Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.

Mutualistic interactions are powerful drivers of biodiversity on Earth that can be represented as complex interaction networks that vary in connection pattern and intensity. One of the most fascinating mutualisms is the interaction between hummingbirds and the plants they visit. We conducted an exhaustive search for articles, theses, reports, and personal communications with researchers (unpublished data) documenting hummingbird visits to flowers of nectar-rewarding plants. Based on information gathered from 4532 interactions between 292 hummingbird species and 1287 plant species, we built an interaction network between nine hummingbird clades and 100 plant families used by hummingbirds as nectar resources at a continental scale. We explored the network architecture, including phylogenetic, morphological, biogeographical, and distributional information. As expected, the network between hummingbirds and their nectar plants was heterogeneous and nested, but not modular. When we incorporated ecological and historical information in the network nodes, we found a generalization gradient in hummingbird morphology and interaction patterns. The hummingbird clades that most recently diversified in North America acted as generalist nodes and visited flowers with ornithophilous, intermediate and non-ornithophilous morphologies, connecting a high diversity of plant families. This pattern was favored by intermediate morphologies (bill, wing, and body size) and by the low niche conservatism in these clades compared to the oldest clades that diversified in South America. Our work is the first effort exploring the hummingbird-plant mutualistic network at a continental scale using hummingbird clades and plant families as nodes, offering an alternative approach to exploring the ecological and evolutionary factors that explain plant-animal interactions at a large scale.

Coexistence between ecologically similar species can promote competition for resources. Hummingbirds (Aves: Trochilidae) are nectarivorous birds that usually coexist in sympatry, and visit flowers using different foraging behaviors and levels of aggressiveness as a strategy to diminish resource competition. Here, we describe the dynamics in territorial and dominance behaviors in a hummingbird community inhabiting a highland during winter in Western Mexico. We explored in natural conditions how foraging strategies and dominance status of the hummingbirds was influenced by community species composition, sex, age and size of the individuals, floral abundance, and nectar resource availability. The community studied was composed of 11 species (four residents, three altitudinal migrants, three latitudinal migrants), and all possible combinations of dominance and territoriality were found. Differences in the dominance status and foraging behavior were related to the species, sex, age and body size of the individuals, as well as the number of flowers in the patches, and the abundance of the migratory species over time. The aggressive and territorial species preferred the places with more flowers, and started the majority of the interactions attacking even birds that did not visited the flowers. The subordinate non‐territorial hummingbirds visited floral patches of different sizes, did not start aggressive interactions and when they were involved in one, this occurred during their visits to the territorial hummingbird's flowers. Hummingbird dominance changed during the winter and at the end of the season, when the latitudinal migrant species left our study site, the resident species were more abundant, dominant and territorial. Dominance status and foraging behavior, together with floral preferences and the spatial distribution of nectar resources, acted as mechanisms organizing this hummingbird community.