Pollinator-mediated selection on the nectar guide phenotype in the Andean monkey flower, Mimulus luteus

medel, R; Botto-Mahan, C; Kalin-Arroyo, M

Abstract

Mimulus luteus (Scrophulariaceae) is a perennial herb occurring in the South American Andes that shows a wide variation in the size and shape of a red spot on the lower lobe of the yellow flower. We describe the preference of four insects (three bees and one butterfly) and one hummingbird species for floral characters, and estimated the strength, direction, and form of pollinator-mediated selection through female fitness. We applied geometric morphometrics to describe the preference of pollinator species for different guide shapes. Our results revealed striking differences in the floral phenotypes preferred by insects and hummingbirds. Insects visited flowers with corollas 1.25-fold larger and guides 1.72-fold larger than the hummingbird species did. While insects preferred flowers with nectar guides pointing toward the corolla tube, the hummingbird preferred flowers with heart-shaped nectar guides. Most of the floral preferences shown by pollinators translated into significant linear and nonlinear selection coefficients. When selection was analyzed on a per-flower basis and for female fitness, corolla size was under positive directional selection, and nectar guide size and shape were under disruptive selection. Because the insect and hummingbird pollinators showed a strong segregation in their daily activity time, we suggest that current disruptive selection on the nectar guide phenotype can result from the differential availability of the rewarding floral variants over a day. Our findings suggest that pollinator-mediated selection favoring extreme phenotypes in M. luteus may not only contribute to high nectar guide variation found in this species, but also can promote divergence of corolla and nectar guide traits.

Más información

Título según WOS: Pollinator-mediated selection on the nectar guide phenotype in the Andean monkey flower, Mimulus luteus
Título según SCOPUS: Pollinator-mediated selection on the nectar guide phenotype in the Andean monkey flower, Mimulus luteus
Título de la Revista: Ecology
Volumen: 84
Número: 7
Editorial: Wiley
Fecha de publicación: 2003
Página de inicio: 1721
Página final: 1732
Idioma: English
URL: http://www.esajournals.org/doi/abs/10.1890/01-0688
DOI:

10.1890/01-0688

Notas: ISI, SCOPUS - ISI