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Arnold Drozdowski (1924-2014) - obituary

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Urbanised areas are capable of exerting a strong impact on the distribution of genetic diversity within populations of animals. Urban invertebrate species are currently either relicts from pre-urban ecosystems, or have immigrated during or following urbanisation. We analysed 10 microsatellite loci in 196 specimens of the harlequin ladybird (Harmonia axyridis), an invasive species in Poland sampled in three of the country’s cities. Of Asiatic origin, this ladybird has been spreading through other continents, including Europe. Results showed that the Polish cities are being invaded by harlequin ladybirds that are uniform in terms of their genetic pool, with no significant genetic differentiation present between the urban populations investigated. Rapid spread and what are probably the large numbers of individuals colonising new areas allow this species to maintain high genetic diversity and avoid bottleneck effects. However, we suggest that urban populations differ in terms of genetic diversity. The highest genetic diversity characterises the most recently invaded area of Olsztyn in the north of Poland. Genetic data further suggest that this population could be still in an expansion phase. The earliest colonising population in Wrocław exhibits signs of a Wahlund effect, suggesting that gene flow among local groups within this urban area could be disturbed or impaired. We conclude that, in the case of an urban population of the harlequin ladybird, successful colonisation is followed by the onset of a decline in genetic diversity, with isolation between local sampling sites appearing. Further studies are required, however, if this process is to be elucidated.
Helicosporidia are gut parasites of invertebrates. These achlorophyllous, non-photosynthetic green algae are the first reported to infect insects. Helicosporidia are members of the green algal class Trebouxiophyceae and are further related to the photosynthetic and non-photosynthetic genera Auxenochlorella and Prototheca, respectively, the latter of which can also turn to parasitism under opportunistic conditions. Molecular analyses suggest that Helicosporidia diverged from other photosynthetic trebouxiophytes less than 200 million years ago and that its adaptation to parasitism is therefore recent. In this minireview, we summarize the current knowledge of helicosporidian genomics. Unlike many well-known parasitic lineages, the Helicosporidium sp. organelle and nuclear genomes have lost surprisingly little in terms of coding content aside from photosynthesis-related genes. While the small size of its nuclear genome compared to other sequenced trebouxiophycean representatives suggests that Helicosporidium is going through a streamlining process, this scenario cannot be ascertained at this stage. Genome expansions and contractions have occurred independently multiple times in the green algae, and the small size of the Helicosporidium genome may reflect a lack of expansion from a lean ancestor state rather than a tendency towards reduction.
In this study, 210 birds belonging to 47 species and 15 families of the Passeriformes collected during the period 1970-1986, were investigated for the presence of helminths. Of these birds, 138 (65.7%) were infected: 47 (22.4%) with digeneans, 82 (39.0%) with cestodes, 95 (45.2%) with nematodes and 36 (17.1%) with acanthocephalans. Eleven species of digeneans were found 5 of ccstodes, 11 of nematodes and 2 of acanthocephalans. Most findings are new records for the Netherlands. New hosts were revealed for one nematode species (Fringilla montifringilla for Pterothominx exilis), four digeneans (Sitta europaea for Echinochasmus beleocephalus, Turdus philomelos for Echinostoma revolutum, Motacilla alba for Notocotylus attenuatus and Passser domesticus as well as Turdus philomelos for Plagiorchis multiglandularis) and one acanthocephalan (Troglodytes troglodytes for Prosthorhynchus cylindraceus). The results showed clearly that birds which feed on invertebrates or are omnivorous - Hirundinidae, 16 investigated, 11 positive (68.8%); Corvidae, 53 investigated, 47 positive (88.7%); Turdidae, 53 investigated, 42 positive (79.2%) and Sturnidae, 17 investigated, 15 positive (88.2%) - are heavier infected than seed eaters - Fringillidae, 18 investigated, 2 positive (11.1%). However, high intensity of infection with capillariids (up to 350 specimens) in one of Fringilla montifringilla should be noticed.
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