Data from: Should we sync? Seascape-level genetic and ecological factors determine seagrass flowering patterns

Spatial and temporal heterogeneity in flowering occur in many plant
species with abiotic pollination and may confer fitness advantages through
mechanisms such as predator satiation or pollination efficiency.
Environmental factors such as light quality or quantity and temperature
play an important role in inducing synchronisation on wide geographic
scales. On a smaller geographic scale, external factors such as resource
availability and herbivory are theorised to trigger flowering, while
genetic factors may also play an important role. In this study, we
assessed the importance of ecological and genetic factors in shaping
seascape-level spatial heterogeneity in flowering of the seagrass
Posidonia oceanica. By investigating spatially close sites (<20 km)
with similar seascape configurations and depth, we assume that major
environmental drivers (temperature and light) were equivalent. We assessed
four ecological factors (productivity, leaf nitrogen and carbon content
and herbivory) and three genetic factors (heterozygosity, relatedness and
clonality) to assess three hypotheses for synchronised flowering in P.
oceanica: (1) clone synchronisation (internal clock hypothesis), (2)
variation in nutrient availability, potentially caused by spatial
heterogeneity in herbivory rates or nutrient translocation via clonal
integration (resource budget hypothesis) or (3) kin selection and sibling
synchronisation. Internal relatedness and heterozygosity had a significant
positive effect on the abundance of flowers. Moreover, productivity and
genotypic richness (clonality) were negatively associated with flower
density, although at a lower level of significance. In addition we found
that clones were almost exclusively shared among mass-flowering patches
and patches without mass-flowering, respectively. Synthesis. The results
shed new light on seagrass flowering patterns and on the mechanisms of
flower synchronisation at the patch level within a wider spatial scale. We
found support for the kin selection hypothesis and indirect evidence for
the resource budget hypothesis. Thus a combination of mainly genetic but
also ecological factors causes the observed heterogeneous flowering
patterns in Posidonia oceanica seascapes. In addition, we found a strong
positive relationship between the number of flowers and heterozygosity,
adding evidence to the controversial association between heterozygosity
and fitness when a limited number of loci are used. To our knowledge, this
study is the first to link both ecological and genetic factors with flower
abundance in a species with a presumed masting strategy.