Abstract
BackgroundSoil-feeding termites are particularly interesting models for studying the effects of fragmentation, a natural or anthropic phenomenon described as promoting genetic differentiation. However, studying the link between fragmentation and genetics requires a method for identifying species unambiguously, especially when morphological diagnostic characters are lacking. In humivorous termites, which contribute to the fertility of tropical soils, molecular taxonomy and phylogenetic relationships are rarely studied, though mitochondrial and nuclear molecular markers are widely used in studies of pest termites. Here, we attempt to clarify the taxonomy of soil-feeding colonies collected throughout the naturally fragmented Lopé Reserve area (Gabon) and morphologically affiliated to Cubitermes sp. affinis subarquatus. The mitochondrial gene of cytochrome oxidase II (COII), the second nuclear rDNA internal transcribed spacer (ITS2) and five microsatellites were analyzed in 19 colonies.ResultsBayesian Inference, Maximum Likelihood and Maximum Parsimony phylogenetic analyses, which were applied to the COII and ITS2 sequences, and Neighbor-Joining reconstructions, applied to the microsatellite data, reveal four major lineages in the Cubitermes sp. affinis subarquatus colonies. The concordant genealogical pattern of these unlinked markers strongly supports the existence of four cryptic species. Three are sympatric in the Reserve and are probably able to disperse within a mosaic of forests of variable ages and savannahs. One is limited to a very restricted gallery forest patch located in the North, outside the Reserve.ConclusionOur survey highlights the value of combined mitochondrial and nuclear markers for exploring unknown groups such as soil-feeding termites, and their relevance for resolving the taxonomy of organisms with ambiguous morphological diagnostic characters.
Highlights
Soil-feeding termites are interesting models for studying the effects of fragmentation, a natural or anthropic phenomenon described as promoting genetic differentiation
Several studies based on mitochondrial genome sequences such as the cytochrome oxidase genes, the AT-rich region and the 16S rDNA have thrown a great deal of light on termite taxonomy and on phylogenetic and phylogeographic analyses of the Reticulitermes [10,11,12,13,14,15], Nasutitermes [16,17,18] and Heterotermes [19] genera
Mitochondrial sequence analyses Mitochondrial sequence dataset consisted in 558 bp sequenced for one individual from each of the 19 colonies collected in the four sites, and for the outgroup taxa, Apili
Summary
Soil-feeding termites are interesting models for studying the effects of fragmentation, a natural or anthropic phenomenon described as promoting genetic differentiation. It has been suggested that ecosystem fragmentation has important consequences for animal populations by reducing and dividing the distribution areas and by limiting connections between the fragments [1,2] As a result, this natural or anthropological phenomenon is described (page number not for citation purposes). Studying the link between genetics and fragmentation requires evaluation of breeding structure, gene flow and genetic differentiation among populations There is intra-individual variation in some taxa, the ITS2 region sequences are considered phylogenetically informative and able to distinguish closely-related species [21] Such an evolutionary pattern has allowed sibling or cryptic species in the Reticulitermes genus to be discriminated [22,23,24]. Microsatellite markers have not been used to investigate termite phylogeny or species discrimination, as has been done for other groups e.g. vertebrates [30], ticks [31], wasps [32] and ants [33]
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