evolution-evolution below species level is known as microevolution

Question 6

What are new alleles generated by?

Answer 6

Mutations-can be harmful or neutral. Provides selective advantage.

Question 7

What does the Hardy-Weinberg Equilibrium model?

Answer 7

Allele frequencies in a population which is NOT evolving.

Question 8

What does the Hardy-Weinberg Equilibrium model require?

Answer 8

Random mating, very large population size, no immigration or emigration, no natural selection, no mutations.

Question 9

What are the two equations for Hardy-Weinberg Equilibrium?

Answer 9

p+q=1 and p2+2pq+q2= 1. q=homozygous recessive and p= homozygous dominant.

Question 10

Why use Hardy-Weinberg if real populations don’t follow this model?

Answer 10

Deviations from Hardy-Weinberg suggest population is evolving. Can be used to estimate number of recessive alleles in a population-useful in public health. Basis for a complex math science of population genetics, which helps us to understand microevolution.

Question 11

Genetic Drift

Answer 11

Allele frequencies vary greatly from generation to generation in small isolated populations due to chance. Chance disappearance of particular genes or alleles due to individuals dying or not reproducing. Can also be due to immigration bringing in new alleles.

Question 12

Bottleneck Effect

Answer 12

Drift due to periods of extreme sudden population contraction followed by pop growth (ex: weather, illness).

Question 13

Founder Effect

Answer 13

Population has few founders-accidental colonization of an island. Population allele frequencies may not reflect those of ancestral populations-sampling error.

Question 14

Fitness

Answer 14

Relative contribution made by an individual in a population to the next gene pool of next generation-how many descendents an individual has.

Question 15

Natural Selection is…

Answer 15

Microevolutionary-changes through feedback. Also works upon variation as it is expressed in phenotype-genotype follows.

Question 16

Adaptive Change

Answer 16

Frequency of favoured alleles rises, deleterious alleles decrease.

Question 17

Stabilizing Selection

Answer 17

Tends to be seen in stable environment, not favouring extreme phenotypes. Population becomes less variable.

Question 18

Directional Selection

Answer 18

Stable or steadily changing environment, favouring an extreme phenotypic range.

Question 19

Disruptive Selection

Answer 19

Seen in heterogenous environments. Eliminates middle of distribution. Population becomes more variable, divided into morphs.

Question 20

Rosemary and Peter Grant

Answer 20

Studied medium ground finches on Daphne Major. Found that they were able to demonstrate morphological changes due to natural selection as environmental conditions changed.

Question 21

Heterozygote Advantage

Answer 21

Heterozygote for a particular gene has selective advantage over homozygotes for either allele. Hidden variation must be heterozygous for sickle cell anaemia to be resistent to malaria.

Question 22

Frequency dependent selection

Answer 22

Most common morph in a population in any given population is selected against. Rare morph has selective advantage until it becomes common in turn.

Question 23

Sexual Dimorphism

Answer 23

Difference in appearance between sexes, not directly associated with reproductive organs. Produced by different selection pressures on sexes, may be result of competition for reproductive opportunities producing secondary sexual characteristics.Useful in competition with one sex, not useful otherwise.

Question 24

Intrasexual Competition

Answer 24

Members of one sex compete directly with one another for opportunities to mate-opposite sex dates winner. (men in a bar fighting over hot woman)

Question 25

Intersexual Selection

Answer 25

Members of one sex choose mates according to some criterion-results in secondary sex characteristics which are an apparent burden but actually signal good genotype (fancy ass birds being fancy).