Meeting Abstract
Locusts are grasshoppers belonging to the family Acrididae (Insecta: Orthoptera) that can form dense migrating swarms through an extreme form of density-dependent phenotypic plasticity, in which cryptically colored, shy individuals (solitarious phase) can transform into conspicuously colored, gregarious individuals (gregarious phase) in response to increases in population density. This syndrome of coordinated changes is known as locust phase polyphenism and the two phases that can result from locust phase polyphenism are among the most striking coordinated alternative phenotypes known. While locusts have the most dramatic expressions of density-dependent phenotypic plasticity, recent studies suggest that non-swarming grasshopper species that are phylogenetically close to locusts also show traces of density-dependent phenotypic plasticity. A comparative quantification of density-dependent reaction norms across locusts and non-swarming grasshoppers that belong to the same genus shows that different components of locust phase polyphenism have followed independent evolutionary trajectories and have not evolved in a coordinated fashion. An evolutionary scenario of how locusts have evolved from grasshoppers and how some grasshoppers have lost their ability to swarm is presented in a phylogenetic framework.
