Data from: Allometric constraints and the evolution of allometry

Morphological traits often covary within and among species according to
simple power laws referred to as allometry. Such allometric relationships
may result from common growth regulation, and this has given rise to the
hypothesis that allometric exponents may have low evolvability and
constrain trait evolution. We formalize hypotheses for how allometry may
constrain morphological trait evolution across taxa, and test these using
more than 300 empirical estimates of static (within-species) allometric
relations of animal morphological traits. Although we find evidence for
evolutionary changes in allometric parameters on million-year,
cross-species time scales, there is limited evidence for microevolutionary
changes in allometric slopes. Accordingly, we find that static allometries
often predict evolutionary allometries on the subspecies level, but less
so across species. Although there is a large body of work on allometry in
a broad sense that includes all kinds of morphological trait–size
relationships, we found relatively little information about the evolution
of allometry in the narrow sense of a power relationship. Despite the many
claims of microevolutionary changes of static allometries in the
literature, hardly any of these apply to narrow-sense allometry, and we
argue that the hypothesis of strongly constrained static allometric slopes
remains viable.