摘要: Geographical divergence in acoustic signals is often affected by multiple selective pressures. Environmental factors are expected to shape signals by adjusting for greater propagation efficiency. Nevertheless, such habitat-driven hypotheses have not been well-examined with multi-signal and multi-habitat types included simultaneously. In this study, we evaluated call similarity of the spot-legged treefrog (Polypedates megacephalus), characterized by multiple call types, from 11 geographic populations across Hainan Island. We also examined multiple factors (i.e. body mass, temperature, altitude, and vegetation) among different acoustical geographic clusters, and tested whether the variation in acoustic length and frequency among different habitats was in accordance with the prediction derived from the acoustic adaptation hypothesis. We showed that P. megacephalus from Hainan Island included 3 acoustic geographic clusters: the northeastern flatlands, the southwest mountains, and the hills around the mountains. We also showed that environmental factors (i.e. altitude and vegetation) varied across these 3 acoustically distinct areas. Moreover, the duration of the different call types supported the hypothesis that they should have optimal transmission in their own habitats. Thus, our results reveal the roles of ecological selection in the geographical divergence of anuran acoustic signals.

摘要: Bite force is often associated with specific morphological features, such as sagittal crests. The presence of a pronounced sagittal crest in some tapirs (Perissodactyla: Tapiridae) was recently shown to be negatively correlated with hard-object feeding, in contrast with similar cranial structures in carnivorans. The aim of this study was to investigate bite forces and sagittal crest heights across a wide range of modern and extinct tapirs and apply a comparative investigation to establish whether these features are correlated across a broad phylogenetic scope. We examined a sample of 71 specimens representing 15 tapir species (5 extant, 10 extinct) using the dry-skull method, linear measurements of cranial features, phylogenetic reconstruction, and comparative analyses. Tapirs were found to exhibit variation in bite force and sagittal crest height across their phylogeny and between different biogeographical realms, with high-crested morphologies occurring mostly in Neotropical species. The highest bite forces within tapirs appear to be driven by estimates for the masseter-pterygoid muscle complex, rather than predicted forces for the temporalis muscle. Our results demonstrate that relative sagittal crest height is poorly correlated with relative cranial bite force, suggesting high force application is not a driver for pronounced sagittal crests in this sample. The divergent biomechanical capabilities of different contemporaneous tapirids may have allowed multiple species to occupy overlapping territories and partition resources to avoid excess competition. Bite forces in tapirs peak in Pleistocene species, independent of body size, suggesting possible dietary shifts as a potential result of climatic changes during this epoch.

摘要: We tested for the effects of latitude and geographic range size (GRS) on body size, leg length, and sexual size dimorphism (SSD) across 103 species of fleas, taking into account phylogenetic between-species relationships. When the data on body size were combined for males and females, the positive correlation between body size and latitude, but not GRS, was revealed. When the analysis was restricted to one sex only, the effect of latitude appeared to be non-significant for females, whereas male body size increased with an increase in latitude. Intraspecific body size variation was not associated with either the latitude or the latitudinal span of the geographic range, independently of which data subset was analyzed. No evidence of association between size-independent tibia length and latitude was found for either females, males, or both sexes combined. The degree of SSD decreased with a decrease in latitude but was not affected by GRS. We conclude that macroecological patterns might be manifested differently in males and females. This should be kept in mind while searching for these patterns.

摘要: The genes of the major histocompatibility complex (MHC) encode cell surface proteins that are essential for adaptive immunity. MHC genes show the most prominent genetic diversity in vertebrates, reflecting the adaptation of populations to their evolving environment, population survival and reproduction. In the present study, we used next -generation sequencing (NGS) to study the loci polymorphism of exon 3 of the MHC class I genes in an ovoviviparous skink, the many-lined sun skink, Eutropis multifasciata and five other species of Scincidae, to quantify genetic variation. In addition, we genotyped the same MHC class I genes of E. multifasciata using clone sequencing, to directly compare the effectiveness of both analytical techniques for MHC genotyping. NGS detected 20 MHC class I alleles in E. multifasciata, and 2 to 15 alleles in the other five Scincidae species. However, clone sequencing detected only 15 of those MHC class I alleles in E. multifasciata. In addition, trans -species polymorphism of MHC class I genes was studied by constructing a phylogenetic tree using the gene sequences obtained by NGS. Phylogenetic analysis revealed that MHC class I alleles were shared among different species of Scincidae with trans-species polymorphism, and did not exhibit specific genealogical inheritance. These results have important implications for understanding polymorphism interspecies diversity in the MHC genes of Scincidae, and the evolution of the MHC more broadly.

摘要: Mitochondrial genomes (mitogenomes) in frogs are essential for reconstructing the phylogenetic relationships and shedding light on the molecular evolution in these animals. However, there are only seven complete Rhacophoridae genomes that have been reported to date. In this paper, two complete mitogenomes of the Chinese whipping frog (Zhangixalus chenfui) and Emei tree frog (Z. omeimontis) were described, each of which was 20520 and 19782 bp in size, and had A+T contents of 64.26% and 63.83%. The two mitogenomes each included two non-coding control region (D-loop, CR), two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and 22 transfer RNA genes (tRNAs), and it was found that the mitogenome of Z. chenfui also includes three tandem tRNAMet gene sequences. A typical clover-leaf structure was found for all tRNAs except for tRNASer1(AGN), which showed a reduced DHU arm. The putative D-loop region contains multiple types of tandem repeats regions. Both of these two mitogenomes showed similar pattern of gene rearrangement (tRNA-Ser-ND6-tRNA-Glu-Cytb-CR1-ND5-CR2-tRNA-Thr-tRNA-Leu-tRNA-Pro). Additionally, three consecutive tRNAMet genes were found for the first time in Z. chenfui, a species in the Rhacophoridae family. For all phylogenetic analyses, which were based on 13 protein-coding genes from 91 Ranoidea mitogenomes, the same phylogenetic trees were observed using either maximum likelihood or Bayesian approaches. These results suggest that the phylogenetic hypotheses for the Ranoidea (including Rhacophoridae, Mantellidae, Ranidae and Dicroglossidae) derived from these mitogenomic data could provide substantiation for the relationships of (Dicroglossidae (Ranidae, (Mantellidae, Rhacophoridae))), and support the presence of a monophyletic group in four families. Moreover, Z. omeimontis and Z. dennysi were found to cluster on the same branch, indicating that they were more closely related as a group. This group may in turn form sister groups with Z. arboreus and Z. schlegelii. However, Z. chenfui is located on the base of other species in the genera. Increased mitogenome sampling should be conducted to provide a more satisfactory resolution to the phylogeny of the Rhacophorus, Rhacophoridae, and Mantellidae.