Increased juvenile predation is not associated with evolved differences in adult brain size in Trinidadian killifish (Rivulus hartii).
Vertebrates exhibit extensive variation in brain size. The long-standing assumption is that this variation is driven by ecologically mediated selection. Recent work has shown that an increase in predator-induced mortality is associated with evolved increases and decreases in brain size. Thus, the manner in which predators induce shifts in brain size remains unclear. Increased predation early in life is a key driver of many adult traits, including life-history and behavioral traits. Such results foreshadow a connection between age-specific mortality and selection on adult brain size. Trinidadian killifish,Rivulus hartii,are found in sites with and without guppies,Poecilia reticulata. The densities ofRivulusdrop dramatically in sites with guppies because guppies prey upon juvenileRivulus. Previous work has shown that guppy predation is associated with the evolution of adult life-history traits inRivulus. In this study, we compared second-generation laboratory-bornRivulusfrom sites with and without guppies for differences in brain size and associated trade-offs between brain size and other components of fitness. Despite the large amount of existing research on the importance of early-life events on the evolution of adult traits, and the role of predation on both behavior and brain size, we did not find an association between the presence of guppies and evolutionary shifts inRivulusbrain size. Such results argue that increased rates of juvenile mortality may not alter selection on adult brain size.
Department of Biology University of Texas at Arlington Arlington TX USA.
Shannon M
0000-0003-0246-1567
SM
Beston
Department of Biology University of Texas at Arlington Arlington TX USA.
Whitnee
W
Broyles
Department of Biology University of Texas at Arlington Arlington TX USA.
Matthew R
MR
Walsh
brain size evolution; early‐life mortality; extrinsic mortality; juvenile mortality; life‐history evolution; predator–prey interactions