Diversification within hummingbird-pollinated clades in the temperate regions of the Americas appears mainly due to habitat specialization and allopatric speciation, not bird pollination per se.
Interaction tanglegrams, even if incomplete, indicate a lack of tight coevolution as perhaps expected for temperate-region mutualisms involving nectar-feeding vertebrates.
The 361 species of hummingbirds that occur from Alaska to Patagonia pollinate ~7,000 plant species with flowers morphologically adapted to them.
To better understand this asymmetric diversity build-up, this study analyzes the origin of hummingbird/plant mutualisms in North America and temperate South America, based on new compilations of the 184 hummingbird-adapted species in North America, the 56 in temperate South America, and complete species-level phylogenies for the relevant hummingbirds in both regions, namely five in temperate South America and eight in North America.
The oldest hummingbirds and hummingbird-adapted plant lineages in the South American assemblage date to 16–17 my, those in the North American assemblage to 6–7 my.
Few hummingbird-pollinated clades in either system have The asymmetric diversity build-up between hummingbirds and the plants dependent on them appears to arise not from rapid speciation within hummingbird-pollinated clades, but instead from a gradual and continuing process in which independent plant species switch from insect to bird pollination.
What are the implications of biased sex ratios in hummingbirds?
Or does it vary with the intensity of sexual dimorphism?
The 184 North American hummingbird-adapted species belong to ca.
70 lineages for 19 of which (comprising 54 species) we inferred divergence times.