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Divergence in floral trait preferences between nonflower‐specialized birds and insects on the Galápagos
Author(s) -
HervíasParejo Sandra,
Heleno Ruben,
Nogales Manuel,
Olesen Jens M.,
Traveset Anna
Publication year - 2019
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/ajb2.1270
Subject(s) - biology , nectar , pollinator , frugivore , foraging , hummingbird , insectivore , ecology , insect , trait , ecological niche , butterfly , pollination , predation , pollen , habitat , computer science , programming language
Premise of the Study The characteristic scarcity of insects on remote oceanic islands has driven nonflower‐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 birds visit a wide range of 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 so, this preference differs from that of insects. Methods Sixteen floral morphology and nectar traits of 26 native species were studied, as well as the frequency with which they are visited by birds and insects. Nonmetric multidimensional scaling ( NMDS ) was used to evaluate the distribution of flower traits values along two main dimensions and measure the similarity between the plants visited mostly by birds versus those by insects. Key Results NMDS of floral traits resulted in two species groups: (1) bell‐shaped, white flowers with wider corollas at nectary level and higher nectar volume, associated with high bird visitation rates; and (2) bowl and tubular‐shaped flowers with narrower corollas at nectary level and lower nectar volume, associated with high insect visitation rates. Conclusions Despite the divergence in floral trait preferences between opportunistic Galápagos birds and insects, bird‐visited flowers display mixed traits not fitting the classical ornithophilous syndrome. This finding is compatible with the existence of a transitional or bet‐hedging phenotype between insect and bird visitors and underscores the importance of coevolution and floral diversification in nonspecialized plant–visitor interactions.