Hardy Weinberg and gene pool

Gene pool

The total genetic information found in a population

Variation

Helps to ensure the survival of a population, assumes that the greater the variation the more likely it is that some members will survive the environmental change however not always true

Mutations

Alteration of an organism, occasionally mutations are beneficial, helping the individual to better adapt to a changing environment

Assortive mating

Selection of mates based in particular phenotypes; can be either positive or negative to the health if the population

Inbreeding

When selection of breeding partners is narrowed to within a very select group ex. Inbred dogs, royal families, Huterite colonies; often show a decline in fertility, growth and survival

Hybrid vigor

When two inbred lines are crossed ex. Mixed breeds

Hardy-Weinberg Law

Conditions for the law to work: random mating, absence of selection, no migration, large populations, no mutations and equal viability; if all conditions are met, gene pool is stable and no evolution will occur

Natural Selection

Occurs when: limited resources, competition for limited resources, genetic variation, better adapted organisms survive, the better adapted (fit) survive, the fit have more offspring, offspring inherit parent’s fitness

Directional Selection

Favours individuals with a trait that is on one extreme of a range, causing the population to shift in that direction; uncommon individuals are now becoming more common

Stabilizing selection

Favours the average or “middle” traits (the means have a higher frequency) while selecting against extremes. Leads to reduced variation and “stabilizes” population’s traits over time

Disruptive selection

Favours both extremes while selecting against the means (average). Resulting in 2 distinct groups over time

Gene flow

Describes when individuals or their genes move from one population to another, introducing new traits or alleles into that population

Genetic drift

Random fluctuations in gene frequencies of SMALL populations. Some organisms may choose not to reproduce which has great effect on small populations. Does NOT generally occur in large populations as more individuals can reproduce

Founder effect

When a small group of organisms from a larger population develop a new population in a once uninhabited area. May have limited genetic compared to original population. Traits from new population become more common even if they differ from the previous population

Bottle-neck effect

When a population is drastically reduced in size due to a disaster or event, reducing the gene pool. Future populations develop from this narrow gene pool resulting in offspring containing limited variety of alleles. LOW DIVERSITY. No gene flow can occur due to parent population not being available.

Micro evolution

Small changes in the gene pool of a population. Affects a single group of organisms NOT the entire population. Can be due to mutation, gene flow, selection or genetic drift; ex. White moths slowly becoming darker

Macro evolution

Increased changes in a gene pool of a population. Results in a new species, new traits or extinction of the old species. Happens over a long period of time, ex. Dinosaurs into chickens

Gause’s principle

States that two species cannot occupy the same niche (food source, habitat, limited resources) without eliminating the other. Those better suited for that resource will survive while the other dies or adapts to another environment.

Coexistence Principle

Species that co-exist for a long time have differences in their niches even if it doesn’t appear so. Ex. Plants in a forest all coexist

Instraspecific

Competition between individuals within the SAME species ex. Fishes of the same species competing for food

Interspecific competition

Competition between DIFFERENT species ex. Carnivores competing with other carnivores (wolves vs coyotes)

Commensalism

One benefits while the other is NOT harmed. Two species that live together sharing food, shelter, support or transport ex. Barnacles attach on whales to access nutrient rich waters