Range overlap between the sword-billed hummingbird and its guild of long-flowered species: An approach to the study of a coevolutionary mosaic

Abstract

The coevolutionary process among free-living mutualists with extremely long matching traits may favor the formation of mutualistic interaction networks through coevolutionary escalation, complementarity and convergence. These networks may be geographically structured; the links among the species of a local network are shaped by the biotic composition of the community, thus creating selection mosaics at broader geographical scales. Therefore, to fully understand a coevolutionary process, it is crucial to visualize the geographical structure of the interaction network across the landscape. In this study we focused on the poorly known interaction system between Ensifera ensifera and its guild of long-flowered plant species. We combined occurrence data and environmental variables to predict E. ensifera distribution, in addition to range polygons available for plant species in order to evaluate the geographical variation in bill length and plant species richness. A positive relationship between bill length and plant species richness within the E. ensifera range suggests a geographical structuring of the interaction networks. At mid-latitude locations of E. ensifera range, where hummingbirds attained the longest bills, richness of long-flowered plant species was higher than at low latitude locations. These locations likely represent coevolutionary vortices where long-lasting reciprocal selection probably drove the evolution of long traits, consequently drawing new plant species into the coevolutionary network. Conversely, areas where the sword-billed hummingbird was absent or had shorter bills probably represent coevolutionary coldspots. Our results provide a first insight into this phenotypically specialized plant-pollinator network across the landscape and show candidate areas to test the predictions of the coevolutionary hypothesis, such as reciprocal selection.

The distributions of morphologically specialized hummingbirds coincide with floral trait matching across an Andean elevational gradient

“…In this respect, it is noticeable that numerous Andean highland flowers have extremely long corollas (e.g., Aetanthus, Brugmansia, Passiflora, and Tristerix ), which was also the case in our networks (Figure S13a). This observation supports the idea of high coevolution and trait matching in the Andean highlands (Soteras et al., ).…”

“…The significance of trait matching for the assembly of plant–pollinator interaction networks has been documented in previous studies (Dehling et al., ; Maglianesi, Blüthgen, Böhning‐Gaese & Schleuning, ; Sazatornil et al., ; Soteras, Moré, Ibañez, del Rosario Iglesias & Cocucci, ; Vizentin‐Bugoni, Maruyama & Sazima, ; Weinstein & Graham, ). Several of these feature hummingbirds and their flowering plants, which exhibit the most specialized co‐adaptations and greatest niche partitioning of any avian‐plant mutualistic association (Fleming & Muchhala, ; Stiles, ; Zanata et al., ).…”

“…Implications of trait matching for pairwise interactions within mutualistic networks have been underlined by several recent studies (Maglianesi et al., , ; Soteras et al., ; Vizentin‐Bugoni et al., ; Weinstein & Graham, ). Yet, none has specifically addressed the determinants of trait matching at an assemblage level across space.…”

Nectar larceny in the trainbearers (Lesbia, Trochilidae)

“…Floral larceny is often targeted at flowers of plants that have close co-evolutionary relationships with other legitimately pollinated animal species, such as the sword-billed hummingbird and its guild of long-flowered species (Soteras et al, 2018). Some characteristics of hummingbirds, including bill length and tomial serrations are thought to be particularly closely associated with primary nectar robbing (Ornelas, 1994).…”

A hurricane alters pollinator relationships and natural selection on an introduced island plant

“…Plants and their pollinators have contributed to this understanding, because often, the morphology of a plant's flower corresponds to the morphology of its pollinator (e.g., Johnson & Steiner, ; Muchhala & Thomson, ; Stein, ). Such trait matching has been interpreted as a product of reciprocal selection and adaptation, and one approach toward confirming this interpretation has been to examine whether and how floral traits change as a result of pollinator shifts across native geographic landscapes (e.g., Pauw, Stofberg, & Waterman, ; Soteras, Moré, Ibañez, Iglesias, & Cocucci, ). These studies suggest that directional selection is strongest where flower and pollinator morphologies are poorly matched (Nattero, Sérsic, & Cocucci, ).…”