Ancestral state reconstruction analysis of hymenopteran sex determination mechanisms

We provide the first phylogenetic evidence supporting complementary sex determination (CSD) as the ancestral mechanism for haplodiploidy in the Hymenoptera. It is currently not possible, however, to distinguish the evolutionary polarity of single locus (sl) CSD and multiple‐locus (ml) CSD given the available data. In this light, we discuss the seemingly maladaptive hypothesis of ml‐CSD ancestry, suggesting that collapse from ml‐CSD to sl‐CSD should remain a viable evolutionary hypothesis based on (i) likely weakening of frequency‐dependent selection on sex alleles under ml‐CSD and (ii) recent findings with respect to the evolutionary novelty of the complementary sex determiner gene in honeybees. Our findings help provide a phylogenetically informed blueprint for future sampling of sex determination mechanisms in the Hymenoptera, as they yield hypotheses for many unsampled or ambiguous taxa and highlight taxa whose further sampling will influence reconstruction of the evolutionary polarity of sex determination mechanisms in major clades.     

Disease development of Pythium root rot in bulbous Iris and Crocus

Iris bulbs and Crocus corms were planted at two planting dates in sandy soil infested with Pythium spp. At monthly intervals during the growing season root rot infection was assessed over 3 consecutive years and disease development curves were predicted for both crops. The disease development was remarkably different for Iris and Crocus and the curve shape was determined by the crop rather than by the Pythium species. Planting date had a significant effect on disease development in both crops. No correlation was found between disease development and soil temperature.     

Curie point pyrolysis mass-spectrometry of fulvic acids from Tjeukemeer, The Netherlands

SUMMARY. Curie point pyrolysis mass-spectrometry of freshwater fulvic acids from Tjeukemeer indicates the presence of polysaccharides, amino sugars, proteinaceous material and phenols. These results resemble those of the pyrolysis of soil fulvic acids. However, freshwater fulvic acids may be richer in aliphatic components than those from soil.