Cryptic invasion drives phenotypic changes in central European threespine stickleback

Kay Lucek

doi:10.1007/s10592-016-0837-2

Abstract

Cryptic invasions are commonly associated with genetic changes of the native species or genetic lineage that the invaders replace. Phenotypic shifts resulting from cryptic invasions are less commonly reported given the relative paucity of historical specimens that document such phenotypic changes. Here, I study such a case in two populations of threespine stickleback from central Europe, comparing contemporary patterns of gene flow with phenotypic changes between historical and contemporary population samples. I find gene flow from an invasive lineage to be associated with significant phenotypic changes, where the degree of phenotypic change corresponds with the level of gene flow that a population receives. These findings underline the utility of combining genetic approaches with phenotypic data to estimate the impact of gene flow in systems where anthropogenic alterations have removed former geographic barriers promoting cryptic invasions.

Highlights

Biological invasions commonly pose a threat to native species and even entire ecosystems in their invaded range (Elton 1958; Sakai et al 2001)
A great system to assess putative phenotypic changes associated with cryptic invasion is the threespine stickleback (Gasterosteus aculeatus) from central Europe
The occurrence of highly plated stickleback is significantly correlated with the presence of the EdaC allele among contemporary individuals (Basel: R2 = 0.794, F1,25 = 96.19, p \ 0.001; Village-Neuf: R2 = 0.818, F1,24 = 108.10, p \ 0.001) and Eda explains a comparable level of the phenotypic variation as for stickleback in other parts of their native range (Colosimo et al 2005)

Summary

Introduction

Biological invasions commonly pose a threat to native species and even entire ecosystems in their invaded range (Elton 1958; Sakai et al 2001). Historic records for central Europe (Bertin 1925; Munzing 1963; Gross 1977) and the Basel region (Fatio 1882; Steinmann 1936; Table S1 in supplementary material; see Fig. 1), representing the southernmost part of the native range of stickleback in the River Rhine, suggest that these populations were fixed for a phenotype with only few lateral plates. This is in agreement with the phylogenetic and biogeographic relationship of these populations (Munzing 1963; Makinen and Merila 2008). I predict the degree of phenotypic changes through time to reflect the relative level of gene flow and admixture that a population receives

Materials and methods

Results and discussion

18 Mont Saint-Michel