High genetic diversity declines towards the geographic range periphery of Adonis vernalis, a Eurasian dry grassland plant (original) (raw)
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Folia Geobotanica a Journal of Plant Ecology and Systematics, 2014
A previous phylogeography and genetic diversity study of Chamaedaphne calyculata (Ericaceae) showed that populations over its geographic range were strongly separated into two groups: a Eurasian/NW North American group and a NE North American one corresponding with the disjunct distribution of Sphagnum-dominated peatlands in northwestern and central-eastern North America. Here, I have extended the survey and focused on the species' detailed postglacial origin and the effect of isolation on genetic diversity patterns, particularly within island-like populations at the western periphery of its range in Europe. Using AFLP markers, estimates of genetic diversity within 16 C. calyculata populations in the Eurasian group were low (percentage of polymorphic loci P PL =14.9-24.8 %, Nei's gene diversity H=0.060-0.119). Genetic diversity patterns within this species did not support the hypothesis that genetic diversity decreases towards the periphery of the range. Bayesian clustering analysis showed that population-level admixture was present in almost all studied 16 populations, suggesting multi-directional gene flow. On the other hand, the majority of assigned individuals (ca. 98 % of individuals) were offspring of the original residents, confirming that C. calyculata populations in the present day acted as discrete genetic units both in its continuous range and at its western periphery, and that gene flow was historic rather than contemporary in Eurasia. There was no correlation between genetic and geographic distance in the Eurasian group (r=0.02, P>0.05, Mantel test) nor at the western periphery (r=0.15, P>0.05, Mantel test). The isolation-by-distance (IBD) scatterplot matched Hutchinson and Templeton's interpretation (case III), and geographic distance between populations was not a reliable predictor of the degree of genetic differentiation between populations. It is suggested that the lack of IBD might be a result of random genetic drift Folia Geobot
Patterns of Genetic Variation across Altitude in Three Plant Species of Semi-Dry Grasslands
PLoS ONE, 2012
Background: Environmental gradients caused by altitudinal gradients may affect genetic variation within and among plant populations and inbreeding within populations. Populations in the upper range periphery of a species may be important source populations for range shifts to higher altitude in response to climate change. In this study we investigate patterns of population genetic variation at upper peripheral and lower more central altitudes in three common plant species of semidry grasslands in montane landscapes.
Many recent studies have explored the effects of present and past landscape structure on species distribution and diversity. However, we know little about the effects of past landscape structure on distribution of genetic diversity within and between populations of a single species. Here we describe the relationship between present and past landscape structure (landscape connectivity and habitat size estimated from historical maps) and current genetic structure in a perennial herb, Succisa pratensis. We used allozymes as co-dominant markers to estimate genetic diversity and deviation from Hardy-Weinberg equilibrium in 31 populations distributed within a 5 km 2 agricultural landscape. The results showed that current genetic diversity of populations was related to habitat suitability, habitat age, habitat size and habitat connectivity in the past. The effects of habitat age and past connectivity on genetic diversity were in most cases also significant after taking the current landscape structure into account. Moreover, current genetic similarity between populations was affected by past connectivity after accounting for current landscape structure. In both cases, the oldest time layer (1850) was the most informative. Most populations showed heterozygote excess, indicating disequilibrium due to recent gene flow or selection against homozygotes. These results suggest that habitat age and past connectivity are important determinants of distribution of genetic diversity between populations at a scale of a few kilometres. Landscape history may significantly contribute to our understanding of distribution of current genetic structure within species and the genetic structure may be used to better understand landscape history, even at a small scale.
Conservation Genetics
Arnica montana is a clonal, self-incompatible herb of economic and intrinsic ecological value which is declining in large parts of its range. With the employment of microsatellite markers, we characterized the population structure and distribution of genetic diversity of 40 populations of A. montana sampled throughout Europe. We detected a clear geographical pattern of isolation and strong population structure, indicating limited gene flow. We also observed a negative latitudinal gradient in genetic diversity. Such patterns can be explained by paleo-historical colonization routes following the last glacial maximum, with regions characterized by higher genetic diversity corresponding to former glacial refugia. We recommend the implementation of conservation measures such as assisted gene flow in the populations characterized by low genetic diversity under consideration of the observed population structure. For the populations where high levels of genetic diversity are still retained,...
2013
A highly selfing breeding system affects gene flow, which may have consequences for patterns of genetic variation and differentiation on both the population and species level. Feather grasses (Stipa spp.) are dominant elements of Eurasian steppes that persist in Central Europe in scattered isolated populations that are of great conservation interest. Cleistogamy is common in the Stipa pennata group, the phylogeny of which is largely unresolved. Intraspecific patterns of genetic variation can be characterised by lack of gene flow due to selfing, but also by large-scale historical migrations and long-term isolation. We analysed both 5 species within the S. pennata group and 33 populations of Stipa pulcherrima sampled across a large part of its range. Using AFLP markers we assessed phylogenetic relationships of the S. pennata group and patterns of genetic variation within and among populations.
Ecosphere, 2014
Analyzing the pattern and causes of phenotypic and genetic variation within and among populations might help to understand life history variability in plants, and to predict their responses to changing environmental conditions. Here we compare phenotypic variation and genetic diversity of the widespread herb Plantago coronopus across Europe, and evaluate their relationship with environmental and geographical factors. Genetic diversity was estimated in 18 populations from molecular markers with AFLP. Phenotypic variation was measured in a subset of 11 populations on six life history traits (plant size, plant growth, fecundity, seed mass, mucilage production and ratio between two functionally different seed morphs). To account for ecological and geographical correlates, we estimated variability in local temperature, precipitation and intraspecific competition, and accounted for the central vs. peripheral position of populations. Phenotypic variation and genetic diversity were not significantly correlated within populations throughout the species' range. Phenotypic variation was positively linked to precipitation variability, whereas genetic diversity was correlated with the position of populations, suggesting that both types of variation are shaped by different processes. Precipitation seems to have acted as a selective agent for variation within populations in most life history traits, whereas the species' post-glacial demographic history has likely reduced genetic diversity in northern peripheral populations with respect to central ones. The positive association between precipitation variability and phenotypic variation also suggests that plant populations may have higher adaptive potential in ecologically variable rather than stable environments. Our study offers an additional criterion when predicting the future performance of species under environmental changes.
AimGrasslands have been pivotal in the development of herbivore breeding since the Neolithic and are still nowadays the most widespread agricultural land-use across Europe. However, it remains unclear whether the current large-scale genetic variation of plant species found in natural grasslands of Europe is the result of human activities or natural processes.LocationEurope.TaxonLolium perenne L (perennial ryegrass).MethodsWe reconstructed the phylogeographic history of L. perenne, a dominant grassland species, using 481 natural populations including 11 populations from closely related taxa. We combined the Genotyping-by-Sequencing (GBS) and Pool-sequencing (Pool-seq) methods to obtain high-quality allele frequency calls of ~ 500 k SNP loci. We performed genetic structure analyses and demographic reconstructions based on the site frequency spectrum (SFS). We additionally used the same genotyping protocol to assess the genomic diversity of a set of 32 cultivars representative of the L...