Résumé
Resource allocation to offspring is the battleground for various
intra-familial conflicts. Understanding these conflicts requires knowledge
of how the different actors (mother, siblings with different paternal
genotypes) influence resource allocation. In angiosperms, resource to
seeds is allocated post-fertilization and the paternally inherited genome
in offspring can therefore influence resource allocation. However, the
precise mode of resource allocation, and in particular the occurrence of
sibling rivalry, has been rarely investigated in plants. In this paper, we
develop a new method to analyze the resource allocation traits of the
different actors (maternal sporophyte and half-sibs) using the data
obtained from a large-scale diallel cross experiment in maize involving
mixed hand pollination and colors markers to assess seed weight of known
paternity. We found strong evidence for the occurrence of sibling rivalry:
all resource to ears was allocated competitively and offspring with
different paternal genotypes aggressively competed for this resource,
entailing a measurable direct cost. We also show how resource allocation
can be described for each genotype into two maternal (source effect,
average sink responsiveness) and two offspring traits (ability to attract
maternal resource, competitive ability towards siblings). We will discuss
how these findings help understanding how genetic conflicts shape resource
allocation traits in angiosperms.