Pollination Syndromes and Floral Specialization

Abstract

▪ Abstract Floral evolution has often been associated with differences in pollination syndromes. Recently, this conceptual structure has been criticized on the grounds that flowers attract a broader spectrum of visitors than one might expect based on their syndromes and that flowers often diverge without excluding one type of pollinator in favor of another. Despite these criticisms, we show that pollination syndromes provide great utility in understanding the mechanisms of floral diversification. Our conclusions are based on the importance of organizing pollinators into functional groups according to presumed similarities in the selection pressures they exert. Furthermore, functional groups vary widely in their effectiveness as pollinators for particular plant species. Thus, although a plant may be visited by several functional groups, the relative selective pressures they exert will likely be very different. We discuss various methods of documenting selection on floral traits. Our review of the literature indicates overwhelming evidence that functional groups exert different selection pressures on floral traits. We also discuss the gaps in our knowledge of the mechanisms that underlie the evolution of pollination syndromes. In particular, we need more information about the relative importance of specific traits in pollination shifts, about what selective factors favor shifts between functional groups, about whether selection acts on traits independently or in combination, and about the role of history in pollination-syndrome evolution.

Reproductive biology of Davilla kunthii A. St-Hil. (Dilleniaceae) in Central Amazonia

“…According to Fenster et al (2004) and Armbruster et al (2002), these functional groups of visitors may collectively drive the evolution of plants, so a similar process could have occurred in the case of D. kunthii. In our study, pollinators have no morphological characters substantially diff erent to mediate any modifi cation in the fl oral traits.…”

“…Contrary to the discussion of generalisation-specialisation of pollination mechanisms, Armbruster et al (2002) and Fenster et al (2004) point out that a plant with an assembly of phylogenetically unrelated fl oral visitors does not necessarily indicate a generalised system. According to these authors, many visitors can be included in functional groups, which permit the understanding of specialisation as adaptive evolution.…”

Atributos florais em um sistema de polinização especializado: Calathea cylindrica (Roscoe) K. Schum. (Marantaceae) e abelhas Euglossini

“…Atualmente existe vasta literatura indicando que os sistemas de polinização das angiospermas se distribuem em um contínuo entre os extremos de generalização e especialização (Fenster et al 2004, Ramírez 2004, Freitas & Sazima 2006, Waser & Ollerton 2006 e uma das questões que emerge desse cenário é o entendimento dos fatores que estão ligados ao surgimento e manutenção de sistemas de polinização com alto grau de especialização (Westerkamp 1997, Aigner 2001, Fenster et al 2004, Cane & Sipes 2006. De acordo com o princípio de Stebbins (1970) do polinizador mais efetivo, uma planta deve especializarse no polinizador mais eficaz e mais abundante quando a disponibilidade deste é confiável.…”

Digging beneath the surface: incipient nest characteristics across three species of harvester ant that differ in colony founding strategy

“…Syndromes are suites of correlated characteristics that exist as a group rather than distinctive entities. They have been previously described for floral traits that have evolved in response to pollinator characteristics (Fenster et al, 2004), such as Australian nutmeg in response to beetle pollinators (Armstrong and Irvine, 1989), correlated behaviors across contexts (behavioral syndromes) such as in funnel web and fishing spiders, and sticklebacks (Sih et al, 2004), and for migratory characteristics of insects such as the sand cricket (Fairbairn, 1994).…”