Low genetic diversity in an endangered species: recent or historic pattern?

Abstract

Examining patterns of genetic diversity has become an integral component of many management plans concerning endangered species, yet interpreting the processes underlying such patterns remains challenging. We demonstrate low genetic diversity in a critically endangered small mammal population. A common interpretation of this pattern would be that it is the result of a known, recent decline in this population. We test this interpretation and fnd it to be incorrect. Instead, by using museum voucher specimens, we show that the pattern of low genetic diversity is historical. This study demonstrates the importance of choosing appropriate reference groups by which to interpret modern levels of genetic diversity in endangered species. We conclude that analysis of archival specimens may be essential in cases where genetic diversity is driving conservation management decisions because it may allow us to distinguish the efects of low genetic diversity from the process of losing diversity. We recognize that this approach can be limited due to several sampling issues: archival material may not be available, statistical power needs to be evaluated, sample sizes and sequence lengths may be suboptimal due to intrinsic difculties associated with amplifcation of degraded DNA. These issues are discussed and possible solutions identifed.

Low genetic differentiation in a sedentary bird: house sparrow population genetics in a contiguous landscape

“…A population decline may result in an increase in differentiation among populations (Bouzat et al, 1998;Muñ os-Fuentes et al, 2005;Martínez-Cruz et al, 2007). Knowledge of the population structure before a decline is essential, as sometimes the pattern of low genetic diversity can be present already in historical samples (Matocq and Villablanca, 2001). Whether decline-derived loss of genetic diversity is found, possible conservation actions need to be considered more population-wise; for example, is it better to manage diverged and unique populations or the larger and more connected ones.…”

Geographic pattern of genetic diversity in natural populations of Rosewood (Aniba rosaeodora), in the Central Amazonia

“…nevertheless, low genetic diversity is likely in threatened species or those that suffered intense and predatory exploitation historically (Frankham 1995;matocq & villablanca, 2001;Baucon et al, 2005). Paradoxically, in tropical species that have suffered intense exploitation [as well as non-tropical ones reviewed by avise (2004)], recent studies using molecular tools have shown high diversity values, e.g., Dinizia excelsa (Fabaceae; Dick et al, 2003) and mahogany (Swietenia macrophylla King, meliaceae;lemes et al, 2003).…”

“…as a result, Rosewood is considered a high priority for collection and in situ conservation in Brazil (vieira, 1999). although there is considerable evidence about loss of variability in other threatened species or those that have suffered heavy exploitation (Frankham, 1995;matocq & villablanca, 2001;avise, 2004;Baucon et al, 2005), for Rosewood no data is available.…”

Genetic Diversity in Swallenia alexandrae (Poaceae, Chloridoideae), a Narrow Endemic From the Eureka Dunes (Inyo County, California)

“…Because S. alexandrae exhibits a combination of very low genetic diversity and infrequent establishment, ex situ conservation of seeds may be appropriate (Kruckeberg and Rabinowitz 1985;Waller et al 1987;Moran et al 1989;Newman and Pilson 1997). Care should be taken to collect seeds from all populations in order to conserve existing ecotypes (Matocq and Villablanca 2001;Hufford and Mazer 2003), and any revegetation efforts must include appropriate placement of seeds and seedlings (Ellstrand and Elam 1993). It may be possible to place seedlings in parts of the dunes not yet colonized by Salsola spp.…”