Evidence of a complex phylogeographic structure in the common dormouse,Muscardinus avellanarius (Rodentia: Gliridae)

This is the first mitochondrial phylogeography of the common dormouse, Muscardinus avellanarius (Linnaeus, 1758), a hibernating rodent strictly protected in Europe (Habitat Directive, annex IV; Bern Convention, annex III). The 84 individuals of M. avellanarius, sampled throughout the distributional range of the species, have been sequenced at the mitochondrial DNA gene (cytochrome b, 704 base pairs). The results revealed two highly divergent lineages, with an ancient separation around 7.7 Mya and a genetic divergence of 7.7%. Lineage 1 occurs in Western Europe (France, Belgium, and Switzerland) and Italy, and lineage 2 occurs in Central–Northern Europe (Poland, Germany, Latvia, and Lithuania), on the Balkan Peninsula, and in Turkey. Furthermore, these two lineages are subdivided into five sublineages genetically isolated with a strong geographical association. Therefore, lineage 1 branches into two further sublineages (Western European and Italian), whereas lineage 2 contained three sublineages (Central–Northern European, Turkish, and Balkan). We observed low genetic diversity within the sublineages, in contrast to the significant level of genetic differentiation between them. The understanding of genetic population structure is essential for identifying units to be conserved. Therefore, these results may have important implications for M. avellanarius conservation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 648–664.     

Survival of dried eukaryotes (anhydrobiotes) after exposure to very high temperatures

Organisms that tolerate essentially complete dehydration are said to be in anhydrobiosis, and can be referred to as anhydrobiotes. Those organisms are of great ecological and medical importance, but also provide models for the study of a variety of biological phenomena. We examined the tolerance of selected eukaryotic anhydrobiotes to high temperatures using slow (∼4 °C min⁻¹) and rapid (∼100 °C min⁻¹) heating to 110, 120, 130, and 140 °C. Test organisms were then either returned to storage temperatures close to 22 °C (preheating), or held at those high temperatures for an additional 10 min. Some anhydrobiotes survived slow heating to 130 °C, whereas rapid heating led to a dramatic reduction in survival. None of these organisms encounter anywhere near these high temperatures in nature, so tolerance is not an obvious result of adaptation to current or recent conditions. We speculate that tolerance could have been achieved during the much earlier evolution of these organisms, and has been retained up to the present.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 15–22.     

Ciliates as engineers of phototrophic biofilms

1. Phototrophic biofilms consist of a matrix of phototrophs, non‐photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the ‘engineering’ effects of these ciliates on the spatial heterogeneity of phototrophic biofilms are poorly studied. 2. We studied the potential engineering effects of two ciliates, Urostyla sp. and Paramecium bursaria, on the spatial heterogeneity of synthetic multispecies biofilms. Biomass of phototrophic organisms, EPS and bacteria was analysed three dimensionally using confocal laser scanning microscopy. Spatial heterogeneity and cover of the phototrophs, bacteria and EPS were determined at several depths within the biofilm. 3. Ciliate species did not interfere with the overall development of phototrophic microorganisms, because the thickness of the biofilm was equal whether the ciliates were present or not, even though their abundance did affect spatial heterogeneity of biofilm components. When Urostyla was present, it reduced aggregation in EPS and bacteria and increased EPS biovolume. This implies a local facilitating effect of ciliates on photosynthetic activity. Biofilms to which Paramecium was added did not differ from controls in terms of phototrophs, EPS cover and biovolume. Nevertheless, ciliates affected the spatial heterogeneity of these components as phototrophs and EPS became more evenly distributed. 4. This study shows that ecosystem engineering by organisms does not only occur at large spatial scales, as in grasslands and estuaries, but also plays a role at the microscopic scale of biofilms. This effect on spatial heterogeneity was not driven by substantial exploitation of biofilm components, but via the subtle engineering effects of ciliates.     

Genetic variation and evolution in the genus Apodemus (Muridae: Rodentia)

Genetic variation was studied using protein electrophoresis of 28–38 gene loci in 1347 specimens of Apodemus agrar-ius, A. peninsulae, A. flavicollis, A. sylvaticus, A. alpicola, A. uralensis, A . cf. hyrcanicus, A. hermonensis, A. m. mystacinus and A. m. epimelas , representing 121 populations from Europe, the Middle East, and North Africa. Mean values of heterozygosity per locus for each species ranged from 0.02 to 0.04. Mean values of Nel's genetic distance ( D ) between the taxa ranged from 0.06 (between A. flavicollis and A. alpicola) to 1.34 (between A. uralensis and A. agrarius ). The highest values of D were found between A. agrarius and other Apodemus species (0.62-1.34). These values correspond to those generally observed between genera in small mammals. Our data show that A. agrarius and A. peninsulae are sister species, well-differentiated from other taxa. High genetic distance between A. m. mystacinus and A. m. epimelas leads us to consider them distinct species and sister taxa to other Western Palaearctic species of the subgenus Sylvaemus . The data also suggest a recent separation of members of the latter group from a common ancestor, and subsequent rapid radiation, making it difficult to infer phylogenetic relationships. Some taxonomic implications of the results are discussed further.© 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 395–419.     

Genetic Structure and Evidence of a Local Bottleneck in Moose in Sweden

ABSTRACT The moose (Alces alces) is the most intensely managed game species in Sweden. Despite the biological and socioeconomical importance of moose, little is known of its population genetic structure. We analyzed 132 individuals from 4 geographically separate regions in Sweden for genetic variability at 6 microsatellite loci. We found evidence of strong substructuring and restricted levels of gene flow in this potentially mobile mammal. F_ST values were around 10%, and assignment tests indicated 3 genetically distinct populations over the study area. Spatial autocorrelation analysis provided a genetic patch size of approximately 420 km, implying that moose less than this distance apart are genetically more similar than 2 random individuals. Allele and genotype frequency distributions suggested a recent bottleneck in southern Sweden. Results indicate that moose may be more genetically divergent than currently anticipated, and therefore, the strong hunting pressure that is maintained over all of Sweden may have considerable local effects on genetic diversity. Sustainable moose hunting requires identification of spatial genetic structure to ensure that separate, genetically distinct subpopulations are not overharvested.     

Successive clutches and parental roles in waders: the importance of timing in multiple clutch systems

Production of successive clutches within the same breeding season has received less attention than many other aspects of avian reproduction. Waders are of particular interest because in these birds, multiple clutches are associated with at least three different breeding systems: double-clutching (uniparental care), monogamous double-brooding (biparental care) and polyandry (uni- or biparental care). Data from eight species and twelve breeding populations suggest that early second clutches, and thus brood overlap, are associated with parental role division and uniparental care, whereas species or populations with biparental care tend to have long intervals between successive clutches. We suggest that ecological factors influencing the relative timing of the second clutch will have consequences for the parental care system. In particular, conditions that favour early laying of the second clutch (large brood overlap) are likely to lead to parental role division, as found in double-clutching species. Factors determining the timing of second clutches are discussed, as are possibilities for testing these ideas.     

Associations between water chemistry and fish community composition: a comparison between isolated and connected lakes in northern Sweden

1. The correlation between water chemistry, physical variables and fish community composition was examined in 40 small (≤30 ha) coastal lakes in northern Sweden. Twenty of the 40 lakes were isolated from other water bodies and 20 were connected to the Baltic Sea. Lakes were fished in summer, using three different methods. Water chemistry was sampled in late winter prior to ice‐out and pH was measured additionally in summer. 2. Our central question was whether water chemistry plays a greater role in the composition of fish communities in isolated lakes than in connected lakes, as isolated lakes cannot be recolonised once a species has become extinct. 3. Results indicate that winter anoxia affects community composition only in isolated lakes, whereas acidity is of importance in both connected and isolated lakes. Methane (indicating anoxia), was significantly correlated with variation in fish community composition in isolated lakes, and a group of variables that indicate anoxia (CH₄, pCO₂, inorganic carbon and dissolved oxygen) explained 24–34% of the variation. pH alone explained 12% of the variation in community composition for connected lakes and a group of variables indicating acidity (summer and winter pH and ANC) explained 10–20% of the variation in isolated lakes. Lake area was the most important physical variable, being significantly correlated with the variation in fish community composition in connected lakes. 4. In isolated lakes, the presence of pike (Esox lucius), perch (Perca fluviatilis) and roach (Rutilus rutilus) was associated with low CH₄. The occurrence of crucian carp (Carassius carassius) and roach was positively correlated with pH, and the crucian carp was apparently also affected by predation by pike and perch. In connected lakes the effect of anoxia was low, probably due to the possibility of recolonisation and pockets of oxygenated water, allowing pike and perch to persist and thereby limiting the distribution of crucian carp.     

Evolutionary history of the bank vole Myodes glareolus: a morphometric perspective

The bank vole experienced a complex history during the Quaternary. Repeated isolation in glacial refugia led to the differentiation of several lineages in less than 300 000 years. We investigated if such a recent differentiation led to a significant divergence of phenotypic characters between European lineages, which might provide insight into processes of intraspecific differentiation. The size and shape of the first and third upper molars, and first lower molar, of bank voles genetically attributed to different lineages were quantified using an outline analysis of their occlusal surface. The three teeth present similar trends of decreasing size towards high latitudes. This trend, the inverse of Bergmann's rule, is interpreted as the result of a balance between metabolic efficiency and food availability, favouring small body size in cold regions. Molar shape appeared to differ between lineages despite genetic evidence of suture zones. A mosaic pattern of evolution between the different teeth was evidenced. The analysis of such phenotypic features appears as a valuable complement to genetic analyses, providing a complementary insight into evolutionary processes, such as selective pressures, that have driven the differentiation of the lineages. It may further allow the integration of the paleontological dimension of the bank vole phylogeographic history. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 681–694.