Data from: A phylogenetic analysis of egg size, clutch size, spawning mode, adult body size, and latitude in reef fishes

Theoretical treatments of egg size in fishes suggest that constraints on reproductive output should create trade-offs between the size and number of eggs produced per spawn. For marine reef fishes, the observation of distinct reproductive care strategies (demersal guarding, egg scattering, and pelagic spawning) has additionally prompted speculation that these strategies reflect alternative fitness optima with selection on egg size differing by reproductive mode and perhaps latitude. Here, we aggregate data from 278 reef fish species and test whether clutch size, reproductive care, adult body size, and latitudinal bands (i.e., tropical, subtropical, and temperate) predict egg size, using a statistically unified framework that accounts for phylogenetic correlations among traits. We find no inverse relationship between species egg size and clutch size, but rather that egg size differs by reproductive mode (mean volume for demersal eggs = 1.22 mm3, scattered eggs = 0.18 mm3, pelagic eggs = 0.52 mm3) and that clutch size is strongly correlated with adult body size. Larger eggs were found in temperate species compared with tropical species in both demersal guarders and pelagic spawners, but this difference was not strong when accounting for phylogenetic correlations, suggesting that differences in species composition underlies regional differences in egg size. In summary, demersal guarders are generally small fishes with small clutch sizes that produce large eggs. Pelagic spawners and egg scatterers are variable in adult and clutch size. Although pelagic spawned eggs are variable in size, those of scatterers are consistently small.

有关鱼类卵粒大小的理论研究表明，繁殖产出的限制因素会导致每次产卵的卵粒大小与产卵数量之间存在权衡（trade-off）关系。针对海洋礁区鱼类，学界观察到其存在多种不同的繁殖抚育策略（底栖护卵（demersal guarding）、散卵（egg scattering）以及浮性产卵（pelagic spawning）），进而推测这些策略对应不同的适合度最优解（fitness optima），且卵粒大小的选择压力会因繁殖模式乃至纬度而异。本研究整合了278种礁区鱼类的数据，采用考虑性状间系统发育相关性（phylogenetic correlations）的统一统计框架，检验窝卵数（clutch size）、繁殖抚育模式、成体体型以及纬度带（即热带、亚热带和温带）能否预测卵粒大小。研究结果显示，鱼类的卵粒大小与窝卵数之间并不存在负相关关系；相反，卵粒大小会因繁殖模式而异（底栖卵平均体积为1.22 mm³，散卵为0.18 mm³，浮性卵为0.52 mm³），且窝卵数与成体体型呈显著正相关。在底栖护卵类群与浮性产卵类群中，温带物种的卵粒均大于热带物种，但在考虑系统发育相关性后，这一差异不再显著，提示卵粒大小的区域差异实则由物种组成差异所驱动。综上，底栖护卵类群通常为体型较小、窝卵数较少且产出大卵粒的鱼类；浮性产卵类与散卵类的成体体型和窝卵数均存在较大变异。尽管浮性产卵的卵粒大小存在变异，但散卵类的卵粒大小始终偏小。