Population Genetics Flashcards

Flashcards about Population Genetics, Hardy Weinberg, and Population Change.

Hardy-Weinberg Principle

The principle that frequencies of alleles and genotypes in a population remain constant from generation to generation if certain conditions are met.

A population can evolve

What is the consequence if the conditions for Hardy-Weinberg Equilibrium are NOT met?

List the conditions for Hardy-Weinberg Principle

Large population, random mating, no mutations, no migration, and no natural selection.

Frequency of the dominant allele

What does 'p' represent in the Hardy-Weinberg equation p + q = 1?

Frequency of the recessive allele

What does 'q' represent in the Hardy-Weinberg equation p + q = 1?

Frequency of the homozygous dominant genotype

What does 'p^2' represent in the Hardy-Weinberg equation p^2 + 2pq + q^2 = 1?

Frequency of the homozygous recessive genotype

What does 'q^2' represent in the Hardy-Weinberg equation p^2 + 2pq + q^2 = 1?

Frequency of the heterozygous genotype

What does '2pq' represent in the Hardy-Weinberg equation p^2 + 2pq + q^2 = 1?

Genetic Drift

A change in the genetic makeup of a population resulting from chance events.

Founder Effect

Few individuals from a large population leave to establish a new population and the allele frequency in the new population is different than the original population.

Bottleneck Effect

Drastic reduction in population size due to environmental factors, where frequencies of alleles in the surviving population is very different from the original population.

Sexual Selection

Selection of a trait that increases reproductive success.

Migration (Gene Flow)

The movement of members of a species into (immigration) or out of (emigration) a population, altering allele frequencies.

Population Size

The number of individuals of a specific species occupying a given area or volume at a given time.

Population Density

The number of individual organisms in a given area or volume.

Dp = N/A or Dp = N/V, where N is the number of individuals, A is the area, and V is the volume.

What is the formula for population density (Dp)?

ΔN = [natality (n) + immigration (i)] - [mortality (m) + emigration (e)]

What is the formula for calculating the change in population (ΔN)?

Growth Rate (gr)

Change in the number of individuals in a population (ΔN) over a specific time frame (Δt).

gr = ΔN / Δt

What is the formula for Growth Rate (gr)?

Per Capita Growth Rate (cgr)

Rate of change per individual in a population.

cgr = ΔN / N

What is the formula for Per capita growth rate (cgr)?

Open Population

The population is influenced by factors of natality (birth), mortality (death), immigration (organisms in) and emigration (organisms out)

Closed Population

The population is influenced by natality and mortality only.

Biotic Potential

Each species has a maximum reproductive rate that could be achieved under ideal conditions.

Exponential Growth

A population is growing at its biotic potential with unlimited biotic and abiotic resources.

Carrying Capacity (K)

Number of organisms that a population can sustainably support over a period of time.

Environmental Resistance

The influence of biotic and abiotic factors that limit the size of the population.

Density Dependent Factors

Any biotic factors brought on by population size that may limit further growth and lead to reduced population numbers. Ex: Competition, Predation, Diseases

Density Independent Factors

Any abiotic factors that affect a population regardless of its size. Ex: Temperature changes, Drought, Floods, Forest Fires

r-selected characteristics

Organisms increase in populations rapidly with exponential growth in unstable environments.

K- selected characteristics

Maximizes population size near carrying capacity. Competition among individuals is relatively strong and found in stable environments.

Interspecific Competition

Competition between different species for limited resources.

Intraspecific Competition

Competition between organisms of the same species for limited resources.

Mutualism (+/+)

A symbiotic relationship where BOTH species benefit from the interaction.

Commensalism (+/0)

A symbiotic relationship where ONE organism benefits and the other organism is unaffected.

Parasitism (+/-)

A symbiotic relationship where one organism benefits and the other organism is HARMED.

Ecological Succession

The slow, progressive replacement of one community by another during the development of vegetation in an area.

Primary Succession

NO SOIL present at the beginning of succession, begins with ROCK. Pioneer species include Lichen and Mosses.

Secondary Succession

Begins with SOIL present from partially destroyed communities → leads to more rapid community development.

Climax Communities

The stage in ecological development that is stable and self-supporting. The FINAL stage in succession with greater species diversity.