Abstract
Litter meadows, historically established for litter production, are species-rich and diverse ecosystems. These meadows drastically declined during the last decades along with decreasing litter use in modern livestock housing. The aim of our study was to identify the drivers of genetic variation in litter meadow species. Therefore, we tested whether genetic diversity and differentiation depend on habitat age, landscape structure, habitat quality, and/or population size. We analysed 892 individuals of Angelica sylvestris, Filipendula ulmaria, and Succisa pratensis from 20 litter meadows across the Allgäu in Baden-Württemberg (Germany) using AFLP analyses. All study species showed moderate levels of genetic diversity, while genetic differentiation among populations was low. Neither genetic diversity nor differentiation were clearly driven by habitat age. However, landscape structure, habitat quality as well as population size revealed different impacts on the genetic diversity of our study species. Past and present landscape structures shaped the genetic diversity patterns of A. sylvestris and F. ulmaria. The genetic diversity of F. ulmaria populations was, moreover, influenced by the local habitat quality. S. pratensis populations seemed to be affected only by population size. All explanatory variables represent past as well as present gene flow patterns by anthropogenic land use. Therefore, we assume that genetic diversity and differentiation were shaped by both historical creation of litter meadows via hay transfer and present mowing with agricultural machines. These land use practices caused and still cause gene flow among populations in the declining habitats.
Highlights
Litter meadows constitute valuable habitats for many specialised, rare, and endangered plant and animal species (Wheeler 1988)
We found a positive impact of past connectivity on the genetic diversity in F. ulmaria complying with the findings of Münzbergová et al (2013), who observed a positive effect of historic habitat connectivity on genetic diversity of S. pratensis
Our study revealed significant and species specific impacts of landscape structure, habitat quality, and population size on genetic diversity
Summary
Litter meadows constitute valuable habitats for many specialised, rare, and endangered plant and animal species (Wheeler 1988). These semi-natural grasslands belong to the most species-rich ecosystems in Central Europe (Kull and Zobel 1991) and represent key areas for biodiversity conservation in agricultural landscapes, despite their comparably short land use history and limited spatial distribution. Habitat fragmentation limits pollen and seed exchange, restricting gene flow among populations (Schmitt 1983; Steffan-Dewenter and Tscharntke 1999; Willerding and Poschlod 2002; Honnay et al 2006) and increasing, the likelihood of inbreeding depression, the accumulation of deleterious mutations, and the extent of genetic drift (Young et al 1996; Picó and Van Groenendael 2007). The knowledge about potential impact factors on genetic variation patterns becomes highly relevant to protect genetic variation, as a fundamental level of biodiversity (May 1994)
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