摘要: One of the most striking radiations in brachyuran evolution is the considerable morphological diversification of the external reproductive structures of primary freshwater crabs: the male first gonopod (G1) and the female vulva (FV). However, the lack of quantitative studies, especially the lack of data on female genitalia, has seriously limited our understanding of genital evolution in these lineages. Here we examined 69 species of the large Chinese potamid freshwater crab genus Sinopotamon Bott, 1967 (more than 80% of the described species). We used a landmark-based geometric morphometric approach to analyze variation in the shape of the G1 and FV, and to compare the relative degree of variability of the genitalia with non-reproductive structures (the third maxillipeds). We found rapid divergent evolution of the genitalia among species of Sinopotamon when compared to non-reproductive traits. In addition, the reconstruction of ancestral groundplans, together with plotting analyses, indicated that the FV show the most rapid divergence, and that changes in FV traits correlate with changes in G1 traits. Here we provide new evidence for coevolution between the male and female external genitalia of Sinopotamon that has likely contributed to rapid divergent evolution and an associated burst of speciation in this lineage.

摘要: On the Qinghai-Tibet Plateau, extreme environmental conditions have imposed intense selective pressure on the evolution of phenotypic traits of wild animals. To date, limited information is available on behavioral and ecological traits concerning niche differentiation among sympatric animals on the Qinghai-Tibet Plateau, especially during winter when the environments are most severe. Here, we studied the seasonal variations in habitat occurrence, territorial behavior, and diet in two sympatric snow finches (the white-rumped snow finch,Onychostruthus taczanowskii, WRSF; and the rufous-necked snow finch,Pyrgilauda ruficollis, RNSF) to determine convergence and divergence of ecological traits in such severe climatic conditions. Our results showed that: (i) WRSF occupied rural areas as a dominant species throughout the annual cycle while RNSF occupied the rural areas in summer and then shifted to human-occupied areas in winter and spring; (ii) WRSFs exhibited robust aggressive behavior and territoriality during winter relative to RNSFs; (iii) the diets of both species varied with the season but did not vary between species except that WRSF ate significantly more seeds but RNSF consumed more starchy material derived from human food waste during winter. Therefore, the separations in the spatial niche and territoriality between WRSF and RNSF, especially in winter, may contribute to alleviating the pressure of interspecific competition, and promoting the coexistence of the two sympatric snow finches in the extreme environments on the Qinghai-Tibet Plateau.

摘要: Biology textbooks describe the small changes in the beaks of the Galapagos finches as exemplars of how birds evolve in response to environmental changes. However, recent studies of the abundant fossil birds at Rancho La Brea find no evidence of evolutionary responses to the dramatic climate changes of the glacial-interglacial cycle over the past 35 000 years: none of the large birds exhibit any change in body size or limb proportions, even during the last glacial maximum approximately 18 000-20 000 years ago, when the southern California chaparral was replaced by snowy coniferous forests. However, these are all large birds with large ranges and broad habitat preferences, capable of living in many different environments. Perhaps the smaller birds at La Brea, which have smaller home ranges and narrower habitats, might respond to climate more like Galapagos finches. The only 3 common small birds at La Brea are the western meadowlark, the yellow-billed magpie and the raven. In this study, we demonstrate that these birds also show complete stasis over the last glacial-interglacial cycle, with no statistically significant changes between dated pits. Recent research suggests that the small-scale changes over short timescales seen in the Galapagos finches are merely fluctuations around a stable morphology, and rarely lead to long-term accumulation of changes or speciation. Instead, the prevalence of stasis supports the view that long-term directional changes in morphology are quite rare. While directional changes in morphology occur frequently over short (<1 ka) timescales, in the long term such changes only rarely remain stable for long enough to appear in the fossil record.

摘要: The compensation hypothesis predicts that if the left testis is defective e.g. due to developmental stress, the increased right testis serves a compensatory role, and thereby displaying testes asymmetry which can be a reliable indicator of male body condition. Here, to test the prediction of the compensation hypothesis, we analyzed difference in size between left testis and right testis and the relationship between testes asymmetry and male body condition in the swelled vent frog (Feirana quadranus). We found that the left testis was larger than right testis, displaying a significant directional asymmetry in testes size. Although testes mass was correlated with body condition, testes asymmetry was not correlated with body condition, which cannot provide evidence that the right testis had a compensatory function. Our findings suggest no evidence for the compensation hypothesis in this species due to lacking the compensatory function in right testis.

摘要: The genus Rhabdophis is a group of widely distributed snakes with more than 20 species. Recent field surveys uncovered a species in southwestern China, which has long been considered as R. pentasupralabialis. Combined molecular and morphological analyses revealed it as a new species Rhabdophis chiwen sp. nov. Based on 12 specimens, this new species is distinguished by the following characters: 1) dorsal body saddlebrown, dorsal scales typically with black margins forming spots and stripes, the margin of the outer row forming two faint dorsolateral black cross-bars alongside body; 2) ventral scales 151-159, the outer margin of ventral scales and several lateral rows of dorsal scales forming ventrolateral longitudinal brownish-red coloration, with faint black spots in the middle of ventral scales; 3) a black oblique stripe present below eyes, often with a black spot between the 2nd and 3rd supralabial and a black stripe on the 5th supralabiat 4) eyes dark khaki, pupils black; 5) infralahials usually 7, the first four in contact with anterior chin-shields; 6) temporal scales 1+1; 7) dorsal scales in 15 rows, feebly keeled except the outer 1-2 rows; 8) anal scale divided; subcaudals 45-59; 9) preocular 1 and postoculars 3 (occasionally 2},10) body medium-sized (snout-vent length: adult males 404-431 mm, adult females 409-476 nun); 11) tail moderate (tail length/total length in adult males 0205-0238. in adult females 0.172-0.193). With the discovery of this new species, the total number of species in genus Rhabdophis is 28 with 12th species known to occur in China.