Department of Biological Sciences, California State University East Bay, Hayward, California, USA.
Department of Environmental Science and Studies, Washington College, Chestertown, Maryland, USA.
Mol Ecol. 2022 Aug;31(16):4254-4270. doi: 10.1111/mec.16580. Epub 2022 Jul 13.
Inducible prey defences occur when organisms undergo plastic changes in phenotype to reduce predation risk. When predation pressure varies persistently over space or time, such as when predator and prey co-occur over only part of their biogeographic ranges, prey populations can become locally adapted in their inducible defences. In California estuaries, native Olympia oyster (Ostrea lurida) populations have evolved disparate phenotypic responses to an invasive predator, the Atlantic oyster drill (Urosalpinx cinerea). In this study, oysters from an estuary with drills, and oysters from an estuary without drills, were reared for two generations in a laboratory common garden, and subsequently exposed to cues from Atlantic drills. Comparative proteomics was then used to investigate molecular mechanisms underlying conserved and divergent aspects of their inducible defences. Both populations developed smaller, thicker, and harder shells after drill exposure, and these changes in shell phenotype were associated with upregulation of calcium transport proteins that could influence biomineralization. Inducible defences evolve in part because defended phenotypes incur fitness costs when predation risk is low. Immune proteins were downregulated by both oyster populations after exposure to drills, implying a trade-off between biomineralization and immune function. Following drill exposure, oysters from the population that co-occurs with drills grew smaller shells than oysters inhabiting the estuary not yet invaded by the predator. Variation in the response to drills between populations was associated with isoform-specific protein expression. This trend suggests that a stronger inducible defence response evolved in oysters that co-occur with drills through modification of an existing mechanism.
当生物经历表型的可塑性变化以降低被捕食的风险时，就会出现可诱导的猎物防御。当捕食压力在空间或时间上持续变化时，例如当捕食者和猎物仅在其生物地理范围的一部分共存时，猎物种群可以在其可诱导的防御中变得局部适应。在加利福尼亚河口，本地 Olympia 牡蛎（Ostrea lurida）种群对入侵的捕食者——大西洋牡蛎钻（Urosalpinx cinerea）产生了不同的表型反应。在这项研究中，来自有钻孔器的河口的牡蛎和来自没有钻孔器的河口的牡蛎在实验室共同花园中被饲养了两代，然后暴露于大西洋钻孔器的线索下。随后，比较蛋白质组学被用于研究其可诱导防御的保守和分歧方面的分子机制。在暴露于钻孔器后，两种种群的壳都变得更小、更厚、更硬，壳表型的这些变化与钙转运蛋白的上调有关，这些蛋白可能影响生物矿化。可诱导的防御在一定程度上是进化而来的，因为当捕食风险较低时，受保护的表型会带来适应性成本。免疫蛋白在两种牡蛎种群暴露于钻孔器后都被下调，这意味着生物矿化和免疫功能之间存在权衡。在暴露于钻孔器后，与钻孔器共存的种群的牡蛎比尚未受到捕食者入侵的河口的牡蛎生长出更小的壳。种群对钻孔器的反应的差异与同工型特异性蛋白表达有关。这种趋势表明，在与钻孔器共存的牡蛎中，通过对现有机制的修改，进化出了更强的可诱导防御反应。
