Intracellular Interactions in the Reproduction Control of Introgressed Strains Involving Species from Drosophila saltans Group(Sophophora Subgenus)with Emphasis to the Effect of Wolbachia Infection

Interspecific hybrids and constructed research models have provided infor-mation on intracellular interactions. We used two introgressed, chromosomally differentiated strains (H4 and H2) derived from F1 hybrids of crosses between D. prosaltans females and D. saltans males. In H4, the D. prosaltans chromosomes were eliminated. In H2, a mixture was maintained, preserving the entire genome of D. prosaltans (except the Y chromosome) and parts of the D. saltans genome. The IIR arm and a segment of chromosome III were eliminated. A third strain, used for comparison, was a normal D. prosaltans strain (P). This study aimed primarily to analyze the effect on the reproductive char-acteristics productivity (number of progeny) and sex-ratio caused by Wolbachia infection in interaction with different chromosome constitutions. For this, infected and uninfected flies were used in intrastrain cross combinations. Firstly, we analyzed the productivity of intracrosses of uninfected parents, in each strain, in order to detect the effects of intracellular interactions, in flies carrying different chromosome constitutions and sharing a Wolbach-ia-free, D. prosaltans cytoplasm. Data indicated that the chromosome parts that were eliminated, in H2, carry the isolating genes that impair productivity in hybrids of the two species, and suggested the occurrence of a nuclear/nuclear interaction. The analysis of Wolbachia-infected flies showed that the three strains presented different responses, depending on the chromosome constitution. As to productivity, the infection was harmful in P strain, in H2 behaved as mutualistic, and, in H4, produced the effect cytoplasmic incompatibility. As to sex-ratio, intracrosses showed significant differences in P and H4 strains. These results, associated with the cytological characteristics of the strains, pointed to the fundamental importance of host chromosome constitution to define the interactive process host/Wolbachia, and showed the flexibility of the endo-symbiont manifested in different forms of self-preservation.

Potential role of lava lizards as pollinators across the Galápagos Islands

Lizards have been reported as important pollinators on several oceanic islands.Here we evaluate the potential role of Galápagos lava lizards(Microlophus spp.)as pollinators across their radiation.Over 3 years,we sampled pollen transport by 9 lava lizard species on the 10 islands where they are present,including 7 single-island endemics.Overall,only 25 of 296 individuals sampled(8.4%)transported pollen of 10 plant species,the most common being Prosopis juliflora,Exodeconus miersii,Sesuvium sp.and Cordia leucophlyctis.At least 8 of these plant species were native,and none were confirmed as introduced to the archipelago.Despite the low overall proportion of individuals carrying pollen,this was observed in 7 of the nine lizard species,and on 8 of the ten main islands(Española,Fernandina,Floreana,Isabela,Marchena,Pinta,Santa Cruz and Santiago),suggesting that this is a widespread interaction.The results reported here support the potential role of lava lizards as pollinators across their radiation,although they may represent a relatively modest contribution when compared with birds and insects.However,we cannot discard that lizards may be ecologically significant for particular plant species and ecosystems given the specific climatic condition and functional diversity of each island.