| 1. |
- Beysard, M, et al.
(författare)
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Asymmetric and differential gene introgression at a contact zone between two highly divergent lineages of field voles (Microtus agrestis)
- 2012
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Ingår i: Journal of Evolutionary Biology. - : Wiley-Blackwell. - 1010-061X .- 1420-9101. ; 25:2, s. 400-408
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Borkowska, Anetta, et al.
(författare)
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Maintenance of genetic variation and moderate differentiation among populations under sex-biased dispersal in the common vole Microtus arvalis in patchy habitats
- 2010
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Ingår i: Acta Theriologica. - : Springer Science and Business Media LLC. - 0001-7051. ; 55:4, s. 333-341
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Tidskriftsartikel (refereegranskat)abstract
- We present a microgeographic analysis of 34 allozyme loci and the control region of mitochondrial DNA (mtDNA) in the common vole Microtus arvalis (Pallas, 1779), performed to assess the effects of environmental heterogeneity on the distribution of genetic variation among populations in the Biebrza river valley, NE Poland The common vole occurs there in two types of habitat open grassland and pastures around the valley (GP populations), and abandoned fields on small hills isolated by wetlands (SH populations) No significant genetic differences were found between SH and GP populations with respect to allelic richness, nor average observed and expected heterozygosities The average genetic differentiation at allozyme loci among the SH populations was significantly lower (F-ST = 0 066) than among the GP populations located around the Biebrza valley (F-ST = 0 112), and an isolation by distance pattern was detected (r = 0 26, p < 0 05) Mitochondrial DNA differentiation among the GP populations was great (F-ST, = 0 357, p < 0 01), indicating that female dispersal was 4 4-6 5 times lower than for males Our results and reviewed published data on M arvalis dispersal suggest that common vole dispersal in patchy natural and semi-natural habitats is male-biased and could generate moderate population divergence, with relatively high levels of genetic variation retained within populations
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| 3. |
- Brunhoff, Cecilia, et al.
(författare)
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Glacial survival or late glacial colonization? Phylogeography of the root vole (Microtus oeconomus) in north-west Norway
- 2006
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Ingår i: Journal of Biogeography. - : Wiley. - 1365-2699 .- 0305-0270. ; 33:12, s. 2136-2144
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Tidskriftsartikel (refereegranskat)abstract
- Aim It has been proposed that the root vole subspecies, Microtus oeconomus finmarchicus, survived the last glacial period on islands on the north-west coast of Norway. The Norwegian island of Andoya may have constituted the only site with permanent ice-free conditions. Geological surveys and fossil finds from Andoya demonstrate that survival throughout the last glacial maximum was probably possible for some plants and animals. In this study we aim to infer the recent evolutionary history of Norwegian root vole populations and to evaluate the glacial survival hypothesis. Methods DNA sequence variation in the mitochondrial cytochrome b gene was studied in 46 root voles from 19 localities. Location Northern Fennoscandia and north-west Russia with a focus on islands on the north-west coast of Norway. Results The phylogeographical analyses revealed two North European phylogroups labelled 'Andoya' and 'Fennoscandia'. The Andoya phylogroup contained root voles from the Norwegian islands of Andoya, Ringvassoya and Reinoya and two localities in north-west Russia. The Fennoscandian phylogroup encompassed root voles from the three Norwegian islands of Kvaloya, Hakoya and Arnoya and the remaining specimens from Norway, northern Sweden and Finland. Nucleotide diversity within the Andoya and Fennoscandian phylogroups was similar, ranging from 0.5% to 0.7%. Main conclusions Both our genetic data and previously published morphological data are consistent with in situ glacial survival of root voles on Andoya during the last glacial maximum. However, the level of genetic diversity observed in the extant island populations, the past periods of severe climatic conditions on Andoya and the ecology of the root vole are somewhat difficult to reconcile with this model. A biogeographical scenario involving late glacial recolonization along the northern coasts of Russia and Norway therefore represents a viable alternative. Our results demonstrate that complex recolonization and extinction histories can generate intricate phylogeographical patterns and relatively high levels of genetic variation in northern populations.
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| 4. |
- Brunhoff, Cecilia, et al.
(författare)
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Holarctic phylogeography of the root vole (Microtus oeconomus): implications for late Quaternary biogeography of high latitudes
- 2003
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Ingår i: Molecular Ecology. - 0962-1083. ; 12:4, s. 957-968
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Tidskriftsartikel (refereegranskat)abstract
- A species-wide phylogeographical study of the root vole (Microtus oeconomus ) was performed using the whole 1140 base pair mitochondrial (mt) cytochrome b gene. We examined 83 specimens from 52 localities resulting in 65 unique haplotypes. Our results demonstrate that the root vole is divided into four main mtDNA phylogenetic lineages that seem to have largely allopatric distributions. Net divergence estimates (2.0-3.5%) between phylogroups, as well as relatively high nucleotide diversity estimates within phylogroups, indicate that the distinct phylogeographical structure was initiated by historical events that predated the latest glaciation. European root voles are divided into a Northern and a Central mtDNA phylogroup. The mtDNA data in concert with fossil records imply that root voles remained north of the classical refugial areas in southern Europe during the last glacial period. The currently fragmented populations in central Europe belong to a single mtDNA phylogroup. The Central Asian and the North European lineages are separated by the Ural Mountains, a phylogeographical split also found in collared lemmings (Dicrostonyx ) and the common vole (M. arvalis ). The Beringian lineage occurs from eastern Russia through Alaska to northwestern Canada. This distribution is congruent with the traditional boundaries of the Beringian refugium and with phylogeographical work on other organisms. In conclusion, similarities between the phylogeographical patterns in the root vole and other rodents, such as Arctic and subarctic lemmings, as well as more temperate vole species, indicate that late Quaternary geological and climatic events played a strong role in structuring northern biotic communities.
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| 5. |
- Fedorov, VB, et al.
(författare)
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Phylogeography of lemmings (Lemmus): no evidence for postglacial colonization of Arctic from the Beringian refugium
- 2003
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Ingår i: Molecular Ecology. - 0962-1083. ; 12:3, s. 725-731
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Tidskriftsartikel (refereegranskat)abstract
- Beringia is considered as an important glacial refugium that served as the main source for colonization of formerly glaciated Arctic regions. To obtain high resolution views of Arctic refugial history, we examined mitochondrial cytochrome b phylogeography in the northern genus of rodents, Lemmus ( true lemmings), sampled across its circumpolar distribution. Strong phylogeographical structure suggests vicariant separation over several glacial-interglacial periods and does not provide evidence supporting the importance of Beringia for extensive colonization of formerly glaciated regions. Rather than a source of postglacial colonization, Beringia represents an area of intraspecific endemism previously undetected by biogeographical analysis. Existing phylogeographical structure suggests that vicariant separation by glacial barriers was an important factor generating genetic divergence and, thus, increasing genetic diversity in lemmings on continental and circumpolar scales. However, there is little evidence for the direct effect of the last glaciation on the level of genetic variation and allele genealogy in lemmings on a regional geographical scale. This finding implies that the population genetic models of postglacial colonization suggested for temperate taxa might have limited applicability for Arctic species.
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| 6. |
- Fritz, Michael, 1981-, et al.
(författare)
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Interferon-ɣ mediated signaling in the brain endothelium is critical for inflammation-induced aversion
- 2018
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Ingår i: Brain, behavior, and immunity. - Maryland Heights : Academic Press. - 0889-1591 .- 1090-2139. ; 67, s. 54-58
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Tidskriftsartikel (refereegranskat)abstract
- Systemic inflammation elicits malaise and a negative affective state. The mechanism underpinning the aversive component of inflammation include cerebral prostaglandin synthesis and modulation of dopaminergic reward circuits, but the messengers that mediate the signaling between the peripheral inflammation and the brain have not been sufficiently characterized. Here we investigated the role of interferon-ɣ (IFN-ɣ) in the aversive response to systemic inflammation induced by a low dose (10μg/kg) of lipopolysaccharide (LPS) in mice. LPS induced IFN-ɣ expression in the blood and deletion of IFN-ɣ or its receptor prevented the development of conditioned place aversion to LPS. LPS induced expression of the chemokine Cxcl10 in the striatum of normal mice, but this induction was absent in mice lacking IFN-ɣ receptors or Myd88 in blood brain barrier endothelial cells. Furthermore, inflammation-induced aversion was blocked in mice lacking Cxcl10 or its receptor Cxcr3. Finally, mice with a selective deletion of the IFN-ɣ receptor in brain endothelial cells did not develop inflammation-induced aversion, demonstrating that the brain endothelium is the critical site of IFN-ɣ action. Collectively, these findings show that circulating IFN-ɣ that binds to receptors on brain endothelial cells and induces Cxcl10, is a central link in the signaling chain eliciting inflammation-induced aversion.
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| 7. |
- Fritz, Michael, et al.
(författare)
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Prostaglandin-dependent modulation of dopaminergic neurotransmission elicits inflammation-induced aversion in mice
- 2016
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Ingår i: Journal of Clinical Investigation. - : AMER SOC CLINICAL INVESTIGATION INC. - 0021-9738 .- 1558-8238. ; 126:2, s. 695-705
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Tidskriftsartikel (refereegranskat)abstract
- Systemic inflammation causes malaise and general feelings of discomfort. This fundamental aspect of the sickness response reduces the quality of life for people suffering from chronic inflammatory diseases and is a nuisance during mild infections like common colds or the flu. To investigate how inflammation is perceived as unpleasant and causes negative affect, we used a behavioral test in which mice avoid an environment that they have learned to associate with inflammation-induced discomfort. Using a combination of cell-type-specific gene deletions, pharmacology, and chemogenetics, we found that systemic inflammation triggered aversion through MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin E-2 (PGE(2)) synthesis. Further, we showed that inflammation-induced PGE(2) targeted EP1 receptors on striatal dopamine D1 receptor-expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, we demonstrated that inflammation-induced aversion was not an indirect consequence of fever or anorexia but that it constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that PGE(2)-mediated modulation of the dopaminergic motivational circuitry is a key mechanism underlying the negative affect induced by inflammation.
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| 8. |
- Ghatnekar, Lena, et al.
(författare)
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The introgression of a functional nuclear gene from Poa to Festuca ovina
- 2006
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 273:1585, s. 395-399
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Tidskriftsartikel (refereegranskat)abstract
- In sheep's fescue, Festuca ovina, genes coding for the cytosolic enzyme phosphoglucose isomerase, PGIC, are not only found at the standard locus, PgiC1, but also at a segregating second locus, PgiC2. We have used PCR-based sequencing to characterize the molecular structure and evolution of five PgiC1 and three PgiC2 alleles in F. ovina. The three PgiC2 alleles were complex in that they carried two gene copies: either two active genes or one active and one pseudogene. All the PgiC2 sequences were very similar to each other but highly diverged from the five PgiC1 sequences. We also sequenced PgiC genes from several other grass species. Phylogenetic analysis of these sequences indicates that PgiC2 has introgressed into F. ovina from the distant genus Poa. Such an introgression may, for example, follow from a non-standard fertilization with more than one pollen grain, or a direct horizontal gene transfer mediated by a plant virus.
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| 9. |
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| 10. |
- Gunduz, Islam, et al.
(författare)
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Multigenic and morphometric differentiation of ground squirrels (Spermophilus, Scuiridae, Rodentia) in Turkey, with a description of a new species
- 2007
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1095-9513 .- 1055-7903. ; 43:3, s. 916-935
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Tidskriftsartikel (refereegranskat)abstract
- This study reports on the molecular phylogenetics of ground squirrels, genus Spermophilus, in Turkey using cytochrome b (1140 bp), part of the D-loop and flanking tRNAs (572 bp), X chromosome (867-1051 bp) and Y chromosome (983-989 bp) DNA sequences. Individuals also were characterized by karyotype and with geometric morphometric analyses of mandibles and skulls. Two hundred fourteen individuals from 91 localities were studied. All the data support the recognition of a new species in SW Anatolia: the Taurus ground squirrel Spermophilus taurensis sp. nov. The new species has a small distribution in the Taurus Mountains in an area that is a hotspot for biodiversity. Molecular clock analysis suggests that the new species diverged from the European ground squirrel, Spermophilus citellus, about 2.5 million years ago and that the ancestor of these two species diverged from the widespread Anatolian ground squirrel, Spermophilus xanthoprymnus, about 5 million years ago. Morphometric differentiation in skull and mandible shape among the three species is incomplete, but statistically significant. S. xanthoprymnus is subdivided into five cytochrome b phylogroups and we use these data to infer the location of glacial refugia where the species lived during the last glacial maximum. This study illustrates the potential of combined molecular and morphometric studies to uncover new Anatolian species and to reconstruct their phylogeographic history. The new species is important for squirrel taxonomy and for understanding Eurasian mammal evolution.
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