Brooks Olivia L, James Jessie J, Saporito Ralph A
School of Biological Sciences, Illinois State University, Normal, IL, 61701, USA.
Department of Biology, John Carroll University, University Heights, OH, 44118, USA.
Oecologia. 2023 Feb;201(2):385-396. doi: 10.1007/s00442-023-05314-z. Epub 2023 Jan 13.
Within and among populations, alkaloid defenses of the strawberry poison frog (Oophaga pumilio) vary spatially, temporally, and with life history stage. Natural variation in defense has been implicated as a critical factor in determining the level of protection afforded against predators and pathogens. Oophaga pumilio tadpoles sequester alkaloids from nutritive eggs and are, thus, entirely dependent on their mothers for their defense. However, it remains unclear how tadpole alkaloid composition relates to that of its mother and how variation in maternally provisioned defenses might result in varying levels of protection against predators. Here, we demonstrate that natural variation in the alkaloid composition of a mother frog is reflected as variation in her tadpole's alkaloid composition. Tadpoles, like mother frogs, varied in their alkaloid composition but always contained the identical alkaloids found in their mother. Alkaloid quantity in tadpoles was highly correlated with alkaloid quantity in their mothers. Additionally, alkaloid quantity was the best predictor of tadpole palatability, wherein tadpoles with higher alkaloid quantities were less palatable. Mother frogs with greater quantities of alkaloids are, thus, providing better protection for their offspring by provisioning chemical defenses during one of the most vulnerable periods of life.
在种群内部和种群之间，草莓箭毒蛙（Oophaga pumilio）的生物碱防御在空间、时间和生命史阶段上存在差异。防御的自然变异被认为是决定对捕食者和病原体防护水平的关键因素。草莓箭毒蛙蝌蚪从营养卵中摄取生物碱，因此，它们的防御完全依赖于母亲。然而，目前尚不清楚蝌蚪的生物碱组成与其母亲的生物碱组成有何关系，以及母体提供的防御变异如何导致对捕食者的防护水平不同。在这里，我们证明了雌蛙生物碱组成的自然变异反映在其蝌蚪的生物碱组成变异中。蝌蚪和雌蛙一样，生物碱组成存在差异，但总是含有与母亲相同的生物碱。蝌蚪体内的生物碱含量与其母亲体内的生物碱含量高度相关。此外，生物碱含量是蝌蚪适口性的最佳预测指标，生物碱含量较高的蝌蚪适口性较差。因此，生物碱含量较高的雌蛙通过在生命中最脆弱的时期之一提供化学防御，为其后代提供了更好的保护。
