Gene Pools

Population

Group of organisms of same type living in same place at same time

Gene Pools

A set of genes within a population of organisms.

Allele Frequency

the percentage of organisms who possess a particular gene in a gene pool.

Alelles

Within gene pool there is VARIATION in the genotypes of the organisms. Different versions of the same gene are called ALLELES.

Variation in Populations

Allele frequencies in a population are dynamic and change over time.

Variations in allele frequency can be caused by the following factors: selection pressures, Mutations, Random genetic drift (including the Founder Effect), Gene flow and barriers to flow

Selection Pressures

Factors that make a certain phenotype more advantageous over alternate phenotypes. either NATURAL or ARTIFICIAL.

Natural Selection

Factors in a population’s environment cause specific phenotypes to be advantageous for survival or reproduction. An organism with genes that code for advantageous phenotype are more likely to survive and reproduce, and pass their genotype onto offspring – affecting allele frequency.

Artificial Selection

Also called selective breeding. The intentional reproduction of individuals in a population that have desirable traits (by humans).

Mutations

Random changes in an individual organisms genes or chromosomes.

The resulting new genotype creates a new phenotype, may be beneficial, neutral or detrimental to survival and reproduction.

Random Genetic Drift

Changes in occurrence of genotypes in small populations due to LUCK, not selection.

Founder Effect

occurs when new colony is started by few members of og population. This small population size means that the colony may have:

1. reduced genetic variation from og population.

2. a non-random sample of genes in og population

Gene Flow and Barriers

Gene flow is when gene pools gain genes from or lose genes to other gene pools (populations in different locations), increases changes in allele frequencies.

BARRIERS to gene flow decrease changes to allele frequencies, gene pools become isolated from other gene pools which prevents gene flow.

Immigration

A population gaining new genes from an external source - genes flow in (organisms coming into population)

Emigration

Population loses genes to other gene pools - genes flow out (organisms move out)

Geographical Barrier

A physical barrier preventing gene flow between (and isolates) populations

Sociocultural Barrier

Cultural or social barriers (i.e. religion, social status, etc) which affect which people will or will not reproduce with each other