Data from: Hitting rock bottom: exaptation, ecological filtering and the benthopelagic divergence of Percid fishes

Ecological filtering and exaptation are related concepts in which prior
traits and adaptations facilitate transitions to new habitats or niches,
sometimes by being co-opted for a new function. I investigated possible
ecological filtering/exaptation in Percidae, a family of freshwater fishes
that shows its highest species richness in small benthic fishes living in
creeks and small streams. I hypothesize that traits associated with
transitions to benthic living subsequently facilitated the colonization of
small river habitats. Using phylogenetic comparative approaches, I found
that transitions in river size were dependent on presence or absence of a
gas bladder, and long-term residency in small rivers in particular was
associated with transitions to benthic living. Based on body size and 3D
whole body shape datasets, I found that selection towards smaller bodies
and longer caudal peduncles in benthic species in large rivers appears to
have enabled transitions to small rivers, while also slowing rates of
shape and size evolution; this may explain the high proportion of small,
benthic darters. Contrasting selective pressures from habitat exaptation
and trophic adaptations in small rivers may constrain ecomorphological
diversification. Overall, ecological filtering and/or exaptation may
impact both the biodiversity and phylogenetic composition of fish
assemblages in small streams.