The influence of host dispersal on the gene flow and genetic diversity of generalist and specialist ectoparasites

Abstract

African Zoology is co-published by NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group) Connectivity and subsequent gene flow among natural populations of species is one of the main factors maintaining conspecificity across a geographic range of a species. In the absence of sufficient gene flow among populations, genetic drift and selection can result in genetic divergence among populations that can ultimately contribute towards an allopatric speciation process (Schneider 2000;Huyse et al. 2005; Clegg and Phillimore 2010). For parasites, the factors affecting the dispersal and connectivity among populations are not well established (Barrett et al. 2008;van Schaik et al. 2014;DiBlasi et al. 2018). Through comparative phylogeographic studies between parasites and their hosts, it is evident that differences in parasite abundances on the hosts (Engelbrecht et al. 2016), ecological interactions between parasites (Cangi et al. 2013), and biogeographic conditions (Dick and Patterson 2007;du Toit et al. 2013; van der Mescht et al. 2015;Martinů et al. 2018;Stefan et al. 2018), can synergistically or separately all play a role in the dispersal and subsequent evolution of parasites. Given the close association between parasites and their hosts, and the fact that most terrestrial ectoparasite species are intrinsically not highly mobile, it is reasonable to suggest that host vagility will be a major contributing factor to facilitate parasite gene flow in terrestrial environments (Blasco-Costa, Waters and Poulin 2012;Araya-Anchetta et al. 2015;Matthee et al. 2018). In addition to host dispersal abilities, the life history of parasites and specifically also the host range (generalist or specialist) is probably equally important from an evolutionary point of view. Specialist parasites (those that can only survive on members of a single host species) often show more impediments to gene flow (high levels of genetic structure) and also often low levels of genetic diversity, a scenario best explained by the Specialist Generalist Variation Hypothesis (SGVH;Li et al. 2014;Matthee et al. 2018). The SGVH suggests that impediments to gene flow result from a lower prevalence of parasite habitat (host availability is less in host specific

Sharing roosts but not ectoparasites: high host-specificity in bat flies and wing mites of Miniopterus schreibersii and Rhinolophus ferrumequinum (Mammalia: Chiroptera)

“…Miniopterus schreibersii , being capable of long-distance flights, simply by covering wider geographical areas and coming in contact with other bats on the way, is expected to encounter a broader parasites diversity than it is the case for sedentary species, like R. ferrumequinum ( Presley 2011 ; Wright et al 2020 ). A high level of migration and a gene flow between distinct parasite populations coming in contact through their host maintains high levels of genetic diversity ( Matthee 2020 ).…”

“…This pattern was not observed in the mites, although the limited power of the single sequence fragment used in this study may partially explain the difference. Though host group size and mobility both positively affect parasite intensity and diversity, other factors such as host specialization, parasite life history, interspecific competition among parasites, time spent on host and landscape also influence gene flow, and consequently genetic diversity in ectoparasites ( Matthee 2020 ). Given their close host association, species diversity, and differences in reproductive life history, Nycteribiid flies and Spiturnicid mites provide a promising comparative framework to explore these dynamics in further detail.…”

Low genetic diversity and population structuring of Amblyomma hebraeum and Rickettsia africae from coastal and inland regions in the Eastern Cape Province of South Africa

“…Previous studies examined a single mtDNA marker and did not find any clear A. hebraeum population structuring between different coastal and a few inland regions in South Africa (Cangi et al, 2013;Matthee, 2020). Exploring the genetic diversity between inland and coastal A. hebraeum populations may help identify sites for evolutionary divergence.…”

Novel insights into symbiont population structure: Globe‐trotting avian feather mites contradict the specialist–generalist variation hypothesis

“…Specifically, based on the expectations of the SGVH and current knowledge on the transmission ecology of feather mites (e.g., vertical transmission on the breeding grounds), we predicted that A. protonotaria (host specialist) on P. citrea hosts would have a stronger population structure than A. ischyros (host generalist) on one of its host species, S. cerulea . The insight gained from this research allows us to address the potential context‐dependency of the SGVH (Matthee, 2020; Matthee et al, 2018) and provides an important first step in testing the combinatory influence of host dispersal and migratory connectivity on symbiont population structure.…”

“…The insight gained from this research allows us to address the potential context-dependency of the SGVH (Matthee, 2020;Matthee et al, 2018) and provides an important first step in testing the combinatory influence of host dispersal and migratory connectivity on symbiont population structure.…”