The heart urchin Abatus cavernosus shows sexual dimorphism characterized by the development of external brood pouches and the enlargement of gonopores in brooding females. Relationships between body size, gonopore size, and gonadal maturation in each sex were examined for inflection points using piecewise regression models (PRM). Opening of the gonopore occurred at 15.5 mm test length. Inflection points in the gonadal growth and gonopore diameter trajectories were clustered at smaller sizes in males (23 and 24.2 mm, respectively) than in females (25.1 and 25.9 mm), indicating sex‐specific differences in sexual maturation. Gonopore growth showed positive allometry at pre‐adult stages of development in both sexes, but isometry and negative allometry in adult females and males, respectively. Gonadal growth was initiated at smaller sizes and proceeded at a higher rate with increasing body size in males than in females. Identification of inflection points in gonopore and gonadal growth trajectories, using objective PRM, allows the determination of life stages and sexual maturation for individuals, thus providing a complementary tool for population studies.

中文翻译：

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在孵化的海胆，Abatus Cavernosus（Spatangoida）中，性腺和性腺生长轨迹的性别差异

心脏顽童Abatus Cavernosus表现出性二态性，其特征是在育雏雌性中外部卵囊的发育和生殖孔的扩大。使用分段回归模型（PRM）检查了每种性别的体型，性腺孔大小和性腺成熟之间的关系，以确定拐点。线孔的开放发生在测试长度为15.5 mm处。男性（分别为23和24.2毫米）的性腺生长和性腺直径轨迹的拐点聚集在女性（分别为25.1和25.9毫米）中较小的大小上，表明性别在性成熟方面存在差异。男女的成虫生长在成年前阶段都显示出正向异性，但是成年雌性和雄性则分别为等距和负性。男性的性腺生长开始于较小的体型，并且随着女性体型的增大以较高的速率进行。使用客观的PRM识别淋巴孔和性腺生长轨迹的拐点，可以确定个体的生命阶段和性成熟，从而为人口研究提供了补充工具。