Carry-over effects of the larval environment on the post-metamorphic performance of Bombina variegata (Amphibia, Anura)

Abstract

Metamorphs of the yellow-bellied toad, Bombina variegata, vary widely in size at metamorphosis in the field. We performed a replicated outdoor mesocosm study to simulate the environmental factor combinations in permanent and ephemeral breeding sites and to quantify their effects on tadpole development (duration of the larval period, metamorph size and body condition). Looking for potential carry-over effects of the larval environment, we quantified locomotor performance of all metamorph phenotypes originating from the mesocosms immediately after metamorphosis under controlled conditions. In contrast to the prediction of life-history theory, tadpoles were unable to adjust developmental rate to water availability, but metamorphs originating from the ephemeral pond treatment were smaller and had a lower body condition than those from the permanent pond treatment. Size-dependent carry-over effects included the length of the first jump following tactile stimulation, burst performance (total length of spontaneous jumps) and endurance (total distance covered in 10 forced jumps). A size-independent effect of larval environment was the prolonged locomotor effort to escape (5.7 consecutive jumps following initial stimulus) of metamorphs from the ephemeral pond treatment compared to same-sized ones (3.7 jumps) from the permanent pond treatment. Thus, we demonstrate that carry-over effects of larval environment on metamorph phenotype and behaviour cause a considerable variation in fitness in the early terrestrial stage of B. variegata. Informed conservation management of endangered populations in the northern range should therefore include the provision of small permanent breeding ponds promoting larger and fitter metamorphs.