The sympatric occurrence of two genetically divergent lineages of sucking louse,Polyplax arvicanthis(Phthiraptera: Anoplura), on the four-striped mouse genus,Rhabdomys(Rodentia: Muridae)

Abstract

Within southern Africa, the widely distributed four-striped mouse genus (Rhabdomys) is parasitized by, amongst others, the specific ectoparasitic sucking louse, Polyplax arvicanthis. Given the presence of significant geographically structured genetic divergence in Rhabdomys, and the propensity of parasites to harbour cryptic diversity, the molecular systematics of P. arvicanthis was investigated. Representatives of P. arvicanthis were sampled from Rhabdomys at 16 localities throughout southern Africa. Parsimony and Bayesian gene trees were constructed for the mitochondrial COI, 12S rRNA, 16S rRNA and nuclear CAD genes. Our findings support the existence of 2 genetic groups within P. arvicanthis separated by at least 25% COI sequence divergence, which is comparable to that observed among recognized Polyplax species. We therefore propose that these 2 genetic lineages probably represent distinct species and that the apparent absence of clear morphological differences may point to cryptic speciation. The 2 taxa have sympatric distributions throughout most of the sampled host range and also occasionally occur sympatrically on the same host individual. The co-occurrence of these genetically distinct lineages probably resulted from parasite duplication via host-associated allopatric divergence and subsequent reciprocal range expansions of the 2 parasite taxa throughout southern Africa.

Biogeography and host‐related factors trump parasite life history: limited congruence among the genetic structures of specific ectoparasitic lice and their rodent hosts

“…Total genomic DNA was extracted from host tissue and whole individual louse specimens, and amplification and sequencing of the various gene fragments were performed following standard protocols and published primers (Table S3, Supporting information; du Toit et al . , ). Sequences were edited in bioedit Sequence Alignment editor 7.0.5 (Hall ), and the alignments were trimmed to avoid missing data (Table ).…”

“…The apparent lack of gross morphological differences between the two lineages suggests the presence of two cryptic species within P. arvicanthis (du Toit et al . ; Table ; Fig. ).…”

“…Recent phylogenetic evidence based on multiple genes indicated that P. arvicanthis consists of two divergent genetic lineages ( P. arvicanthis 1 and 2) with sympatric distributions across most of the sampled range (du Toit et al . ). The apparent lack of gross morphological differences between the two lineages suggests the presence of two cryptic species within P. arvicanthis (du Toit et al .…”

Comparative phylogeography of parasitic Laelaps mites contribute new insights into the specialist-generalist variation hypothesis (SGVH)

“…The complexity and diversity of parasite systems, however, render accurate predictions on the factors responsible for parasite dispersal problematic. For example, host dispersal is not consistently correlated with parasite movement [14], parasites with broad host ranges can be highly structured due to biogeographic influences [15], and even obligate host-specific parasites do not necessarily show significant co-evolutionary patterns [5]. Through concerted efforts, however, some generalizations emerge such as the specialist-generalist variation hypothesis (SGVH) as proposed by Li et al [16].…”

“…The strength of our comparative approach lies in the fact that the parasites used in this study overlap in range (keeping environmental conditions constant), they have very similar life history characteristics, and published data on host dispersal and evolutionary history are available [5, 15, 25, 26]. It is proposed that this study will provide more direct insights into the effects of host specialization versus host movement on the genetic diversity and population structure of nest bound ectoparasites.…”