Divergent selection and genetic structure of Sideritis scardica populations from southern Balkan Peninsula as revealed by AFLP fingerprinting

Martina Grdiša,Ivan Radosavljević,Zlatko Šatović,Paschalina S Chatzopoulou,Klaudija Carović-Stanko,Zlatko Liber,Parthenopi Ralli,Gjoshe Stefkov

doi:10.1038/s41598-019-49097-x

Abstract

Sideritis scardica Giseb. is a subalpine/alpine plant species endemic to the central part of the Balkan Peninsula. In this study, we combined Amplified Fragment Length Polymorphism (AFLP) and environmental data to examine the adaptive genetic variations in S. scardica natural populations sampled in contrasting environments. A total of 226 AFLP loci were genotyped in 166 individuals from nine populations. The results demonstrated low gene diversity, ranging from 0.095 to 0.133 and significant genetic differentiation ranging from 0.115 to 0.408. Seven genetic clusters were revealed by Bayesian clustering methods as well as by Discriminant Analysis of Principal Components and each population formed its respective cluster. The exception were populations P02 Mt. Shara and P07 Mt. Vermio, that were admixed between two clusters. Both landscape genetic methods Mcheza and BayeScan identified a total of seven (3.10%) markers exhibiting higher levels of genetic differentiation among populations. The spatial analysis method Samβada detected 50 individual markers (22.12%) associated with bioclimatic variables, among them seven were identified by both Mcheza and BayeScan as being under directional selection. Four bioclimatic variables associated with five out of seven outliers were related to precipitation, suggesting that this variable is the key factor affecting the adaptive variation of S. scardica.

Highlights

Adaptive genetic variation evolves as a result of changing environmental conditions imposing selective pressure on individuals living in heterogeneous habitats[1]
In non-model organisms with a large number of individuals included in a study, Amplified Fragment Length Polymorphism (AFLP) technique has been frequently used in search of such genome regions under selection, when no prior knowledge of their position or importance exists[9,10]
The Mantel test was significant, and we found a positive correlation between pairwise genetic distances and spatial distances among all nine populations (r = 0.397, PMantel = 0.017), and 15.7% of the genetic variation could be explained by geographical distances (Supplementary Fig. S5)

Summary

Introduction

Adaptive genetic variation evolves as a result of changing environmental conditions imposing selective pressure on individuals living in heterogeneous habitats[1]. Elucidating the genetic basis of species adaptations to their environments, the nature of selection imposed by environmental changes and the capacity of a species to respond by evolutionary adaptation[2,3] is one of the challenging tasks of evolutionary biology. Such information may direct conservation strategies for the long-term persistence of species, especially for those facing rapid climate changes and are threatened with extinction and population decline. Numerous phylogeographical investigations carried out over the recent years, have confirmed the latter, elucidating the impact of both ancient and recent history on current European flora and fauna distribution patterns and of genetic variations[38,39,40,41,42]

Methods

Results

Discussion

Conclusion