Ecosystems and Natural Selection

Flashcards based on lecture notes about ecosystems, gene pools, allele frequencies, natural selection, and the Hardy-Weinberg equation.

What is a gene pool?

All the genes and their different alleles, present in a population.

What kind of population has a large gene pool?

A population that shows substantial variety in its traits.

What is inbreeding and how does it affect the gene pool?

Mating with closely related organisms, narrowing the gene pool.

What is allele frequency?

A measure of the proportion of a specific version of a gene in a population.

How can gene pools change over time?

New alleles introduced by mutation, old alleles disappear as organisms die, natural selection favors advantageous alleles.

How does geographical isolation affect allele frequencies?

Geographically isolated populations can diverge due to different selective pressures in their environments.

What is the HLA (human leucocyte antigen) complex?

A set of genes on human chromosome 6 involved in immune system function and organ transplant compatibility.

What does it mean for a gene to be polymorphic?

Multiple variations of a gene or group of genes.

What is neo-Darwinism (the modern synthesis)?

The integration of genetics with natural selection.

What is an example of a change in allele frequency in a gene pool over time?

A change in allele frequency in a gene pool over time, exemplified by the peppered moth during the industrial revolution.

What is reproductive isolation?

A barrier that prevents populations of the same species from reproducing together, such as geographical, temporal, or behavioral barriers.

What is directional selection?

One phenotype is favored over another, leading to an increase in the frequency of the favored phenotype over time.

What is stabilizing selection?

An intermediate phenotype is favored over extreme phenotypes.

What is disruptive selection?

Two extreme phenotypes are favored over an intermediate phenotype.

What is a phenotype?

The expression of an organism's genotype.

What is a genotype?

The set of alleles an organism received from its parents.

What is the Hardy-Weinberg equation?

A mathematical equation used to calculate the frequencies of alleles within a population.

What are the two equations of the Hardy-Weinberg equation?

p + q = 1 and p² + 2pq + q² = 1

When does genetic equilibrium is not maintained?

When genotype frequencies in a population do not fit the Hardy-Weinberg equation.

What conditions must be met for Hardy-Weinberg equilibrium?

A population needs to be large, organisms must reproduce sexually, mating must be random, and there can be no migration into or out of the population.

What is artificial selection?

Humans breed organisms for desirable traits.

What is an example of natural selection?

Evolution of resistance in bacteria when an antibiotic is used