Functional traits can determine pairwise species interactions, such as those between plants and pollinators. However, the effects of biogeography and evolutionary history on trait‐matching and trait‐mediated resource specialization remain poorly understood. We compiled a database of 93 mutualistic hummingbird–plant networks (including 181 hummingbird and 1,256 plant species), complemented by morphological measures of hummingbird bill and floral corolla length. We divided the hummingbirds into their principal clades and used knowledge on hummingbird biogeography to divide the networks into four biogeographical regions: Lowland South America, Andes, North & Central America, and the Caribbean islands. We then tested: (a) whether hummingbird clades and biogeographical regions differ in hummingbird bill length, corolla length of visited flowers and resource specialization, and (b) whether hummingbirds' bill length correlates with the corolla length of their food plants and with their level of resource specialization. Hummingbird clades dominated by long‐billed species generally visited longer flowers and were the most exclusive in their resource use. Bill and corolla length and the degree of resource specialization were similar across mainland regions, but the Caribbean islands had shorter flowers and hummingbirds with more generalized interaction niches. Bill and corolla length correlated in all regions and most clades, that is, trait‐matching was a recurrent phenomenon in hummingbird–plant associations. In contrast, bill length did not generally mediate resource specialization, as bill length was only weakly correlated with resource specialization within one hummingbird clade (Brilliants) and in the regions of Lowland South America and the Andes in which plants and hummingbirds have a long co‐evolutionary history. Supplementary analyses including bill curvature confirmed that bill morphology (length and curvature) does not in general predict resource specialization. These results demonstrate how biogeographical and evolutionary histories can modulate the effects of functional traits on species interactions, and that traits better predict functional groups of interaction partners (i.e. trait‐matching) than resource specialization. These findings reveal that functional traits have great potential, but also key limitations, as a tool for developing more mechanistic approaches in community ecology. A free Plain Language Summary can be found within the Supporting Information of this article.

Las interacciones mutualistas han moldeado la biodiversidad en la tierra. A pesar de ello, hasta recientemente era difícil encontrar patrones en la estructura de este tipo de interacciones en las comunidades. En años recientes se ha promovido el análisis de las interacciones mutualistas como redes que muestran las conexiones entre las especies. Esta aproximación permite la descripción de patrones estructurales que operan en las interacciones ecológicas en el nivel de comunidad y constituye un nuevo campo en la ecología. En este estudio definimos, caracterizamos y analizamos 4 subredes de polinización, formadas por las interacciones entre colibríes y plantas en varios paisajes del centro-este de México. Las interacciones en las comunidades analizadas muestran un patrón anidado en su estructura, similar al reportado para otras redes de mutualismos. Se ha sugerido que esta característica, en conjunto con otras que se han descrito para este tipo de redes, promueve la coexistencia de las especies en una comunidad, teniendo por lo tanto implicaciones ecológicas y conservacionistas para las comunidades de colibríes y plantas del centro-este de México.

No abstract

The global climatic change could cause, in some places, appearance of meteorological phenomena considered rare. If we understand the effect of these phenomena on birds we can understand how birds respond to weather changes. We report here the effect of a severe snowfall on hummingbird activity, flower abundance and hummingbird-plant interaction in a temperate forest of central Mexico. During our study we registered 1 hummingbird species (Hylocharis leucotis) and 7 plant species (Fuchsia thymifolia, F. microphyla, Salvia amarissima, S. elegants, Cestrum roseum, Penstemon campanulatus and Lonicera mexicana). Before the sudden climatic phenomena we registered 66 records of hummingbirds, 8 700 flowers, and 6 hummingbird visits to flowers. During the phenomena, there were zero hummingbird records, 160 flowers and zero visits. A month after the event there were 67 hummingbirds records, 1 825 flowers and 13 visits. Hummingbird activity recovered rapidly after the snowstorm, but 6 of 7 plants species lost all their flowers, except for L. mexicana, which received all hummingbird visits a month after the climatic event. Key words: bird pollinated flowers, global climate change, hummingbirds, ornithophylous plant species, snowstorm effect, sudden changes in the average state of the time. Resumen. El cambio climático global podría causar fenómenos meteorológicos considerados como raros. Si entendemos el efecto de estos fenómenos en las aves podríamos comprender como las aves responden a este tipo de cambios en el tiempo. Aquí documentamos el efecto de una nevada severa sobre la actividad de colibríes, la abundancia floral y la interación colibrí-planta en un bosque templado del centro de México. Durante nuestro estudio registramos 1 especie de colibrí (Hylocharis leucotis) y 7 especies de plantas (Fuchsia thymifolia, F. microphyla, Salvia amarissima, S. elegants, Cestrum roseum, Penstemon campanulatus y Lonicera mexicana). Antes de la nevada registramos 66 avistamientos de colibríes, 8 700 flores y 6 visitas de colibríes a las flores. Durante el fenómeno hubo cero registros de colibríes, 160 flores y cero visitas. Un mes después del evento climático hubo 67 registros de colibríes, 1 825 flores y 13 visitas. La actividad de los colibríes se recuperó rápido después de la nevada, pero 6 de 7 especies de plantas perdieron todas sus flores, exceptuando a L. mexicana, que recibió todas las visitas de colibríes 1 mes después del evento climático inusual. Palabras clave: flores polinizadas por colibríes, cambio climático global, colibríes, plantas ornitofílicas, efecto de nevada, cambios repentinos en el estado del tiempo.