Data from: Quantitative genetic analysis of subspecific differences in body shape in the snail-feeding carabid beetle Damaster blaptoides

A dimorphic pattern of macrocephalic (wide, short) and stenocephalic (narrow, long) body shapes is observed in snail-feeding carabid beetles globally. The former exhibits high performance in crushing snail shells with powerful jaws, whereas the latter specializes in eating snails' soft body directly by inserting the head into the shell. In the snail-feeding species Damaster blaptoides, the subspecies D. b. capito has a wide short forebody, and D. b. fortunei has a narrow, long forebody. They exhibit distinct morphologies despite their geographic and phylogenetic proximity. To examine the genetic basis of the morphological differences between these two subspecies, we conducted quantitative genetic analyses by crossing these subspecies and producing F_1 and backcross hybrids. The hybrids had body shapes intermediate between the parental subspecies. The variation between wide, short and narrow, long forebodies was based on negative geneti c correlations between width and length of the head and thorax. Between one and eight genetic factors were involved in the morphological differences between subspecies. We suggest that the morphological integration of forebody parts in a small number of loci has facilitated the marked morphological diversification between subspecies of D. blaptoides.

全球范围内取食蜗牛的步甲科甲虫（carabid beetles）均呈现出头部与躯体的两种形态二态模式：大头型（宽短体型）与狭头型（窄长体型）。前者凭借发达颚部击碎蜗牛外壳的能力出众，后者则特化出将头部伸入螺壳、直接取食蜗牛软体组织的取食策略。在取食蜗牛的亮步行虫（Damaster blaptoides）物种中，其亚种D. b. capito具有宽短的前体，D. b. fortunei则具有窄长的前体；尽管二者地理分布与系统发育关系均较为接近，但形态特征差异显著。为探究这两个亚种间形态差异的遗传基础，我们通过杂交该两个亚种获得F₁及回交杂种，并开展了数量遗传学分析。杂种的体型介于两个亲本亚种之间。宽短与窄长前体间的形态变异，源于头部与胸部的宽度和长度之间存在负遗传相关。这两个亚种间的形态差异由1至8个遗传因子调控。我们推测，少数基因位点上的前体部件形态整合，推动了亮步行虫（Damaster blaptoides）亚种间显著的形态分化。