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- Cortes, Andres J., et al.
(author)
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Small-scale patterns in snowmelt timing affect gene flow and the distribution of genetic diversity in the alpine dwarf shrub Salix herbacea
- 2014
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In: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 113:3, s. 233-239
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Journal article (peer-reviewed)abstract
- Current threats to biodiversity, such as climate change, are thought to alter the within-species genetic diversity among microhabitats in highly heterogeneous alpine environments. Assessing the spatial organization and dynamics of genetic diversity within species can help to predict the responses of organisms to environmental change. In this study, we evaluated whether small-scale heterogeneity in snowmelt timing restricts gene flow between microhabitats in the common long-lived dwarf shrub Salix herbacea L. We surveyed 273 genets across 12 early-and late-snowmelt sites (that is, ridges and snowbeds) in the Swiss Alps for phenological variation over 2 years and for genetic variation using seven SSR markers. Phenological differentiation triggered by differences in snowmelt timing did not correlate with genetic differentiation between microhabitats. On the contrary, extensive gene flow appeared to occur between microhabitats and slightly less extensively among adjacent mountains. However, ridges exhibited significantly lower levels of genetic diversity than snowbeds, and patterns of effective population size (Ne) and migration (Nem) between microhabitats were strongly asymmetric, with ridges acting as sources and snowbeds as sinks. As no recent genetic bottlenecks were detected in the studied sites, this asymmetry is likely to reflect current metapopulation dynamics of the species dominated by gene flow via seeds rather than ancient re-colonization after the last glacial period. Overall, our results suggest that seed dispersal prevents snowmelt-driven genetic isolation, and snowbeds act as sinks of genetic diversity. We discuss the consequences of such small-scale variation in gene flow and diversity levels for population responses to climate change.
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| 2. |
- Page, Paul, et al.
(author)
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Do Flower Color and Floral Scent of Silene Species affect Host Preference of Hadena bicruris, a Seed-Eating Pollinator, under Field Conditions?
- 2014
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:6, s. e98755-
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Journal article (peer-reviewed)abstract
- Specialization in plant-insect interactions is an important driver of evolutionary divergence; yet, plant traits mediating such interactions are poorly understood. In this study, we investigated how flower color and floral scent are related to seed predation by a seed-eating pollinator. We used field-transplanted recombinant F-2 hybrids between Silene latifolia and S. dioica that are the preferred and alternative hosts of the moth Hadena bicruris and crosses within these species for comparison. We scored seed predation and flower color and analyzed floral scent. Pinker S. dioica-like flowers and emission of a-pinene decreased the odds of seed predation while emission of benzyl acetate and 6-methyl-5-hepten-2-one increased the odds of seed predation. Emission of these compounds did not differ significantly between the two Silene species. Our results suggest that flower color plays an important role in the specific interaction of H. bicruris with its preferred host S. latifolia. The compounds alpha-pinene, benzyl acetate and 6-methyl-5-hepten-2-one could represent non-specific deterrents and attractants to ovipositing moths. Alternatively, emission of these compounds could be related to herbivory or pathogen attack and act as a signal for host quality. This would weaken the predictability of the plant's costs and benefits of the interaction and act to maintain an imperfect degree of specialization.
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| 3. |
- Rahme, Joelle, et al.
(author)
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Inheritance and Reproductive Consequences of Floral Anthocyanin Deficiency in Silene Dioica (Caryophyllaceae)
- 2014
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 101:8, s. 1388-1392
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Journal article (peer-reviewed)abstract
- Premise of the study: Flower color is one of the most important traits for pollinator attraction. However, natural plant populations often harbor rare flower color variants resulting from mutations in biochemical pathways for floral pigment production. It is unclear how such mutations can persist because they can affect not only pollinator visitation but also plant fertility and performance. Methods: We collected rare white-flowered (anthocyanin-deficient) and common pink-flowered morphs of Silene dioica from natural populations in Switzerland. First-and second-generation hybrids between pink and white morphs, as well as back-crosses toward white morphs were produced, and the proportion of white-flowered offspring was determined. We compared seed siring ability and seed production between morphs using hand pollination experiments. Moreover, we scored the transfer of pollen analogues (fluorescent dyes) in a 50: 50 array of the two morphs. Key results: The proportions of white-flowered plants in the offspring of our crosses were consistent with more than one recessive mutation as the cause of floral anthocyanin deficiency and further suggested a role of maternal effects for flower color. Seed siring ability and seed set did not differ significantly between pink and white morphs. Pollen transfer occurred preferentially within morphs. Conclusions: Overall, our results imply that the white morph of S. dioica likely is caused by recessive mutations that do not impair reproduction. However, as this flower color polymorphism led to assortative mating in our experiment, it may represent standing genetic variation with the potential to contribute to evolutionary divergence.
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