Contrasting patterns of neutral and functional genetic diversity in stable and disturbed environments.

Anders Forsman,Jon Tinnert,Yeşerin Yıldırım

doi:10.1002/ece3.4667

Abstract

Genetic structure among and diversity within natural populations is influenced by a combination of ecological and evolutionary processes. These processes can differently influence neutral and functional genetic diversity and also vary according to environmental settings. To investigate the roles of interacting processes as drivers of population‐level genetic diversity in the wild, we compared neutral and functional structure and diversity between 20 Tetrix undulata pygmy grasshopper populations in disturbed and stable habitats. Genetic differentiation was evident among the different populations, but there was no genetic separation between stable and disturbed environments. The incidence of long‐winged phenotypes was higher in disturbed habitats, indicating that these populations were recently established by flight‐capable colonizers. Color morph diversity and dispersion of outlier genetic diversity, estimated using AFLP markers, were higher in disturbed than in stable environments, likely reflecting that color polymorphism and variation in other functionally important traits increase establishment success. Neutral genetic diversity estimated using AFLP markers was lower in disturbed habitats, indicating stronger eroding effects on neutral diversity of genetic drift associated with founding events in disturbed compared to stable habitats. Functional diversity and neutral diversity were negatively correlated across populations, highlighting the utility of outlier loci in genetics studies and reinforcing that estimates of genetic diversity based on neutral markers do not infer evolutionary potential and the ability of populations and species to cope with environmental change.

Highlights

Spatial and temporal changes in the environment can impact the size, stability, and connectedness of populations and thereby affect eco‐ logical processes such as dispersal, founder events, and extinction
Results of the nested AMOVA did not reveal any significant overall genetic differences depending on disturbance regime (Supporting Information Table S1), indicating that disturbed and stable envi‐ ronments were not populated by grasshoppers that represented different reproductively isolated evolutionary lineages
The lack of the genetic differentia‐ tion between different regimes is evident in multidimensional scaling ordination plots based on analysis of Jaccard distances for neutral and for outlier loci according to population and environ‐ mental state (Figure 2)

Summary

Introduction

Spatial and temporal changes in the environment can impact the size, stability, and connectedness of populations and thereby affect eco‐ logical processes such as dispersal, founder events, and extinction. Functional genetic and phenotypic variability can in turn have a positive impact on the fitness of popu‐ lations, by increasing evolvability, dampening fluctuations, increas‐ ing production of dispersers (emigrants), improving establishment success, and reducing extinction (Forsman, 2014; Forsman, Ahnesjö, Caesar, & Karlsson, 2008; Forsman & Wennersten, 2016; Forsman, Wennersten, Karlsson, & Caesar, 2012; Hughes, Inouye, Johnson, Underwood, & Vellend, 2008; Mills et al, 2018; Reed & Frankham, 2003; Rius & Darling, 2014; Vergeer, Sonderen, & Ouborg, 2004; Wennersten & Forsman, 2012; Whitlock, 2014; Willi, Van Buskirk, & Hoffmann, 2006)

Results

Discussion

Conclusion