Data from: Disentangling the relative contributions of factors determining seed physical defence: a global-scale data synthesis

Physical defence investment in seeds varies greatly among plant species
and is associated with many potential factors. Exploring the factors
explaining the interspecific variation in physical defence has long
attracted particular attention in both ecology and evolution studies.
However, the relative importance of the factors has not yet been
quantitatively evaluated, which may lead to the misunderstanding of the
main driver generating such interspecific variation. Here, by compiling a
global database of the seed coat ratio (SCR), a proxy of seed physical
defence, for 1,362 species, we provided the first quantification of the
relative explanations of six factors that have been commonly considered to
be associated with the interspecific variation in SCR: seed mass, seed
desiccation response (desiccation-sensitive vs. desiccation-tolerant),
seed dormancy (nondormant, physical dormant or other dormant types),
growth form (herbaceous vs. woody), fruit type (dry vs. fleshy), and
climate (19 bioclimatic variables representing temperature and
precipitation). Using partial R2 calculation that can estimate
the reduction in explained variance of a given factor after removing it
from a full model containing all the other factors, we disentangled the
relative contribution of each factor to explain variation in the SCR. Seed
desiccation response was the most important factor associating with SCR
variation, followed by seed dormancy, with a partial R2lik value
of 9.70% and 1.41%, respectively. Plant growth form, seed mass, climate
and fruit type showed little power to explain SCR variation, although they
are often cited in the literature as potential factors. Our results
highlight the important roles of seed desiccation response in shaping
interspecific variation in the SCR. These findings provide a detailed
interpretation of ecological patterns underlying the physical defence
mechanisms and allocation strategies of plant seeds.