Data from: Paternity and gregariousness in the sex-changing sessile marine gastropod Crepidula convexa: comparison with other protandrous Crepidula species

In sex-changing animals with internal fertilization, gregarious behavior may increase mating opportunities and the frequency of multiple paternity, thus increasing maternal reproductive success. Crepidula convexa is a direct-developing protandrous gastropod characterized by only modest gregarious behavior compared with previously studied members of the genus: females are frequently found isolated. Using 6 microsatellite markers, we analyzed paternity profiles in 10 broods (25 embryos per mother). The number of assigned fathers varied among families from 1 to 4 fathers per brood. Interestingly, polyandry was not detected in solitary females but only in females grouped with conspecific individuals. Overall, we found an average of 1.8 fathers per brood, but this increased to 2.6 fathers per brood when considering only the nonisolated females. Among 18 unambiguously identified fathers, only 5 were collected in our samples, suggesting substantial male mobility. Comparison with previous paternity analyses in Crepidula fornicata and Crepidula coquimbensis revealed that polyandry appears as a common trait of these sex-changing gastropods despite their different grouping behaviors and life histories. As expected, the level of polyandry was nevertheless lower in the modestly gregarious C. convexa.

在具有体内受精特性的性别转换动物中，群居行为可提升交配机会与多父本现象的发生频率，进而提高母体的繁殖成功率。舟形履螺（Crepidula convexa）是一类直接发育的雄性先熟腹足类，与该属此前已被研究的类群相比，其群居行为仅处于较低水平——雌性个体常呈单独栖息状态。本研究利用6个微卫星标记（microsatellite markers），对10个孕卵批次（每头母体对应25枚胚胎）的父本谱系展开分析。各孕卵批次的确定父本数量介于1至4个，家系间存在差异。值得注意的是，单独栖息的雌性个体未检测到一妻多夫现象，该现象仅存在于与同种个体聚集的雌性中。整体而言，本研究观测到每个孕卵批次的平均父本数量为1.8个；但若仅统计非单独栖息的雌性个体，该数值可提升至2.6个。在18个明确鉴定的父本个体中，仅5个在本研究的采样样本中被捕获，这表明雄性个体具备较强的移动能力。通过与此前对缠绕履螺（Crepidula fornicata）和科金博履螺（Crepidula coquimbensis）的父本分析结果对比可知，尽管这两类性别转换腹足类的群居行为与生活史存在差异，但一妻多夫现象均为其共有特征。正如预期，群居行为程度较低的舟形履螺，其一妻多夫现象的发生水平同样更低。