Can fractal dimensions objectivize gastropod shell morphometrics? A case study from Lake Lugu (SW China)

Morphometrics are fundamental for statistical analyses of fossils, particularly because soft parts or DNA are rarely preserved and thus hard parts such as shells are commonly the only source of information. Geometric morphometrics i.e. landmark analysis has been successfully established but exhibits a couple of shortcomings. On the one hand landmarking is rather subjective and on the other hand the application at the level of micro-sculpture is difficult.
With the aid of high-resolution 3D scanning technology and analyses of fractal dimensions, we test whether shortcomings of linear and geometric morphometrics can be overcome. As a model group, we selected a clade of modern viviparid gastropods from Lake Lugu, the shells of which show a high degree of sculptural variation. Linear and landmark analyses were applied to the same shells, in order to root the fractal dimensions. The genetic diversity of the gastropod clade was basically assessed.
The genetic results suggest that the gastropo...

形态测量学（Morphometrics）是化石统计分析的核心基础，因化石中的软组织与DNA鲜有保存，壳体等硬组织通常是唯一的信息来源。几何形态测量学（Geometric morphometrics）即地标分析（landmark analysis）已得到成熟应用，但仍存在若干局限：一方面地标标记主观性较强，另一方面该方法难以适配微观纹饰层面的分析。
本研究借助高分辨率三维扫描技术与分形维数（fractal dimensions）分析方法，旨在验证是否可克服线性形态测量学与几何形态测量学的上述缺陷。我们选取泸沽湖（Lake Lugu）的一支现生胎生螺类（viviparid gastropods）演化支（clade）作为模型类群，该类群壳体的纹饰变异程度极高。我们对同一批壳体同步开展线性形态测量与地标分析，以确立分形维数分析的参照基准；同时对该螺类演化支的遗传多样性（genetic diversity）进行了基础评估。
遗传学分析结果显示，该螺类...