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Giles, Barbara
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Publications (10 of 16) Show all publications
Carlsson-Graner, U., Giles, B. & Thrall, P. H. (2014). Patterns of disease and host resistance in spatially structured systems. European journal of plant pathology, 138(3), 499-511
Open this publication in new window or tab >>Patterns of disease and host resistance in spatially structured systems
2014 (English)In: European journal of plant pathology, ISSN 0929-1873, E-ISSN 1573-8469, Vol. 138, no 3, p. 499-511Article in journal (Refereed) Published
Abstract [en]

We use data from species of the anther-smut fungi and the host plants Lychnis alpina and Silene dioica to show that spatial structuring at different scales can influence patterns of disease and host resistance. Patterns of disease and host resistance were surveyed in an archipelago subject to land-uplift where populations of S. dioica constitute an age-structured metapopulation, and in three contrasting areas within the mainland range of L. alpina, where population distributions range from continuous, through patchy but spatially connected to highly isolated demes. In S. dioica, disease levels depend on the age, size and density of local patches and populations. Disease is most predictably found in larger dense host patches and populations of intermediate age, and more frequently goes extinct in small old populations. The rate of local disease spread is affected by the level of host resistance; S. dioica populations showing an increase in disease over time are more susceptible than populations where the disease has remained at low levels. Among-population variation in resistance is driven by founding events and populations remain differentiated due to limited gene flow between islands. As observed in the L. alpina system, when populations are more connected, a greater fraction of populations have disease present. Results from a simulation model argue that, while increased dispersal in connected systems can increase disease spread, it may also favour selection of host resistance which ultimately reduces disease levels within populations. This could explain the observed lower disease prevalence in L. alpina in regions where populations are more continuous.

Place, publisher, year, edition, pages
Netherlands: Springer, 2014
Keywords
Spatial structure, Disease, Resistance, Anther-smut, Microbotryum, Silene dioica, Lychnis alpina
National Category
Ecology Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-87397 (URN)10.1007/s10658-013-0316-2 (DOI)000331657800007 ()
Available from: 2014-04-01 Created: 2014-03-31 Last updated: 2018-06-08Bibliographically approved
Ågren, K., Giles, B. & Lindkvist, M. (2012). Akademiska bedömningsuppdrag - ännu en jämställdhetsfälla?: Slutrapport av projektet Kompensation av tid för uppdrag.
Open this publication in new window or tab >>Akademiska bedömningsuppdrag - ännu en jämställdhetsfälla?: Slutrapport av projektet Kompensation av tid för uppdrag
2012 (Swedish)Report (Other (popular science, discussion, etc.))
Publisher
p. 41
Series
Skrifter från rådet för lika villkor vid Umeå universitet ; nr 1/2013
National Category
Social Sciences
Identifiers
urn:nbn:se:umu:diva-68660 (URN)978-91-7459-666-3 (ISBN)
Available from: 2013-09-12 Created: 2013-04-22 Last updated: 2018-06-08Bibliographically approved
Drotz, M. K., Brodin, T., Saura, A. & Giles, B. E. (2012). Ecotype Differentiation in the Face of Gene Flow within the Diving Beetle Agabus bipustulatus (Linnaeus, 1767) in Northern Scandinavia. PLoS ONE, 7(2), e31381
Open this publication in new window or tab >>Ecotype Differentiation in the Face of Gene Flow within the Diving Beetle Agabus bipustulatus (Linnaeus, 1767) in Northern Scandinavia
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 2, p. e31381-Article in journal (Refereed) Published
Abstract [en]

The repeated occurrence of habitat-specific polyphyletic evolved ecotypes throughout the ranges of widely distributed species implies that multiple, independent and parallel selection events have taken place. Ecological transitions across altitudinal gradients over short geographical distances are often associated with variation in habitat-related fitness, these patterns suggest the action of strong selective forces. Genetic markers will therefore contribute differently to differences between ecotypes in local hybrid zones. Here we have studied the adaptive divergence between ecotypes of the water beetle Agabus bipustulatus along several parallel altitudinal gradients in northern Scandinavia. This water beetle is well known for its remarkable morphological variation associated with mountain regions throughout the western Palaearctic. Two morphological ecotypes are recognised: a montane type with reduced flight muscles and a lowland type with fully developed muscles. Using a multilocus survey of allozyme variation and a morphological analysis with landmark-based morphometrics, across thirty-three populations and seven altitudinal gradients, we studied the local adaptive process of gene flow and selection in detail. Populations were sampled at three different elevations: below, at and above the tree line. The results indicate that the levels of divergence observed between ecotypes in morphology and allele frequencies at alpha-Glycerophosphate dehydrogenase relative to those shown by neutral molecular markers reflects local diversifying selection in situ. Four main lines of evidence are shown here: (1) A repeated morphological pattern of differentiation is observed across all altitudinal transects, with high reclassification probabilities. (2) Allele and genotype frequencies at the alpha-Gpdh locus are strongly correlated with altitude, in sharp contrast to the presumable neutral markers. (3) Genetic differentiation is two to three times higher among populations across the tree line than among populations at or below. (4) Genetic differentiation between ecotypes within independent mountain areas is reflected by different sets of allozymes.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-55396 (URN)10.1371/journal.pone.0031381 (DOI)000302733900044 ()
Available from: 2012-05-15 Created: 2012-05-14 Last updated: 2018-06-08Bibliographically approved
Riba, M., Mayol, M., Giles, B. E., Ronce, O., Imbert, E., van der Velde, M., . . . Olivieri, I. (2009). Darwin's wind hypothesis: does it work for plant dispersal in fragmented habitats?. New Phytologist, 183(3), 667-677
Open this publication in new window or tab >>Darwin's wind hypothesis: does it work for plant dispersal in fragmented habitats?
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2009 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 183, no 3, p. 667-677Article in journal (Refereed) Published
Abstract [en]

Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. Inverse terminal velocity () of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to different metrics of landscape connectivity, at two spatial scales: in a detailed analysis of eight landscapes in Spain and along a latitudinal gradient using 29 landscapes across three European regions. In the highly patchy Spanish landscapes, seed increased significantly with increasing connectivity. A common garden experiment suggested that differences in may be in part genetically based. The was also found to increase with landscape occupancy, a coarser measure of connectivity, on a much broader (European) scale. Finally, was found to increase along a south2013north latitudinal gradient. Our results for M. muralis are consistent with 'Darwin's wind dispersal hypothesis' that high cost of dispersal may select for lower dispersal ability in fragmented landscapes, as well as with the 'leading edge hypothesis' that most recently colonized populations harbour more dispersive phenotypes.

Place, publisher, year, edition, pages
John Wiley & Sons, 2009
National Category
Ecology Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-25541 (URN)10.1111/j.1469-8137.2009.02948.x (DOI)
Available from: 2009-08-19 Created: 2009-08-19 Last updated: 2018-06-08Bibliographically approved
Carlsson-Granér, U., Ericson, L. & Giles, B. E. (2009). Plant disease and islands. In: Rosemary G. Gillespie and David A. Clague (Ed.), Encyclopedia of Islands (pp. 748-752). University of California Press
Open this publication in new window or tab >>Plant disease and islands
2009 (English)In: Encyclopedia of Islands / [ed] Rosemary G. Gillespie and David A. Clague, University of California Press , 2009, p. 748-752Chapter in book (Refereed)
Place, publisher, year, edition, pages
University of California Press, 2009
Series
Encyclopedias of the natural world ; 2
Identifiers
urn:nbn:se:umu:diva-40358 (URN)9780520256491 (ISBN)0-520-25649-2 (ISBN)
Available from: 2011-02-22 Created: 2011-02-22 Last updated: 2018-06-08Bibliographically approved
Granberg, Å., Carlsson-Granér, U., Arnqvist, P. & Giles, B. E. (2008). Variation in breeding system traits within and among populations of Microbotryum violaceum on Silene dioica. International journal of plant sciences, 169(2), 293-303
Open this publication in new window or tab >>Variation in breeding system traits within and among populations of Microbotryum violaceum on Silene dioica
2008 (English)In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 169, no 2, p. 293-303Article in journal (Refereed) Published
Abstract [en]

Breeding systems exert profound effects on the amount and distribution of genetic diversity within and among populations. Knowledge of breeding systems is also important for understanding dynamics between coevolving organisms, e.g., pathogen‐host interactions. Here we study the breeding system of the obligate anther smut Microbotryum violaceum on Silene dioica. Microbotryum violaceum is capable of both inbreeding and outcrossing, but several recent studies on other host races have indicated that automixis via intrapromycelial mating is the predominant breeding system. Compared with conjugations between cells from different meioses, automixis results in slower loss of heterozygosity and faster production of infectious hypha. However, high rates of intrapromycelial matings have been suggested to invoke a fitness cost due to production of fewer infectious dikaryons. Working with single strains under standardized laboratory conditions, we studied traits that could influence the distribution of genetic variability and pathogen fitness. We found that intrapromycelial mating is the dominant conjugation form for M. violaceum var. dioica but that the breeding system varies, partly because of genetic differences, both within and among populations. Further, we did not find the predicted fitness reduction for intrapromycelial matings, suggesting that intrapromycelial mating is a highly favorable breeding system for M. violaceum.

Place, publisher, year, edition, pages
University of Chicago Press, 2008
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-8477 (URN)10.1086/523964 (DOI)000252400200008 ()
Available from: 2008-01-24 Created: 2008-01-24 Last updated: 2019-08-06Bibliographically approved
Chauvet, S., van der Velde, M., Imbert, E., Guillemin, M., Mayol, M., Riba, M., . . . Giles, B. (2004). Past and current gene flow in the selfing wind-dispersed species Mycelis muralis in western Europe. Molecular Ecology, 13(6), 1391-1407
Open this publication in new window or tab >>Past and current gene flow in the selfing wind-dispersed species Mycelis muralis in western Europe
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2004 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 13, no 6, p. 1391-1407Article in journal (Refereed) Published
Abstract [en]

The distribution of genetic diversity in Mycelis muralis, or wall lettuce, was investigated at a European scale using 12 microsatellite markers to infer historical and contemporary forces from genetic patterns. Mycelis muralis has the potential for long-distance seed dispersal by wind, is mainly self-pollinated, and has patchily distributed populations, some of which may show metapopulation dynamics. A total of 359 individuals were sampled from 17 populations located in three regions, designated southern Europe (Spain and France), the Netherlands, and Sweden. At this within-region scale, contemporary evolutionary forces (selfing and metapopulation dynamics) are responsible for high differentiation between populations (0.34 < FST < 0.60) but, contrary to expectation, levels of within-population diversity, estimated by Nei's unbiased expected heterozygosity (HE) (0.24 < HE < 0.68) or analyses of molecular variance (50% of the variation found within-populations), were not low. We suggest that the latter results, which are unusual in selfing species, arise from efficient seed dispersal that counteracts population turnover and thus maintains genetic diversity within populations. At the European scale, northern regions showed lower allelic richness (A = 2.38) than populations from southern Europe (A = 3.34). In light of postglacial colonization hypotheses, these results suggest that rare alleles may have been lost during recolonization northwards. Our results further suggest that mutation has contributed to genetic differentiation between southern and northern Europe, and that Sweden may have been colonized by dispersers originating from at least two different refugia.

Identifiers
urn:nbn:se:umu:diva-26334 (URN)10.1111/j.1365-294X.2004.02166.x (DOI)
Available from: 2009-10-06 Created: 2009-10-06 Last updated: 2018-06-08
Granberg, Å., Carlsson-Granér, U. & Giles, B. E.Genetic architecture of biochemical resistance to the anther smut Microbotryum violaceum in Silene dioica.
Open this publication in new window or tab >>Genetic architecture of biochemical resistance to the anther smut Microbotryum violaceum in Silene dioica
(English)Manuscript (Other (popular science, discussion, etc.))
Identifiers
urn:nbn:se:umu:diva-2622 (URN)
Available from: 2007-10-08 Created: 2007-10-08 Last updated: 2018-06-09Bibliographically approved
Peedu, E., Giles, B. E. & Ingvarsson, P. K.Genetic diversity and differentiation in a Silene dioica metapopulation.
Open this publication in new window or tab >>Genetic diversity and differentiation in a Silene dioica metapopulation
(English)Manuscript (preprint) (Other academic)
National Category
Botany Evolutionary Biology
Identifiers
urn:nbn:se:umu:diva-153691 (URN)
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2018-11-27
Pettersson, V., Gardfjell, H., Ericson, L. & Giles, B. E.Male and female resposes to florivory in the perennial herb Silene dioica.
Open this publication in new window or tab >>Male and female resposes to florivory in the perennial herb Silene dioica
(English)Manuscript (Other academic)
Abstract [en]

 In dioecious species the two sexes differ in amount and timing of allocation to reproduction and as a consequence we would expect different sex specific responses to equal losses to herbivory. We studied the response of Silene dioica male and female plants to herbivory of two specialist insect herbivores Caryocolum viscariella and Delia criniventris that share the same food resource, the floral stems. We tracked the fates of marked individuals located in nine populations over eight consecutive years in a Bothnian archipelago. We found no differences in survival probabilities between attacked and non-attacked plants or between the sexes. We found that attacked plants of both sexes re-flowered to a higher extent compared to non-attacked plants. However, there was an inter-sexual difference in response to attack. Attacked females tended to re-flower more often than males and therefore showed a stronger compensatory response to this type of herbivore attack. The likely mechanism for this difference is that females in response to attack of floral stems early in season will save more resources than males and that these resources will be retained in the basal rosette to be used for future reproductive events. This suggests a positive effect on plant life time fecundity in females. However, there is also a negative effect of florivory on number of capsules produced as capsule production was halved in attacked compared to non-attacked females. The demographic implications of these direct and indirect effects of florivory remain to be understood.

 

National Category
Ecology
Research subject
Ecological Botany
Identifiers
urn:nbn:se:umu:diva-21001 (URN)
Available from: 2009-03-31 Created: 2009-03-31 Last updated: 2018-06-09
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