Genetic signs of multiple colonization events in Baltic ciscoes with radiation into sympatric spring- and autumn-spawners confined to early postglacial arrival.

Presence of sympatric populations may reflect local diversification or secondary contact of already distinct forms. The Baltic cisco (Coregonus albula) normally spawns in late autumn, but in a few lakes in Northern Europe sympatric autumn and spring- or winter-spawners have been described. So far, the evolutionary relationships and taxonomic status of these main life history forms have remained largely unclear. With microsatellites and mtDNA sequences, we analyzed extant and extinct spring- and autumn-spawners from a total of 23 Swedish localities, including sympatric populations. Published sequences from Baltic ciscoes in Germany and Finland, and Coregonus sardinella from North America were also included together with novel mtDNA sequences from Siberian C. sardinella. A clear genetic structure within Sweden was found that included two population assemblages markedly differentiated at microsatellites and apparently fixed for mtDNA haplotypes from two distinct clades. All sympatric Swedish populations belonged to the same assemblage, suggesting parallel evolution of spring-spawning rather than secondary contact. The pattern observed further suggests that postglacial immigration to Northern Europe occurred from at least two different refugia. Previous results showing that mtDNA in Baltic cisco is paraphyletic with respect to North American C. sardinella were confirmed. However, the inclusion of Siberian C. sardinella revealed a more complicated pattern, as these novel haplotypes were found within one of the two main C. albula clades and were clearly distinct from those in North American C. sardinella. The evolutionary history of Northern Hemisphere ciscoes thus seems to be more complex than previously recognized.

Sperm from pheromone primed brown trout (Salmo trutta L.) produce more larvae.

Male goldfish (Carassius auratus) exposed to female hormonal pheromones express increased milt volumes and their sperm fertilize more eggs than sperm from unprimed males. Ovulated salmonid females also release odours that increase volumes of strippable milt in males. It is, however, not known if the priming pheromones affect the ability of sperm to fertilize eggs in salmonids. In this study, we compare the proportion of larvae produced from in vitro fertilization tests between primed brown trout (Salmo trutta) males exposed to a mix of female urine and ovarian fluids, and control males exposed only to 0.9 % sodium chloride. We also investigate priming effects on milt yield and sperm motility. Fertilization tests with sperm from single males, as well as sperm from two males (i.e., sperm competition), were performed. Primed males generated more larvae in both the single male and competition fertilization tests. No differences between treatments in milt yield and sperm motility could be established.

Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta.

There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A Q(ST) - F(ST) approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in 1 year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. Q(ST) in body size did not differ between the rearing environments, and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system, constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a suboptimal management strategy for trout populations facing selection in the stream environment.

Permanent genetic resources added to Molecular Ecology Resources Database 1 October 2011-30 November 2011.

This article documents the addition of 139 microsatellite marker loci and 90 pairs of single-nucleotide polymorphism sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Aglaoctenus lagotis, Costus pulverulentus, Costus scaber, Culex pipiens, Dascyllus marginatus, Lupinus nanus Benth, Phloeomyzus passerini, Podarcis muralis, Rhododendron rubropilosum Hayata var. taiwanalpinum and Zoarces viviparus. These loci were cross-tested on the following species: Culex quinquefasciatus, Rhododendron pseudochrysanthum Hay. ssp. morii (Hay.) Yamazaki and R. pseudochrysanthum Hayata. This article also documents the addition of 48 sequencing primer pairs and 90 allele-specific primers for Engraulis encrasicolus.

Effects of altered glucocorticoid sensitivity in the T cell lineage on thymocyte and T cell homeostasis.

The homeostatic regulation that controls total thymocyte and peripheral T-cell numbers is not clearly understood. We describe here a direct hormonal influence of endogenous levels of glucocorticoids (GCs) on thymocyte and peripheral T-cell homeostasis independent of indirect systemic effects of GCs. The results were obtained by generating transgenic mice with an altered GC sensitivity targeted to thymocytes and peripheral T cells by increasing or decreasing glucocorticoid receptor (GR) expression specifically in thymocytes and peripheral T cells. A twofold increase in GC sensitivity resulted in a major decrease in thymocyte number, affecting all subpopulations, although single-positive CD8+ cells were less influenced. In the thymus, this was due to increased apoptosis in the organ, whereas proliferation of thymocyte populations was unaffected. In the periphery, a pronounced reduction in T-cell number was seen, demonstrating an effect of endogenous GCs also on T-cell homeostasis. The effects were confirmed in transgenic mice with reduced GR expression, which showed increased thymocyte and T-cell numbers. Thus, our data demonstrate that physiological GC levels are directly involved in controlling the size of both thymocyte and T-cell pools.