He leaps, she beats: The role of social interactions on the overland movements of an Amazonian amphibious killifish

Abstract

Amphibious habits are present in a variety of fish and are allowed by a set of physiological, morphological and behavioural adaptations. The most intriguing question, however, is what motivates an aquatic organism to venture into the land? Unfavourable abiotic and biotic conditions in the aquatic environment have been reported as main stimuli for fish to emerge from water. However, few attempts have been made to disentangle the effects of different social contexts on the propensity of amphibious fishes to leave the water. Trying to separate the effects of predator threat, intraspecific competition and mate searching on overland movement of amphibious fish, we ran a mesocosm experiment with the Amazonian killifish Anablepsoides micropus. Overland movement was quantified based on fish leaps between artificial pools set in enclosures in a primary forest area. Males moved overland more frequently than females and their movement depended on the social context, being higher in the presence of predators and lower in the presence of females. Females, instead, showed context-independent movement rates. This suggests that males move between pools searching for mates, stopping when successful in this search. On the other hand, occasional encounters with predators may force males to abandon the pool as a defence mechanism. Female aggressiveness towards the predator may influence its low movement in the presence of the predator. Such differential responses may play important ecological and evolutionary roles, allowing A. micropus to occupy a wide range of environmental conditions under varied ecological and social contexts. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd