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  • 1.
    Beysard, M
    et al.
    University of Bern.
    Perrin, N
    University of Lausanne.
    Jaarola, Maarit
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Heckel, G
    University of Bern.
    Vogel, P
    University of Lausanne.
    Asymmetric and differential gene introgression at a contact zone between two highly divergent lineages of field voles (Microtus agrestis)2012In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 25, no 2, p. 400-408Article in journal (Refereed)
    Abstract [en]

    Secondary contact zones have the potential to shed light on the mode and rate at which reproductive isolation accumulates during allopatric speciation. We investigated the population genetics of a contact zone between two highly divergent lineages of field voles (Microtus agrestis) in the Swiss Jura mountains. To shed light on the processes underlying introgression, we used maternally, paternally, and bi-parentally inherited markers. Though the two lineages maintained a strong genetic structure, we found some hybrids and evidence of gene flow. The extent of introgression varied with the mode of inheritance, being highest for mtDNA and absent for the Y chromosome. In addition, introgression was asymmetric, occurring only from the Northern to the Southern lineage. Both patterns seem parsimoniously explained by neutral processes linked to differences in effective sizes and sex-biased dispersal rates. The lineage with lower effective population size was also the more introgressed, and the mode-of-inheritance effect correlated with the male-biased dispersal rate of microtine rodents. We cannot exclude, however, that Haldanes effect contributed to the latter, as we found a marginally significant deficit in males (the heterogametic sex) among hybrids. We propose a possible demographic scenario to account for the patterns documented, and empirical extensions to further investigate this contact zone.

  • 2.
    Dowling, D K
    et al.
    Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia.
    Maklakov, A A
    Animal Ecology ⁄ Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden / School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia.
    Friberg, Urban
    Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, USA.
    Hailer, F
    Center for Conservation and Evolutionary Genetics, National Zoological Park and National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
    Applying the genetic theories of ageing to the cytoplasm: cytoplasmic genetic covariation for fitness and lifespan.2009In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 22, no 4, p. 818-27Article in journal (Refereed)
    Abstract [en]

    Two genetic models exist to explain the evolution of ageing - mutation accumulation (MA) and antagonistic pleiotropy (AP). Under MA, a reduced intensity of selection with age results in accumulation of late-acting deleterious mutations. Under AP, late-acting deleterious mutations accumulate because they confer beneficial effects early in life. Recent studies suggest that the mitochondrial genome is a major player in ageing. It therefore seems plausible that the MA and AP models will be relevant to genomes within the cytoplasm. This possibility has not been considered previously. We explore whether patterns of covariation between fitness and ageing across 25 cytoplasmic lines, sampled from a population of Drosophila melanogaster, are consistent with the genetic associations predicted under MA or AP. We find negative covariation for fitness and the rate of ageing, and positive covariation for fitness and lifespan. Notably, the direction of these associations is opposite to that typically predicted under AP.

  • 3.
    Dowling, Damian K.
    et al.
    Animal Ecology ⁄ Department of Ecology and Evolution, Evolut ionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Friberg, Urban
    Department of Ecology and Environmental Science, Umea ˚ University, Umeå , Sweden / Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA.
    Arnqvist, Göran
    Animal Ecology ⁄ Department of Ecology and Evolution, Evolut ionary Biology Centre, Uppsala University, Uppsala, Sweden.
    A comparison of nuclear and cytoplasmic genetic effects on sperm competitiveness and female remating in a seed beetle2007In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, no 6, p. 2113-2125Article in journal (Refereed)
    Abstract [en]

    It is widely assumed that male sperm competitiveness evolves adaptively. However, recent studies have found a cytoplasmic genetic component to phenotypic variation in some sperm traits presumed important in sperm competition. As cytoplasmic genes are maternally transmitted, they cannot respond to selection on sperm and this constraint may affect the scope in which sperm competitiveness can evolve adaptively. We examined nuclear and cytoplasmic genetic contributions to sperm competitiveness, using populations of Callosobruchus maculatus carrying orthogonal combinations of nuclear and cytoplasmic lineages. Our design also enabled us to examine genetic contributions to female remating. We found that sperm competitiveness and remating are primarily encoded by nuclear genes. In particular, a male's sperm competitiveness phenotype was contingent on an interaction between the competing male genotypes. Furthermore, cytoplasmic effects were detected on remating but not sperm competitiveness, suggesting that cytoplasmic genes do not generally play a profound evolutionary role in sperm competition.

  • 4.
    Eroukhmanoff, F
    et al.
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Hargeby, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Arnberg, N N
    Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA, USA.
    Hellgren, O
    The EGI, Department of Zoology, Oxford, UK.
    Bensch, S
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Svensson, E I
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Parallelism and historical contingency during rapid ecotype divergence in an isopod2009In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 22, no 5, p. 1098-1110Article in journal (Refereed)
    Abstract [en]

    Recent studies on parallel evolution have focused on the relative role of selection and historical contingency during adaptive divergence. Here, we study geographically separate and genetically independent lake populations of a freshwater isopod (Asellus aquaticus) in southern Sweden. In two of these lakes, a novel habitat was rapidly colonized by isopods from a source habitat. Rapid phenotypic changes in pigmentation, size and sexual behaviour have occurred, presumably in response to different predatory regimes. We partitioned the phenotypic variation arising from habitat (selection: 81-94%), lake (history: 0.1-6%) and lake x habitat interaction (unique diversification: 0.4-13%) for several traits. There was a limited role for historical contingency but a strong signature of selection. We also found higher phenotypic variation in the source populations. Phenotype sorting during colonization and strong divergent selection might have contributed to these rapid changes. Consequently, phenotypic divergence was only weakly influenced by historical contingency.

  • 5.
    Friberg, Urban
    et al.
    Department of Ecology and Environmental Science, Section of Animal Ecology, Umeå University, Sweden.
    Arnqvist, Göran
    Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Sweden.
    Fitness effects of female mate choice: preferred males are detrimental for Drosophila melanogaster females2003In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 16, no 5, p. 797-811Article in journal (Refereed)
    Abstract [en]

    The evolution of female mate choice, broadly defined to include any female behaviour or morphology which biases matings towards certain male phenotypes, is traditionally thought to result from direct or indirect benefits which females acquire when mating with preferred males. In contrast, new models have shown that female mate choice can be generated by sexual conflict, where preferred males may cause a fitness depression in females. Several studies have shown that female Drosophila melanogaster bias matings towards large males. Here, we use male size as a proxy for male attractiveness and test how female fitness is affected by reproducing with large or small males, under two different male densities. Females housed with large males had reduced lifespan and aged at an accelerated rate compared with females housed with small males, and increased male density depressed female fitness further. These fitness differences were due to effects on several different fitness components. Female fitness covaried negatively with male courtship rate, which suggests a cost of courtship. Mating rate increased with male size, whereas female fitness peaked at an intermediate mating rate. Our results suggest that female mate choice in D. melanogaster is, at least in part, a by-product of sexual conflict over the mating rate.

  • 6.
    Friberg, Urban
    et al.
    Animal Ecology, Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden / Department of Ecology and Environmental Science, Umeå University, Umeå , Sweden /Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, USA.
    Dowling, D.K.
    Animal Ecology, Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    No evidence of mitochondrial genetic variation for sperm competition within a population of Drosophila melanogaster2008In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 21, no 6, p. 1798-1807Article in journal (Refereed)
    Abstract [en]

    Recent studies have advocated a role for mitochondrial DNA (mtDNA) in sperm competition. This is controversial because earlier theory and empirical work suggested that mitochondrial genetic variation for fitness is low. Yet, such studies dealt only with females and did not consider that variation that is neutral when expressed in females, might be non-neutral in males as, in most species, mtDNA is never selected in males. We measured male ability to compete for fertilizations, at young and late ages, across 25 cytoplasms expressed in three different nuclear genetic backgrounds, within a population of Drosophila melanogaster. We found no cytoplasmic (thus no mtDNA) genetic variation for either male offence or offensive sperm competitiveness. This contrasts with previous findings demonstrating cytoplasmic genetic variation for female fitness and female ageing across these same lines. Taken together, this suggests that mitochondrial genes do not contribute to variation in sperm competition at the within-population level.

  • 7.
    Griffin, R. M.
    et al.
    Uppsala University, Sweden.
    Le Gall, D.
    Uppsala University, Sweden; Ecole Normale Super, France.
    Schielzeth, H.
    University of Bielefeld, Germany.
    Friberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering. Uppsala University, Sweden.
    Within-population Y-linked genetic variation for lifespan in Drosophila melanogaster2015In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, no 11, p. 1940-1947Article in journal (Refereed)
    Abstract [en]

    The view that the Y chromosome is of little importance for phenotypic evolution stems from early studies of Drosophila melanogaster. This species Y chromosome contains only 13 protein-coding genes, is almost entirely heterochromatic and is not necessary for male viability. Population genetic theory further suggests that non-neutral variation can only be maintained at the Y chromosome under special circumstances. Yet, recent studies suggest that the D.melanogaster Y chromosome trans-regulates hundreds to thousands of X and autosomal genes. This finding suggests that the Y chromosome may play a far more active role in adaptive evolution than has previously been assumed. To evaluate the potential for the Y chromosome to contribute to phenotypic evolution from standing genetic variation, we test for Y-linked variation in lifespan within a population of D.melanogaster. Assessing variation for lifespan provides a powerful test because lifespan (i) shows sexual dimorphism, which the Y is primarily predicted to contribute to, (ii) is influenced by many genes, which provides the Y with many potential regulatory targets and (iii) is sensitive to heterochromatin remodelling, a mechanism through which the Y chromosome is believed to regulate gene expression. Our results show a small but significant effect of the Y chromosome and thus suggest that the Y chromosome has the potential to respond to selection from standing genetic variation. Despite its small effect size, Y-linked variation may still be important, in particular when evolution of sexual dimorphism is genetically constrained elsewhere in the genome.

  • 8.
    Hayward, A
    et al.
    Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
    Tsuboi, M
    Department of Animal Ecology, Uppsala University, Uppsala, Sweden.
    Owusu, C
    Department of Animal Ecology, Uppsala University, Uppsala, Sweden.
    Kotrschal, A
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Buechel, S D
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Zidar, Josefina
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Cornwallis, C K
    Department of Ecology, Lund University, Lund, Sweden.
    Løvlie, Hanne
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Kolm, N
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Evolutionary associations between host traits and parasite load: insights from Lake Tanganyika cichlids.2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 6, p. 1056-1067Article in journal (Refereed)
    Abstract [en]

    Parasite diversity and abundance (parasite load) vary greatly among host species. However, the influence of host traits on variation in parasitism remains poorly understood. Comparative studies of parasite load have largely examined measures of parasite species richness and are predominantly based on records obtained from published data. Consequently, little is known about the relationships between host traits and other aspects of parasite load, such as parasite abundance, prevalence and aggregation. Meanwhile, understanding of parasite species richness may be clouded by limitations associated with data collation from multiple independent sources. We conducted a field study of Lake Tanganyika cichlid fishes and their helminth parasites. Using a Bayesian phylogenetic comparative framework, we tested evolutionary associations between five key host traits (body size, gut length, diet breadth, habitat complexity and number of sympatric hosts) predicted to influence parasitism, together with multiple measures of parasite load. We find that the number of host species that a particular host may encounter due to its habitat preferences emerges as a factor of general importance for parasite diversity, abundance and prevalence, but not parasite aggregation. In contrast, body size and gut size are positively related to aspects of parasite load within, but not between species. The influence of host phylogeny varies considerably among measures of parasite load, with the greatest influence exerted on parasite diversity. These results reveal that both host morphology and biotic interactions are key determinants of host-parasite associations and that consideration of multiple aspects of parasite load is required to fully understand patterns in parasitism.

1 - 8 of 8
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