Testing Pollination Syndromes in <i>Oenothera</i> (Onagraceae)

Abstract

Pollinators are considered a major selective force in shaping the diversification of angiosperms. It has been hypothesized that convergent evolution of floral form has resulted in “pollination syndromes” - i.e. suites of floral traits that correspond to attraction of particular pollinator functional groups. Across the literature, the pollination syndrome concept has received mixed support. This may be due to studies using different methods to describe floral traits and/or the pollination syndrome concept being supported more often in species highly reliant on pollinators for reproduction. Here, we assess the predictive ability of pollination syndromes in Oenothera, a species rich clade with pollination systems existing on a gradient of specialization, and in which species are either self-compatible or self-incompatible. We ask the following questions: Do Oenothera species follow the pollination syndrome concept using traditional, categorical floral trait descriptions and/or quantitative floral trait measurements? And, are floral traits more predictive of primary pollinators in species with specialized pollination systems and/or species that are self-incompatible? Mapping floral traits of 54 Oenothera species into morphospace, we do not find support for the pollination syndrome concept using either categorical or quantitative floral trait descriptions. We do not find support for specialization or breeding system influencing the prediction of primary pollinators. However, we find pollination syndromes were more predictive in Oenothera species with moth pollination systems. Collectively, these results suggest that the pollination syndrome concept cannot be generally applied across taxa and that evolutionary history is important to consider when evaluating the relationship between floral form and contemporary pollinators.

Causes and consequences of variation in heterospecific pollen receipt in Oenothera fruticosa

“…We recorded diurnal insect visitation on each flower for approximately 1 h using high‐definition video cameras (Sony, San Diego, CA, USA) during pollinator activity (08:00–16:00 hours) on warm, sunny days, capturing a total of 130 h of film. We note that although many Oenothera species are visited by both diurnal and nocturnal floral visitors, the importance of these groups as pollinators varies across species (Rhodes et al, 2017 ; Antoń and Denisow, 2018 ; Krakos and Austin, 2021 ). Prior work has demonstrated that O. fruticosa is visited by diurnal pollinators including, butterflies, bees, and beetles, with no record of nocturnal visitors (Primack and Silander, 1975 ; Silander and Primack, 1978 ; Krakos and Austin, 2021 ).…”

“…We note that although many Oenothera species are visited by both diurnal and nocturnal floral visitors, the importance of these groups as pollinators varies across species (Rhodes et al, 2017 ; Antoń and Denisow, 2018 ; Krakos and Austin, 2021 ). Prior work has demonstrated that O. fruticosa is visited by diurnal pollinators including, butterflies, bees, and beetles, with no record of nocturnal visitors (Primack and Silander, 1975 ; Silander and Primack, 1978 ; Krakos and Austin, 2021 ). From the video footage, we identified pollinators and determined pollinator visitation rates of each, only considering insects that were observed contacting the reproductive structures of the flowers.…”

Síndrome de Polinização das Espécies Arbóreas e Arbustivas do Campus do Pici - Fortaleza, Ceará, Brasil

“…Os polinizadores são atraídos pelos recursos primários oferecidos pelas flores como pólen, néctar e óleos, e por recursos secundários como a coloração das estruturas florais e seus odores (Endress, 1994). Esses recursos ofertados fazem parte dos atributos florais de grupos vegetais não relacionados, que se adaptaram evolutivamente para atrair determinados tipos de agentes polinizadores e afastar outros, procurando garantir o sucesso de sua reprodução, fenômeno esse investigado pelos botânicos com o objetivo de obter possíveis explicações para melhor compreendê-los (Barônio et al, 2016;Gomes e Quirino, 2016;Lóz et al, 2019;Krakos & Austin, 2020;Kar et al, 2021;Stevenson et al, 2022).…”

Are floral traits good predictors of effective pollinators? A test of pollination syndromes

“…Studies evaluating the predictability of pollination syndromes have found variable results. For instance, several studies have found that pollination syndromes are partially predictable (they are met for some of the species studied, but not for others), and their predictability varies among habitats (Abrahamczyk et al, 2017; Gómez et al, 2014; Krakos & Austin, 2020; Martén‐Rodríguez et al, 2009; Ollerton et al, 2009; Pérez et al, 2006; Wester & Claßen‐Bockhoff, 2011; Zhang et al, 2005). Moreover, it has been found that pollination syndromes are usually predictable for plant species pollinated by bats, birds, and bees (Armbruster et al, 2011; Ashworth et al, 2015; Bestea et al, 2019; Cortés‐Flores et al, 2017; Danieli‐Silva et al, 2012; Hargreaves et al, 2004; Lázaro et al, 2008; Martén‐Rodríguez et al, 2009; Muchhala, 2003, 2006; Murúa & Espíndola, 2015; Pauw, 2006), and, less frequently, by flies (Rosas‐Guerrero et al, 2014), but not by other groups of animals.…”

“…Moreover, it has been found that pollination syndromes are usually predictable for plant species pollinated by bats, birds, and bees (Armbruster et al, 2011; Ashworth et al, 2015; Bestea et al, 2019; Cortés‐Flores et al, 2017; Danieli‐Silva et al, 2012; Hargreaves et al, 2004; Lázaro et al, 2008; Martén‐Rodríguez et al, 2009; Muchhala, 2003, 2006; Murúa & Espíndola, 2015; Pauw, 2006), and, less frequently, by flies (Rosas‐Guerrero et al, 2014), but not by other groups of animals. Likewise, it has been found that the predictability of pollination syndromes is increased when pollinators, instead of floral visitors, are used in the analysis (Armbruster et al, 2011; Danieli‐Silva et al, 2012; Hargreaves et al, 2004; Krakos & Austin, 2020; Lázaro et al, 2008; Murúa & Espíndola, 2015; Pauw, 2006; Strakosh & Ferguson, 2005).…”