Floral traits differentiate pollination syndromes and species but fail to predict the identity of floral visitors to <i>Castilleja</i>

Hilpman, Evan T.; Busch, Jeremiah W.

doi:10.1002/ajb2.1784

Cited by 5 publications

(7 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this study we characterize geographic variation in pollinator visitation and reproductive fitness across the range of four species of Castilleja. By sampling multiple populations over several years, we document a wide spectrum of visitors spanning hummingbirds, Lepidoptera (butterflies and hawkmoths), Hymenoptera (mostly small solitary bees and bumblebees) and Diptera (bee-flies and occasional hoverflies), demonstrating a diversity of visitors consistent with studies of other Castilleja species (Hersch and Roy, 2007;Hilpman and Busch, 2021). Despite exhibiting significant divergence in floral traits, we show that our four focal Castilleja species were visited broadly by all pollinator groups (with two exceptions: the lack of hummingbird visits to C. sessiliflora and of large bee visits to C. lindheimeri).…”

Section: Discussionsupporting

confidence: 72%

Pollinator mosaics mirror floral trait divergence within and between species ofCastilleja

Wenzell

Skogen

Fant

2022

Preprint

View full text Add to dashboard Cite

Pollinator interactions are important in the evolution of floral traits, given that pollinators can directly influence plant fitness and mating patterns through interactions with flowers. However, geographic variation in both plant traits and floral visitors across multiple populations is largely understudied, despite being ubiquitous. This study explores whether a geographic mosaic of ecological interactions underlies observed patterns of floral divergence 1) among species of the Castilleja purpurea complex (C. purpurea, C. citrina, and C. lindheimeri) and the congener C. sessiliflora, as well as 2) within C. sessiliflora, across its wide geographic range. We sampled floral visitors and floral traits (morphology and color) at 23 populations over 1-3 years, with reproductive fitness (fruit set) data for 18 of these populations. We documented a wide diversity of pollinator functional groups visiting the four focal species, including bees, butterflies, hawkmoths, and hummingbirds. Visitor assemblages varied among species and across geography both in terms of the composition and diversity of floral visitors. We found support for relationships between floral traits and visitation by certain pollinator groups, which often aligned with syndrome-associated predictions. Additionally, we found evidence that visitation from pollinators predicted via syndromes was associated with increased reproductive fitness for two species: the red-flowered C. lindheimeri and its hummingbird visitors, and the long-floral-tubed C. sessiliflora when visited by hawkmoths. Beyond these cases, we found that pollinator functional groups were not restricted to plant species, and instead pollinators were largely generalist in their foraging behavior, suggesting the likelihood for incomplete reproductive isolation and the potential for ongoing gene flow among plant species where their ranges overlap. This study provides a large-scale exploration of how variation in pollinator assemblages across distributions may underlie floral trait divergence within and among recently diverged species, even when characterized by largely generalized modes of pollination. Our extensive sampling of 23 populations over multiple years across a large geographic area highlights the value of range-wide studies for characterizing patterns of divergence and speciation mediated by ecological interactions.

show abstract

Section: Discussionsupporting

confidence: 72%

Pollinator mosaics mirror floral trait divergence within and between species ofCastilleja

Wenzell

Skogen

Fant

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…In particular, it is common to name a proposed syndrome after its putative driver, long before such a driver has been critically examined. Pollination syndromes are one prototypical example: even studies that do not find support for pollination syndromes include statements such as "pollination syndrome was a poor predictor of [floral] visitors" (Hilpman & Busch, 2021) simply because this is the language used historically to refer to that syndrome. This results in confusing statements that appear to support the idea of a pollination syndrome when the data suggest otherwise, further obscuring the concept of a syndrome and the strength of evidence supporting (or refuting) that syndrome.…”

Section: Box 1 Definitions Of Terms Usedmentioning

confidence: 99%

“…One of the major problems in our hypothetical example is that we did not test explicitly for convergence of traits on a phylogeny. Because traits may be shared due to common ancestry rather than adaptation (Felsenstein, 1985), failing to test for convergence can give the impression of a strong relationship between traits and adaptation that are not a result of selection acting on independent lineages (see Hilpman & Busch, 2021 for a discussion of this in the context of pollination syndromes). For instance, we might travel to a third island and observe another pair of beetles.…”

Section: Introductionmentioning

confidence: 99%

How to approach the study of syndromes in macroevolution and ecology

Sinnott‐Armstrong

Deanna

Pretz

et al. 2022

Ecology and Evolution

View full text Add to dashboard Cite

Syndromes, wherein multiple traits evolve convergently in response to a shared selective driver, form a central concept in ecology and evolution. Recent work has questioned the utility and indeed the existence of some of the classic syndromes, such as pollination and seed dispersal syndromes. Here, we discuss some of the major issues that have plagued research into syndromes in macroevolution. First, observation of co-evolving traits (sometimes called "trait syndromes'') is often used as evidence of adaptation to a particular driver, even when the link between traits and adaptation is not well-tested. Second, the study of syndromes often uses a biased sampling approach, focusing on the most extreme examples, which may obscure significant continuous variation between traits. Finally, researchers often focus on the traits that are easiest to measure even though these may not be the most directly relevant to adaptive hypotheses. We argue that these issues can be avoided by combining macroevolutionary studies of trait variation across entire clades with explicit tests of adaptive hypotheses, and that taking this approach will lead to a better understanding of syndrome-like evolution and its drivers.

show abstract

“…The challenge is to find "detectable associations between plant phenotypes and pollinators" (Waser et al 1996). Some studies have found this association (Hargreaves et al 2004;Wilson et al 2004;Pauw 2006;Geerts & Pauw 2009;Marten-Rodriguez et al 2009;Danieli-Silva et al 2012;Rosas-Guerrero et al 2014;Johnson & Wester 2017;Lagomarsino et al 2017;Bilbao et al 2021;Rose & Sytsma 2021), whereas in other cases, floral traits and pollinators were not associated, because each plant species was found to be pollinated by many kinds of animal (Waser et al 1996;Ollerton et al 2009;Hilpman & Busch 2021;Amorim et al 2022), or primarily by animals that do not match the prediction (Huang & Fenster 2007;Li & Huang 2009;Pauw et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Pollination syndrome accurately predicts pollination by tangle‐veined flies (Nemestrinidae: Prosoeca s.s.) across multiple plant families

Pauw

2022

Plant Biol J

View full text Add to dashboard Cite

The idea that a syndrome of floral traits predicts pollination by a particular functional group of pollinators remains simultaneously controversial and widely used because it allows plants to be rapidly assigned to pollinators. To test the idea requires demonstrating that there is an association between floral traits and pollinator type.• I conducted such a test in the Cape Floristic Region of South Africa, by studying the pollination of eight plant species from six families that flower in spring and have scentless, actinomorphic, upwards-facing flowers, with orbicular petals all held in the same plane. The petals are brilliant-white with red-purple nectar guides. The tubes are short and hold small volumes of concentrated nectar, except in the rewardless Disa fasciata (Orchidaceae). Pollinators were photographed and captured, pollen loads were analysed and pollination networks were constructed.• Consistent with the pollination syndrome hypothesis, the species with the defined syndrome shared a small group of pollinators. The most frequent pollinators belonged to a clade of four tangle-veined fly species with relatively short proboscises (Nemestrinidae: Prosoeca s.s.), while functionally similar Bombyliidae and Tabanidae played minor roles. Among the four Prosoeca species, only Prosoeca westermanni has been described, a result that highlights our ignorance about pollinators.• The demonstration of an association between the syndrome of traits and pollination by this group of flies explains the repeated evolution of the syndrome across multiple plant families, and allows prediction of pollinators in additional species. More generally, the result validates the idea that the traits of organisms determine their ecology.

show abstract

Floral traits differentiate pollination syndromes and species but fail to predict the identity of floral visitors to Castilleja

Cited by 5 publications

References 66 publications

Pollinator mosaics mirror floral trait divergence within and between species ofCastilleja

Pollinator mosaics mirror floral trait divergence within and between species ofCastilleja

How to approach the study of syndromes in macroevolution and ecology

Pollination syndrome accurately predicts pollination by tangle‐veined flies (Nemestrinidae: Prosoeca s.s.) across multiple plant families

Contact Info

Product

Resources

About