Burgess Scott C, Hart Simon P, Marshall Dustin J
School of Biological Sciences, University of Queensland, Brisbane QLD 4072, Australia.
Biol Bull. 2009 Jun;216(3):344-54. doi: 10.1086/BBLv216n3p344.
Larval behaviors prior to settlement are important for both dispersal and the likelihood that larvae will encounter settlement habitat. The role of endogenous factors such as larval age and size are likely to be important in determining pre-settlement behavior but are less well understood than exogenous factors. In a simple experiment we explored the role of larval age and size on pre-settlement behavior in two species of bryozoan. We then used the results of this experiment to develop a theoretical model, which explored potential fitness benefits associated with phenotype-dependent changes in larval behavior (i.e., behaviors that changed depending on larval age or larval size) in a heterogeneous environment. In the experiment we delayed the metamorphosis of larvae of Bugula neritina andWatersipora arcuata and assessed the changes in the behavior of individual larvae (exploring the substratum vs. swimming away from it) as a function of larval age and size. In B. neritina, larval size had no effect on larval swimming behavior, but the youngest and oldest larvae spent more time exploring the substrate than did larvae of intermediate age. In W. arcuata, larval size and age had interactive effects on larval behavior. Our theoretical model predicted that phenotype-dependent behaviors carried a fitness benefit relative to phenotype-independent behaviors, but this depended strongly on the availability and quality of habitat elsewhere. We suggest that, taken together, larval age and size are important endogenous factors that act to affect pre-settlement larval behavior and that changes in behavior may act to increase fitness.
幼虫在附着之前的行为对于扩散以及幼虫遇到附着栖息地的可能性都很重要。诸如幼虫年龄和大小等内源性因素在决定附着前行为方面可能很重要，但与外源性因素相比，人们对其了解较少。在一个简单的实验中，我们探究了幼虫年龄和大小对两种苔藓虫附着前行为的作用。然后，我们利用该实验结果建立了一个理论模型，该模型探讨了在异质环境中与幼虫行为的表型依赖性变化（即根据幼虫年龄或大小而改变的行为）相关的潜在适应性益处。在实验中，我们延迟了红藓苔虫和弧水藓苔虫幼虫的变态，并评估了个体幼虫行为（探索基质与远离基质游动）随幼虫年龄和大小的变化。在红藓苔虫中，幼虫大小对幼虫游动行为没有影响，但最年幼和最年长的幼虫比中间年龄的幼虫花费更多时间探索基质。在弧水藓苔虫中，幼虫大小和年龄对幼虫行为有交互作用。我们的理论模型预测，相对于表型独立行为，表型依赖性行为具有适应性益处，但这在很大程度上取决于其他地方栖息地的可用性和质量。我们认为，综合来看，幼虫年龄和大小是影响附着前幼虫行为的重要内源性因素，行为变化可能会提高适应性。
