Abstract
Small, isolated, and/or peripheral populations are expected to harbour low levels of genetic variation and may therefore have reduced adaptability to environmental change, including climate warming. In the Arctic, global warming has already caused vegetation change across the region and is acting as a significant stressor on Arctic biodiversity. Many of the rare plants in the Arctic are relicts from early Holocene warm periods, but their ability to benefit from the current warming is dependent on the viability of their populations. We therefore examined Amplified Fragment Length Polymorphism (AFLP) data from regional red listed vascular plant species in the High Arctic archipelago of Svalbard and reference populations from the main distribution area of: 1) Botrychium lunaria, 2) Carex capillaris ssp. fuscidula, 3) Comastoma tenellum, 4) Kobresia simpliciuscula ssp. subholarctica, 5) Ranunculus wilanderi, 6) Sibbaldia procumbens and 7) Tofieldia pusilla In addition, we gathered population size data in Svalbard. The Svalbard populations had low genetic diversity and distinctiveness and few or no private markers compared to populations outside the archipelago. This is similar to observations in other rare species in Svalbard and the genetic depletion may be due to an initial founder effect and/or a genetic bottleneck caused by late Holocene cooling. There seems to be limited gene flow from other areas and the Svalbard populations should therefore be considered as demographically independent management units. Overall, these management units have small and/or few populations and are therefore prone to stochastic events which may further increase vulnerability to inbreeding depression, loss of genetic variation, and reduced evolutionary potential. Our results support theory predicting lower levels of genetic diversity in small, isolated and/or peripheral populations and may be of importance for management of other rare plant species in the Arctic.
Highlights
Small, isolated and/or peripheral populations may harbour low levels of genetic variation due to genetic drift, inbreeding, bottlenecks and founder effects (Ellstrand and Elam 1993; Frankham 1996; Cole 2003; Frankham et al 2010)
The number of populations found in Svalbard (Table 1) ranged from one
The population sizes ranged from less than five individuals (T. pusilla, Ossian Sarsfjellet) to more than 2000 (C. capillaris ssp. fuscidula, Bockfjorden). These new population size data led to a downgrading of C. capillaris ssp. fuscidula, T. pusilla, S. procumbens, C. tenellum and R. wilanderi in the 2010 Red List [see Supporting Information—Table S1]
Summary
Small, isolated and/or peripheral populations may harbour low levels of genetic variation due to genetic drift, inbreeding, bottlenecks and founder effects (Ellstrand and Elam 1993; Frankham 1996; Cole 2003; Frankham et al 2010). Levels of genetic variation are key information when trying to understand and predict the response of small, isolated and/or peripheral populations to future environmental change. Genetic data may give valuable information about species history (e.g. population fragmentation, bottlenecks, refugia and range shifts; Young et al 1996; Petit et al 2003; Meirmans et al 2011), and is essential for delineating conservation units like evolutionarily significant units (ESUs) and management units (MUs) (Moritz 1994; Sherwin and Moritz 2000; Funk et al 2012). Management units are important for the long-term persistence of the species and are often useful for shortterm management goals like monitoring habitat and population status (Funk et al 2012)
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