Comparative population genetics and phylogeography of two lacertid lizards (Eremias argus and E. brenchleyi) from China

Gender-Specific Toxic Effects of S-Metolachlor and Its Metabolite on Hibernating Lizards: Implications for Reproductive Health and Ecosystem Vulnerability

Reptiles rely on hibernation to survive harsh winters, but climate change and pesticide use in agriculture jeopardize their survival, making the ecosystem vulnerable. S-metolachlor (SM), a commonly found herbicide in soil, and its metabolite metolachlor oxanilic acid (MO) induce oxidative stress and disrupt reproductive hormones. In this study, lizards were exposed to SM- and MO-contaminated soil for 45 days during hibernation. Weight loss and deaths occurred at the beginning of hibernation in all groups. Furthermore, the exposure group experienced severe oxidative stress and damage in the liver, kidney, heart, gonad, and brain. The testosterone levels significantly decreased in male lizards in both the SM and MO groups, whereas estradiol levels increased significantly in female lizards in the SM group. Gender-specific expression of steroidogenic-related genes in the brains and gonads of lizards was observed. Histological analysis revealed toxic effects induced by both SM and MO in vital organs during hibernation. Moreover, MO induced more severe reproductive toxicity in male lizards during hibernation. Therefore, this study suggests gender-specific toxic effects were observed in hibernating lizards exposed to SM and MO, underscoring the importance of vigilant monitoring of pesticide application in agriculture and assessing the potential harm of its metabolites.

Range-Wide Phylogeography and Ecological Niche Modeling Provide Insights into the Evolutionary History of the Mongolian Racerunner (Eremias argus) in Northeast Asia

The Mongolian racerunner, Eremias argus, is a small lizard endemic to Northeast Asia that can serve as an excellent model for investigating how geography and past climate change have jointly influenced the evolution of biodiversity in this region. To elucidate the processes underlying its diversification and demography, we reconstructed the range-wide phylogeographic pattern and evolutionary trajectory, using phylogenetic, population genetic, landscape genetic, Bayesian phylogeographic reconstruction and ecological niche modeling approaches. Phylogenetic analyses of the mtDNA cyt b gene revealed eight lineages that were unbounded by geographic region. The genetic structure of E. argus was mainly determined by geographic distance. Divergence dating indicated that E. argus and E. brenchleyi diverged during the Mid-Pliocene Warm Period. E. argus was estimated to have coalesced at~0.4351 Ma (Marine Isotope Stage 19). Bayesian phylogeographic diffusion analysis revealed out-of-Inner Mongolia and rapid colonization events from the end of the Last Interglacial to the Last Glacial Maximum, which is consistent with the expanded suitable range of the Last Glacial Maximum. Pre-Last Glacial Maximum growth of population is presented for most lineages of E. argus. The Glacial Maximum contraction model and the previous multiple glacial refugia hypotheses are rejected. This may be due to an increase in the amount of climatically favorable habitats in Northeast Asia. Furthermore, E. argus barbouri most likely represents an invalid taxon. The present study is the first to report a range-wide phylogeography of reptiles over such a large region in Northeast Asia. Our results make a significant contribution towards understanding the biogeography of the entire Northeast Asia.

Cryptic Species in Ecotoxicology

The advent of genetic methods has led to the discovery of an increasing number of species that previously could not be distinguished from each other on the basis of morphological characteristics. Even though there has been an exponential growth of publications on cryptic species, such species are rarely considered in ecotoxicology. Thus, the particular question of ecological differentiation and the sensitivity of closely related cryptic species is rarely addressed. Tackling this question, however, is of key importance for evolutionary ecology, conservation biology, and, in particular, regulatory ecotoxicology. At the same time, the use of species with (known or unknown) cryptic diversity might be a reason for the lack of reproducibility of ecotoxicological experiments and implies a false extrapolation of the findings. Our critical review includes a database and literature search through which we investigated how many of the species most frequently used in ecotoxicological assessments show evidence of cryptic diversity. We found a high proportion of reports indicating overlooked species diversity, especially in invertebrates. In terrestrial and aquatic realms, at least 67% and 54% of commonly used species, respectively, were identified as cryptic species complexes. The issue is less prominent in vertebrates, in which we found evidence for cryptic species complexes in 27% of aquatic and 6.7% of terrestrial vertebrates. We further exemplified why different evolutionary histories may significantly determine cryptic species' ecology and sensitivity to pollutants. This in turn may have a major impact on the results of ecotoxicological tests and, consequently, the outcome of environmental risk assessments. Finally, we provide a brief guideline on how to deal practically with cryptic diversity in ecotoxicological studies in general and its implementation in risk assessment procedures in particular. Environ Toxicol Chem 2023;42:1889-1914. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Female lizards (Eremias argus) reverse Bergmann's rule across altitude

The evolution of body size within and among species is predicted to be influenced by multifarious environmental factors. However, the specific drivers of body size variation have remained difficult to understand because of the wide range of proximate factors that covary with ectotherm body sizes across populations with varying local environmental conditions. Here, we used female Eremias argus lizards collected from different populations across their wide range in China, and constructed linear mixed models to assess how climatic conditions and/or available resources at different altitudes shape the geographical patterns of lizard body size across altitude. Lizard populations showed significant differences in body size across altitudes. Furthermore, we found that climatic and seasonal changes along the altitudinal gradient also explained variations in body size among populations. Specifically, body size decreased with colder and drier environmental conditions at high altitudes, reversing Bergmann's rule. Limited resources at high altitudes, measured by the low vegetative index, may also constrain body size. Therefore, our study demonstrates that multifarious environmental factors could strongly influence the intraspecific variation in organisms' body size.

Impacts of Quaternary glaciation, geological history and geography on animal species history in continental East Asia: A phylogeographic review

Continental East Asia has a mild Pleistocene climate and a complex recent geological history. Phylogeographic studies of animals over the last 30 years have produced several distinctive patterns. Glaciation refugia are numerous and are not restricted to any particular regions. Most of them are localized and species-specific, although several large refugia, for example the mountains of SW China, are shared by multiple species and have refugia-within-refugia. Furthermore, postglaciation range expansion events vary greatly in time, scale and direction. Large-scale south-to-north post-LGM expansions are few and mostly occurred in the northern regions. Additionally, several unique geographic features, including the three-step terrain of China and the northern arid belt, have significant impacts on many species histories. Overall, the impacts of Pleistocene glaciations, particularly the LGM, on species history vary drastically from nondetectable to significant. The impacts are the least for species from the southwestern region and are most dominant for species from the north. Geological events play a more significant role in shaping species history than Pleistocene climatic changes. Phylogeographic patterns among animals species are highly consistent with those of plants. Future phylogeographic endeavour in East Asia should be hypothesis-driven and seek processes that underlie common patterns. The wide use of genomic data allow accurate estimates of historical population processes and exploration of older history beyond the Pleistocene.

Description of Gyrodactylus paludinosus sp. nov. (Monogenea: Gyrodactylidae) from the Straightfin Barb, Enteromius paludinosus (Peters, 1852), in South Africa

INTRODUCTION

Parasites of the genus Gyrodactylus von Nordmann, 1832, are predominantly parasites of freshwater and marine bony fishes. To date, 40 species of the genus have been described from Africa, with only 6 of these reported from South Africa. This represents only a small fraction of the known diversity of almost 500 species known worldwide.

METHODS

In total, 43 of Straighhfin barb, Enteromius paludinosus were collected from Barberspan Bird Sanctuary, North West Province, South Africa. Monogenean parasites were isolated from the fins and fixed on microscope slides in ammonium picrate glycerine. Morphometric evaluation of opisthaptoral hard parts confirmed the identity of these specimens as a new species.

RESULTS

The description of Gyrodactylus paludinosus sp. nov. is presented. The new species has well-developed, slightly curved superficial inner roots and well-developed rectangular-like ventral bar membrane. Despite the small differences between the hamuli size, it can be distinguished from its congeners, G. kyogae and G. ivindoensis, the only species known from small African barbs, by the shape of ventral bars and marginal hook sickle propers.

CONCLUSION

The description of Gyrodactylus paludinosus n. sp. increases the total number of Gyrodactylus spp. known from African cyprinid fish to three. Undoubtedly, more attention should be given to studies on small barbs as potential hosts for new species.

Demographic history and local adaptation of Myripnois dioica (Asteraceae) provide insight on plant evolution in northern China flora

The flora of northern China forms the main part of the Sino-Japanese floristic region and is located in a south-north vegetative transect in East Asia. Phylogeographic studies have demonstrated that an arid belt in this region has promoted divergence of plants in East Asia. However, little is known about how plants that are restricted to the arid belt of flora in northern China respond to climatic oscillation and environmental change. Here, we used genomic-level data of Myripnois dioica across its distribution as a representative of northern China flora to reconstruct plant demographic history, examine local adaptation related to environmental disequilibrium, and investigate the factors related to effective population size change. Our results indicate M. dioica originated from the northern area and expanded to the southern area, with the Taihang Mountains serving as a physical barrier promoting population divergence. Genome-wide evidence found strong correlation between genomic variation and environmental factors, specifically signatures associated with local adaptation to drought stress in heterogeneous environments. Multiple linear regression analyses revealed joint effects of population age, mean temperature of coldest quarter, and precipitation of wettest month on effective population size (Ne). Our current study uses M. dioica as a case for providing new insights into the evolutionary history and local adaptation of northern China flora and provides qualitative strategies for plant conservation.

Evolutionary history of endangered and relict tree species Dipteronia sinensis in response to geological and climatic events in the Qinling Mountains and adjacent areas

Geological and climatic events are considered to profoundly affect the evolution and lineage divergence of plant species. However, the evolutionary histories of tree species that have responded to past geological and climate oscillations in central China's mountainous areas remain mostly unknown. In this study, we assessed the evolutionary history of the endangered and relict tree species Dipteronia sinensis in the Qinling Mountains (QM) and adjacent areas in East Asia based on variations in the complete chloroplast genomes (cpDNA) and reduced-genomic scale single nucleotide polymorphisms (SNPs). Population structure and phylogenetic analysis based on the cpDNA variations suggested that D. sinensis could be divided into two intraspecific genetic lineages in the eastern and western sides of the QM (EQM and WQM, respectively) in East Asia. Molecular dating suggested that the intraspecific divergence of D. sinensis occurred approximately 39.2 million years ago during the later Paleogene. It was significantly correlated with the orogeny of the QM, where the formation of this significant geographic barrier in the region may have led to the divergence of independent lineages. Bayesian clustering and demographic analysis showed that intraspecific gene flow was restricted between the EQM and WQM lineages. Isolation-with-migration analysis indicated that the two genetic lineages experienced significant demographic expansions after the Pleistocene ice ages. However, the genetic admixture was determined in some populations between the two lineages by the large scale of SNP variations due to DNA incompatibility, the large significant population size, and rapid gene flow of nuclear DNA markers. Our results suggest that two different conservation and management units should be constructed for D. sinensis in the EQM and WQM areas. These findings provide novel insights into the unprecedented effects of tectonic changes and climatic oscillations on lineage divergence and plant population evolution in the QM and adjacent areas in East Asia.

Age-related reproduction of female Mongolian racerunners (Eremias argus; Lacertidae): Evidence of reproductive senescence

The reproductive maturation hypothesis, the terminal investment hypothesis, and the senescence hypothesis are the most extensively evaluated hypotheses proposed to explain age-related patterns of reproduction in iteroparous organisms. Here, we evaluated these hypotheses for the Mongolian racerunner (Eremias argus), a short-lived lacertid lizard, by comparing reproductive traits between females that completed reproductive cycles under the same laboratory conditions in two consecutive years (2008 and 2009). Reproductive females gained linear size (snout-vent length) not only as they got 1 year older but also during the breeding season. Larger females generally laid eggs earlier and invested more in reproduction than did smaller ones. Females switched from laying smaller eggs in the first clutch to larger eggs in the subsequent clutches but kept clutch size and postpartum body mass constant between successive clutches in a breeding season and between years. Females that laid more clutches or eggs in 2008 did not lay fewer clutches or eggs in 2009. Of the traits examined, only clutch frequency, annual fecundity, and annual reproductive output were susceptible to ageing. Specifically, the clutch frequency was reduced by 1.1 clutches, annual fecundity by 3.1 eggs and annual reproductive output by 1.0 g in 2009 compared with 2008. Our results suggest that the reproductive maturation hypothesis better explains patterns of reproduction in young or prime-aged females of E. argus, whereas the senescence hypothesis better explains reproductive patterns in old females. The terminal investment hypothesis does not apply to any trait examined because no trait value was maximized in old females.

Genetic divergence, population differentiation and phylogeography of the cicada Subpsaltria yangi based on molecular and acoustic data: an example of the early stage of speciation?

Background

Geographical isolation combined with historical climatic fluctuations have been identified as two major factors that contribute to the formation of new species. On the other hand, biotic factors such as competition and predation are also able to drive the evolution and diversification of organisms. To determine whether geographical barriers contributed to population divergence or speciation in the rare endemic cicada Subpsaltria yangi the population differentiation, genetic structure and phylogeography of the species were investigated in the Loess Plateau and adjacent areas of northwestern China by analysing mitochondrial and nuclear DNA and comparing the calling song structure of 161 male individuals.

Results

The results reveal a low level of genetic differentiation and relatively simple phylogeographic structure for this species, but two independent clades corresponding to geographically isolated populations were recognised. Genetic and geographical distances were significantly correlated among lineages. Results of divergence-time estimation are consistent with a scenario of isolation due to glacial refugia and interglacial climate oscillation in northwestern China. Significant genetic divergence was found between the population occurring in the Helan Mountains and other populations, and recent population expansion has occurred in the Helan Mountains and/or adjacent areas. This population is also significantly different in calling song structure from other populations.

Conclusions

Geographical barriers (i.e., the deserts and semi-deserts surrounding the Helan Mountains), possibly coupled with related ecological differences, may have driven population divergence and allopatric speciation. This provides a possible example of incipient speciation in Cicadidae, improves understanding of population differentiation, acoustic signal diversification and phylogeographic relationships of this rare cicada species of conservation concern, and informs future studies on population differentiation, speciation and phylogeography of other insects with a high degree of endemism in the Helan Mountains and adjacent areas.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1317-8) contains supplementary material, which is available to authorized users.

Genetic differentiation of regional populations of the widespread Asiatic toad (Bufo gargarizans), as revealed by development of novel microsatellite markers

Dispersal is a key component of a species’ life history, by influencing population persistence, genetic structure, adaptation and maintenance of genetic diversity. The Asiatic toad (Bufo gargarizans) is a widespread species in east Asia. However, we still have no knowledge of what kind of geographical scale equates to genetic differentiation within B. gargarizans. In this study, the population genetics of B. gargarizans was studied at five localities, with the Yangtze River running through the sampling area, in order to detect the level of genetic differentiation and the natural barriers to the species’ dispersal on a small geographic scale, by means of the development and use of novel microsatellite loci. These markers revealed a relatively high level of genetic diversity. Distinct genetic structure among populations in B. gargarizans was observed, as described by genetic distance, AMOVA, PCA and Geneland results. A weak but significant positive correlation between genetic distance and geographical distance. The combination of these findings suggests that the Yangtze River and geographic distance may act as effective barriers for B. gargarizans. These results serve as benchmark data for understanding the impacts of dispersal barriers and continued landscape research on B. gargarizans.

Yangtze River, an insignificant genetic boundary in tufted deer (Elaphodus cephalophus): the evidence from a first population genetics study

Great rivers were generally looked at as the geographical barrier to gene flow for many taxonomic groups. The Yangtze River is the third largest river in the world, and flows across South China and into the East China Sea. Up until now, few studies have been carried out to evaluate its effect as a geographical barrier. In this study, we attempted to determine the barrier effect of the Yangtze River on the tufted deer (Elaphodus cephalophus) using the molecular ecology approach. Using mitochondrial DNA control region (CR) sequences and 13 nuclear microsatellite loci, we explored the genetic structure and gene flow in two adjacent tufted deer populations (Dabashan and Wulingshan populations), which are separated by the Yangtze River. Results indicated that there are high genetic diversity levels in the two populations, but no distinguishable haplotype group or potential genetic cluster was detected which corresponded to specific geographical population. At the same time, high gene flow was observed between Wulingshan and Dabashan populations. The tufted deer populations experienced population decrease from 0.3 to 0.09 Ma BP, then followed by a distinct population increase. A strong signal of recent population decline (T = 4,396 years) was detected in the Wulingshan population by a Markov-Switching Vector Autoregressions(MSVAR) process population demography analysis. The results indicated that the Yangtze River may not act as an effective barrier to gene flow in the tufted deer. Finally, we surmised that the population demography of the tufted deer was likely affected by Pleistocene climate fluctuations and ancient human activities.

Geologic events coupled with Pleistocene climatic oscillations drove genetic variation of Omei treefrog (Rhacophorus omeimontis) in southern China

BACKGROUND

Pleistocene climatic oscillations and historical geological events may both influence current patterns of genetic variation, and the species in southern China that faced unique climatic and topographical events have complex evolutionary histories. However, the relative contributions of climatic oscillations and geographical events to the genetic variation of these species remain undetermined. To investigate patterns of genetic variation and to test the hypotheses about the factors that shaped the distribution of this genetic variation in species of southern China, mitochondrial genes (cytochrome b and NADH dehydrogenase subunit 2) and nine microsatellite loci of the Omei tree frog (Rhacophorus omeimontis) were amplified in this study.

RESULTS

The genetic diversity in the populations of R. omeimontis was high. The phylogenetic trees reconstructed from the mitochondrial DNA (mtDNA) haplotypes and the Bayesian genetic clustering analysis based on microsatellite data both revealed that all populations were divided into three lineages (SC, HG and YN). The two most recent splitting events among the lineages coincided with recent geological events (including the intense uplift of the Qinghai-Tibet Plateau, QTP and the subsequent movements of the Yun-Gui Plateau, YGP) and the Pleistocene glaciations. Significant expansion signals were not detected in mismatch analyses or neutrality tests. And the effective population size of each lineage was stable during the Pleistocene.

CONCLUSIONS

Based on the results of this study, complex geological events (the recent dramatic uplift of the QTP and the subsequent movements of the YGP) and the Pleistocene glaciations were apparent drivers of the rapid divergence of the R. omeimontis lineages. Each diverged lineages survived in situ with limited gene exchanges, and the stable demographics of lineages indicate that the Pleistocene climatic oscillations were inconsequential for this species. The analysis of genetic variation in populations of R. omeimontis contributes to the understanding of the effects of changes in climate and of geographical events on the dynamic development of contemporary patterns of genetic variation in the species of southern China.

Phylogeny and divergence times of some racerunner lizards (Lacertidae: Eremias) inferred from mitochondrial 16S rRNA gene segments

Eremias, or racerunners, is a widespread lacertid genus occurring in China, Mongolia, Korea, Central Asia, Southwest Asia and Southeast Europe. It has been through a series of taxonomic revisions, but the phylogenetic relationships among the species and subgenera remain unclear. In this study, a frequently studied region of the mitochondrial 16S rRNA was used to (i) reassess the phylogenetic relationships of some Eremias species, (ii) test if the viviparous species form a monophyletic group, and (iii) estimate divergence time among lineages using a Bayesian relaxed molecular-clock approach. The resulting phylogeny supports monophyly of Eremias sensu Szczerbak and a clade comprising Eremias, Acanthodactylus and Latastia. An earlier finding demonstrating monophyly of the subgenus Pareremias is corroborated, with Eremias argus being the sister taxon to Eremias brenchleyi. We present the first evidence that viviparous species form a monophyletic group. In addition, Eremias przewalskii is nested within Eremias multiocellata, suggesting that the latter is likely a paraphyletic species or a species complex. Eremias acutirostris and Eremias persica form a clade that is closely related to the subgenus Pareremias. However, the subgenera Aspidorhinus, Scapteira, and Rhabderemias seem not to be monophyletic, respectively. The Bayesian divergence-time estimation suggests that Eremias originated at about 9.9 million years ago (with the 95% confidence interval ranging from 7.6 to 12 Ma), and diversified from Late Miocene to Pleistocene. Specifically, the divergence time of the subgenus Pareremias was dated to about 6.3 million years ago (with the 95% confidence interval ranging from 5.3 to 8.5 Ma), which suggests that the diversification of this subgenus might be correlated with the evolution of an East Asian monsoon climate triggered by the rapid uplift of the Tibetan Plateau approximately 8 Ma.