Dissertation Research: Testing the Effects of Changes in Egg Size on Development Time and Juvenile Quality in Echinoderms

论文研究：测试卵子大小的变化对棘皮动物发育时间和幼体质量的影响北卡罗来纳大学教堂山分校的Robert D.Podolsky和Jonathan D.Allen在生活史进化中的一个重要权衡是雌性后代的大小和数量之间的权衡。对于自由产卵的海洋无脊椎动物，许多生活史进化模型认为，卵大小减少带来的繁殖力增加被变态时间的增加或幼鱼质量的下降所抵消。对蛋大小的实验操作是检验这一假设的有力方法，并证实单凭蛋大小的变化就可以解释海洋无脊椎动物生活史策略的差异。这个项目的目标是在四种棘皮棘皮动物身上测试实验性缩小卵子大小的效果，这些棘皮棘皮动物跨越了一系列自然的卵子大小。卵裂球分离将被用来模拟以下物种的卵大小减少的影响：斑点沙棘、紫球石龙眼、偏心树枝和红腹石鸡。在不同的卵子大小下，父母投资的减少预计会对生活史参数产生不同的影响。这些实验的结果将检验关于棘皮动物卵大小、发育时间和幼体质量之间关系的重要假设。此外，这些实验将有助于阐明卵大小的变化在生活史转变中的作用，例如从专职摄食转变为兼职摄食。

Dissertation Research: Testing the effects of changes in egg size on development time and juvenile quality in echinodermsRobert D. Podolsky and Jonathan D. AllenUniversity of North Carolina at Chapel HillOne important trade-off in life-history evolution is between the size and number of offspring that a female produces. For free-spawning marine invertebrates, many models of life-history evolution assume that the fecundity gains of a reduction in egg size are offset by an increase in time to metamorphosis or a reduction in juvenile quality. Experimental manipulations of egg size are a powerful method for testing this assumption and confirming that changes in egg size alone can account for the variation in life-history strategies among marine invertebrates. The goal of this project is to test the effects of an experimental reduction in egg size in four species of echinoid echinoderms, which span a range of natural egg sizes. Blastomere separations will be used to mimic the effects of a reduction in egg size for the following species: Arbacia punctulata, Stongylocentrotus purpuratus, Dendraster excentricus and Clypeaster rosaceus. At different egg sizes, reductions in parental investment are predicted to have different effects on life-history parameters. The results of these experiments will test important assumptions about the relationships between egg size, development time and juvenile quality in echinoderms. In addition, these experiments will help to clarify the role of changes in egg size in life history transitions, such as the shift from obligate to facultative feeding.