McEdward L R
Department of Zoology, University of Florida, Gainesville, Florida 32611, USA.
Am Nat. 1997 Jul;150(1):48-72. doi: 10.1086/286056.
Fecundity-time models of reproductive strategies in marine invertebrates all predict that reproductive success is maximized only at the extreme levels of investment. Selection should drive egg sizes toward small eggs and planktotrophy or large eggs and lecithotrophy. The existence of two distinct larval types, feeding and nonfeeding, has been taken as confirmation of this prediction and has established the current paradigm for larval ecology. However, comparative and experimental evidence does not support the prediction that egg size is minimized in species with planktotrophic larvae. Recent discoveries have documented the existence of planktotrophs that have intermediate egg sizes, differing degrees of dependence on exogenous food, and differing capacities for facultative feeding. A fecundity-time model is presented that includes facultative larval feeding by dissociating the onset of feeding capability from the need for exogenous food. The facultative feeding model shows that reproductive success can be maximized at intermediate levels of investment per offspring between the minimum for development and the threshold for lecithotrophy, depending on the amount of food available to larvae and the intensity of planktonic mortality. A continuum of larval strategies is predicted.
海洋无脊椎动物生殖策略的繁殖力-时间模型均预测,只有在极端的投资水平下,繁殖成功率才能最大化。自然选择应促使卵的大小朝着小卵和浮游营养型或大卵和卵黄营养型发展。两种不同幼虫类型(摄食型和非摄食型)的存在被视为这一预测的证据,并确立了当前幼虫生态学的范式。然而,比较和实验证据并不支持浮游营养型幼虫的物种中卵大小最小化这一预测。最近的发现记录了存在具有中等卵大小、对外源食物不同程度的依赖以及不同兼性摄食能力的浮游营养型生物。本文提出了一个繁殖力-时间模型,该模型通过将摄食能力的开始与对外源食物的需求分离,纳入了幼虫的兼性摄食。兼性摄食模型表明,根据幼虫可获得的食物量和浮游生物死亡率的强度,在每个后代介于发育所需最小值和卵黄营养阈值之间的中等投资水平下,繁殖成功率可以最大化。预测存在一系列连续的幼虫策略。