Molecular evolution and phylogenetic utility of Wolbachia ftsZ and wsp gene sequences with special reference to the origin of male-killing

A detailed assessment of the evolution and phylogenetic utility of two genes, ftsZ and wsp, was used to investigate the origin of male-killing Wolbachia, previously isolated from the ladybird Adalia bipunctata and the butterfly Acraea encedon. The analysis included almost all available sequences of B-group Wolbachia and two outgroup taxa and showed that (1) the two gene regions differ in phylogenetic utility, (2) sequence variation is here correlated with phylogenetic information content, (3) both genes show significant rate heterogeneity between lineages, (4) increased substitution rates are associated with homoplasy in the data, (5) wsp sequences of some taxa appear to be subject to positive selection, and (6) only a limited number of clades can be inferred with confidence due to either lack of phylogenetic information or the presence of homoplasy. With respect to the evolution of male-killing, the two genes nevertheless seemed to provide unbiased information. However, they consistently produce contradictory results. Current data therefore do not permit clarification of the origin of this behavior. In addition, A. bipunctata was found to be a host to two recently diverged strains of male-killing Wolbachia that showed increased substitution rates for both genes. Moreover, the wsp gene, which codes for an outer membrane protein, was found to be subject to positive selection in these taxa. These findings were postulated to be the product of high selection pressures due to antagonistic host-symbiont interactions in this ladybird species. In conclusion, our study demonstrates that the results of a detailed phylogenetic analysis, including characterization of the limitations of such an approach, can serve as a valuable basis for an understanding of the evolution of Wolbachia bacteria. Moreover, particular features of gene evolution, such as elevated substitution rates or the presence of positive selection, may provide information about the dynamics of Wolbachia-host associations

Scientific opportunities presented by the arrival of the harlequin ladybird, Harmonia axyridis, in Britain

The first confirmed report of the harlequin ladybird, Harmonia axyridis, in Britain was of a male melanic found in Sible Heddingham, Essex, on 19th September 2004. Subsequent media attention has brought to light many other reports of this beetle, some pre-dating the Essex record, but none from before the summer of 2004. With only two exceptions, all reports have been from the south-east of England, and it appears that although widely distributed and established in south-eastern counties, the harlequin is at present largely restricted to this region

ERRATUM: HADDRILL P.R., SHUKER D.M., MAYES S. MAJERUS M.E.N. 2007: Temporal effects of multiple mating on components of fitness in the two-spot ladybird, Adalia bipunctata (Coleoptera: Coccinellidae). Eur. J. Entomol. 104(3): 393-398.

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De bomen en het bos. Over de procesrechtelijke complexiteit van de WMO 1992

Item does not contain fulltextEen inventarisatie van de mogelijkheden die de WMO 1992 biedt en een vergelijking met de Algemene wet bestuursrecht. Dat levert een woud aan procedures op. Een uiteenzetting van de complexiteit en voorstellen tot systematisering, vereenvouding en betere toegankelijkheid.16 p

The value of an egg: Resource reallocation in ladybirds (Coleoptera: Coccinellidae) infected with male-killing bacteria

Male‐killing bacteria are thought to persist in host populations by vertical transmission and conferring direct and/or indirect fitness benefits to their hosts. Here, we test the role of indirect fitness benefits accrued from resource reallocation in species that engage in sibling egg cannibalism. We found that a single‐egg meal significantly increased larval survival in 12 ladybird species, but the value of an egg (to survival) differed substantially between species. Next, we tested the impact of three male‐killing bacteria on larval survival in one ladybird species, Adalia bipunctata. Spiroplasma reduced larval survival, whereas Wolbachia and Rickettsia had no effect. However, Spiroplasma‐infected larvae showed the greatest response to a single‐egg meal. The indirect fitness benefit obtained from a single egg is thus so large that even male‐killing bacteria with direct fitness costs can persist in host populations. This study supports the hypothesis that fitness compensation via resource reallocation can explain male‐killing bacteria persistence