Population Dynamics Following the Last Glacial Maximum in Two Sympatric Lizards in Northern China

Phylogeographic studies of Eremias lizards （Lacertidae） in East Asia have been limited, and the impact of major climatic events on their population dynamics remains poorly known. This study aimed to investigate population histories and refugia during the Last Glacial Maximum of two sympatric Eremias lizards （E. argus and E. brenchleyi） inhabiting northern China. We sequenced partial mitochondrial DNA from the ND4 gene for 128 individuals of E. argus from nine localities, and 46 individuals of E. brenchleyi from five localities. Forty-four ND4 haplotypes were determined from E. argus samples, and 33 from E. brenchleyi samples. Population expansion events began about 0.0044 Ma in E. argus, and 0.031 Ma in E. brenchleyi. The demographic history of E. brenchleyi indicates a long-lasting population decline since the most recent common ancestor, while that of E. argus indicates a continuous population growth. Among-population structure was significant in both species, and there were multiple refugia across their range. Intermittent gene flow occurred among expanded populations across multiple refugia during warmer phases of the glacial period, and this may explain why the effective population size has remained relatively stable in E. brenchleyi and grown in E. argus.

Mitogenomic Conservation Genetics of the Critically Endangered Liaoning Clawed Salamander

The Liaoning clawed salamander(Onychodactylus zhaoermii)is an endemic and critically endangered amphibian species of China.To study the population genetics of natural populations of this species,32 samples were collected from six different locations,and the mitochondrial genome was sequenced.Population genetic analyses showed that the Liaoning clawed salamander is composed of only one radialized cluster with ultralow nucleotide diversity.Late Pleistocene climate cooling(-100 to-30 kya)may have reduced the effective population size of the Liaoning clawed salamander,and the subsequent temperature increase(~25 kya to present)provided the opportunity for population expansion.Because of heat sensitivity,the maximum temperature of the prebreeding period,especially from March to May,is very important for the surface environment living in the Liaoning clawed salamander.Three suitable regions were predicted by the MaxEnt model,and the largest suitable region(approximately 899 km2)was at the four-county boundary area and was larger than the present’Natural Conservation Community of the Liaoning Clawed Salamander’.To ensure more effective protection of all Liaoning clawed salamanders,we suggest extending the current’Natural Conservation Community of the Liaoning Clawed Salamander’to include the four-county boundary area.

Phylogeography of the Phrynocephalus vlangalii Species Complex in the Upper Reaches of the Yellow River Inferred from mtDNA ND4-tRNA^(LEU) Segments

The Ching Hai Toad-headed Agama(Phrynocephalus vlangalii) complex is a small toad-headed viviparous lizard that is endemic to the Qinghai-Tibetan Plateau. A fragment of mtDNA ND4-tRNALEU from 189 samples in 26 populations was used to infer the phylogeographic history of this species complex in the upper reaches of the Yellow River. Phylogenetic analyses revealed that P. vlangalii and another proposed species(P. putjatia) do not form a monophyletic mtDNA clade,which in contrast with a previous study,includes P. theobaldi and P. forsythii. Lineage diversification occurred in the Middle Pleistocene for P. vlangali(ca. 0.95 Ma) and in the Early Pleistocene for P. putjatia(ca. 1.78 Ma). The uplift of the A’nyemaqen Mountains and glaciations since the mid-late Pleistocene,especially during the Kunlun Glaciation,are considered to have promoted the allopartric divergence of P. vlangalii. The diversification of P. putjatia may be triggered by the tectonic movement in the Huangshui River valley during the C phase of Qingzang Movement. Subsequently,the glacial climate throughout the Pleistocene may have continued to impede the gene flow of P. putjatia,eventually resulting in the genetic divergence of P. putjatia in the allopatric regions. Demographic estimates revealed weak population expansion in one lineage of P. vlangalii(A2,the Qaidam Basin lineage) and one lineage of P. putjatia(B2,the north Qinghai Lake lineage) after approximately 42 000 years before present. However,constant population size through time was inferred for two lineages(A1 and B1),the source of Yellow River lineage of P. vlangalii and the southeast of Qinghai Lake lineage of P. putjatia,possibly due to stable populations persisting in areas unaffected by glacial advances. Our results also suggest: 1) at least four differentiated lineages of P. vlangalii complex may have evolved allopatrically in different regions during the Pleistocene glaciation events; 2) in support of several recent studies,P. putjatia is a valid species,having a more wide distribution than previously considered; and 3) a hypothesis referring to P. v. hongyuanensis,inhabiting in the source region of the Yellow River,being synonymous with P. v. pylozwi is supported.

Shaken not stirred: A molecular contribution to the systematics of genus Mugil (Teleostei, Mugilidae)

With this work we addressed some molecular systematic issues within the Mugil cephalus species complex.Par­ticular attention was paid to the debated situations of:(i)Mugil liza,occurring in partial sympatry with Mugil cephalus in the northwestern Atlantic,and(ii)Mugil platanus,considered by some authors a synonymy of the former species and distributed in the southwestern Atlantic.We sequenced 79 individuals of a 465-bp portion of the mitochondrial control region(CR)from 8 western Atlantic and 2 Mediterranean localities.In addition,all CR sequences available from GenBank for the studied taxa were added to our dataset,for a total of 323 indi­viduals.Overall,229 haplotypes corresponding to 8 divergent monophyletic lineages were detected.Results of phylogenetic analyses were consistent with the occurrence of past speciation events producing the observed lin­eages.Of these lineages,7 correspond to cryptic species and one is constituted by M.liza and M.platanus.As a matter of fact,these 2 taxa constitute a single lineage within the M.cephalus species complex.However,in­dividuals of M.liza/M.platanus lineage analyzed by means of the 18 mitochondrial markers available in Gen­Bank exhibited a degree of genetic diversity consistent with highly divergent populations.Of the 8 lineages de­tected,the Mediterraean one(type locality)corresponds to M.cephalus;the lineage M.liza/M.platanus should be named M.liza,under the priority principle,and the left 6 lineages need formal description.

Low diversity,little genetic structure but no inbreeding in a high-density island endemic pit-viper Gloydius shedaoensis

Island species and their ecosystems play an important role in global biodiversity preservation,and many vulnerable island species are conservation priorities.Although insular habitat likely facilitates the species diversification process,it may also aggravate the fragility of these species with high risk of inbreeding.The Shedao pit-viper Gloydius shedaoensis is an island endemic species with an extremely high population density,which has been categorized as vulnerable in the IUCN(International Union for the Conservation of Nature and Natural Resources)Red List.We collected 13,148 SNP(Single Nucleotide Polymorphism)from across its genome and examined its genetic diversity and demographic history.The Shedao pit-viper has a low genetic diversity but shows no sign of inbreeding.Furthermore,population genetic structure analysis,including the neighbor-joining tree,principal coordinate analysis,clustering,and spatial autocorrelation,revealed a general lack of spatial structure.Only the isolation by distance residues suggested a weak patchiness.Overall,the population is nearly panmictic and gene flow is evenly distributed across the island.A large number of individuals,small size of the island,and the lack of population structure likely all contribute to the lack of inbreeding in this species.We also detected signs of male-biased dispersal,which likely is another inbreeding avoidance strategy.Historical demographic analysis suggested that the historical population size and distribution of the species are much larger than their current ones.The multiple transgressive–regressive events since the Late Pleistocene are likely the main cause of the population size changes.Taken together,our results provide a basic scientific foundation for the conservation of this interesting and important species.