ABSTRACT Dispersal influences the evolution and adaptation of organisms, but it can be difficult to detect. Host-specific parasites provide information about the dispersal of their hosts and may be valuable for examining host dispersal that does not result in gene flow or that has low signals of gene flow. We examined the population connectivity of the buffy flower bat, Erophylla sezekorni (Chiroptera: Phyllostomidae), and its associated obligate ectoparasite, Trichobius frequens (Diptera: Streblidae), across a narrow oceanic channel in The Bahamas that has previously been implicated as a barrier to dispersal in bats. Due to the horizontal transmission of T. frequens , we were able to test the hypothesis that bats are dispersing across this channel, but this dispersal does not result in gene flow, occurs rarely, or started occurring recently. We developed novel microsatellite markers for the family Streblidae in combination with previously developed markers for bats to genotype individuals from 4 islands in The Bahamas. We provide evidence for a single population of the host, E. sezekorni , but 2 populations of its bat flies, potentially indicating a recent reduction of gene flow in E. sezekorni , rare dispersal, or infrequent transportation of bat flies with their hosts. Despite high population differentiation in bat flies indicated by microsatellites, mitochondrial DNA shows no polymorphism, suggesting that bacterial reproductive parasites may be contributing to mitochondrial DNA sweeps. Parasites, including bat flies, provide independent information about their hosts and can be used to test hypotheses of host dispersal that may be difficult to assess using host genetics alone.

Parasitic lice have been valuable informants of their host's evolutionary history because they complete their entire life cycle on the host and move between hosts primarily through direct host-to-host contact. Therefore, lice are confined to their hosts both in ecological and evolutionary time. Lice on great apes have been studied to examine details of their host's evolutionary history; however, species of Pedicinus , which parasitize the Old World monkeys, are less well known. We sampled lice from 2 groups of red colobus ( Procolobus spp.) in Kibale National Park in Uganda and from red colobus and black and white colobus ( Procolobus polycomos ) in Taï National Park in Côte d'Ivoire. We used next-generation sequencing data analysis and the human body louse ( Pediculus humanus humanus ) genome to search for microsatellites for population genetic studies of Pedicinus lice. The 96 primer sets for microsatellite loci designed from the human body louse genome failed to amplify microsatellites in Pedicinus sp., perhaps due to the fast rate of evolution in parasitic lice. Of 63 microsatellites identified by next-generation sequencing data analysis of Pedicinus sp., 12 were variable among populations and 9 were variable within a single population. Our results suggest that these loci will be useful across the genus Pedicinus . We found that the lice in Uganda are not structured according to their hosts' social group; rather, 2 non-interbreeding populations of lice were found on both groups of red colobus. Because direct host-to-host contact is usually required for lice to move among hosts, these lice could be useful for identification and study of behavioral interactions between primate species.

Human head lice ( Pediculus humanus capitis ) are subdivided into 3 deeply divergent mitochondrial clades (Clades A, B, and C), each having unique geographical distributions. Determining the evolutionary history and geographic distribution of these mitochondrial clades can elucidate the evolutionary history of the lice as well as their human hosts. Previous data suggest that lice belonging to mitochondrial Clade B may have originated in North America or Asia; however, geographic sampling and sample sizes have been limited. With newly collected lice, we calculate the relative frequency, geographic distribution, and genetic diversity of louse mitochondrial clades to determine the geographic origin of lice belonging to Clade B. In agreement with previous studies, genetic diversity data support a North American origin of Clade B lice. It is likely that lice belonging to this mitochondrial clade recently migrated to other geographic localities, e.g., Europe and Australia, and, if not already present, may disperse further to occupy all geographic regions.

Chewing lice, Geomydoecus and Thomomydoecus, coexist on pocket gophers, Thomomys spp. We investigated the spatial distribution of the 2 genera on their hosts and explored possible mechanisms of resource partitioning by chewing lice. Chewing lice appear to partition available host resources spatially, with Geomydoecus occurring primarily on the lateral and dorsal regions of the host, and Thomomydoecus occurring primarily on the lateral and ventral regions. Although spatial partitioning of the host habitat is evident, it does not appear to be explained by hair diameter. Spatial partitioning of the host's body could be the result of some other factor, possibly temperature or humidity gradients of the host's body.