Population Structure and Social Relations Lecture Notes

Practice flashcards covering population genetics, Hardy-Weinberg Equilibrium, behavioral ecology, and sociality from the EEMB 120 Class 7 lecture.

Population structure

The static demographic makeup of a population, including age, sex, geographic distribution, allele frequencies, and other composition factors at a specific moment in time.

Population genetics

A field that describes how genetic variation is distributed in a population and how that variation changes over time.

Alleles

Different versions of DNA coding for the same trait, such as B and b.

Genotype

The specific combination of alleles an individual inherited (e.g., BB, Bb, or bb).

Homozygous genotype

A genotype consisting of two of the same allele (e.g., BB or bb).

Heterozygous genotype

A genotype consisting of two different alleles (e.g., Bb).

Phenotype

The physical expression or outward appearance of an individual's genotype.

Trait

A heritable feature of an organism that can be measured on a single individual.

Hardy-Weinberg Equilibrium (HWE)

A principle stating that genotype frequencies will be directly proportional to allele frequencies when no evolution is occurring.

Expected HWE Genotype Frequencies

If $p$ and $q$ are allele frequencies, the expected frequencies are: Homozygous $p = p^2$, Heterozygous $qp = 2pq$, and Homozygous $q = q^2$.

HWE Assumptions

Five conditions required for evolution not to occur: 1. Mating is random; 2. No mutations are occurring; 3. Large population size; 4. No gene flow; 5. No natural selection.

Behavioral ecology

The study of social relations mediated by behavior occurring between organisms and between organisms and their environment.

Sociobiology

A branch of behavioral ecology focusing on social relations between individuals, such as dominance relations, reproductive interactions, and cooperative behaviors.

Intraspecific interactions

Interactions between members of the same species, such as mating, competition, or courtship displays.

Interspecific interactions

Interactions between members of different species, including mutualism, competition, and predation.

Intrasexual selection

A scenario where individuals of one sex compete among themselves for mates, often favoring weapons or large body size.

Intersexual selection

The process of mate choice where individuals of the 'choosier' sex select partners based on specific traits like ornamentation, songs, or gifts.

Evolutionary trade-offs

The concept that developing 'attractive' traits may be detrimental in other areas, such as increased predation risk for brightly colored guppies.

Sociality

The development of group social behaviors among individuals within a population, beginning with living in groups and cooperation.

Cooperative breeder species

Species where individuals help in the process of producing or raising offspring that are not their own.

Inclusive fitness

Fitness determined by an individual's ability to survive and reproduce plus the survival of their genetic relatives.

Kin selection

A type of selection that favors helping behavior directed toward genetic relatives.

Hamilton’s rule

The theory that kin selection is favored only when the benefits of helping outweigh the costs to the helper.

Eusociality

A complex form of sociality characterized by multiple generations living together, cooperative care of young, and division into reproductive and nonreproductive castes.

Castes

Highly stratified social structure groups in eusocial species, often based on body size or specialized roles like defense versus reproduction.

What are the three components required for eusociality?

Eusociality requires: 1. multiple generations living together, 2. cooperative care of young, 3. division into reproductive and non-reproductive castes.