Offering offspring as food to cannibals:: oviposition strategies of Amazonian poison frogs (Dendrobates ventrimaculatus)

Species utilizing distinct resources for offspring production often show plasticity in reproductive strategies as a function of resource quality. For species using ephemeral pools, strategies are mainly shaped by a time constraint related to pool stability, resource availability and the colonizing community. We studied reproductive strategies in Amazonian poison frogs (Dendrobates ventrimaculatus) that are characterized by oviposition in distinct, small and resource-limited water bodies in leaf axils of plants and the transport of newly hatched tadpoles on the back of males to similar water bodies. Cannibalism of eggs by tadpoles was found to be the main cause of egg mortality. Typically, at the end of the rainy season new clutches of eggs were deposited in water bodies already containing a tadpole. Manipulation of the available number of water bodies showed that this observation did not result from resource limitation. We conclude that D. ventrimaculatus has a plastic reproductive strategy that includes provisioning its tadpoles with fertilized eggs as a function of desiccation risk of water bodies housing its offspring. Provisioning behavior is expected to increase developmental rate and, therefore, chances of metamorphosis for tadpoles that hatched towards the end of the rainy season. The plastic food provisioning strategy may be an important evolutionary link to bi-parental and female care with development of obligate unfertilized egg provisioning in the genus Dendrobates.