Genetic population structure, fitness variation and the importance of population history in remnant populations of the endangered plant Silene chlorantha (Willd.) Ehrh. (Caryophyllaceae)

Abstract

Habitat fragmentation can lead to a decline of genetic diversity, a potential risk for the survival of natural populations. Fragmented populations can become highly differentiated due to reduced gene flow and genetic drift. A decline in number of individuals can result in lower reproductive fitness due to inbreeding effects. We investigated genetic variation within and between 11 populations of the rare and endangered plant Silene chlorantha in northeastern Germany to support conservation strategies. Genetic diversity was evaluated using AFLP techniques and the results were correlated to fitness traits. Fitness evaluation in nature and in a common garden approach was conducted. Our analysis revealed population differentiation was high and within population genetic diversity was intermediate. A clear population structure was supported by a Bayesian approach, AMOVA and neighbour-joining analysis. No correlation between genetic and geographic distance was found. Our results indicate that patterns of population differentiation were mainly caused by temporal and/or spatial isolation and genetic drift. The fitness evaluation revealed that pollinator limitation and habitat quality seem, at present, to be more important to reproductive fitness than genetic diversity by itself. Populations of S. chlorantha with low genetic diversity have the potential to increase in individual number if habitat conditions improve. This was detected in a single large population in the investigation area, which was formerly affected by bottleneck effects.

Genetic diversity of calcareous grassland plant species depends on historical landscape configuration

“…Neither the current habitat area, nor the actual number of individuals per grassland fragment had an impact on genetic diversity. Similar findings have been reported in other fragmentation studies [12, 42]. Lag effects, a delayed reaction of genetic diversity on the reduction of population size [43], which is comparable to the extinction debt reported for species diversity [44, 45], could be a reason for the observed lack of a relationship between genetic diversity and population size [46].…”

Habitat Fragmentation Differentially Affects Genetic Variation, Phenotypic Plasticity and Survival in Populations of a Gypsum Endemic

“…In other words, the population’s genetic variation and evolutionary potential of important functional traits (and their plasticity) were not related to population fitness. Altogether, and contrary to expectations, these results suggest that genetic variation –either molecular or quantitative– and phenotypic plasticity may be in some instances poor predictors of population survival, and are in agreement with other studies where correlations between quantitative genetic variation and various components of plant fitness were not found (Lauterbach et al, 2011; Walisch et al, 2015). More generally, our findings call for caution on the use of standing genetic variation and/or plasticity, as is usually done in biological conservation contexts, to forecast the future performance of populations.…”

High genetic diversity declines towards the geographic range periphery of Adonis vernalis, a Eurasian dry grassland plant

“…Due to their threatened status, dry grassland plants in Europe have been studied extensively in the last two decades, e.g. Astragalus exscapus (Becker 2003), Eryngium campestre (Bylebyl et al 2008), Iris aphylla (Wr oblewska & Brzosko 2006), Silene chlorantha (Lauterbach et al 2011), S. otites (Lauterbach et al 2012) and Stipa capillata . Yet, few studies have compared the genetic diversity and differentiation in peripheral dry grassland populations to that found in range-central steppe populations.…”