Abstract  One main challenge in conservation biology is to preserve genetic variability and adaptive variation within and among populations. However, constant anthropogenic habitat modifications have severe effects on the evolutionary dynamics shaping wild populations and pose a serious threat to the natural evolution of biodiversity. The aim of the present study was to unravel the genetic structuring of brown trout (Salmo trutta) populations in the largest freshwater catchment in Ireland, whose habitats have experienced major human-mediated changes over at least two centuries. A total of 419 juvenile fish were sampled from nine main rivers in the Corrib catchment and were genotyped using 12 microsatellites. Both Bayesian clustering and F ST-based analyses of genetic variance sorted these populations into five main genetically distinct groups, characterized by different extent of genetic differentiation among populations. These groups were also characterized by some degree of admixture, which can be partly explained by recent gene flow. Overall, the study suggests that the Corrib trout may conform to a metapopulation model with local populations that show different degrees of isolation and are interconnected by various level of gene flow. Results add further insights into metapopulation evolutionary dynamics and provide a useful basis to implement appropriate conservation strategies.

• Content Type Journal Article
• Category Research Article
• DOI 10.1007/s10592-010-0061-4
• Authors
  • Alexia Massa-Gallucci, University College Dublin UCD School of Biology and Environmental Science Dublin 4 Ireland
  • Ilaria Coscia, University College Dublin UCD School of Biology and Environmental Science Dublin 4 Ireland
  • Martin O’Grady, Swords Business Campus Central Fisheries Board Co. Dublin Ireland
  • Mary Kelly-Quinn, University College Dublin UCD School of Biology and Environmental Science Dublin 4 Ireland
  • Stefano Mariani, University College Dublin UCD School of Biology and Environmental Science Dublin 4 Ireland

• Journal Conservation Genetics
• Online ISSN 1572-9737
• Print ISSN 1566-0621

Abstract  Predator-induced cloning (asexual reproduction), with reduced size as consequence of cloning, suggests a novel adaptation to the threat of predation. Although cloning is a common reproductive strategy of many plants and animals, cloning in response to stimuli from predators has, at present, been documented only in the larvae (plutei) of the sand dollar, Dendraster excentricus. Other studies report larval cloning in echinoderms under optimal conditions of food and temperature. A burst of asexuality should be favored when environmental conditions are conducive to growth, but it is less clear that cloning is advantageous when conditions indicate risk from predators. This study tested the hypothesis that the small size of predator-induced clones reduces vulnerability during encounters with planktivorous fish. Successful cloning was inferred from an increase in larval density, a reduction in larval size and stage, and some direct observations of budding. All clones were smaller than uncloned sibling larvae, suggesting an advantage against visual predators. Pair-wise predation trials demonstrated that planktivorous fish ate more uncloned sibling plutei than small clones. These results offer a new ecological context for asexual reproduction: rapid size reduction as a defense. If the identifiable cues for cloning in echinoderm larvae (food and predators) are linked in nature, then larval cloning may be a response to a single ecological scenario rather than two separate and unrelated conditions.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s00227-010-1410-z
• Authors
  • Dawn Vaughn, University of Washington Department of Biology, Friday Harbor Laboratories Seattle Washington 98195 USA

• Journal Marine Biology
• Online ISSN 1432-1793
• Print ISSN 0025-3162

Abstract  Animals inhabiting hydrothermal vents and cold seeps face conditions that are challenging for survival. In particular, these two habitats are characterized by chronic hypoxia, sometimes reaching complete anoxia. The characteristics of the scaphognathite and gills were studied in four species of shrimp and three species of crabs from hydrothermal vents and cold seeps, in order to highlight potential adaptations that could enhance oxygen acquisition in comparison with shallow-water relatives. All the vent and seep species studied here exhibit significantly larger scaphognathites, likely allowing more water to flow over their gills per stroke of this appendage. This is probably more energetically efficient that prolonged hyperventilation. In contrast to annelids, vent and seep decapods usually do not possess enlarged gills, a phenomenon likely due to the physical limitations imposed by the size of the gill chamber. In the vent shrimp Rimicaris exoculata and the vent crab Bythograea thermydron, however, there is a significantly higher specific gill surface area linked to a higher number of lamellae per gram of gill. Again in contrast to annelids, the diffusion distance through the gills is not strikingly different between the vent shrimp Alvinocaris komaii and the shallow-water species Palaemon spp. This may indicate that the epithelium and cuticle of the decapod gills are already optimized for oxygen uptake and that reducing the thickness of these compartments is not physically possible without affecting the physical integrity of the gills.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s00227-010-1406-8
• Authors
  • Johan Decelle, Station Biologique de Roscoff, CNRS-UPMC Equipe Ecophysiologie des Invertébrés des Milieux Extrêmes 29680 Roscoff France
  • Ann C. Andersen, Station Biologique de Roscoff, CNRS-UPMC Equipe Ecophysiologie des Invertébrés des Milieux Extrêmes 29680 Roscoff France
  • Stéphane Hourdez, Station Biologique de Roscoff, CNRS-UPMC Equipe Génétique de l’Adaptation en Milieux Extrêmes 29680 Roscoff France

• Journal Marine Biology
• Online ISSN 1432-1793
• Print ISSN 0025-3162

Abstract  Cork oak forests invaded by the Argentine ant Linepithema humile have a lower abundance and biomass of arthropod prey for birds than uninvaded forests. We studied whether the biomass of breeding insectivorous birds was also lower in invaded areas. We explored this and other possible effects of the ant invasion on the bird community by censusing birds in transects located in four invaded and four uninvaded forest sites in Catalonia (NE Spain) for 3 years. Redundancy analysis showed only slight differences in the community composition between forests. Two insectivorous species, Luscinia megarhynchos and Fringilla coelebs, tended to be less abundant in invaded areas although two others, Phylloscopus bonelli and Sylvia melanocephala, showed the opposite trend. Overall, the differences in prey biomass between invaded and uninvaded areas did not entail a biomass shift in the guild of insectivorous birds, regardless of whether they were shrub or canopy foragers. The main role of the habitat structure in determining bird densities and food resources being non-limiting in the studied forests are two possible non-exclusive explanations for this inconsistency. At today’s levels, the Argentine ant invasion does not appear to have greatly determined the insectivorous bird assemblage of the forests evaluated.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s10531-010-9799-8
• Authors
  • Pere Pons, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain
  • Josep Maria Bas, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain
  • David Estany-Tigerström, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain

• Journal Biodiversity and Conservation
• Online ISSN 1572-9710
• Print ISSN 0960-3115