The influence of species abundance, diet and phylogenetic affinity on the co-occurrence of butterflyfishes

Understanding “why species are where they are” at different scales is one of the main focuses of ecological
and biogeographical studies. Although ecological features, such as trophic group and species abundance,
are thought to be more important for driving co-occurrence patterns at the habitat scale, it is not yet known
if phylogenetic constraints can also exert some influence. Here, we studied global co-occurrence patterns
of butterflyfishes in relation to species abundance, trophic characteristics and evolutionary histories,
specifically examining two questions—Question (1): does phylogenetic affinity and/or abundance explain
co-occurrence at the habitat scale? To answer this, we used abundance data from 23 global localities to
evaluate whether phylogenetic affinity alone as well as after accounting for differences in diet among
sympatric species explains co-occurrences at the habitat scale. Question (2): are the diets of sister species
from the Atlantic Ocean and the Eastern Pacific phylogenetically conserved? To examine this, we used a
more detailed diet classification of species present within these realms. We found that phylogenetic
distance per se fails to explain the co-occurrence of butterflyfish species pairs. Instead, species abundance
exerted a major influence in interspecific co-occurrences. We also found no correlation between
phylogenetic distance and diet similarities for Atlantic and East Pacific butterflyfishes; thus, in these
regions, species' diets do not seem to be phylogenetically conserved. This suggests that evolutionary
processes are not the main drivers of butterflyfish co-occurrence highlighting species' abundance and
niche-related processes as the most important factors in determining whether species co-occur at the
habitat scale.