Do island populations have less genetic variation than mainland populations?

Frankham, Richard

doi:10.1038/hdy.1997.46

Cited by 862 publications

(707 citation statements)

References 126 publications

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“…Our results indicated that low genetic variation may also have been a contributor, as previously suggested (Simberloff 1988). It is also possible that some of this low genetic variation may reflect the smaller effective population size of island populations (Frankham 1997). Unfortunately, no known samples exist from mainland populations (Gross 1928).…”

Section: Discussionmentioning

confidence: 99%

Low Genetic Variation in the Heath Hen Prior to Extinction and Implications for the Conservation of Prairie-Chicken Populations

Johnson

Dunn

2006

Conserv Genet

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Low genetic variation is often considered to contribute to the extinction of species when they reach small population sizes. In this study we examined the mitochondrial control region from museum specimens of the Heath Hen (Tympanuchus cupido cupido), which went extinct in 1932. Today, the closest living relatives of the Heath Hen, the Greater (T. c. pinnatus), Attwater's (T. c. attwateri) and Lesser (T. pallidicinctus) Prairie-chicken, are declining throughout most of their range in Midwestern North America, and loss of genetic variation is a likely contributor to their decline. Here we show that 30 years prior to their extinction, Heath Hens had low levels of mitochondrial genetic variation when compared with contemporary populations of prairie-chickens. Furthermore, some current populations of Greater Prairie-chickens are isolated and losing genetic variation due to drift. We estimate that these populations will reach the low levels of genetic variation found in Heath Hens within the next 40 years. Genetic variation and fitness can be restored with translocation of individuals from other populations; however, we also show that choosing an appropriate source population for translocation can be difficult without knowledge of historic population bottlenecks and their effect on genetic structure.

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Section: Discussionmentioning

confidence: 99%

Low Genetic Variation in the Heath Hen Prior to Extinction and Implications for the Conservation of Prairie-Chicken Populations

Johnson

Dunn

2006

Conserv Genet

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“…Its range is becoming increasingly fragmented as a result of habitat loss and highway construction, causing the fragmented populations to become genetically isolated and increasing their risk of local extinction from random processes (Velázquez, 1993;Frankham, 1997). However, genetic variation in R. diazi is similar to that of more widespread and less fragmented genera of Mexican rabbits, such as Sylvilagus and Lepus (Cervantes et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Factors affecting the distribution and abundance of the Endangered volcano rabbit Romerolagus diazi on the Iztaccihuatl volcano, Mexico

Hunter

Cresswell

2014

Oryx

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The volcano rabbit Romerolagus diazi is an Endangered species endemic to Mexico, with a range of , 400 km 2 . We investigated threats from destruction, fragmentation and degradation of habitat, hunting, and cattle grazing intensity in relation to the distribution and abundance of the volcano rabbit on the Iztaccihuatl volcano. Faecal pellet counts were taken as a proxy for rabbit abundance in 1,718 random 0.2 m 2 quadrats at 859 sampling points along 25 transects, covering an area of c. 100 km 2 at altitudes of 3,400-4,000 m. Presence of the species was significantly associated with absence of closed forest, absence of long grass types (not bunchgrass), shallow inclines, absence of cattle grazing, lower altitude, low hunting pressure (measured by proximity to ranger station), absence of bare ground and, contrary to previous findings, increased frequency of fire. The species was significantly more abundant in habitats with a greater percentage cover of zacaton (bunchgrass) and short grass types. It was significantly less abundant in areas with more hunting (measured by proximity to ranger station) and cattle grazing. Key conservation priorities are therefore the protection of the subalpine zacaton bunchgrass-dominated habitat type, strict enforcement of hunting laws and the removal of livestock from relevant national park boundary areas. However, the results suggest that frequent fires have a significant positive effect on the occurrence of the volcano rabbit as a result of habitat improvement and this is often a consequence of anthropogenic management of land for cattle grazing.

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“…Several studies have also reported correlations between surrogates of population size and genetic diversity, such as range size in plants, island area (both positive), rates of chromosomal evolution and body size (both negative) (see Frankham, 1996; Table 1). Further, average genetic diversity of island populations (presumed to have smaller N) is lower than that for mainland populations (Frankham, 1997).…”

Section: Correlations Of Genetic Diversity With Population Size and Fmentioning

confidence: 99%

How closely does genetic diversity in finite populations conform to predictions of neutral theory? Large deficits in regions of low recombination

Frankham

2011

Heredity

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Levels of genetic diversity in finite populations are crucial in conservation and evolutionary biology. Genetic diversity is required for populations to evolve and its loss is related to inbreeding in random mating populations, and thus to reduced population fitness and increased extinction risk. Neutral theory is widely used to predict levels of genetic diversity. I review levels of genetic diversity in finite populations in relation to predictions of neutral theory. Positive associations between genetic diversity and population size, as predicted by neutral theory, are observed for microsatellites, allozymes, quantitative genetic variation and usually for mitochondrial DNA (mtDNA). However, there are frequently significant deviations from neutral theory owing to indirect selection at linked loci caused by balancing selection, selective sweeps and background selection. Substantially lower genetic diversity than predicted under neutrality was found for chromosomes with low recombination rates and high linkage disequilibrium (compared with 'normally' recombining chromosomes within species and adjusted for different copy numbers and mutation rates), including W (median 100% lower) and Y (89% lower) chromosomes, dot fourth chromosomes in Drosophila (94% lower) and mtDNA (67% lower). Further, microsatellite genetic and allelic diversity were lost at 12 and 33% faster rates than expected in populations adapting to captivity, owing to widespread selective sweeps. Overall, neither neutral theory nor most versions of the genetic draft hypothesis are compatible with all empirical results.

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Do island populations have less genetic variation than mainland populations?

Cited by 862 publications

References 126 publications

Low Genetic Variation in the Heath Hen Prior to Extinction and Implications for the Conservation of Prairie-Chicken Populations

Low Genetic Variation in the Heath Hen Prior to Extinction and Implications for the Conservation of Prairie-Chicken Populations

Factors affecting the distribution and abundance of the Endangered volcano rabbit Romerolagus diazi on the Iztaccihuatl volcano, Mexico

How closely does genetic diversity in finite populations conform to predictions of neutral theory? Large deficits in regions of low recombination

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