Data for predator-induced defense decreases growth rate and photoprotective capacity in a nitrogen-limited dinoflagellate

Many phytoplankton produce defensive toxins with grazer deterrent effects when exposed to grazers. While the benefits are obvious, the costs of toxin production remain elusive. However, there must be costs, otherwise, all phytoplankton would be equally defended, and the search for and quantification of defense costs has been a long-standing research topic. Our experiment demonstrate both a direct growth penalty and - for the first time – an indirect photoprotection cost of gazer-induced toxin production in a dinoflagellate, and we suggest possible mechanisms for the costs. Toxin-producing cells benefit lower grazing risk at the cost of reduced growth and protection against damaging light.

许多浮游植物（phytoplankton）在暴露于牧食者（grazer）时，会产生具有驱避牧食者效应的防御性毒素。尽管产毒带来的防御益处显而易见，但其生产所需付出的代价却始终难以探明。然而，此类代价必然存在——否则所有浮游植物都会具备同等程度的防御能力，因此对防御代价的探索与定量表征长期以来都是一个持续已久的研究议题。本研究通过实验，在一种甲藻（dinoflagellate）中同时证实了牧食者诱导产毒带来的直接生长抑制代价，以及首次被发现的间接光保护代价，并提出了该类代价的潜在作用机制。产毒细胞虽可通过降低自身遭受牧食的风险获得益处，但却以生长速率下降与抵御有害光照损伤的能力受损作为代价。