Since organic falls are ephemeral and distributed sporadically, organisms in organic-fall communities must acquire high dispersal ability to migrate from one organic fall to another. However, the dispersal ability of ...Since organic falls are ephemeral and distributed sporadically, organisms in organic-fall communities must acquire high dispersal ability to migrate from one organic fall to another. However, the dispersal ability of obligate organic-fall organisms has not been investigated thoroughly and the stability of the genetic structure of their communities is unknown. In this study, in order to elucidate the dispersal ability and genetic structure in the organic-fall communities, we carried out population genetic analyses based on sequences of mitochondrial NADH dehydrogenase subunit 4 in two mytilid mussels.?Adipicola pacifica was obtained from whale and cow bones artificially settled in Japanese waters off Cape Noma (CN) and in the Nansei-Shoto Trench (NS) and Sagami Bay (SB), and Benthomodiolus geikotsucola from natural whale bones in the Torishima Seamount (TS);both species are symbiotic with chemoautotrophic bacteria. Genetic differentiation (Fst) indicated almost no annual change in genetic structure between 2003, 2004, 2005, and 2007 collections of A. pacificafrom CN (depth 225 - 229 m), although the 2010 collection had somewhat different genetic structure from the others. Similarly, there was not significant genetic differentiation between 1993 and 2005 collections of B.geikotsucola from TS (depth 4020 m). The Fst and gene bidirectional mean rate of gene flow (Nm) indicated high gene flow and no significant genetic differentiation between A. pacifica specimens collected from CN, NS, and SB. The results suggest that the genetic structure is stable and A. pacifica has high dispersal ability. The mismatch distribution suggests that A. pacificaexpanded their distribution from SB to NS via CN, as expansion time (τ = 2ut) decreased from SB to CN and NS.展开更多
使用PFC3D按照其用户手册上的步骤构建模型时,存在半径放大系数(mul)确定困难、构造的不同属性颗粒体的边界连接程度难以保证等问题。由此,提出了基于"下落法(Particles Fall Method,PFM)"的PFC3D岩土模型的构造方法。该方法...使用PFC3D按照其用户手册上的步骤构建模型时,存在半径放大系数(mul)确定困难、构造的不同属性颗粒体的边界连接程度难以保证等问题。由此,提出了基于"下落法(Particles Fall Method,PFM)"的PFC3D岩土模型的构造方法。该方法根据颗粒岩体的自然形成过程,在规定区域内使颗粒自然下落堆积、压实和充分接触,然后通过删除规定形状外的颗粒进行构型,计算至平衡得到初始地应力场。与经典步骤相比该方法不用计算mul,不用建立边坡墙和土层间的分界墙,不用消除悬浮颗粒;但增加了颗粒下落计算和构型过程。提供了整体下落法(Overall Particles Fall Method,OPFM)和分层下落法(Hierarchical Particles Fall Method,HPFM)两种方式。通过实际工程分析,总体上模型的精确度和构造便捷程度优于经典方法,一次模型构建的成功率较高。展开更多
文摘Since organic falls are ephemeral and distributed sporadically, organisms in organic-fall communities must acquire high dispersal ability to migrate from one organic fall to another. However, the dispersal ability of obligate organic-fall organisms has not been investigated thoroughly and the stability of the genetic structure of their communities is unknown. In this study, in order to elucidate the dispersal ability and genetic structure in the organic-fall communities, we carried out population genetic analyses based on sequences of mitochondrial NADH dehydrogenase subunit 4 in two mytilid mussels.?Adipicola pacifica was obtained from whale and cow bones artificially settled in Japanese waters off Cape Noma (CN) and in the Nansei-Shoto Trench (NS) and Sagami Bay (SB), and Benthomodiolus geikotsucola from natural whale bones in the Torishima Seamount (TS);both species are symbiotic with chemoautotrophic bacteria. Genetic differentiation (Fst) indicated almost no annual change in genetic structure between 2003, 2004, 2005, and 2007 collections of A. pacificafrom CN (depth 225 - 229 m), although the 2010 collection had somewhat different genetic structure from the others. Similarly, there was not significant genetic differentiation between 1993 and 2005 collections of B.geikotsucola from TS (depth 4020 m). The Fst and gene bidirectional mean rate of gene flow (Nm) indicated high gene flow and no significant genetic differentiation between A. pacifica specimens collected from CN, NS, and SB. The results suggest that the genetic structure is stable and A. pacifica has high dispersal ability. The mismatch distribution suggests that A. pacificaexpanded their distribution from SB to NS via CN, as expansion time (τ = 2ut) decreased from SB to CN and NS.
文摘使用PFC3D按照其用户手册上的步骤构建模型时,存在半径放大系数(mul)确定困难、构造的不同属性颗粒体的边界连接程度难以保证等问题。由此,提出了基于"下落法(Particles Fall Method,PFM)"的PFC3D岩土模型的构造方法。该方法根据颗粒岩体的自然形成过程,在规定区域内使颗粒自然下落堆积、压实和充分接触,然后通过删除规定形状外的颗粒进行构型,计算至平衡得到初始地应力场。与经典步骤相比该方法不用计算mul,不用建立边坡墙和土层间的分界墙,不用消除悬浮颗粒;但增加了颗粒下落计算和构型过程。提供了整体下落法(Overall Particles Fall Method,OPFM)和分层下落法(Hierarchical Particles Fall Method,HPFM)两种方式。通过实际工程分析,总体上模型的精确度和构造便捷程度优于经典方法,一次模型构建的成功率较高。
