Sexual dimorphism in intra‐ and interspecific competitive ability of the dioecious herb <i>Mercurialis annua</i>

Vilas, Julia Sanchez; Turner, Andrew M.; Pannell, John R.

doi:10.1111/j.1438-8677.2010.00408.x

Cited by 32 publications

(20 citation statements)

References 24 publications

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“…). Sexual dimorphism in resource utilization may contribute to the competitive ability and fitness of each sex (Sanchez‐Vilas, Turner & Pannell ). Earlier studies have reported that males have lower resource demands than females (Dawson & Bliss ; Li et al .…”

Section: Discussionmentioning

confidence: 99%

Intra‐ and inter‐sexual competition of Populus cathayana under different watering regimes

et al. 2013

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Summary1. Previous studies have demonstrated that poplar is sexually dimorphic in its responses to environmental stresses and provided evidence of sex-related differences in protein composition, gene transcription and morphological and physiological processes. However, sexual competition of poplar has not yet been studied. 2. We employed Populus cathayana males and females as a model to investigate intra-and intersexual competition under well-watered condition and drought stress. 3. Our results indicated that competition significantly affected sexual dimorphism of P. cathayana under different watering regimes. Sexual competition was environment-dependent and modified by drought. In females, drought intensified the negative effect of intrasexual competition. Similar resource utilization patterns of females may aggravate pressure for resources under drought stress. Under intersexual competition, females showed a greater competitive ability than males under well-watered condition, while males showed a slight competitive advantage under drought stress. Intersexual competition seems to alleviate the sexual dimorphism of P. cathayana in response to drought stress, as females increase fitness and males decrease fitness compared with intrasexual competition. 4. Sexual dimorphism in resource utilization patterns and niche segregation may contribute to sexual competition in a given environment. Sexual competition was found to affect competitive ability and fitness of both sexes, which may cause spatial segregation of sexes in P. cathyana populations.

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Section: Discussionmentioning

confidence: 99%

Intra‐ and inter‐sexual competition of Populus cathayana under different watering regimes

et al. 2013

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“…However, SSD was consistently female‐biased on the mainland. Female plants often outcompete males and leaf size scales positively with competitive ability (Thuiller et al , Sanchez‐Vilas et al , Barrett and Hough ). Selection may also favour larger stems in females in order to support the weight of seeds and structures that aid the seed dispersal process (Kavanagh et al ).…”

Section: Discussionmentioning

confidence: 99%

Sexual size dimorphism in island plants: the niche variation hypothesis and insular size changes

Kavanagh

Burns

2014

Oikos

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The niche variation hypothesis predicts insular populations exhibit increased sexual size dimorphism (SSD), to minimize intraspecific competition. Although many animal taxa conform to this prediction, insular patterns of SSD have yet to be investigated in plants. Here, we tested for differences in SSD of dioecious plants that colonised four island groups (Kermadec, Three Kings, Chatham and Auckland Islands) from New Zealand. Using herbarium collections, we quantified leaf and stem sizes of 263 individuals from 28 dioecious taxa. We developed a novel analytical technique to explore changes in the direction of SSD on islands. Lastly, we tested for evolutionary size changes of male and female plants on islands. The degree of SSD did not vary predictably between insular and mainland taxa, contrary to predictions of the niche variation hypothesis. Furthermore, the direction of SSD was not predictable on islands, while it was consistently female biased on the mainland. Our results suggest that selection favours increased size of both sexes on islands and that SSD is unpredictable for insular plants.

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“…Inter and intrasexual competition has been proposed as one of the probable mechanisms behind local spatial segregation of the sexes (Bertiller, Sain & Carrera 2002b;Eppley 2006;Mercer & Eppley 2010). Nevertheless, there has been a conspicuous lack of investigation into sex-related effects on the competitive interaction with other plant species (S anchez-Vilas, Turner & Pannell 2010). Differences in competitive ability between the sexes are expected as a result of allocation trade-offs associated with gender-specific reproductive costs.…”

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confidence: 99%

Changes in sex ratios of a dioecious grass with grazing intensity: the interplay between gender traits, neighbour interactions and spatial patterns

2013

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Summary1. Dioecious plants frequently face sex-related resource allocation trade-offs. Differential traits of male and female plants can have important consequences that influence their direct and indirect interactions with neighbours and herbivores. 2. Gender differences in traits have been considered to be inherently linked to sex-biased ratios along environmental stress gradients. However, the mechanisms behind the variation in sex ratios with increasing biotic stress remain elusive. 3. We linked the results of process-based field experiments with fine-scale spatial patterns of naturally established plants (both sexes) at different grazing intensities. We demonstrated that slowgrowing females were better defended against insects and small mammals but were more susceptible than males to competition from neighbours. 4. In large-herbivore exclosures, we found that sex-biased spatial patterns at the microsite scale can be predicted from gender-specific traits, with females more segregated from competitors (unpalatable grasses) than males. Traits related to growth/defence trade-off in females, coupled with their higher competition costs than males, suggest that gender dimorphism in traits can directly influence species interactions and spatial organization. 5. In the presence of large herbivores, female individuals were preferentially browsed despite their larger investment in antiherbivore compounds. The greater distance of females from unpalatable competitors was the main determinant of female-biased consumption by domestic herbivores. Females growing close to neighbours successfully eluded browsing but also faced competition. Scaling up to a population level, population sex ratios drift from female-to male-bias with increasing domestic grazing intensity. 6. Synthesis: The sexual dimorphism in traits of a dioecious bunchgrass results in differential herbivory by natural enemies, differential competitive ability and differential spatial distribution of sexes. Domestic grazers disrupt this balance by shifting species interactions and their spatial organization. Changes in dioecious plant populations towards male-biased sex ratios with grazing intensity could not be predicted solely by gender-specific traits.

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Sexual dimorphism in intra‐ and interspecific competitive ability of the dioecious herb Mercurialis annua

Cited by 32 publications

References 24 publications

Intra‐ and inter‐sexual competition of Populus cathayana under different watering regimes

Intra‐ and inter‐sexual competition of Populus cathayana under different watering regimes

Sexual size dimorphism in island plants: the niche variation hypothesis and insular size changes

Changes in sex ratios of a dioecious grass with grazing intensity: the interplay between gender traits, neighbour interactions and spatial patterns

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