Tests of adaptation: functional studies of pollen removal and estimates of natural selection on anther position in wild radish

Conner, Jeffrey K.; Sahli, Heather F.; Karoly, Keith

doi:10.1093/aob/mcp071

Cited by 32 publications

(41 citation statements)

References 58 publications

(63 reference statements)

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“…[13]); (ii) there is correlational selection on the traits; and (iii) functional studies show how the traits work together in an integrated unit. For example, our work on wild radish flowers has provided these three lines of evidence for anther exsertion and the difference in lengths of the short and long stamens (see also [23]). Most wild radish floral correlations are low to moderate (0.28 -0.59), with the exception of the three correlations among the short and long filaments (the filaments mainly determine the length of the stamens) and the corolla tube ( [22]; table 2).…”

Section: Discussionmentioning

confidence: 92%

Patterns of phenotypic correlations among morphological traits across plants and animals

Conner

Cooper

Rosa

et al. 2014

Phil. Trans. R. Soc. B

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Despite the long-standing interest of biologists in patterns of correlation and phenotypic integration, little attention has been paid to patterns of correlation across a broad phylogenetic spectrum. We report analyses of mean phenotypic correlations among a variety of linear measurements from a wide diversity of plants and animals, addressing questions about function, development, integration and modularity. These analyses suggest that vertebrates, hemimetabolous insects and vegetative traits in plants have similar mean correlations, around 0.5. Traits of holometabolous insects are much more highly correlated, with a mean correlation of 0.84; this may be due to developmental homeostasis caused by lower spatial and temporal environmental variance during complete metamorphosis. The lowest mean correlations were those between floral and vegetative traits, consistent with Berg's ideas about functional independence between these modules. Within trait groups, the lowest mean correlations were among vertebrate head traits and floral traits (0.38–0.39). The former may be due to independence between skull modules. While there is little evidence for floral integration overall, certain sets of functionally related floral traits are highly integrated. A case study of the latter is described from wild radish flowers.

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Section: Discussionmentioning

confidence: 92%

Patterns of phenotypic correlations among morphological traits across plants and animals

Conner

Cooper

Rosa

et al. 2014

Phil. Trans. R. Soc. B

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“…The most common pollinator genus of wild radish in the upper Midwest is the sweat bee Dialictus, which exerts stabilizing selection on anther exsertion, while two of the larger pollinators, honey bees and cabbage butterflies (Pieris rapae), exert directional selection on exsertion (Conner et al 2009;H. F. Sahli and J. K. Conner, unpublished manuscript).…”

Section: Introductionmentioning

confidence: 99%

“…The underlying functional basis for this selection has also been studied in wild radish. Visits by sweat bees have maximal pollen removal (a component of male fitness) with intermediate anther exsertion, while pollen removal by honey bees and cabbage butterflies increases with increasing exsertion (Conner et al 1995(Conner et al , 2009.…”

Section: Introductionmentioning

confidence: 99%

Rapid Independent Trait Evolution despite a Strong Pleiotropic Genetic Correlation

Conner¹,

Karoly²,

Stewart³

et al. 2011

The American Naturalist

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. abstract: Genetic correlations are the most commonly studied of all potential constraints on adaptive evolution. We present a comprehensive test of constraints caused by genetic correlation, comparing empirical results to predictions from theory. The additive genetic correlation between the filament and the corolla tube in wild radish flowers is very high in magnitude, is estimated with good precision ( ), and is caused by pleiotropy. Thus, evolu-0.85 ‫ע‬ 0.06 tionary changes in the relative lengths of these two traits should be constrained. Still, artificial selection produced rapid evolution of these traits in opposite directions, so that in one replicate relative to controls, the difference between them increased by six standard deviations in only nine generations. This would result in a 54% increase in relative fitness on the basis of a previous estimate of natural selection in this population, and it would produce the phenotypes found in the most extreme species in the family Brassicaceae in less than 100 generations. These responses were within theoretical expectations and were much slower than if the genetic correlation was zero; thus, there was evidence for constraint. These results, coupled with comparable results from other species, show that evolution can be rapid despite the constraints caused by genetic correlations.

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“…We refer to the length difference between the long stamen and the short stamen as stamen dimorphism; note that this is a continuous trait, as all flowers have both "morphs," unlike a typical dimorphism. We define exsertion as the degree to which the long stamen anthers protrude above the opening of the corolla tube.These floral traits have been well-studied in wild radish (reviewed in Conner et al 2009). Previous studies have detected both stabilizing and directional selection (in different years) on both anther exsertion and stamen dimorphism by the pollinator assemblage as a whole (Morgan and Conner 2001;Conner et al 2003).…”

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Testing for Conflicting and Nonadditive Selection: Floral Adaptation to Multiple Pollinators Through Male and Female Fitness

2011

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Although conflicting selection from different resources is thought to play a critical role in the evolution of specialized species, the prevalence of conflicting selection in generalists is poorly understood. Plants may experience conflicting selection on floral traits by different pollinators and between genders. Using artificial selection to increase phenotypic variation, we tested for conflicting and nonadditive selection on wild radish (Raphanus raphanistrum) flowers. To do this, we measured selection by each of the major pollinator taxa through both male and female fitness, and tested for a single-generation response to selection by a subset of these pollinators. We found some evidence for conflicting selection on anther exsertion--sweat bees exerted stabilizing selection and larger bees selected for increased exsertion. Stamen dimorphism was only under selection by honey bees, causing a response to selection in the next generation, and flower size was under similar selection by multiple pollinators. Selection differed significantly between genders for two traits, but there was no evidence for stronger selection through male fitness or for conflicting selection between genders. Our results suggest wild radish flowers can adapt to multiple pollinators, as we found little evidence for conflicting selection and no evidence for nonadditive selection among pollinators. Janzen's seminal paper, "When is it coevolution" (Janzen 1980), emphasized that selection on traits is likely more complex than simple pairwise interactions. Instead, evolution is diffuse when the selection on a given trait is dependent upon the broader community context in which a species is found (Hougen-Eitzman and Rausher 1994;Iwao and Rausher 1997;Inouye and Stinchcombe 2001). The majority of studies of diffuse evolution have measured mean fitness of the interacting species (Strauss and Irwin 2004); this does not provide any information about natural selection, defined as the slope of the relationship between fitness and a particular phenotypic trait (Strauss et al. 2005). Diffuse selection, where this slope changes depending on which species of selective agent are present, has been documented mainly in plant-herbivore systems (e.g., Pilson 1996;Juenger and Bergelson 1998;Stinchcombe and Rausher 2001) and in systems involving plant mutualists and antagonists (e.g., Gomez 2003;Cariveau et al. 2004;Irwin et al. 2004).There are at least four nonmutually exclusive ways in which multiple selective agents may affect trait evolution. First, adaptation in a heterogeneous environment may be constrained if conflicting selection by different selective agents causes a tradeoff, whereby an adaptation that is beneficial in the presence of one selective agent is deleterious in the presence of another (e.g., Irwin 2006;Lankau 2007;Gomez 2008). In an extreme example of conflicting selection, exactly opposing selection gradients could lead to no net selection on a trait (Fig. 1A). Second, multiple selective agents may select on the same trait in the same manne...

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Tests of adaptation: functional studies of pollen removal and estimates of natural selection on anther position in wild radish

Cited by 32 publications

References 58 publications

Patterns of phenotypic correlations among morphological traits across plants and animals

Patterns of phenotypic correlations among morphological traits across plants and animals

Rapid Independent Trait Evolution despite a Strong Pleiotropic Genetic Correlation

Testing for Conflicting and Nonadditive Selection: Floral Adaptation to Multiple Pollinators Through Male and Female Fitness

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