BIO220 (Genomes to Ecosystems) - SimUText Terminology

Definition of census population

Total number of individuals in a population

Definition of effective population size (Ne)

Idealized population (i.e., random mating, equal operational sex ratio, etc.) that loses heterozygosity at the same rate as the observed population.

Function of effective population size

Produce an increasingly accurate measure of allele frequency (i.e., genetic diversity) over a period of time relative to the census population.

Definition of fixation

When all individuals in the population are homozygous for an allele.

Definition of founder effect

When a few individuals from the source population, establish a new population in isolation from the source population

Phenomena observed between the allele frequencies present in the founder population relative to the source population

Sampling error, resulting in genetic drift.

Definition of genetic drift

Mechanism of evolution which alters in the composition of allele frequencies in a population over a period of time due to sampling error (ex. random event, phenotype does not inform fittness)

Definition of natural selection

Occurs when some individuals in the population leave more offspring (i.e., differential fitness), altering the composition of allele frequencies within the subsequent generation (i.e., gene pool)

Definition of operational sex ratio

Relative number of sexually reproductive females and sexually reproductive males.

Definition of physical sex ratio

Relative number of females and males, regardless of whether or not they are sexually active

Definition of population bottleneck

When a sudden and considerable reduction in a population’s size occurs.

Definition of sampling error

When the subset of a population sample is not representative of the source population (e.g., genetic drift), resulting in deviations in allele frequencies.