Adult predation shapes the evolution of swimming performance in guppies (Poecilia reticulata)

Predation pressure plays an important role in shaping animal behaviour and
physiology, driving prey species to evolve stronger escape strategies.
Swimming performance is a key trait for many aquatic organisms to evade
predation. It is therefore intuitive that increased predation pressure
should select for faster swimming abilities when outswimming predators is
a viable option for prey. However, experimental evidence allowing for a
causal link between predation and the evolution of swimming performance is
currently lacking. Here, we used artificial selection lines of guppies
(Poecilia reticulata) based on predation survival to test the evolutionary
relationship between predation pressure and swimming speed. We used a swim
tunnel with an incremental increase in water flow to test critical
swimming speed. Our results show that predation-line females, but not
males, outperformed those of the control lines in critical swimming speed.
We also found that in predation-line females, the variance in critical
swimming speed was reduced in comparison to control-line females, which is
congruent with directional selection against slow-swimming genotypes. This
study provides experimental evidence for the evolutionary role of
predation pressure in enhancing swimming performance and shaping
behavioural adaptations in prey species.