Abstract
Environmental gradients are important factors that can potentially influence the genetic diversity and differentiation of populations. The present study examines the effect of environmental heterogeneity of the Hyrcanian forests on populations of Circaea lutetiana L. (Onagraceae). Using morphometrics, scanning electron microscopy (SEM) of leaf epidermis, and molecular markers, we analyzed genetic diversity and differentiation among nine populations from environmentally divergent habitats. Three different gene pools were observed. Our results indicate that the genetic structure is significantly correlated to environmental factors, but not to the geographical distance. Genetic clustering in C. lutetiana is affected by temperature, humidity, elevation, and average annual rainfall. Overall, our data indicate that gene flow does not contribute to explaining spatial patterns of genetic structure and the adaptation to the environment is the main factor shaping the genetic structure of the C. lutetiana populations. The populations belonging to each of the three gene pools have similarities in microclimate parameters, despite their geographical proximity, and populations from the same genetic pool can be up to 470 km apart. This evidence, as well as morphological and genetic similarities of the populations with greater geographical distance, suggest the possibility of cryptic speciation in this species.
Highlights
The maintenance of genetic diversity is a fundamental prerequisite for species evolution that determines the ability of natural populations to cope with multiple biotic and abiotic stress factors (Frankham & al. 2002; Khan & al. 2015)
Leaf epidermal scanning and two genetic markers, start codon targeted (SCoT) and direct amplification of minisatellite DNA (DAMD), we aim to answer the following questions: (i) Is there a significant relationship between morphological and genetic diversity of populations; (ii) how is genetic diversity distributed among and within populations of C. lutetiana; (iii) is genetic diversity related to geographical distance of population or to differences in climate conditions
Among them 17 features were selected based on Principal components analysis (PCA)-biplot (Fig. 1)
Summary
The maintenance of genetic diversity is a fundamental prerequisite for species evolution that determines the ability of natural populations to cope with multiple biotic and abiotic stress factors (Frankham & al. 2002; Khan & al. 2015). The maintenance of genetic diversity is a fundamental prerequisite for species evolution that determines the ability of natural populations to cope with multiple biotic and abiotic stress factors The genetic diversity of populations is mainly controlled by gene flow, genetic drift and natural selection Landscape barriers and environmental isolation of populations can limit gene flow Such adaptive genetic changes are often fixed within populations through natural selection resulting in genetic differentiation and diversity among populations from different environmental ranges. Temperature and moisture are among the main environmental factors that can affect genetic differentiation and diversity among populations Temperature and moisture are among the main environmental factors that can affect genetic differentiation and diversity among populations (Still & al. 2005)
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