Local adaptation and divergence in colour signal conspicuousness between monomorphic and polymorphic lineages in a lizard.

Population differences in visual environment can lead to divergence in multiple components of animal coloration including signalling traits and colour patterns important for camouflage. Divergence may reflect selection imposed by different receivers (conspecifics, predators), which depends in turn on the location of the colour patch. We tested for local adaptation of two genetically and phenotypically divergent lineages of a rock-inhabiting lizard, Ctenophorus decresii, by comparing the visual contrast of colour patches to different receivers in native and non-native environments. The lineages differ most notably in male throat coloration, which is polymorphic in the northern lineage and monomorphic in the southern lineage, but also differ in dorsal and lateral coloration, which is visible to both conspecifics and potential predators. Using models of animal colour vision, we assessed whether lineage-specific throat, dorsal and lateral coloration enhanced conspicuousness to conspecifics, increased crypsis to birds or both, respectively, when viewed against the predominant backgrounds from each lineage. Throat colours were no more conspicuous against native than non-native rock but contrasted more strongly with native lichen, which occurs patchily on rocks inhabited by C. decresii. Conversely, neck coloration (lateral) more closely matched native lichen. Furthermore, although dorsal coloration of southern males was consistently more conspicuous to birds than that of northern males, both lineages had similar absolute conspicuousness against their native backgrounds. Combined, our results are consistent with local adaptation of multiple colour traits in relation to multiple receivers, suggesting that geographic variation in background colour has influenced the evolution of lineage-specific coloration in C. decresii.

Phylogeographic structure, demographic history and morph composition in a colour polymorphic lizard.

In polymorphic species, population divergence in morph composition and frequency has the potential to promote speciation. We assessed the relationship between geographic variation in male throat colour polymorphism and phylogeographic structure in the tawny dragon lizard, Ctenophorus decresii. We identified four genetically distinct lineages, corresponding to two polymorphic lineages in the Northern Flinders Ranges and Southern Flinders Ranges/Olary Ranges regions respectively, and a monomorphic lineage in the Mt Lofty Ranges/Kangaroo Island region. The degree of divergence between these three lineages was consistent with isolation to multiple refugia during Pleistocene glacial cycles, whereas a fourth, deeply divergent (at the interspecific level) and monomorphic lineage was restricted to western New South Wales. The same four morphs occurred in both polymorphic lineages, although populations exhibited considerable variation in the frequency of morphs. By contrast, male throat coloration in the monomorphic lineages differed from each other and from the polymorphic lineages. Our results suggest that colour polymorphism has evolved once in the C. decresii species complex, with subsequent loss of polymorphism in the Mt Lofty Ranges/Kangaroo Island lineage. However, an equally parsimonious scenario, that polymorphism arose independently twice within C. decresii, could not be ruled out. We also detected evidence of a narrow contact zone with limited genotypic admixture between the polymorphic Olary Ranges and monomorphic Mt Lofty Ranges regions, yet no individuals of intermediate colour phenotype. Such genetic divergence and evidence for barriers to gene flow between lineages suggest incipient speciation between populations that differ in morph composition.

Sex-specific ecomorphological variation and the evolution of sexual dimorphism in dwarf chameleons (Bradypodion spp.).

Natural selection can influence the evolution of sexual dimorphism through selection for sex-specific ecomorphological adaptations. The role of natural selection in the evolution of sexual dimorphism, however, has received much less attention than that of sexual selection. We examined the relationship between habitat structure and both male and female morphology, and sexual dimorphism in size and shape, across 21 populations of dwarf chameleon (genus Bradypodion). Morphological variation in dwarf chameleons was strongly associated with quantitative, multivariate aspects of habitat structure and, in most cases, relationships were congruent between the sexes. However, we also found consistent relationships between habitat and sexual dimorphism. These resulted from both differences in magnitude of ecomorphological relationships that were otherwise congruent between the sexes, as well as in sex-specific ecomorphological adaptations. Our study provides evidence that natural selection plays an important role in the evolution of sexual dimorphism.

Gadolinium-based coronarography in a patient with renal failure: first clinical report.

This article reports the use of gadolinium to perform a coronarography in a patient with renal insufficiency, unstable angina, and peripheral vascular disease. The examination was well tolerated and the images obtained of good quality. Cathet Cardiovasc Intervent 2001;54:68-69.

Reversible severe vascular rejection after plasmapheresis.

Vascular rejection in a transplanted child is frequently associated with bad prognosis on the short and long term. All therapeutic modalities available nowadays as monoclonal antibodies, intravenous cyclosporine or plasma exchange have given conflicting results. We report the case of a boy who was transplanted from his mother at the age of three. His primary disease was a cortico-resistant rapidly progressive glomerulonephritis; the immediate postoperative period was satisfactory but he developed a severe vascular rejection on day 5 post-transplantation, while on triple immunosuppression therapy associating antithymocyte globuline, prednisolone and azathioprine. Acute vascular rejection was corticoresistant but responded well to plasma exchange. In our patient, we believe that plasmapheresis was efficaceous on the reversibility of vascular rejection and moreover that he had not responded to corticotherapy even a week post methylprednisolone in the absence of any change in immunosuppression during plasmapheresis. No randomized study was realized until now to prove the efficacy of plasmapheresis in children with vascular rejection. The sporadic cases reported on the reversibility of such rejection after plasmapheresis, the innocuity of this therapy, if well performed in children, encourage us to consider this treatment modality in resistant vascular rejection.