Degree Of Lineage Sorting Research Articles

Multi-locus DNA sequence variation in a complex of four leaf beetle species with parapatric distributions: Mitochondrial and nuclear introgressions reveal recent hybridization

While the importance for including multiple independent loci in phylogeographic studies is largely acknowledged, a majority of these still focus on a single species. We combine the study of multilocus DNA sequence variation (one mitochondrial and four unlinked nuclear fragments) at both the inter- and intraspecific levels to explore the evolutionary history of four closely related specialized herbivorous insects (Chrysomelidae, genus Gonioctena). Analyzing the sequences for samples collected across their entire European range allows us to (1) characterize the genetic boundaries among species, i.e. the degree of lineage sorting, (2) infer their phylogenetic relationships and (3) explore reproductive barriers among them in regions where their ranges overlap. For two sister species, we identify multiple independent cases of unidirectional transfer of genetic material (introgression) at both mitochondrial and nuclear loci, demonstrating recent hybridization between both species in the overlapping regions of their range. The highlighted pattern of genetic variation suggests that Gonioctena intermedia expanded its range into that of G. quinquepunctata, and that both species may experience mutual exclusion. Overall, this study illustrates that interpreting intraspecific genetic variation for the purpose of evolutionary inference without the broader context of the other closely related species could lead to erroneous conclusions.

Spatial but not temporal co-divergence of a virus and its mammalian host

Co-divergence between host and parasites suggests that evolutionary processes act across similar spatial and temporal scales. Although there has been considerable work on the extent and correlates of co-divergence of RNA viruses and their mammalian hosts, relatively little is known about the extent to which virus evolution is determined by the phylogeographic history of host species. To test hypotheses related to co-divergence across a variety of spatial and temporal scales, we explored phylogenetic signatures in Andes virus (ANDV) sampled from Chile and its host rodent, Oligoryzomys longicaudatus. ANDV showed strong spatial subdivision, a phylogeographic pattern also recovered in the host using both spatial and genealogical approaches, and despite incomplete lineage sorting. Lineage structure in the virus seemed to be a response to current population dynamics in the host at the spatial scale of ecoregions. However, finer scale analyses revealed contrasting patterns of genetic structure across a latitudinal gradient. As predicted by their higher substitution rates, ANDV showed greater genealogical resolution than the rodent, with topological congruence influenced by the degree of lineage sorting within the host. However, despite these major differences in evolutionary dynamics, the geographic structure of host and virus converged across large spatial scales.