Sexual dimorphism in floral traits of gynodioecious <i>Lobelia siphilitica</i> (Lobeliaceae) is consistent across populations

Caruso, Christina M.

doi:10.1139/b2012-094

Cited by 9 publications

(15 citation statements)

References 39 publications

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“…Pistillate flowers are smaller and more numerous than perfect flowers (Caruso et al 2003a;Caruso and Yakobowski 2008;Caruso 2012). The number of seeds per fruit does not differ between females and hermaphrodites.…”

Section: Study Systemmentioning

confidence: 89%

“…There are two possible explanations for this result. (Caruso 2012). Second, interspecific pollen transfer may not decrease seed set because L. siphilitica has traits that confer tolerance to competition for pollination (Rathcke 1988).…”

Section: Discussionmentioning

confidence: 99%

“…Second, two of these traits (corolla lobe length and corolla tube length) differ between female and hermaphrodite L. siphilitica (Caruso et al 2003a;Caruso and Yakobowski 2008;Caruso 2012). Third, the traits that we selected include both traits that can affect pollinator attraction (e.g., petal brightness; Caruso et al 2010) and traits that can affect the fit between flower and pollinator (e.g., stigma-nectary distance; Johnston 1991a).…”

Section: Floral Trait and Fitness Measurementsmentioning

confidence: 99%

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Effect of coflowering Mimulus ringens on phenotypic selection on floral traits of gynodioecious Lobelia siphilitica

WassinkErica

Caruso

2013

Botany

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Although interspecific competition for pollination is hypothesized to result in divergence in floral traits (i.e., character displacement), few studies have tested whether selection on these traits differs in the presence and absence of a competitor for pollination. We measured phenotypic selection on floral traits of Lobelia siphilitica growing in the presence and absence of Mimulus ringens, a potential competitor for pollination. Because L. siphilitica is gynodioecious, we estimated selection separately for female and hermaphrodite plants. The presence of M. ringens did not decrease seed set of L. siphilitica. However, the presence of M. ringens did affect selection on daily display size of female L. siphilitica; there was significant selection for smaller daily displays in the absence of M. ringens, but non-significant selection for larger displays in the presence of M. ringens. In addition, selection on flower color did not differ in the presence and absence of M. ringens, but did differ between female and hermaphrodite L. siphilitica. Consequently, our results suggest that the evolution of floral traits in L.siphilitica, but not the evolution of sexual dimorphism in these traits, can be affected by interactions for pollination with M. ringens.

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Section: Study Systemmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Floral Trait and Fitness Measurementsmentioning

confidence: 99%

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Effect of coflowering Mimulus ringens on phenotypic selection on floral traits of gynodioecious Lobelia siphilitica

WassinkErica

Caruso

2013

Botany

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“…However, floral longevity is significantly reduced by both pollen removal (Dudle 1999) and pollen deposition (Beaudoin Yetter 1989). Females produce ß30% (Caruso and Yakobowski 2008;Caruso 2012) more flowers than hermaphrodites over the course of a flowering season. Because of this difference in flower production, females also produce significantly more fruits and seeds per plant than hermaphrodites (Caruso and Yakobowski 2008).…”

Section: Study Speciesmentioning

confidence: 99%

“…We studied L. siphilitica for two reasons. First, the sex ratio of L. siphilitica populations varies from 0 to 100% females (Caruso andCase 2007, 2013;Case and Caruso 2010). This wide variation in sex ratio creates the opportunity for frequency-dependent selection to operate.…”

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confidence: 99%

Frequency-dependent fitness in gynodioeciousLobelia siphilitica

2015

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Selection is frequency dependent when an individual's fitness depends on the frequency of its phenotype. Frequency-dependent selection should be common in gynodioecious plants, where individuals are female or hermaphroditic; if the fitness of females is limited by the availability of pollen to fertilize their ovules, then they should have higher fitness when rare than when common. To test whether the fitness of females is frequency dependent, we manipulated the sex ratio in arrays of gynodioecious Lobelia siphilitica. To test whether fitness was frequency dependent because of variation in pollen availability, we compared open-pollinated and supplemental hand-pollinated plants. Open-pollinated females produced more seeds when they were rare than when they were common, as expected if fitness is negatively frequency dependent. However, hand-pollinated females also produced more seeds when they were rare, indicating that variation in pollen availability was not the cause of frequency-dependent fitness. Instead, fitness was frequency dependent because both hand- and open-pollinated females opened more flowers when they were rare than when they were common. This plasticity in the rate of anthesis could cause fitness to be frequency dependent even when reproduction is not pollen limited, and thus expand the conditions under which frequency-dependent selection operates in gynodioecious species.

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Simulated pollinator decline has similar effects on seed production of female and hermaphrodite Lobelia siphilitica, but different effects on selection on floral traits

Hossack¹,

Caruso

2023

American J of Botany

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Premise: Pollinator decline, by reducing seed production, is predicted to strengthen natural selection on floral traits. However, the effect of pollinator decline on gender dimorphic species (such as gynodioecious species, where plants produce female or hermaphrodite flowers) may differ between the sex morphs: if pollinator decline reduces the seed production of females more than hermaphrodites, then it should also have a larger effect on selection on floral traits in females than in hermaphrodites. Methods: To simulate pollinator decline, we experimentally reduced pollinator access to female and hermaphrodite Lobelia siphilitica plants. We compared the seed production of plants in the reduced pollination treatment to plants that were exposed to ambient pollination conditions. Within each treatment, we also measured directional selection on four floral traits of females and hermaphrodites. Results: Experimentally reducing pollination decreased seed production of both females and hermaphrodites by ~21%. Reducing pollination also strengthened selection on floral traits, but this effect was not larger in females than in hermaphrodites. Instead, reducing pollination intensified selection for taller inflorescences in hermaphrodites, but did not intensify selection on any floral trait in females. Conclusions: Our results suggest that pollinator decline will not have a larger effect on either seed production or selection on floral traits of female plants. As such, any effect of pollinator decline on seed production may be similar for gender dimorphic and monomorphic species. However, the potential for floral traits of females (and thus of gender dimorphic species) to evolve in response to pollinator decline may be limited.

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Sexual dimorphism in floral traits of gynodioecious Lobelia siphilitica (Lobeliaceae) is consistent across populations

Cited by 9 publications

References 39 publications

Effect of coflowering Mimulus ringens on phenotypic selection on floral traits of gynodioecious Lobelia siphilitica

Effect of coflowering Mimulus ringens on phenotypic selection on floral traits of gynodioecious Lobelia siphilitica

Frequency-dependent fitness in gynodioeciousLobelia siphilitica

Simulated pollinator decline has similar effects on seed production of female and hermaphrodite Lobelia siphilitica, but different effects on selection on floral traits

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