Tadpole diet selection varies with the ecological context in predictable ways

Abstract

Summary Ecological conditions and food quality have influence on age and size at metamorphosis of organisms with complex life cycles. However, little is known about the foraging behaviour and how diet choice is influenced by the ecological conditions. The present study poses two major questions: (1) how do different diets (high protein, low protein and both diets together) influence larval performance, and (2) how does diet choice change with ecological conditions (interference competition, predation and pond drying)? To address the second question, we offered both types of food to tadpoles under the different circumstances. We measured food consumption of the two food types, along with the growth rate and developmental stage of tadpoles. We expected that under unfavourable growth conditions, larvae would select high-protein food, which would promote development and allow individuals to escape these high-risk environments. High-protein food promotes development, but results in smaller tadpoles, whereas low-protein food promotes growth with slower development. The mixture of the two is better only in terms of growth rate. Our study of tadpoles showed that diet selection may not be constant but can vary depending on the ecological context in predictable ways. When exposed to interference competition and drying ponds, tadpoles fed on food that enhanced development, whereas in the control group and in predation treatments, they fed selectively on food that favoured growth. Our data indicate that diet selection by tadpoles may confer adaptive responses to ecological changes. Such selection/responses would increase growth, development, and survival.