United in difference: on the divergence in floral preferences between Galápagos birds and insects

Dataset

Sixteen
morphological and nectar traits of 31 Galápagos plant species studied in the arid zone between March 2016 and April 2017.

Study Abstract
The
characteristic scarcity of insects on remote oceanic islands has driven non-flower
specialized vertebrates to broaden their trophic niches and explore floral
resources. From our previous studies in the Galápagos, we know that native
insectivorous and frugivorous Galápagos birds visit a wide range of typical entomophilous
flowers and can also act as effective pollinators. Here, we tested whether opportunistic
Galápagos birds show any preference for specific floral traits, and if this
preference differs from that of insects. Sixteen morphological and
nectar traits of 31 Galápagos plant species were studied, as well as their
visitation frequency by birds and insects. Non-metric multidimensional scaling
(NMDS) was used to evaluate the dispersal of flower trait values along two main
dimensions and measure the similarity between the plants visited mostly by
birds versus those by insects. A NMDS of
floral traits resulted in two species groups: i) larger, bell-shaped flowers
with slight larger nectar volume, associated with high bird visitation rates;
and ii) smaller, bowl-shaped flowers with lower nectar volume, associated with
high insect visitation rates. Galápagos
birds preferred species with floral traits intermediate between those of insect-
and bat-pollination syndromes. This finding is coherent with the existence of a
transitional or bet-hedging phenotype between insect and bird pollination and underscores the
importance of coevolution and floral diversification in non-specialized
plant-pollinator mutualisms.