Comparative genetic diversity of parasites and their hosts: population structure of an urban cockroach and its haplo‐diploid parasite (oxyuroid nematode)

Abstract

Few studies have investigated the genetic structure of both host and parasite populations at a level of populations and at a level of individuals. We investigated the genetic structure of the urban cockroach Blattella germanica and its oxyuroid parasite Blatticola blattae. Random amplified polymorphic DNA (RAPD) markers were used to quantify genetic diversity between and within four populations (from two cities in France) of the host and its parasite. Diversity based on phenotypic frequencies was calculated for each RAPD marker using Shannon-Wiener's index. We used multivariate analyses to test the significance of genetic differentiation between host and parasite populations. Analysis of molecular variance was also used. Both methods gave similar results. Diversity between pairs of individuals was estimated by Nei & Li's index. Genetic diversity was higher within host or parasite populations (80% and 82%, respectively, of explained diversity) than between host or parasite populations (20% and 18%, respectively, explained diversity). The genetic distances between pairs of parasite populations (or individuals) were not correlated with the genetic distances between the corresponding pairs of host populations (or individuals).

High within-host genetic variation of the nematode Spirocerca lupi in a high-density urban dog population

“…Although studies on parasitic helminths have found situations where there is no genetic distinction between infrapopulations (Criscione and Blouin, 2006;Johnson et al 2006) it is more common to have some discernable genetic differences between infrapopulations although these differences tend to be small (Mulvey et al, 1991;Anderson et al, 1995;Jobet et al, 2000;Sire et al, 2001;Criscione et al, 2007). Significant between-host differences are frequently explained as a result of clumped transmission and small infrapopulation sizes resulting in little gene flow and strong drift (Nadler, 1995;Criscione et al, 2010), whereas small differences are associated with larger infrapopulations (Sire et al, 2001;Theron et al, 2004;Johnson et al, 2006).…”

Labile associations between fungus-growing ant cultivars and their garden pathogens

“…Therefore, given that gene flow plays a critical role in coevolutionary dynamics, to understand the evolution of host-parasite interactions, it is important to have information on the relative population structure of the two players within a system. To date, only a handful of studies have characterized the population genetic structure of natural host and parasite metapopulations across their geographic range (Mulvey et al, 1991;Dybdahl and Lively, 1996;Davies et al, 1999;Delmotte et al, 1999;Martinez et al, 1999;Jobet et al, 2000;Sire et al, 2001;Jerome and Ford, 2002;Johannesen and Seitz, 2003), a very small fraction of which involve microbial pathogens (Delmotte et al, 1999). Jobet et al (2000), for example, found similar genetic differentiation between populations of the urban cockroach (Blatella germanica) and its nematode parasite (Blatticola blattae).…”

Comparative population genetic study of two oligophagous insects associated with the same hosts

“…A way to unravel the relative effects of intrinsic and extrinsic factors on the spatial structure of species is to develop a parallel study of multiple taxa associated with the same host(s) but showing contrasting patterns of host use. Yet, comparative genetic studies are still quite rare, and mostly involve closely related species (Brouat et al, 2003(Brouat et al, , 2004, or hosts and parasites or mutualists (Jobet et al, 2000;Anderson et al, 2004). We report on a comparative study of two insect species associated with the same hosts (xylophagous vs defoliator), each sampled following the same scheme and analysed with similar neutral markers, to assess the effects of both geographic isolation and host-plant availability on gene flow.…”