Data from: Chilean fish body size is influenced by multiple drivers

There is evidence that organisms have become smaller during the past
periods of global warming. Global change has substantial effects on
biodiversity, with body size reduction being the third most common
response to global warming. Body size allometry in ectotherms needs to be
explored further; the objectives of this study were to better understand
the mechanisms regulating body size in fish by testing: i) Bergmann’s rule
with temperature and elevation, ii) additional environmental drivers, iii)
the role of isolation, iv) ecoevolutionary hypotheses comparing native and
exotic species, and v) the role of migration propensity in comparing
migratory and resident species. We analyzed an extensive dataset of
Chilean fish composed of 75,198 records which included 25 species from 12
different families between latitudes -28.80 to -51.42 using linear mixed
models to discern the best environmental variables contributing to body
size changes, as well as incorporating factors related to dispersal
capabilities, biogeographic isolation, and levels of exotic/native
interactions. Bergmann’s rule is supported by changes in elevation, and
our study shows that freshwater fish body size also increases with
increasing environmental heterogeneity and productivity. In general,
inland native fish tend to be smaller than coastal ones, supporting the
island rule with evidence of gigantism or dwarfism in selected species.
Ecological variables affecting fish body size do not differ between native
and exotic fish unless other factors are considered, such as dispersal
capacity (migrating vs. resident fish) or mechanisms related to their
isolation. Although temperature is not a direct driver of body size in
Chilean fish, heterogeneity, productivity, geography, migratory ability,
and species origin may affect body size. A better understanding of the
mechanisms driving body size in ectotherms will aid in determining
management priorities in the face of global climate disruption.