Genetic diversity and structure of the hedgehogs Erinaceus europaeus and Erinaceus roumanicus: evidence for ongoing hybridization in Eastern Europe

Secondary contact zones between related species are key to understanding speciation mechanisms. The Central European sympatry zone of West European (Erinaceus europaeus) and northern white-breasted (Erinaceus roumanicus) hedgehogs is well studied, whereas data on the Eastern European sympatry zone are scarce. We examined the genetic variation in Russian populations using the mitochondrial Cytb gene, TTR intron 1 and 11 microsatellites to assess genetic variability and distribution patterns. In contrast to the Central European sympatry zone, we found evidence of ongoing hybridization between the two species in the sympatry zone of European Russia, where the proportion of individuals with mixed ancestry was c. 20%. Our data indicate bi-directional mtDNA introgression, but with a higher frequency of E. europaeus haplotypes in hybrids. The proportion of pure specimens with introgressed mitotypes is higher in E. roumanicus than in E. europaeus. Nuclear data showed the prevalence of the genetic contribution from E. roumanicus in admixed individuals. Demographic analyses indicated recent population growth in E. europaeus and little change in E. roumanicus, suggesting that E. europaeus colonized East Europe later than E. roumanicus.

Ecological niche partitioning in a fragmented landscape between two highly specialized avian flush-pursuit foragers in the Andean zone of sympatry

In the Andes, pairs of ecologically similar species are often separated by narrow elevational sympatry zones but the mechanisms mediating sympatry are not fully understood. Here, we describe niche partitioning within a sympatry zone in a fragmented Andean landscape between two closely related flush-pursue species: a high-elevation montane forest dweller, (Myioborus melanocephalus), and a mid-elevation montane forest dweller, (M. miniatus). As all flush-pursuers use very similar hunting techniques involving visual displays to flush and pursue insects in air, and benefit from being the “rare predators”, ecological sorting between species in sympatry zones should allow their co-existence. We found that both species occupied vegetation resembling their typical allopatric habitats: a mosaic of pastures, clearings, and shrubs with small proportion of high trees for M. melanocephalus, and dense high forests with high proportion of trees, lower irradiance and higher humidity for M. miniatus. M. melanocephalus often foraged in bushes and at lower heights, whereas M. miniatus often foraged in tree crowns. The two species differed relatively little in their foraging technique. These results demonstrate how ecological sorting permits species of divergent elevational distributions and habitats to successfully coexist in sympatric zones where habitat diversity allows both species to find their preferred habitat.

Species and Genetic Diversity of Representatives of the Anaplasmataceae Family Found in the Sympatry Zone of the Ixodes, Dermacentor and Haemaphysalis Genera Ticks

Introduction.On the territory of the Ekhirit-Bulagatsky district of the Irkutsk region zones of sympatry of four Ixodes ticks species are found, where the species and genetic diversity of infectious agents transmitted through tick bites may be more pronounced than in foci with a mono-dominant type of ticks’ population. In this connection, the study of the species and genetic diversity of representatives of the Anaplasmataceae family in the sympatry zone of the Ixodes ticks of closely related species was of scientific interest.Objective:To study the species and genetic diversity of members of the Anaplasmataceae family in the zones of sympatry of Ixodes ticks Ixodes persulcatus, Dermacentor silvarum, D. nuttalli and Haemaphysalis concinna, to identify the main carriers and potential reservoir hosts of ehrlichia and anaplasma.Methods.In the course of the study, 1106 specimens of adult ticks and 49 samples of small mammalian livers from the Ekhirit-Bulagatsky area were analyzed. Anaplasma and ehrlichia DNA were detected by two-round PCR in the presence of genus- and species-specific primers from the 16S rRNA gene region. The nucleotide sequences of the 16S rRNA gene and the fragment of the groESL operon were identified in some samples. Sequencing was carried out according to the Sanger method. Comparative analysis was performed using the BLASTN program and ClustalW method. Epidemiological data analysis was performed using parametric methods of statistical processing of the material.Results.The DNA of Ehrlichia muris and Anaplasma phagocytophilum were detected in all studied species of ticks in their sympatry area. However, the rate of infection of taiga ticks was significantly higher than that of H. concinna and Dermacentor spp. Potential reservoir hosts of the Anaplasmataceae family members can be classified as Microtus oeconomus, M. gregalis, Myodes rutilus and Sorex spp. When analyzing the nucleotide sequences of the 16S rRNA gene, three genetic variants of anaplasma were detected. The nucleotide sequences of the A. phagocytophilum groESL operon belonged to two genetic groups.

Asymmetric introgression between Pinus sibirica and Pinus pumila in the Aldan plateau (Eastern Siberia)

Pinus sibirica and P. pumila are Asian five-needle pines with vast geographic distributions that are partially overlapping. Natural hybrids with intermediate morphology have been found previ­ously, but there is a lack of evidence of ongoing introgression. The goal of our study was to elucidate the genetic structure of P. sibirica and P. pumila populations growing in the north-east of their sympatry zone (Aldan plateau) using cytoplasmic DNA markers. All studied P. sibirica and P. pumila trees had usual spe­cies-specific growth habits. Using nad1 intron2 of mitochond­rial DNA (mtDNA) and trnV of chloroplast DNA (cpDNA) we found that trees morphologically identified as P. sibirica had pumila-specific mtDNA. Moreover, some of them also had pumila-specific cpDNA. P. pumila trees were typical and had pumila-type cytoplasmic DNA markers. These results suggest that interspecific hybridization took place long ago and lead to introgression and cryptic hybrids with P. sibirica appearance and P. pumila mtDNA

Sotalia dolphins in their potential sympatry zone: searching for hybrids in the Amazonian estuary

The two Sotalia species (the marine S. guianensis and the freshwater S. fluviatilis) have only recently been recognized, and both face several conservation challenges. We investigated the existence of hybridization between the two species in their possible area of sympatry in the Amazon Estuary, in northern Brazil. A fast and cheap PCR-RFLP diagnostic method using nuclear DNA was developed to discriminate between the two species, while allowing the detection of hybrids. All samples that could be identified (N = 51) were identified as S. guianensis, and no hybrids were detected. Our results, coupled with previous mitochondrial data, suggest that S. fluviatilis is not present in the Amazon delta. Thus, sympatry with S. guianensis, if it does occur, may be restricted to upstream areas of the Amazon River.