Data from: Phenotypic divergence of the common toad (Bufo bufo) along an altitudinal gradient: evidence for local adaptation

Variation in the environment can induce different patterns of genetic and
phenotypic differentiation among populations. Both neutral processes and
selection can influence phenotypic differentiation. Altitudinal phenotypic
variation is of particular interest in disentangling the interplay between
neutral processes and selection in the dynamics of local adaptation
processes but remains little explored. We conducted a common garden
experiment to study the phenotypic divergence in larval life-history
traits among nine populations of the common toad (Bufo bufo) along an
altitudinal gradient in France. We further used correlation among
population pairwise estimates of quantitative trait (QST) and neutral
genetic divergence (FST from neutral microsatellite markers), as well as
altitudinal difference, to estimate the relative role of divergent
selection and neutral genetic processes in phenotypic divergence. We
provided evidence for a neutral genetic differentiation resulting from
both isolation by distance and difference in altitude. We found evidence
for phenotypic divergence along the altitudinal gradient (faster
development, lower growth rate and smaller metamorphic size). The
correlation between pairwise QSTs–FSTs and altitude differences suggested
that this phenotypic differentiation was most likely driven by
altitude-mediated selection rather than by neutral genetic processes.
Moreover, we found different divergence patterns for larval traits,
suggesting that different selective agents may act on these traits and/or
selection on one trait may constrain the evolution on another through
genetic correlation. Our study highlighted the need to design more
integrative studies on the common toad to unravel the underlying processes
of phenotypic divergence and its selective agents in the context of
environmental clines.