Phenotype manipulation influences microhabitat choice in pygmy grasshoppers

The matching habitat choice hypothesis posits that individuals actively choose those microhabitats that best match their specific phenotype to maximize fitness. Despite the profound implications, matching habitat choice has not been unequivocally demonstrated. We conducted two experiments to examine the impact of pigmentation pattern in the color polymorphic pygmy grasshopper Tetrix subulata on habitat choice in a laboratory thermal mosaic arena. We found no behavioral differences in the thermal mosaic among pygmy grasshoppers belonging to either pale, intermediate or dark natural color morphs. However, after manipulating the grasshoppers’ phenotype, the utilization through time of warmer and colder parts of the arena was different for black-painted and white-painted individuals. White-painted individuals used warmer parts of the arena, at least during the initial stage of the experiment. We conclude that microhabitat choice represents a form of behavioural plasticity. Thus, even if the choice itself is flexible and not genetically determined, it can still lead to spatial genetic structure in the population because the phenotypes themselves may be genetically mediated [Current Zoology 58 (3): 392-400, 2012].