Search

Chironomids of the genus Diamesa (Meigen, 1835, Diptera: Chironomidae) inhabit cold, oxygen-rich running waters. We have investigated the presence of Diamesa and other freshwater macroinvertebrates at 22 stream sampling sites in 3 European high mountain regions (the Central Pyrenees, the Ötztal Alps, and the Tatra Mountains) to establish suitable temperature conditions for Diamesa dominance. It has been generally accepted that their high abundance was linked to the presence of glaciers; however, we have shown that in the Tatra Mountains, where there are no glaciers, the conditions for the dominance of Diamesa species are created due to permanent snowfields, the geographical orientation of the valley and shading by the surrounding high peaks. The historical connection of Diamesa to glaciers was investigated from the paleolimnological records of subfossil chironomid assemblages from the Bohemian Forest, where glaciers disappeared before or during the Late Glacial period. As expected, water temperature seems to be the main driver of Diamesa distribution, and we determined that the relative abundance of Diamesa species was significantly higher at the sites with a mean July water temperature below 6.5 °C. The Diamesa -dominated stream communities seems to be endangered due to ongoing climate warming and this assumption is supported by our paleolimnological results from the Bohemian Forest lakes, where Diamesa has disappeared due to warming of lake inflows at the beginning of the Holocene. These findings strengthen the former suggestions that some Diamesa species could be used as an indicator for tracking recent environmental changes in vulnerable ecosystems of cold mountain streams. [ABSTRACT FROM AUTHOR]

Background and Aims Rubus ser. Glandulosi provides a unique model of geographical parthenogenesis on a homoploid (2 n  = 4 x) level. We aim to characterize evolutionary and phylogeographical patterns in this taxon and shed light on the geographical differentiation of apomicts and sexuals. Ultimately, we aim to evaluate the importance of phylogeography in the formation of geographical parthenogenesis. Methods Rubus ser. Glandulosi was sampled across its Eurasian range together with other co-occurring Rubus taxa (587 individuals in total). Double-digest restriction site-associated DNA sequencing (ddRADseq) and modelling of suitable climate were used for evolutionary inferences. Key Results Six ancestral species were identified that contributed to the contemporary gene pool of R. ser. Glandulosi. Sexuals were introgressed from Rubus dolichocarpus and Rubus moschus in West Asia and from Rubus ulmifolius agg. Rubus canescens and Rubus incanescens in Europe, whereas apomicts were characterized by alleles of Rubus subsect. Rubus. Gene flow between sexuals and apomicts was also detected, as was occasional hybridization with other taxa. Conclusions We hypothesize that sexuals survived the last glacial period in several large southern refugia, whereas apomicts were mostly restricted to southern France, whence they quickly recolonized Central and Western Europe. The secondary contact of sexuals and apomicts was probably the principal factor that established geographical parthenogenesis in R. ser. Glandulosi. Sexual populations are not impoverished in genetic diversity along their borderline with apomicts, and maladaptive population genetic processes probably did not shape the geographical patterns. [ABSTRACT FROM AUTHOR]

Habitat fragmentation can facilitate local adaptation of species to heterogeneous environments and affect population demographic history. To understand the factors influencing evolutionary dynamics, such as climatic fluctuations and complex geomorphological features, we used 18 chloroplast microsatellites, 15 nuclear microsatellites, three chloroplast fragments, and two nuclear regions to explore the genetic structure and phylogeographical history of Pseudotaxus chienii. Furthermore, its current and past distributions were constructed based on ecological niche modelling. Moderate to high levels of genetic diversity were found at the species level. Precipitation was a decisive factor influencing the genetic structure of P. chienii. In addition, local adaptation to heterogeneous environments also contributed to maintain the fragmented distribution. Finally, incomplete lineage sorting led to the cyto-nuclear discordance. Overall, we show that pre-Quaternary and Quaternary climatic fluctuations and restricted gene flow exerted significant effects on the formation and maintenance of the fragmented distribution of P. chienii. The study provides new insights into the evolutionary history of plants in subtropical China. [ABSTRACT FROM AUTHOR]

Cherries (subg. Cerasus) belong to Prunus s.l. (Rosaceae) and are widely distributed in temperate and subtropical regions of the Northern Hemisphere. Given its ornamental and edible functions, it is a hugely preferred germplasm resource for human societies. However, the interspecific phylogenetic relationships, divergence times, and routes of this subgenus remain unclear. To reveal its enigmatic and intricate evolutionary history, we newly sequenced 12 subg. Cerasus species, reconstructed the plastome phylogeny with 24 previously published subg. Cerasus species. This study supports that subg. Cerasus split into five clades, among which P. mahaleb is the basal group of subg. Cerasus ; P. campanulata is genetically distantly related to P. cerasoides and is not recommended for treatment as a variety of the latter; P. subhirtella is involved in the speciation of P. yedoensis. Molecular dating and ancestral area reconstructions infer that subg. Cerasus originated in the Eastern Mediterranean–Central Asia before 11.57 Mya (95% HPD = 5.34–19.1 Mya) and subsequently spread into the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The first dispersal event of modern subg. Cerasus was facilitated by 'out-of-QTP', colonizing North America across the Bering Land Bridge and re-dispersing into Europe from the Late Miocene to Pliocene and forming the initial distribution pattern of extant subg. Cerasus in the Pliocene; The end of the Quaternary glacial period witnessed a second dispersal event, and core subg. Cerasus population diversity flourished radially in its separate refugia during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

Evolutionary processes behind lineage divergence often involve multidimensional differentiation. However, in the context of recent divergences, the signals exhibited by each dimension may not converge. In such scenarios, incomplete lineage sorting, gene flow, and scarce phenotypic differentiation are pervasive. Here, we integrated genomic (RAD loci of 90 individuals), phenotypic (linear and geometric traits of 823 and 411 individuals, respectively), spatial, and climatic data to reconstruct the evolutionary history of a speciation continuum of liolaemid lizards (Liolaemus kingii group). Specifically, we (a) inferred the population structure of the group and contrasted it with the phenotypic variability; (b) assessed the role of postdivergence gene flow in shaping phylogeographic and phenotypic patterns; and (c) explored ecogeographic drivers of diversification across time and space. We inferred eight genomic clusters exhibiting leaky genetic borders coincident with geographic transitions. We also found evidence of postdivergence gene flow resulting in transgressive phenotypic evolution in one species. Predicted ancestral niches unveiled suitable areas in southern and eastern Patagonia during glacial and interglacial periods. Our study underscores integrating different data and model-based approaches to determine the underlying causes of diversification, a challenge faced in the study of recently diverged groups. We also highlight Liolaemus as a model system for phylogeographic and broader evolutionary studies. [ABSTRACT FROM AUTHOR]

The southern three-banded armadillo, Tolypeutes matacus , is one of the most representative species of the South American Chaco region. The susceptibility of this species to climatic changes and its good number of paleontological records has led to the study of their range dynamics for untangling the effects of Quaternary oscillations. These studies yielded contradictory results, suggesting expansion processes under opposite conditions: some during glacial periods and others during interglacial periods. Here, we assess the population structure of T. matacus in Argentina based on mitochondrial genes, and estimate demographic and spatial dynamics that contribute to unveiling the evolutionary process that moulded its biogeography. We found no clear phylogeographical breaks, although there were differences in the composition and frequency of haplotypes between the northern and southern localities studied. Demographic inferences indicate that the species has undergone population and range expansion processes. The higher diversity found in the north and the spatial diffusion analysis allow us to infer a north–south direction of this expansive process. Our results yield essential evidence for disentangling the evolution of this Chacoan species linked with Quaternary climates and provide genetic information about its populations that should be taken into account for the conservation of this threatened mammal. [ABSTRACT FROM AUTHOR]

I do not support modern ideas regarding the sheltering of northern species of amphibians and reptiles in southern refugia during glacial periods. The current article presents arguments that reject the traditional point of view. The northern species did not fall within southern refugia, and therefore new forms (haplotypes) appeared within the periglacial hyperzone. I describe how these processes may have taken place. [ABSTRACT FROM AUTHOR]

Identifying the drivers of microgeographic speciation (i.e. speciation over small, local geographic scales) is key to understand the origin of speciose groups. Here, we use genomic data to infer the demographic processes underlying diversification in Poecilimon luschani (Orthoptera: Tettigoniidae), a species complex belonging to the most diverse genus of bush crickets from the Mediterranean region (>170 taxa) that comprises three recognized subspecies with small allopatric distributions in the topographically complex Teke Peninsula, southwestern Anatolia. Phylogenomic reconstructions that include all other taxa within the species group confirmed that subspecies of P. luschani originated from a common ancestor during the Pleistocene, supporting recent (<1 Ma) diversification within a small geographical area (ca. 120 × 80 km). Genetic clustering analyses corroborated the distinctiveness of each subspecies and the cohesiveness of their respective populations, with abrupt genetic discontinuities coinciding with contemporary range boundaries. Indeed, our analyses uncovered the presence of two sympatric cryptic sister lineages that diverged <300 ka ago and do not admix despite being co-distributed. Collectively, these results support that all lineages within the complex represent independently evolving entities corresponding to full-fledged species. Statistical evaluation of alternative models of speciation strongly supports a scenario of divergence in isolation followed by a period of limited gene flow during the last glacial period, when all lineages experienced marked expansions according to demographic reconstructions. Our study exemplifies how localized allopatric divergence and fast evolution of reproductive isolation can promote microgeographic speciation and explain the high rates of endemism characterizing biodiversity hotspots. [ABSTRACT FROM AUTHOR]