Host specificity driving genetic structure and diversity in ectoparasite populations: Coevolutionary patterns in Apodemus mice and their lice.

Jana Martinů,Jan Štefka,Václav Hypša

doi:10.1002/ece3.4424

Abstract

A degree of host specificity, manifested by the processes of host–parasite cospeciations and host switches, is assumed to be a major determinant of parasites’ evolution. To understand these patterns and formulate appropriate ecological hypotheses, we need better insight into the coevolutionary processes at the intraspecific level, including the maintenance of genetic diversity and population structure of parasites and their hosts. Here, we address these questions by analyzing large‐scale molecular data on the louse Polyplax serrata and its hosts, mice of the genus Apodemus, across a broad range of European localities. Using mitochondrial DNA sequences and microsatellite data, we demonstrate the general genetic correspondence of the Apodemus/Polyplax system to the scenario of the postglacial recolonization of Europe, but we also show several striking discrepancies. Among the most interesting are the evolution of different degrees of host specificity in closely related louse lineages in sympatry, or decoupled population structures of the host and parasites in central Europe. We also find strong support for the prediction that parasites with narrower host specificity possess a lower level of genetic diversity and a deeper pattern of interpopulation structure as a result of limited dispersal and smaller effective population size.

Highlights

Genetic structure and diversity of populations, and their genetic connectivity are the key elements in long-term population survival and evolution, and in the origin of new species
We address the impact of host specificity on the genetics of parasite populations using the system of a sucking louse Polyplax serrata and its hosts, mice of the genus Apodemus
Phylogenetic analyses clustered the sequences into three well supported lineages (Fig. 2), designated here as N, S and Aa

Summary

Introduction

Genetic structure and diversity of populations, and their genetic connectivity are the key elements in long-term population survival and evolution, and in the origin of new species. Why the Laelaps mites show seemingly higher level of intimacy than the permanent Polyplax lice, could be the limited dispersal abilities due to the low abundance and prevalence on the hosts From similar studies, it becomes obvious, that the key to understanding the co-evolutionary pattern is the investigation of the parasites’ population genetics and dynamics, and their main determinants. It becomes obvious, that the key to understanding the co-evolutionary pattern is the investigation of the parasites’ population genetics and dynamics, and their main determinants At this intra-specific level, the current research showed that parasite diversity and population structure is affected by several factors, mainly shared demographic history (e.g. Nieberging et al 2004; Štefka et al 2011), host dispersal capabilities affecting parasite’s gene flow Do the parasitic lineages A and B with different width of host-specificity, follow the Nadler’s rule (Nadler 1995) in the sense of i) deeper population structure in the more host specific lineage, caused by lower dispersal possibilities and ii) significant differences in genetic diversity between sympatric populations correspondingly to the width of their host spectrum?

Materials and methods

Results

Discussion