Evolutionary constraints and adaptation shape the size and colour of rain forest fruits and flowers at continental scale

Aim: Large-scale patterns in flower and fruit traits provide critical
insights into selection processes and the evolutionary history of plant
lineages. To isolate and identify the role of selective pressures
including different plant-animal interactions, and the factors driving
trait evolution, we investigate convergence and divergence between flower
and fruit traits in shared environments. Location: Australia to Southeast
Asia. Time period: Eocene (~45 My) to Present. Major taxa studied: Woody
angiosperm rainforest species (2248 species, 133 families). Methods: Using
a continental scale data set for all woody angiosperm species in the
Australian rainforest (1816 free-standing and 432 climbing species) we
compare the colour and size of fleshy fruits and flowers in relation to
life form (trees/shrubs and vines), species biogeographic histories and
origins (Sunda vs. Sahul), and bio-regional distributions. Results: Fleshy
fruits in the Australian rainforest are mostly small, with a diversity of
colours (<30mm; 81%), while flowers are mostly small (<10mm;
65%) and whitish (~80%). Compared to trees and shrubs, climbing species
showed a higher proportion of red fleshy fruits, and large coloured
flowers. Small whitish flowers were dominant across lineages from
different biogeographic origins (Sunda-Sahul) and geographical regions,
while both small and large fleshy fruits retained a range of disperser
attractant colours. Main conclusions: Continental scale size and
colour characteristics of flowers and fleshy fruits differed despite
sharing environments with similar abiotic selective pressures through
time. Plant-animal interactions including pollination and dispersal likely
mediate different evolutionary outcomes for plant traits, and reflect both
adaptation and evolutionary constraints.