Data and code from: Head morphology predicts prey traits and drives individual dietary specialization in generalist anurans

Functional morphology often constrains the diversity of resources an
organism can exploit, but the extent to which morphological variation
drives differences in the magnitude of individual specialization across
populations remains unclear. We investigated whether predator functional
morphology (i.e. head shape) predicts individual variation in prey traits
(size and mobility) and, ultimately, explains differences in the degree of
dietary individual specialization across populations of two co-occurring
species of tropical generalist frogs. Specifically, we tested three
morphology-function predictions: i) individual frogs with laterally short
jaws relative to head height primarily consume slow and large prey; (ii)
individuals with laterally long jaws relative to head height primarily
consume fast prey; and (iii) individuals with relatively wide heads
primarily consume large prey. We found support for all three
morphology-function predictions, although patterns were species-specific
and depended on predator and prey traits. Also, we found that populations
with stronger head shape-prey size relationships showed higher degrees of
individual specialization in prey size. Our findings provide the first
empirical evidence that functional morphology is a key driver of
individual dietary specialization in populations of generalist anurans and
highlight the potential role of intraspecific niche variation in
maintaining phenotypic variation in natural populations.