Convergence, Competition, and Mimicry in a Temperate Community of Hummingbird-Pollinated Flowers

We studied the pollination ecology of nine species of red, tubular flowers which bloom together in different combinations in the White Mountains of Arizona, USA. All species were strikingly convergent in floral color, size, and shape. Hummingbirds, the primary pollinators, usually did not visit flower species selectively, and individual birds often simultaneously carried four or more species of pollen. Flowers may have competed interspecifically for these shared pollinators, but competition was reduced because character displacement in orientation of anthers and stigma resulted in some species using different parts of the bird to transport their pollen. Most flower species secreted nectar at similar rates, particularly when the bloomed together in mixed stands. A population of Lobelia cardinalis secreted no nectar; it attracted hummingbirds by mimicing more abundant, nectar—producing species. This temperate flower community, which resembles some associations of convergent Mullerian and Batesian mimics, appear to have evolved its characteristics convergent structure because the advantages of using similar signals and rewards to share the same hummingbird pollinators outweigh the advantages of diverging to reduce interspecific competition.