The present study reports on population structure analysis of the marbled crab Pachygrapsus marmoratus （Fabricius, 1787） from the Tunisian coast, an appropriate location to study biogeographical processes because of...The present study reports on population structure analysis of the marbled crab Pachygrapsus marmoratus （Fabricius, 1787） from the Tunisian coast, an appropriate location to study biogeographical processes because of the presence of a well-known discontinuous biogeographic area （the Siculo-Tunisian Strait）. Patterns of morphological and genetic variation of this highly dispersive and continuously distributed decapod species were assessed among its geographically close populations which cover almost the entire Tunisian coastline. A total of 386 specimens from nine sites were collected and examined for morphometric variability at 14 morphometric traits. The results of multivariate analyses of linear morphometric traits showed the existence of sexual dimorphism in this species by PERMANOVA （Permutational multivariate analysis of variance）. In addition, both CDA （Canonical discriminant analysis） and NPMANOVA （Non parametric MANOVA test） analyses revealed statistically significant differences among the studied locations for both sexes. Overall, the outcome of CDA analysis showed that over 87% of individuals could be assigned correctly to three regional groups in both sexes （North, Center and South）. Specifically, SIMPER （Similarity Percentages） analysis showed that carapace length, carapace width and merus length were major contributors to the morphometric separation between populations. The pattern of phenotypic variation suggested by morphometric analyses was found to be highly discordant with that suggested by the analysis of a mitochondrial marker （cytochrome oxidase I, COI）. Indeed, the results inferred from restriction fragment analysis of the COI in 180 crabs, suggested high genetic homogeneity. Very low levels of haplotype diversity （h） were found in almost all the studied populations, associated with non significant genetic distances for nearly all population comparisons. Explanations to these morphometric and mtDNA patterns as well as the discrepancy between them are discussed.展开更多
Effective conservation of threatened biota relies on accurate assessments and scientific guidance.As an unfortunate example,Chinese giant salamanders(Andrias,CGS)remain critically endangered in nature.Misguided conser...Effective conservation of threatened biota relies on accurate assessments and scientific guidance.As an unfortunate example,Chinese giant salamanders(Andrias,CGS)remain critically endangered in nature.Misguided conservation efforts,e.g.,commercial propagation and releasing of millions of likely non-indigenous or interspecific hybrids,have further compromised conservation initiatives.Limited information on wild populations of CGS poses a significant conservation challenge.Following 18-month long field monitoring,we now report the discovery of a wild population of CGS in a closed nature reserve in Jiangxi Province,China.Genomic assessments reveal its genetic distinctiveness and do not detect genetic admixture with other species.Based on morphological and molecular evidences,we describe this CGS as a new species Andrias jiangxiensis sp.nov.This is the only known species of CGS today with a genetically pure,reproducing,in situ population.This discovery emphasizes the important role that closed nature reserves play in protecting species,and the necessity of integrating long-term field monitoring and genetic assessments.It sets a new pathway for discovering and conserving endangered species,especially for those biotas that are similarly being extirpated by anthropogenic translocations and overexploitation.展开更多
文摘The present study reports on population structure analysis of the marbled crab Pachygrapsus marmoratus （Fabricius, 1787） from the Tunisian coast, an appropriate location to study biogeographical processes because of the presence of a well-known discontinuous biogeographic area （the Siculo-Tunisian Strait）. Patterns of morphological and genetic variation of this highly dispersive and continuously distributed decapod species were assessed among its geographically close populations which cover almost the entire Tunisian coastline. A total of 386 specimens from nine sites were collected and examined for morphometric variability at 14 morphometric traits. The results of multivariate analyses of linear morphometric traits showed the existence of sexual dimorphism in this species by PERMANOVA （Permutational multivariate analysis of variance）. In addition, both CDA （Canonical discriminant analysis） and NPMANOVA （Non parametric MANOVA test） analyses revealed statistically significant differences among the studied locations for both sexes. Overall, the outcome of CDA analysis showed that over 87% of individuals could be assigned correctly to three regional groups in both sexes （North, Center and South）. Specifically, SIMPER （Similarity Percentages） analysis showed that carapace length, carapace width and merus length were major contributors to the morphometric separation between populations. The pattern of phenotypic variation suggested by morphometric analyses was found to be highly discordant with that suggested by the analysis of a mitochondrial marker （cytochrome oxidase I, COI）. Indeed, the results inferred from restriction fragment analysis of the COI in 180 crabs, suggested high genetic homogeneity. Very low levels of haplotype diversity （h） were found in almost all the studied populations, associated with non significant genetic distances for nearly all population comparisons. Explanations to these morphometric and mtDNA patterns as well as the discrepancy between them are discussed.
基金equally supported by the STS Program of Chinese Academy of Sciencesand the Strategic Priority Research Program of Chinese Academy of Sciences(XDB31000000)+1 种基金The Animal Branch of the Germplasm Bank of Wild Species,Chinese Academy of Sciences(Large Research Infrastructure Funding)Jiangxi Academy of Sciences(2021YSBG50008)partially supported it。
文摘Effective conservation of threatened biota relies on accurate assessments and scientific guidance.As an unfortunate example,Chinese giant salamanders(Andrias,CGS)remain critically endangered in nature.Misguided conservation efforts,e.g.,commercial propagation and releasing of millions of likely non-indigenous or interspecific hybrids,have further compromised conservation initiatives.Limited information on wild populations of CGS poses a significant conservation challenge.Following 18-month long field monitoring,we now report the discovery of a wild population of CGS in a closed nature reserve in Jiangxi Province,China.Genomic assessments reveal its genetic distinctiveness and do not detect genetic admixture with other species.Based on morphological and molecular evidences,we describe this CGS as a new species Andrias jiangxiensis sp.nov.This is the only known species of CGS today with a genetically pure,reproducing,in situ population.This discovery emphasizes the important role that closed nature reserves play in protecting species,and the necessity of integrating long-term field monitoring and genetic assessments.It sets a new pathway for discovering and conserving endangered species,especially for those biotas that are similarly being extirpated by anthropogenic translocations and overexploitation.
