Search

The fitness effects associated with Wolbachia infection have wide-ranging ecological and evolutionary consequences for host species. How these effects are modulated by the relative influence of host and Wolbachia genomes has been described as a balancing act of genomic cooperation and conflict. For vertically transmitted symbionts, like cytoplasmic Wolbachia, concordant host-symbiont fitness interests would seem to select for genomic cooperation. However, Wolbachia's ability to manipulate host reproductive systems and distort offspring sex ratios presents an evolutionary conflict of interest with infected hosts. In the parthenogenesis-inducing (PI) form of Wolbachia found in many haplodiploid insects, Wolbachia fitness is realized through females and is enhanced by their feminization of male embryos and subsequent parthenogenetic reproduction. In contrast, as long as Wolbachia is not fixed in a population and sexual reproduction persists, fitness for the host species is realized through both male and female offspring production. How these cooperating and competing interests interact and the relative influence of host and Wolbachia genomes were investigated in the egg parasitoid Trichogramma kaykai, where Wolbachia infection has remained at a low frequency in the field. A factorial design in which laboratory cultures of Wolbachia-infected T. kaykai were cured and re-infected with alternative Wolbachia strains was used to determine the relative influence of host and Wolbachia genomes on host fitness values. Our results suggest fitness variation is largely a function of host genetic background, except in the case of offspring sex ratio where a significant interaction between host and Wolbachia genomes was found. We also find a significant effect associated with the horizontal transfer of Wolbachia strains, which we discuss in terms of the potential for coadaptation in PI-Wolbachia symbioses.

As one of the most widely distributed bacterial cytoplasmic symbionts on earth, Wolbachia pipientis Hertig serves as a model organism for the understanding of hostsymbiont interactions. Many mosquito species are infected with Wolbachia strains that induce a form of reproductive manipulation called cytoplasmic incompatibility, in which infected females gain a reproductive advantage over uninfected females in mixed infection populations. The selective advantage of cytoplasmic incompatibility often results in a population sweep of Wolbachia and co-transmitted mitochondrial genomes. Mitochondrial evolution and phylogenetic inferences drawn from mitochondrial gene sequences are thus potentially compromised by reproductive manipulating symbionts, like Wolbachia. Our initial analyses of phylogenetic patterns among collected Wolbachia-infected and uninfected mosquito species suggested significant Wolbachia-induced effects on mitochondrial evolutionary patterns. Discordant mitochondrial and nuclear phylogenies among Aedes and Culex species were associated with infections status, with a distinct mitochondrial clade of infected Aedes and Culex species, separate from uninfected species of the genera. Statistical analyses of molecular substitution among infected and uninfected sequence samples revealed elevated rates of substitution for the mitochondrial sequences of the discordant infected Aedes/Culex clade. Subsequent phylogenetic analyses suggested that the observed discordance could be attributed to long-branch attraction effects associated with elevated rates of substitution. Our results highlight the impact cytoplasmic selection can have on phylogenetic inference in limited sample sets with Wolbachia-infected and uninfected species. [ABSTRACT FROM AUTHOR]

Wolbachia pipientis represents one of the most pervasive bacterial infections in the world, with estimates of over one million arthropods species infected. Parthenogenesis-inducing (PI) Wolbachia in various haplodiploid species effectively feminizes male offspring through a process called gamete duplication and converts the reproductive mode of infected females from arrhenotoky (fertilized eggs undergo female development, unfertilized eggs undergo male development) to thelytoky (fertilized and unfertilized eggs undergo female development). The fitness consequences associated with PI Wolbachia infection are of particular interest to ecologists and evolutionary biologists given the extreme effect that infection has on the reproductive mode of infected individuals. We use a model PI Wolbachia infected species, Trichogramma kaykai Pinto (Hymenoptera: Trichogrammatidae), to investigate the effects of infection status and mating status on T. kaykai fitness. Three genotypically distinct isofemale cultures were used to test whether fitness (number of offspring reaching pupal stage, number of female offspring, and pupal survival) differed among infected unmated, infected mated, and antibiotically curedmated females. Significant survival costs were observed for mated Wolbachia-infected females, and fecundity costs were observed for mated and unmatedWolbachia-infected females, with significant variation for these costs across host genotypes. [ABSTRACT FROM AUTHOR]

The article discusses the technical specifications and offers historical information on the design and construction of an organ in the St. Kilian Catholic church in Heilbronn-Böckingen, Germany. The author discusses bombing damages to the church building and organ in World War II, renovations to the building and organ which happened in 2009, and provides a review of the organ written by Michael Saum.