Data from: Higher seed number compensates for lower fruit set in deceptive orchids

1. Floral deception is widespread in orchids, with more than one third of
the species being pollinated this way. The evolutionary success of
deceptive orchids is puzzling, as species employing this strategy are
thought to have low reproductive success (less flowers yielding fruits)
because of low pollination rates. However, direct measurements of total
seed production in orchids – which is a better measure of reproductive
success – are scarce due to the extremely small size of their seeds. 2.
Here, we quantified seed numbers in 1,015 fruits belonging to 48 orchid
species from the Pannonian ecoregion (central Europe) and obtained
fruit-set and thousand-seed weight data for these species from the
literature. We used phylogenetic comparative methods to test the
hypothesis that deceptive species should compensate for their lower
fruit-set by having either more flowers, larger seeds or more seeds in a
fruit. 3. Similarly to previous studies, we found that deceptive orchids
have substantially lower fruits-set than nectar-rewarding ones. Also, we
found that deceptive species have more seeds in a fruit but not more
flowers or larger seeds compared to nectar-rewarding ones. Based on our
results, deceptive species compensate for their lower fruit-set by having
higher seed numbers per fruit. As a consequence, their seed numbers per
shoot do not differ from that of nectar-rewarding ones. 4. Together with
other benefits of deceptive pollination (e.g. lower energy expenditure due
to the lack of nectar production and higher genetic variability due to
decreased probability of geitonogamous pollination), our results can
explain why deceptive strategies are so widespread in the orchid family.
5. Synthesis. Our results indicate that deceptive orchids can compensate
for their lower fruit-set by having more (but not larger) seeds in a fruit
than rewarding species. These findings highlight possible ways in which
plants can increase their reproductive success in face of pollinator
limitation. We emphasize that fruit-set in itself is an inappropriate
measure of the reproductive success of orchids – the total number of seeds
per shoot is a much better approximation.