Pollinator‐mediated selection in a specialized hummingbird–Heliconiasystem in the Eastern Caribbean

Abstract

Phenotypic matches between plants and their pollinators often are interpreted as examples of reciprocal selection and adaptation. For the two co-occurring plant species, Heliconia bihai and H. caribaea in the Eastern Caribbean, we evaluated for five populations over 2 years the strength and direction of natural selection on corolla length and number of bracts per inflorescence. These plant traits correspond closely to the bill lengths and body masses of their primary pollinators, female or male purple-throated carib hummingbirds (Eulampis jugularis). In H. bihai, directional selection for longer corollas was always significant with the exception of one population in 1 year, whereas selection on bract numbers was rare and found only in one population in 1 year. In contrast, significant directional selection for more bracts per inflorescence occurred in all three populations of the yellow morph and in two populations of the red morph of H. caribaea, whereas significant directional selection on corolla length occurred in only one population of the red morph and one population of the yellow morph. Selection for longer corollas in H. bihai may result from better mechanical fit, and hence pollination, by the long bills of female E. jugularis, their sole pollinator. In contrast, competition between males of E. jugularis for territories may drive selection for more bracts in H. caribaea. Competitive exclusion of female E. jugularis by territorial males also implicates pollinator competition as a possible ecological mechanism for trait diversification in these plants.

Florivory and floral larceny by fly larvae decrease nectar availability and hummingbird foraging visits at Heliconia (Heliconiaceae) flowers

“…The influence of the larvae on hummingbird foraging behavior is a novel finding, given that these birds mediate the selection of specialized floral traits in Heliconia (Temeles et al . ). The aggregations of larvae observed in infested flowers (Fig.…”

“…, Missagia & Verçoza , , Temeles et al . ) and the reproductive biology (Kress , Meléndez‐Ackerman et al . ) of a number of different Heliconia species, the role of these larvae in pollinator–plant interactions has not been investigated systematically.…”

“…Gill (1987) suggested that pollinating hummingbirds may avoid the flowers of H. stilesii Daniels infested with larvae, but did not present any quantitative evidence. While a number of studies in recent decades have focused on the pollination ecology (Stiles 1975, Bruna et al 2004, Cruz et al 2007, Missagia & Verc ßoza 2011, 2015, Temeles et al 2013) and the reproductive biology (Kress 1983, Mel endez-Ackerman et al 2008) of a number of different Heliconia species, the role of these larvae in pollinator-plant interactions has not been investigated systematically. We observed that the flowers of Heliconia spathocircinata were frequently infested with dipteran larvae from two families (Stratiomyidae and Syrphidae) in an area of Atlantic forest in the Pedra Branca State Park (PBSP), in the municipality of Rio de Janeiro, Brazil.…”

Floral specialization and angiosperm diversity: phenotypic divergence, fitness trade-offs and realized pollination accuracy

“…In turn, males had shorter handling times than females on artificial flowers with short, straight corollas (but only when hovering). Although the measured trade-offs were experienced by the pollinator, they suggested an indirect plant fitness trade-off, where both birds and plants should specialize on the appropriate morphs, with selection against generalists (Temeles et al 2013). …”

Digest: The effect of the pollinator composition and abundance on pollen-related floral traits*

“…; Temeles et al. ; Boberg et al. ), and pollinators have been observed to be the agents exerting selection on floral traits (Sletvold et al.…”