Data from: Experimental tests of sex allocation theory with two species of simultaneously hermaphroditic acorn barnacles

Sex allocation theory for simultaneous hermaphrodites predicts increases in relative allocation to male-specific function as competition for fertilizations increases. Theoretical models developed specifically for competing acorn barnacles predict that the proportional allocation to male function increases towards an asymptote of 50% as the number of competitors for fertilizations increases. Experimental manipulations were used to investigate how mate competition affected both relative and absolute allocation to the sex functions for two species of acorn barnacle: Semibalanus balanoides and Balanus glandula. The ratio of male to female allocation did not increase with the number of competitors for either species. However, both species showed increased allocation to male function (estimated as total mass of sex-specific tissues) with increased crowding. Allocation to female function seemed to be limited by other factors and did not vary with mating group size as predicted. Allocation to male and female function were both positively related to body size, but a trade-off between male and female function, a key assumption of prior models, was not observed.针对同时雌雄同体生物（simultaneous hermaphrodites）的性别分配理论（sex allocation theory）预测，随着受精竞争加剧，物种对雄性特异性功能的相对资源分配将随之提升。专门针对竞争型橡子藤壶（competing acorn barnacles）构建的理论模型预测，随着受精竞争对手数量增加，雄性功能的资源分配比例将逐渐趋近于50%的渐近值。本研究通过实验操控手段，探究了配偶竞争对两种橡子藤壶——白纹藤壶（Semibalanus balanoides）与腺藤壶（Balanus glandula）——的性别功能相对与绝对资源分配的影响。两种藤壶的雄性与雌性资源分配比值均未随竞争对手数量的增加而上升。然而，二者均表现出：随着种群拥挤程度提升，雄性功能的资源分配（以性别特异性组织的总质量作为估算依据）显著增加。雌性功能的资源分配似乎受其他因素制约，并未如理论预测般随交配群体规模发生变化。雄性与雌性功能的资源分配均与个体体型呈正相关，但此前模型的核心假设——雄性与雌性功能间存在资源权衡——并未在本研究中得到验证。