Integration between swimming and feeding evolves repeatedly in Trinidadian guppies and aligns with suction-feeding fishes

Well-supported correlations between swim speed and mouth size during prey capture suggest broad existence of an integrated relationship between locomotion and feeding in suction-feeding fishes. However, the influence of specialization on this relationship is unclear. We use divergent populations of Trinidadian guppies (Poecilia reticulata) to test whether integration during suction is generalizable to a non-suction specialist and whether intraspecific specialization of component systems affects their integration. Guppies from replicate high and low predation streams were recorded capturing wild-type zooplankton using suction. Alternative general linear models supported a positive correlation between swim speed and mouth size in derived low predation populations suggesting that the relationship can be extended in some cases. High predation populations lack this integration which may be the result of direct selection or constraints imposed by selection on locomotion. As guppies invade new habitats they may be evolving a new, integrated performance phenotype from a non-integrated ancestor.