Intergenotypic interactions in plant mixtures

Turkington, Roy

doi:10.1007/bf00022835

Cited by 24 publications

(16 citation statements)

References 93 publications

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“…For example, pairwise competition experiments have revealed genetic variation for competitive ability so that the outcome of competition between species depends on which genotypes are represented (Aarssen 1989, Turkington 1996. These empirical results provide the basis of Aarssen's (1983) ''competitive combining ability'' hypothesis in which specieslevel coexistence depends, in part, on the ability of each species to respond to localized and spatially variable selection imposed by the identity of immediate neighbors.…”

Section: Introductionmentioning

confidence: 90%

The Consequences of Genetic Diversity in Competitive Communities

Vellend

2006

Ecology

153

188

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Several lines of evidence suggest that the species diversity and composition of communities should depend on genetic diversity within component species, but there has been very little effort to directly assess this possibility. Here I use models of competition among genotypes and species to demonstrate a strong positive effect of the number of genotypes per species on species diversity across a range of conditions. Genetic diversity allows species to respond to selection imposed by competition, resulting in both functional convergence and divergence among species depending on their initial niche positions. This ability to respond to selection promotes species coexistence and contributes to a reduction in variation in species composition among communities. These models suggest that whenever individual fitness depends on the degree of functional similarity between a focal individual and its competitors, genetic diversity should promote species coexistence; this prediction is consistent with the few relevant empirical data collected to date. The results point to the importance of considering the genetic origin and diversity of material used in ecological experiments and in restoration efforts, in addition to highlighting potentially important community consequences of the loss of genetic diversity in natural populations.

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Section: Introductionmentioning

confidence: 90%

The Consequences of Genetic Diversity in Competitive Communities

Vellend

2006

Ecology

153

188

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“…The sward performance in 1992 and 1993 has been described previously (Elgersma and Schlepers, 1994;1996). The winter of 1993-94 was mild, but there was a sudden and severe frost in February, with temperatures reaching -12°C, which severely Table 2.…”

Section: Sward Performancementioning

confidence: 96%

Effects of cultivar and cutting frequency on dynamics of stolon growth and leaf appearance in white clover grown in mixed swards

Elgersma

1997

Grass and Forage Science

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The hypothesis that dynamics of growth, branching of stolons and appearance of leaves are important for the persistence of white clover (Trifolium repens) in mixed swards was tested. The effect of cutting frequency and white clover cultivar on stolon and leaf dynamics was studied throughout the growing season in a field experiment. Mixtures of perennial ryegrass {Lolium perenne) and white clover cultivars with different leaf sizes, cvs. Alice, Gwenda and Retor, were evaluated for white clover persistence at two cutting frequencies. Stolon dynamics, stolon survival, leaf and node appearance rate, branching, flowering and stolon elongation rate were analysed and related to white clover content and yield.There were clear seasonal fluctuations in stolon and leaf characteristics. Stolon elongation rate and appearance rates of nodes, leaves and branches declined in autumn. Temperature and irradiation explained a major part of the variation of stolon elongation rate and leaf appearance rate and 25% of the variation in stolon branching rate.Significant and consistent differences in yield and botanical composition were found between mixtures. Mixtures with cv. Alice had the highest total and white clover yield and the highest white clover content, whereas mixtures with cv. Retor had the lowest yield and the lowest white clover content. Stolon Correspondence: I>r A. Elgersma elongation rate and stolon intemode length were significantly higher in cv. Alice than in the other white clover cultivars, whereas cv. Retor had a significantly higher percentage of leaves with damage caused by insects and slugs than the other cultivars. Little support was found for the hypothesis that branching characteristics are a key component of competitive success in mixed pasture, as most measured branching characteristics were not associated with differences in white clover yield between cultivars and cutting regimes.

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“…Differences in community composition among localities have produced divergent selection and/or evolutionary responses in several communities (Turkington and Harper 1979;Linhart 1988;Sork et al 1993;Galen 1996;Linhart and Grant 1996;Turkington 1996;Galen and Cuba 2001;Rudgers 2004;Rudgers and Strauss 2004;J. A. Lau, unpubl.…”

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confidence: 99%

Evolutionary Responses of Native Plants to Novel Community Members

Lau

2006

Evolution

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Both ecological and evolutionary processes can influence community assembly and stability, and native community members may respond both ecologically and evolutionarily as additional species enter established communities. Biological invasions provide a unique opportunity to examine these responses of native community members to novel species additions. Here, I use reciprocal transplant experiments among naturally invaded and uninvaded environments, along with experimental removals of exotic species, to determine whether exotic plant competitors and exotic insect herbivores evoke evolutionary changes in native plants. Specifically, I address whether the common native plant species Lotus wrangelianus has responded evolutionarily to a series of biological invasions by adapting to the presence of the exotic plant Medicago polymorpha and the exotic insect herbivore Hypera brunneipennis. Despite differences in selection regimes between invaded and uninvaded environments and the presence of genetic variation for traits relevant to the novel competitive and plant-herbivore interactions, these experiments failed to reveal evidence that Lotus has responded evolutionarily to the double invasion of Medicago followed by H. brunneipennis. However, when herbivory from H. brunneipennis was experimentally reduced, Lotus plants from source populations invaded by Medicago outperformed plants from uninvaded source populations when transplanted into heavily invaded destination environments. Therefore, Lotus showed evidence of adaptation to Medicago invasion but not to the newer invasion of an exotic shared herbivore. The presence of this exotic insect herbivore alters the outcome of evolutionary responses in this system and counteracts adaptation by the native Lotus to invasion by the exotic plant Medicago. This result has broad implications for the conservation of native communities. While native species may be able to adapt to the presence of one or a few exotics, a multitude of invasions may limit the ability of natives to respond evolutionarily to the novel and frequently changing selection pressures that arise with subsequent invasions.

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Intergenotypic interactions in plant mixtures

Cited by 24 publications

References 93 publications

The Consequences of Genetic Diversity in Competitive Communities

The Consequences of Genetic Diversity in Competitive Communities

Effects of cultivar and cutting frequency on dynamics of stolon growth and leaf appearance in white clover grown in mixed swards

Evolutionary Responses of Native Plants to Novel Community Members

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