Diamondback terrapins(Malaclemys terrapin centrata)exhibit strong environmental adaptability and live in both freshwater and saltwater.However,the genetic basis of this adaptability has not been the focus of research....Diamondback terrapins(Malaclemys terrapin centrata)exhibit strong environmental adaptability and live in both freshwater and saltwater.However,the genetic basis of this adaptability has not been the focus of research.In this study,we successfully constructed a~2.21-Gb chromosome-level genome assembly for M.t.centrata using highcoverage and high-depth genomic sequencing data generated on multiple platforms.The M.t.centrata genome contains 25 chromosomes and the scaffold N50 of~143.75 Mb,demonstrating high continuity and accuracy.In total,53.82% of the genome assembly was composed of repetitive sequences,and 22435 protein-coding genes were predicted.Our phylogenetic analysis indicated that M.t.centrata was closely related to the red-eared slider turtle(Trachemys scripta elegans),with divergence approximately~23.6 million years ago(Mya)during the early Neogene period of the Cenozoic era.The population size of M.t.centrata decreased significantly over the past~14 Mya during the Cenozoic era.Comparative genomic analysis indicated that 36 gene families related to ion transport were expanded and several genes(AQP3,solute carrier subfamily,and potassium channel genes)underwent specific amino acid site mutations in the M.t.centrata genome.Changes to these ion transport-related genes may have contributed to the remarkable salinity adaptability of diamondback terrapin.The results of this study not only provide a high-quality reference genome for M.t.centrata but also elucidate the possible genetic basis for salinity adaptation in this species.展开更多
Diamondback terrapins(Malaclemys terrapin)inhabit estuaries in eastern USA and may tolerate salinity of seawater for short durations.Many North American estuaries are adversely affected by anthropogenic impacts,such a...Diamondback terrapins(Malaclemys terrapin)inhabit estuaries in eastern USA and may tolerate salinity of seawater for short durations.Many North American estuaries are adversely affected by anthropogenic impacts,such as pollution,dredging and invasion by non-native plants.Many nesting areas have been altered or destroyed,causing terrapins to nest on roadsides and artificial islands made of dredged substrate from bottom sediments.Shading by non-native plants may suppress development and reduce survival of embryos.In Barnegat Bay,New Jersey,USA,there is a mosaic of natural and degraded terrapin nesting habitats.We investigated the effects of dredge soil and shade on the hatching success of diamondback terrapins to determine whether nesting habitat could be increased by using dredged bottom sediments.In year 1,unshaded nests in natural loamy-sand had the highest hatching success(55.2%),while nests in dredge soil produced no hatchlings.In year 2,nests in unshaded loamy-sand had a hatching success of 85.3%,whereas those in dredge soil,aged 1 year,had a hatching success of 59.4%.Dredge soil improved as an incubation substrate after aging 1 year by the washout of salt.Nest temperatures were generally cool and produced mostly male hatchlings.Uncontaminated dredge soil may provide suitable nesting substrates for diamondback terrapins if used after one year,and may be particularly beneficial if used for constructing islands that provide new nesting sites with reduced access of mammalian predators.展开更多
基金supported by the National Natural Science Foundation of China Regional Fund Project(32160135)the National Natural Science Foundation of China(32322018)+3 种基金the Fundamental Research Funds for the Central Universities(23GH02025)the Double First-Class Construction Special Fund(G2022KY05105)the Foundation of Shaanxi Academy of Sciences(2023K-10)the National Natural Science Foundation of China(32000383).
文摘Diamondback terrapins(Malaclemys terrapin centrata)exhibit strong environmental adaptability and live in both freshwater and saltwater.However,the genetic basis of this adaptability has not been the focus of research.In this study,we successfully constructed a~2.21-Gb chromosome-level genome assembly for M.t.centrata using highcoverage and high-depth genomic sequencing data generated on multiple platforms.The M.t.centrata genome contains 25 chromosomes and the scaffold N50 of~143.75 Mb,demonstrating high continuity and accuracy.In total,53.82% of the genome assembly was composed of repetitive sequences,and 22435 protein-coding genes were predicted.Our phylogenetic analysis indicated that M.t.centrata was closely related to the red-eared slider turtle(Trachemys scripta elegans),with divergence approximately~23.6 million years ago(Mya)during the early Neogene period of the Cenozoic era.The population size of M.t.centrata decreased significantly over the past~14 Mya during the Cenozoic era.Comparative genomic analysis indicated that 36 gene families related to ion transport were expanded and several genes(AQP3,solute carrier subfamily,and potassium channel genes)underwent specific amino acid site mutations in the M.t.centrata genome.Changes to these ion transport-related genes may have contributed to the remarkable salinity adaptability of diamondback terrapin.The results of this study not only provide a high-quality reference genome for M.t.centrata but also elucidate the possible genetic basis for salinity adaptation in this species.
基金Earthwatch Institutethe Ocean County Foundation for Vocational Education+2 种基金Exelon Energy CorporationToyota Motor Sales–USAthe Betz Chair of Environmental Science at Drexel University for funding this project.
文摘Diamondback terrapins(Malaclemys terrapin)inhabit estuaries in eastern USA and may tolerate salinity of seawater for short durations.Many North American estuaries are adversely affected by anthropogenic impacts,such as pollution,dredging and invasion by non-native plants.Many nesting areas have been altered or destroyed,causing terrapins to nest on roadsides and artificial islands made of dredged substrate from bottom sediments.Shading by non-native plants may suppress development and reduce survival of embryos.In Barnegat Bay,New Jersey,USA,there is a mosaic of natural and degraded terrapin nesting habitats.We investigated the effects of dredge soil and shade on the hatching success of diamondback terrapins to determine whether nesting habitat could be increased by using dredged bottom sediments.In year 1,unshaded nests in natural loamy-sand had the highest hatching success(55.2%),while nests in dredge soil produced no hatchlings.In year 2,nests in unshaded loamy-sand had a hatching success of 85.3%,whereas those in dredge soil,aged 1 year,had a hatching success of 59.4%.Dredge soil improved as an incubation substrate after aging 1 year by the washout of salt.Nest temperatures were generally cool and produced mostly male hatchlings.Uncontaminated dredge soil may provide suitable nesting substrates for diamondback terrapins if used after one year,and may be particularly beneficial if used for constructing islands that provide new nesting sites with reduced access of mammalian predators.
