Molecular evidence for Pleistocene refugia at the eastern edge of the Tibetan Plateau

The role of the Quaternary ice ages in forming the contemporary genetic structure of populations has been well studied in a number of global regions. However, due to the different nature of glaciations and complex topography, their role in shaping eastern Eurasian genetic diversity, particular in areas surrounding the Tibetan Plateau have remained largely unstudied. We aimed to address this question by examining the genetic structure of an alpine forest-associated taxon, the blood pheasant (Ithaginis cruentus) to infer its phylogeographic history. We detected three phylogenetic lineages and four current population groups. By comparing molecular and palaeovegetation data, we found that major glaciations during the Pleistocene have had a major impact upon the current genetic diversity of this species. Coalescent simulations indicate that the populations retreated to different refugia during some glacial periods in the Pleistocene, but persisted through the last glacial maximum (LGM). The most significant recent population expansion was found to have occurred before the LGM, during which palaeoclimatic data indicate that the climate was both warmer and wetter than today. In contrast, during the LGM populations may have adopted an altitudinal shift strategy in order to track changes in alpine glaciers, exemplifying a general response for montane species in the region where alpine glaciations were not large enough to cause qualitative changes in vegetation. Although analysis based on a plumage related gene showed that divergent selection may have contributed to current patterns of intra-specific diversity, demographic isolation is inferred to have played a more dominant role.     

Comparative phylogeography of unglaciated eastern North America

Regional phylogeographical studies involving co-distributed animal and plant species have been conducted for several areas, most notably for Europe and the Pacific Northwest of North America. Until recently, phylogeographical studies in unglaciated eastern North America have been largely limited to animals. As more studies emerge for diverse lineages (including plants), it seems timely to assess the phylogeography across this region: (i) comparing and contrasting the patterns seen in plants and animals; (ii) assessing the extent of pseudocongruence; and (iii) discussing the potential applications of regional phylogeography to issues in ecology, such as response to climatic change. Unglaciated eastern North America is a large, geologically and topographically complex area with the species examined having diverse distributions. Nonetheless, some recurrent patterns emerge: (i) maritime - Atlantic vs. Gulf Coast; (ii) Apalachicola River discontinuity; (iii) Tombigbee River discontinuity; (iv) the Appalachian Mountain discontinuity; (v) the Mississippi River discontinuity; and (vi) the Apalachicola River and Mississippi River discontinuities. Although initially documented in animals, most of these patterns are also apparent in plants, providing support for phylogeographical generalizations. These patterns may generally be attributable to isolation and differentiation during Pleistocene glaciation, but in some cases may be older (Pliocene). Molecular studies sometimes agree with longstanding hypotheses of glacial refugia, but also suggest additional possible refugia, such as the southern Appalachian Mountains and areas close to the Laurentide Ice Sheet. Many species exhibit distinct patterns that reflect the unique, rather than the shared, aspects of species' phylogeographical histories. Furthermore, similar modern phylogeographical patterns can result from different underlying causal factors operating at different times (i.e. pseudocongruence). One underemphasized component of pseudocongruence may result from the efforts of researchers to categorize patterns visually - similar patterns may, in fact, not fully coincide, and inferring agreement may obscure the actual patterns and lead to erroneous conclusions. Our modelling analyses indicate no clear spatial patterning and support the hypothesis that phylogeographical structure in diverse temperate taxa is complex and was not shaped by just a few barriers.     

Diversification within glacial refugia: tempo and mode of evolution of the polytypic fish Barbus sclateri

A diversity of evolutionary processes can be responsible for generating and maintaining biodiversity. Molecular markers were used to investigate the influence of Plio-Pleistocene climatic oscillations on the evolutionary history of taxa restricted to the freshwaters of a classical glacial refugium. Population genetic, phylogenetic and phylogeographical methods allowed the inference of temporal dynamics of cladogenesis and processes shaping present-day genetic constitution of Barbus sclateri , a polytypic taxon found in several independent river drainages in southern Iberian Peninsula. Results from different analyses consistently indicate several range expansions, high levels of allopatric fragmentation, and admixture following secondary contacts throughout its evolutionary history. Using a Bayesian demographical coalescent model on mitochondrial DNA sequences calibrated with fossil evidence, all cladogenetic events within B. sclateri are inferred to have occurred during the Pleistocene and were probably driven by environmental factors. Our results suggest that glaciation cycles did not inhibit cladogenesis and probably interacted with regional geomorphology to promote diversification. We conclude that this polytypic taxon is a species complex that recently diversified in allopatry, and that Pleistocene glaciation–deglaciation cycles probably contributed to the generation of biological diversity in a classical glacial refugium with high endemicity.     

Plant survival in Iceland during periods of glaciation?

Aim The paper addresses the classical question of possible plant survival in Iceland during the last glacial period in the light of a palaeobotanical record from northern Iceland, spanning the period 11,300–9000 BP , including the Younger Dryas stadial. We review the Late Cenozoic fossil plant record, the past debate on glacial plant refugia in Iceland, and the evidence for ice-free areas during the Weichselian. Location The investigated lake sediment record comes from Lake Torfadalsvatn, which is situated in the northwestern part of the Skagi peninsula in northern Iceland. Methods The sediment chronology was constructed from the cccurrence of the Vedde Ash and the Saksunarvatn ash, two well-dated Icelandic tephras, together with the results from five AMS and conventional radiocarbon dates performed on bulk sediment samples. The vegetational reconstruction was based on detailed pollen analysis of the sediment sequence. Results The pollen analysis revealed that many of the taxa present in the area prior to the Younger Dryas stadial continued to produce pollen during that cold event. The more or less immediate reappearance of a few other pollen taxa at the Younger Dryas-Preboreal boundary suggests that these plants also survived, even if they did not produce sufficient pollen to be recorded during the Younger Dryas stadial. Main conclusions We conclude that the relatively high plant diversity found in high Arctic areas and present-day nunataks in Iceland and Greenland, together with the fact that many plant species were able to survive the Younger Dryas stadial on the Skagi peninsula, suggest that species with high tolerance for climate fluctuations also survived the whole Weichselian in Iceland. This conclusion is supported by recent palaeoclimatic data from ice-cores and deep-sea sediments, indicating that Icelandic climate during the last glacial was only occasionally slightly colder than during the Younger Dryas stadial.     

Phylogenetic relationships of Eurasian Nuthatches (Sitta europaea Linnaeus, 1758) from the Alborz and Zagros Mountains,Iran

The Eurasian Nuthatch (Sitta europaea Linnaeus, 1758) is a resident bird in the Alborz and Zagros deciduous forests. We investigated the phylogenetic relationships and the taxonomic position of the Eurasian Nuthatch among other separated lineages of Eurasia with the help of blood samples collected from 19 individuals belonging to four populations in the Eastern and Western Alborz, as well as in the Northern and Southern Zagros forests. Genetic variation was then analysed using complete ND2 gene sequence (1041?bp) and phylogenetic analysis was done using Bayesian and maximum likelihood inference. Additionally, a median-joining algorithm was used to reveal the relationships among haplotypes. The results of the phylogenetic and haplo-type network analyses indicated that Eurasian Nuthatch haplotypes from the Alborz and Zagros Mountains form lineages distinct from the Asian, Caucasian and European haplotypes. Furthermore, an analysis of molecular variance (AMOVA) detected significant (P<0.001) genetic structure among the lineages. The Asian, European, Caucasian and Alborz lineages diverged from one another by an uncorrected genetic distance ranging from 0.029 to 0.039, while the Zagros lineage showed a slightly lower genetic divergence from the Caucasian lineage (0.006), but it did not share any haplotype with the Caucasian lineage. Thus, we suggest considering five Conservation Significant Units (CSU) for the Eurasian Nuthatches as the result of used dataset.     

Geographic variation of Gloydius halys caucasicus (Serpentes: Viperidae) in Iran

We compared the morphological characters of populations of the Caucasian Pit Viper, Gloydius halys caucasicus, from different regions of the Alborz mountain range. For this purpose, we studied 7 metric and 21 meristic characters in 12 specimens from the western Alborz, 44 specimens from the eastern Alborz and nine specimens from the central Alborz Mountains. The results of the statistical analyses by npMANOVA, ANOVA and Kruskal Wallis tests showed significant differences between all three populations, while the western Alborz and the eastern Alborz populations are more distinct from each other. The important characters showing differences between them are: Subcaudals, dorsal scales in anterior part, dorsal scales in posterior part, supralabial scales, scales between gulars, gulars, ventrals, ratio of snout length over snout width, and ratio of snout length over head length.     

Discovery of new open-air Paleolithic localities in Central Alborz, Northern Iran

The cooperative French-Iranian Paleoanthropological Project (FIPP) discovered three Paleolithic localities in Central Alborz, Northern Iran during its 2005 field mission. In the northern foothills near Baliran in Mazandaran province, Garm Roud yielded an open-air site with an archaeological layer attributable to the last glacial period that dates from the end of OIS 3 (28,486+/-190 cal BP). These geochronological data and the typo-technical observations converge to place the Garm Roud 2 assemblage in the Upper Paleolithic. Garm Roud 2 is thus the first site of this kind discovered in the area. In the southern foothills near Damavand in Tehran province, Moghanak and Otchounak represent two open-air surface localities with lithic assemblages of Mousterian to Ante-Mousterian affinity. Garm Roud, Moghanak, and Otchounak provide some of the first direct field evidence of early human settlements in this central area of the Middle East.     

青藏高原及其周边地区高山植物谱系地理学研究进展

青藏高原及其周边地区是世界上高山植物最丰富的地区,通过谱系地理学研究可以探讨高山植物演化历史与高原隆升和第四纪冰期的关系。根据对已经报道的36种高山植物的谱系地理分析,其谱系地理模式主要表现为:一、冰期退却到高原边缘的避难所,冰后期回迁到高原面;二、地理隔离造成冰期存在多处避难所(含微型避难所),冰后期发生局域性扩张。青藏高原在晚第三纪的快速隆升促进了物种的分化和成种,而第四纪冰期更是加剧了物种的快速分化,高原隆升和第四纪周期性气候波动是形成青藏高原高山植物现代谱系地理格局的主要原因。横断山脉地区作为第四纪冰期高山植物的主要避难所,在进化生物学和保护生物学方面具有重要启示。最后在物种选择、采样策略、基因片段选择和研究方法等4个方面提出青藏高原地区谱系地理学的研究方向。