Department of Ecology and Evolutionary Biology and Neurosciences Program and Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095-1606, USA.
Proc Natl Acad Sci U S A. 2011 Aug 9;108(32):13200-5. doi: 10.1073/pnas.1018666108. Epub 2011 Jul 25.
Chemical communication is fundamental to sexual reproduction, but how sperm search for and find an egg remains enigmatic. For red abalone (Haliotis rufescens), a large marine snail, the relationship between chemical signaling and fluid motion largely determines fertilization success. Egg-derived attractant plumes are dynamic, changing their size and shape in response to unique combinations of physical and chemical environmental features. Attractant plumes that promote sexual reproduction, however, are limited to a precise set of hydrodynamic conditions. Performance-maximizing shears are those that most closely match flows in native spawning habitats. Under conditions in which reproductive success is chronically limited by sperm availability, gametes are under selection for mechanisms that increase sperm-egg encounter. Here, chemoattraction is found to provide a cheap evolutionary alternative for enhancing egg target size without enlarging cytoplasmic and/or cell volume. Because egg signaling and sperm response may be tuned to meet specific fluid-dynamic constraints, shear could act as a critical selective pressure that drives gamete evolution and determines fitness.
化学通讯对有性生殖至关重要，但精子如何寻找卵子仍然是个谜。对于大型海洋蜗牛红鲍（Haliotis rufescens）来说，化学信号和流体运动之间的关系在很大程度上决定了受精的成功。由卵子产生的引诱羽流是动态的，会根据物理和化学环境特征的独特组合改变其大小和形状。然而，促进有性生殖的引诱羽流仅限于一组精确的水动力条件。能实现最大性能的剪应力是最接近自然产卵栖息地中流动的剪应力。在由于精子供应而长期限制生殖成功的情况下，配子受到选择，以增加精子-卵子相遇的机制。在这里，化感吸引被发现为增加卵子靶标大小提供了一种廉价的进化替代方案，而无需扩大细胞质和/或细胞体积。由于卵子信号和精子反应可能被调整以满足特定的流体动力学限制，因此剪应力可以作为一种关键的选择压力，驱动配子进化并决定适应性。
