Facing enemies in an ephemeral world: Tadpole responses to biological and environmental risk

Animals must successfully assess the world around them to survive. Quantifying how animals respond to their environment reveals traits (i.e., kin recognition, sensory plasticity) that have evolved to maximise an individual’s fitness. In this thesis, I examine an amphibian system characterised by its intensive parental care and larval cannibalism. Males of the poison frog species Dendrobates tinctorius transport recently hatched tadpoles to pools of water formed by vegetation, called phytotelmata. Tadpoles are confined to phytotelmata chosen by fathers, and left to face the varied sources of risk associated with these microhabitats throughout development. The range in phytotelmata community and quality is vast and, thus, the possible rearing conditions experienced by tadpoles are variable. Faced with predators, poor visibility, and pathogens, tadpoles have had to evolve diverse strategies to assess risk. Here, I evaluate adult and larval decision-making through field observations and behavioural experiments. These studies are framed within the ecology of the Neotropics, and involve measures of broad multi-species comparisons as well as fine-scale characterisation of phytotelmata that range from the quantification of water chemistry and pool turbidity to the presence of pathogenic zoospores. The combination of laboratory and field methods allows for the study of behaviour within an ecologically relevant context. In addition to elucidating deposition strategies by adults, such an approach has allowed me to (1) demonstrate that D. tinctorius tadpoles are visually oriented and that the turbidity of rearing conditions influences their response to visual stimuli in novel conditions; and (2) that tadpoles are able to discriminate kin, and the interaction between relatedness and size are what governs aggression between these cannibalistic larvae. I close by considering an emerging infectious fungi both across life stages and within the environment to establish a framework of disease transmission for this species. As a whole, this work demonstrates how different sensory cues, physiology, and the surrounding environment shape an animal’s response to risk in dynamic ecological contexts. Keywords: Aggression; inclusive fitness; Neotropical ecology; parental care; poison frog; predator-prey interactions; risk.