Ecology. 2014 Mar;95(3):587-93. doi: 10.1890/13-0927.1.
Many organisms use chemical defenses to reduce predation risk. Aposematic dendrobatid frogs sequester alkaloid-based chemical defenses from a diet of arthropods, but research on these defenses has been limited to adults. Herein, we investigate chemical defense across development in a dendrobatid frog, Oophaga pumilio. This species displays complex parental care: at hatching, mothers transport tadpoles to phytotelmata, and then return to supply them with an obligate diet of nutritive eggs for about six weeks. We collected eggs, tadpoles, juveniles, and adults of O. pumilio, and detected alkaloids in all life stages. The quantity and number of alkaloids increased with frog and tadpole size. We did not detect alkaloids in the earliest stage of tadpoles, but alkaloids were detected as trace quantities in nutritive eggs and as small quantities in ovarian eggs. Tadpoles hand-reared with eggs of an alkaloid-free heterospecific frog did not contain alkaloids. Alkaloids that are sequestered from terrestrial arthropods were detected in both adults and phytotelm-dwelling tadpoles that feed solely on nutritive eggs, suggesting that this frog may be the first animal known to actively provision post-hatch offspring with chemical defenses. Finally, we provide experimental evidence that maternally derived alkaloids deter predation of tadpoles by a predatory arthropod.
许多生物利用化学防御来降低被捕食的风险。警戒色的树蛙从节肢动物的饮食中摄取生物碱为基础的化学防御物质，但对这些防御物质的研究仅限于成年个体。在此，我们研究了树蛙 Oophaga pumilio 从发育到成熟的整个阶段的化学防御。这种物种表现出复杂的亲代照顾：在孵化时，母亲将蝌蚪运送到植物性蓄水器中，然后返回为它们提供必需的营养卵作为约六周的食物。我们收集了 O. pumilio 的卵、蝌蚪、幼体和成年个体，并在所有生命阶段都检测到了生物碱。生物碱的数量和种类随着青蛙和蝌蚪的大小而增加。我们在最早的蝌蚪阶段没有检测到生物碱，但在营养卵中检测到痕量生物碱，在卵巢卵中检测到少量生物碱。用没有生物碱的异源青蛙的卵喂养的手养蝌蚪不含生物碱。从陆地节肢动物中摄取的生物碱被同时在仅以营养卵为食的成年个体和生活在植物蓄水器中的蝌蚪中检测到，这表明这种青蛙可能是第一个已知的主动为孵化后的后代提供化学防御的动物。最后，我们提供了实验证据表明，母体衍生的生物碱可以阻止捕食性节肢动物对蝌蚪的捕食。
