Extinction Vortices are a means through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. Developed by M. E. Gilpin and M. E. Soulé in their (now) famous 1986 paper Minimal viable populations: Processes of species extinction, there are currently four classes of extinction vortices. The first two (R and D) deal with environmental factors that have an effect the ecosystem or community level, such as disturbance, pollution, habitat loss etc. Whereas the second two (F and A) deal with genetic factors such as inbreeding and outbreeding depression, genetic drift etc. Some conservation biologists have been concerned about the Amazon rainforest. ... Conservation genetics is a science that aims to apply genetic methods to deal with the maintenance, loss, and restoration of biodiversity. ... This is a list of ecologists who have articles, in alphabetical order by surname. ... 1986 (MCMLXXXVI) was a common year starting on Wednesday of the Gregorian calendar. ... An environment is a complex of external factors that acts on a system and determines its course and form of existence. ... In ecology, the word ecosystem is an abbreviation of the term, ecological system. ... This article needs a complete rewrite for the reasons listed on the talk page. ... Water pollution Pollution is the release of environmental contaminants. ... This article is in need of attention. ... Inbreeding Depression is reduced fitness in a given population as a result of breeding of related individuals. ... Outbreeding depression This phenomenon can occur in two ways. ... Genetic drift is the term used in population genetics to refer to the statistical drift over time of allele frequencies in a finite population due to random sampling effects in the formation of successive generations. ...

Types of Vortex

• R Vortex: The R vortex is initiated when there is a disturbance which facilitates a lowering of population size (N) and a corresponding increase in Variability (Var(r)). This event can make populations vulnurable to additional disturbances which will lead to an additionally decreased value for N and an increased value for Var(r). A prime example of this would be the disruption of sex ratios in a population away from 50:50.

• D Vortex: The D vortex is initiated when N decreases and Var(r) increases such that the spatial distribution (D) of the population is increased and the population becomes 'patchy' or fragmented. Within these fragments local extinction rates increase which, through positive feedback, further increases D.

• F Vortex: The F vortex is initiated by a decrease in N which leads to an increase in heterozygosity and genetic drift, which results in increased degrees of inbreeding depression and an increase in population genetic load, which over time will result in extinction.

• A Vortex: The A vortex is a result of an increase in genetic drift and a corresponding decrease in genetic variance which leads to a decrease in population adaptive potential, and eventual extinction. This vortex can result from biological invasion, resulting in large scale hybridization and outbreeding depression.

Sex ratio by country for total population Sex ratio is the ratio of males to females in a population. ... Positive feedback is a type of feedback. ... Heterozygote cells are diploid or polyploid and have different alleles at a locus (position) on homologous chromosomes. ... In population genetics, genetic load or genetic burden is a measure of the cost of lost alleles due to selection (selectional load) or mutation (mutational load). ... In probability theory and statistics, the variance of a random variable is a measure of its statistical dispersion, indicating how far from the expected value its values typically are. ... The term invasive species refers to a subset of those species defined as introduced species or non-indigenous species. ... In biology, hybrid has three meanings. ...

Reference

Gilpin, M. E. and Soulé, M. E., (1986). "Minimum Viable Populations: Processes of Species Extinction." pp. 19-34 in M. E. Soulé, ed. Conservation Biology: The Science of Scarcity and Diversity. Sinauer, Sunderland, Mass.