Natural Selection

Question 1

Purifying Selection

Answer 1

Selective removal of alleles that are deleterious. This can result in stabilizing selection through the purging of deleterious variations that arise.

Question 2

Stabilizing Selection

Answer 2

Type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

Question 3

Directional Selection

Answer 3

Mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

Question 4

Disruptive Selection

Answer 4

Happens when two extremes of a phenotype are favored relative to the intermediate type from the original population. In this case, the variance of the trait increases, and the population is divided into two distinct groups.

Question 5

Mutation-Selection Balance

Answer 5

Equilibrium in the number of deleterious alleles in a population that occurs when the rate at which deleterious alleles are created by mutation equals the rate at which deleterious alleles are eliminated by selection.

Question 6

Heterozygote Advantage

Answer 6

Case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype, often due to overdominance.

Question 7

Negative Frequency-Dependent Selection

Answer 7

Fitness of a phenotype decreases as it becomes more common. The trait is only advantageous as long as it is the minority.

Question 8

Force of Mutation

Answer 8

Genetic variation will persist if the force of mutation is strengthened or that of selection weakened. For polygenic characteristics the effective strength of mutation is proportional to the number of genes involved -> each gene involved has an independent chance of mutating

Question 9

Inconsistent Selection

Answer 9

The environment changes fast over a short period of time so the selection that begun must be reversed.

Question 10

Sexually Antagonistic Selection

Answer 10

The optimal phenotype may not be the same for males and females. An allele that increases height may be optimal to increase fitness amoung men, but not in women. Thus we will always have variation.

Question 11

Reproductive success

Answer 11

The passing of genes on to the next generation in a way that they can too pass on those genes. This not solely the number of offspring produced by an individual, but also, the probably reproductive success of those offspring, making mate choice (a form of sexual selection) an important factor in this success.

Question 12

Human sickle-cell diesease

Answer 12

Heterozygote: immune to malaria and can’t get the disease, Homozygote: immune to malaria but could get the disease

Question 13

Fitness of alleles

Answer 13

Quantitative representation of natural and sexual selection within evolutionary biology, can be defined with respect to either a genotype or a phenotype.

Question 14

Components of natural selection

Answer 14

Heritability, Variation, and Competition

Question 15

Force of mutation

Answer 15

For polygenic characteristics, the effective strength of mutation is proportional to the number of genes involved. Genetic variation will persist if the force of mutation is strengthened or that of selection is weakened.

Question 16

Adaptionist stance

Answer 16

If some feature or behaviour is commonly found in a type of organism, then it is probably an efficient design solution to some problem that that organism has faced. If it were not, then the alleles building that feature would have been out-competed by alternatives that built a
different feature

Question 17

Phenotypic gambit

Answer 17

The strategy of forming adaptationist hypothesis directly about the
phenotype without needing to know what the genetic or
developmental mechanisms that produce the phenotype are (validity of this can not be taken for granted).

Question 18

Time lags

Answer 18

Period of time between one event and another

Question 19

Phenotypic plasticity

Answer 19

Ability of one genotype to produce more than one phenotype when
exposed to different environments.

Question 20

Genetic correlation

Answer 20

Estimate of the additive genetic effect that is shared between our pair of traits. For example, self-reported mood and physiological reactivity could both be heritable, but their genetic correlation can tell you if they are likely to share the same genes

Question 21

Shape of the adaptive landscape

Answer 21

Used to visualize the relationship between genotypes and reproductive success.

Question 22

Optimality modeling

Answer 22

Tool used to evaluate the costs and benefits of different organismal
features, traits, and characteristics, including behaviour, in the natural
world. This evaluation allows researchers to make predictions about an organism’s optimal behaviour or other aspects of its phenotype

Question 23

Sexual dimorphism

Answer 23

Condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs.

Question 24

Sexual selection

Answer 24

Natural selection on the ability to gain mates

Question 25

Sexy son hypothesis

Answer 25

A female’s ideal mate choice among potential mates is one whose genes will produce male offspring with the best chance of reproductive success.

Question 26

Batemen’s principle

Answer 26

The principle that males gain more reproductive success from each additional mating partner than females do.

Question 27

Good genes hypothesis

Answer 27

Explanation which suggests that the traits females choose when selecting a mate are honest indicators of the male’s ability to pass on genes that will increase the survival or reproductive success of her offspring.

Question 28

Biological adaptations

Answer 28

Attribute that helps a creature to survive and reproduce, become better suited or fit to an environment as an historical end product of the process of evolution.

Question 29

Sex-ratio

Answer 29

Ratio of males to females in a population. In most sexually reproducing species, the ratio tends to be 50:50. This tendency is explained by Fisher’s principle.

Question 30

Hitch-hiking traits/ genetic hitchhiking

Answer 30

an allele changes frequency not because it itself is under natural
selection, but because it is near another gene that is undergoing a
selective sweep and that is on the same DNA chain.

Question 31

Trade-off traits

Answer 31

Arises when two traits have opposite effects on fitness but are genetically correlated with each other.

Question 32

Malthus

Answer 32

English cleric and scholar, influential in the field of political economy and demography, proposed the principle that human populations grow exponentially while food production grows at an arithmetic rate.

Question 33

Local resource competition

Answer 33

Relatices compete with one another since the local resources are limited

Question 34

Local resource enhancement

Answer 34

occurs when relatives help on another instead competing with one another in LRC

Question 35

Sex-role reversal

Answer 35

When males do all the post-fertilization care the cost asymmetry between the sexes is reversed (i.e., the males are choosier; Females will be larger/ more ornamented etc.)

Question 36

Nomological networks

Answer 36

Representation of the concepts (constructs) of interest in a study, their observable manifestations, and the interrelationships among and between these.

Question 37

Absolute fitness

Answer 37

How many genes contribute to the gene pool of the next generation.

Question 38

Relative fitness

Answer 38

The contribution an individual makes to the gene pool of the next generation, relative to the other contributions of other individuals.