Cue choice and spatial learning ability are affected by habitat complexity in intertidal gobies

Variation in the structural complexity of a habitat is known to have significant affects on the evolution of different populations and can shape behavior, morphology, and life-history traits. Here, we investigated whether habitat complexity influences a species’ capacity for spatial learning and cue choice by comparing the performance of 4 goby species from 2 contrasting habitats in a spatial task. Gobies were collected from dynamic, homogenous sandy shores and stable, spatially complex rock pool habitats. We trained fish to use a T-maze to find a hidden reward and asked whether they used local visual landmarks or body-centered methods for orientation (i.e. turn direction) to do so. It was expected that fish from rock pools would learn the spatial task much faster and use different orientation cues than fish from sandy shores. We found that rock pool species learnt the location of the reward arm much faster, made fewer errors and used both types of cues available (visual landmarks and turn direction) to locate the reward, whereas sand species relied on turn direction significantly more than plant landmarks to orientate. The results of this study provide support for the hypothesis that the spatial complexity of habitats in marine environments has a significant effect on the evolution of fish cognition.