Data from: Natural selection favors a larger eye in response to increased competition in natural populations of a vertebrate

1.Eye size varies notably across taxa. Much work suggests that this
variation is driven by contrasting ecological selective pressures.
However, evaluations of the relationship between ecological factors and
shifts in eye size have largely occurred at the macroevolutionary scale.
Experimental tests in nature are conspicuously absent. 2.Trinidadian
killifish, Rivulus hartii, are found across fish communities that differ
in predation intensity. We recently showed that increased predation is
associated with the evolution of a smaller eye. Here, we test how
divergent predatory regimes alter the trajectory of eye size evolution
using comparative mark‐recapture experiments in multiple streams. 3.We
found that increases in eye size are associated with enhanced survival,
irrespective of predation intensity. More importantly, eye size is
associated with enhanced growth in communities that lack predators, while
this trend is absent when predators are present. 4.Such results argue that
increased competition for food in sites that lack predators is the key
driver of eye size evolution.