Influence of geography and environment on patterns of genetic differentiation in a widespread submerged macrophyte, Eurasian watermilfoil (Myriophyllum spicatum L., Haloragaceae).

Zhigang Wu,Xinwei Xu,Dan Yu,Xing Li

doi:10.1002/ece3.1882

Abstract

The effects of geographic and environmental variables on the pattern of genetic differentiation have been thoroughly studied, whereas empirical studies on aquatic plants are rare. We examined the spatial genetic differentiation of 58 Myriophyllum spicatum populations distributed throughout China with 12 microsatellite loci, and we analyzed its association with geographic distance, geographic barriers, and environmental dissimilarity using causal modeling and multiple matrix regression with randomization (MMRR) analysis. Two genetic clusters were identified, and their geographic distribution suggested mountain ranges as a barrier to gene flow. The causal modeling revealed that both climate and geographic barriers significantly influenced genetic divergence among M. spicatum populations and that climate had the highest regression coefficient according to the MMRR analysis. This study showed that geography and environment together played roles in shaping the genetic structure of M. spicatum and that the influence of environment was greater. Our findings emphasized the potential importance of the environment in producing population genetic differentiation in aquatic plants at a large geographic scale.

Highlights

Assessing the relative importance of environmental and geographic factors on the genetic structure of populations is one of the fundamental issues of population genetic studies
It is generally accepted that Isolation by distance (IBD) is one of the main factors that drive genetic divergence of natural populations
Significant values are presented in bold. They live in the discrete wetlands in terrestrial landscapes, which may reduce gene flow and strengthen the isolation (Young et al 1996)

Summary

Introduction

Assessing the relative importance of environmental and geographic factors on the genetic structure of populations is one of the fundamental issues of population genetic studies. Isolation by distance (IBD) is the common model of gene flow and often serves as an explanation for the effect of geographic isolation on the pattern of genetic differentiation (Slatkin 1987; Jenkins et al 2010; Lee and Mitchell-Olds 2011). The influences of the geographic factors besides distance and ecological selection on population genetic differentiation have been well discussed (Cushman et al 2006; McRae 2006; Storfer et al 2010; Lee and Mitchell-Olds 2011; Shafer and Wolf 2013; Wang and Bradburd 2014).

Objectives

Methods

Results

Conclusion