'Genetic diversity' is a characteristic of
ecosystems and
gene pools that describes an attribute which is commonly held to be advantageous for survival -- that there are many different versions of otherwise similar
organisms. For example, the
Great Irish Famine (1845-1849) can be attributed in part to the fact that the
genetic distance of all potatoes in the country was very low, making it easier for one
virus to infect and kill much of the
crop.
The academic field of
population genetics includes several hypotheses regarding genetic diversity. The
neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions.
Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at a particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it.
Frequency-dependent selection is the hypothesis that as alleles become more common, they become less fit. This is often invoked in host-pathogen interactions, where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it is able to overcome that allele.
There are many different ways to measure genetic diversity, some of which are listed below. The modern causes for the loss of animal genetic diversity have also been studied and identified.
[1][2]
See also
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Biodiversity
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Genetic distance
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Ecosystem diversity
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Ewens' sampling formula
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Heterozygote
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Nucleotide diversity
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Population genetics
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Small population size
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Species diversity
References
1. Groom, M.J., Meffe, G.K. and Carroll, C.R. (2006) ''Principles of Conservation Biology (3rd ed.)''. Sunderland, MA: Sinauer Associates. Website with additional information: http://www.sinauer.com/groom/
2. Tisdell, C. (2003). Socioeconomic causes of loss of animal genetic diversity: analysis and assessment. ''Ecological Economics'' 45(3): 365-376.