贝类壳-体质量比和静水沉降特性的相关性

软体动物贝壳表型是适应性进化的结果，为探究贝壳形态特性与软体动物随水流扩散功能的相关性，实验选取9种具代表性的腹足纲和双壳纲贝类作为研究对象，研究了其成体的壳-体质量比与静水沉降特性及二者的相关性。结果表明：体质量的变异系数（C.V.=1.11）大于壳长（C.V.=0.67）、壳宽（C.V.=0.54）的变异系数；壳-体质量比具较强的种属特异性，种内变异系数小（C.V.=0.20），而种间差异极显著（P < 0.01）。受试贝类的平均壳-体质量比为0.32±0.13，陆生贝类的壳-体质量比显著小于水生贝类（P < 0.01），壳-体质量比最大的河蚬（0.54±0.06）是最小的非洲大蜗牛（0.17±0.04）的3倍，福寿螺的壳-体质量比为0.50±0.06。双壳类和螺类的沉降行为差异明显，只有中华园田螺、铜锈环棱螺和河蚬不能在静水中漂浮；沉降速度最大的河蚬（（24.99±4.22）cm/s）是最小的椭圆萝卜螺（（4.13±0.96）cm/s）的6倍，入侵种非洲大蜗牛（（18.30±3.64）cm/s）和福寿螺（（21.77±5.23）cm/s）与土著种铜锈环棱螺（（19.48±3.14）cm/s）和中华园田螺（（21.44±3.92）cm/s）在沉降速度上无显著差异（P < 0.01）。成体贝类的壳-体质量比与沉降速度（R²=0.28）、沉降加速度（R²=0.39）之间存在一定的相关性。在此基础上，贝类沉降特性随生活史变化的研究将进一步揭示贝类进化与种群扩散中的生态水力学作用。

Correlation between shell-body mass ratio and hydrostatic settling characteristics of mollusc species

Shell phenotype is the result of adaptive evolution in molluscs. In order to explore the specificity of shell phenotype and its relationship with eco-hydraulics, this study examined the shell-body mass ratio and the hydrostatic settling characteristics of nine mollusc species, as well as their interspecific differences and correlations. The results showed that body mass (C.V.=1.11) was the most significant morphological index, compared to shell length (C.V.=0.67) and shell width (C.V.=0.54). The shell-body mass ratio differed significantly between species (P < 0.01), however, with a small variation coefficient (C.V.=0.20). The average shell-body mass ratio was 0.32 ±0.13, and was significantly smaller in terrestrial molluscs than in aquatic molluscs (P < 0.01). The largest shell-body mass ratio was found in Corbicula fluminea (0.54±0.06), which was more than three times that of the smallest species, Achatina fulica (0.17±0.04). The shell mass of Pomacea canaliculata was half of its body mass (0.50±0.06). The settling behavior was significantly different between bivalves and snails. Cipangopaludina cathayensis, Bellamya aeruginosa, and C. fluminea were the only three species which could not float in still water, in the present study. The fastest settling velocity of C. fluminea ((24.99±4.22) cm/s) was nearly six times that of the slowest, Radix swinhoei ((4.13±0.96) cm/s). Settling velocity and settling acceleration did not differ significantly between the invasive snails A. fulica ((18.30±3.64) cm/s) and P. canaliculata ((21.77±5.23) cm/s), and the native snails B. aeruginosa ((19.48±3.14) cm/s) and C. cathayensis ((21.44±3.92 cm/s). Shell-body mass ratio was correlated with settling velocity (R²=0.28) and settling acceleration (R²=0.39) in adults. Following current research, the study of settling behavior changing with life history will further reveal the role of eco-hydraulics in evolution and population expansion in molluscs.