Endosymbiotic organisms are known to manipulate the reproductive biology of their hosts. Incomplete prevalence of endosymbiont inducing thelytokous parthenogenesis results in the coexistence of sexual and asexual individuals, and could account for the maintenance of sexual reproduction in certain populations or species. In the parasitoid Venturia canescens, arrhenotokous ("sexual") and thelytokous ("asexual") individuals occur sympatrically. We aimed to determine whether endosymbionts are implicated in the thelytoky of V. canescens. After screening females of the two reproductive modes for several reproductive parasites: bacteria (Wolbachia, Rickettsia, Bacteroidetes, Spiroplasma, Arsenophonus) and Microsporidia, we concluded that thelytoky in V. canescens is not induced by any of these parasites and confirmed its suitability as a biological model for solving the evolutionary enigma of the maintenance of sexual reproduction., Vincent Foray ... [et al.]., and Obsahuje seznam literatury
The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. This study focuses on the occurrence of this exotic species and its seasonal abundance in various field crops. The abundance of adults, larvae and pupae of H. axyridis was evaluated over a three-year period, from 2009 to 2011, in four important agronomical crops (wheat, corn, broad bean and potato) in Belgium. From May to September, 48 1-m² quadrats were visually inspected in each of the fields sampled on several farms every seven days. H. axyridis colonized and reproduced in all of the four crops studied, with the largest numbers recorded in corn and broad bean crops. Larvae and adults of H. axyridis were recorded mainly in corn and to a much less extent in wheat and potato crops. From 2009 to 2011, the mean weekly abundance of H. ayxridis remained constant except in corn crops, where the recorded densities of all the immature stages and adults were higher in 2011 than in 2009. The population dynamics of aphids and H. axyridis are well described by a symmetric logistic function (S-shape) of cumulative population size. H. axyridis was not always recorded where aphids were abundant, e.g. aphids were abundant on wheat where no H. axyridis were recorded. H. axyridis start reproducing after the peak in aphid population, suggesting that H. axyridis is able to complete its development by feeding on alternative prey such as larvae and pupae of the same and other species of ladybird and other aphidophagous species. H. axyridis is often considered to be bivoltine but it only completes one generation per year in field crops. The second generation generally develops late in the season in other habitats., Axel Vandereycken ... [et al.]., and Obsahuje seznam literatury
Ovaries of Puto superbus and Ceroputo pilosellae are composed of numerous short telotrophic ovarioles that are arranged around the distal part of the lateral oviduct. An individual ovariole consists of a distal trophic chamber (= tropharium) and proximal vitellarium. The tropharia enclose individual trophocytes (= nurse cells) and early previtellogenic oocytes termed arrested oocytes. A single oocyte develops in each vitellarium. Analysis of serial sections has shown that ovarioles of P. superbus contain from 16 to 51 germ cells (13–43 trophocytes, 2–7 arrested oocytes, 1 developing oocyte) while those of C. pilosellae from only 8 to 10 germ cells (5–7 trophocytes, 0–2 arrested oocytes, 1 developing oocyte). The classification and phylogeny of scale insects are discussed taking into consideration the results of this study., Anna Michalik ... [et al.]., and Obsahuje seznam literatury
Molekulární genetika vstoupila na antropologické kolbiště koncem 60. let, ale teprve přímá analýza archaické DNA (aDNA) z fosilních pozůstatků od 80. let umožnila přesnější vhled do evoluce našeho druhu ve středním a mladém pleistocénu. Navzdory různým „Jurským parkům“ totiž DNA po smrti organismu rychle degraduje a časové okno její možné analýzy je poměrně omezené. Navíc jsou vzorky kontaminovány DNA okolních organismů. Nicméně velice záhy se pozornost paleogenetiků soustředila na naše příbuzné - neandertálce. Analýza jejich genomu ukázala, že ~2 % jejich DNA se vyskytuje v genomu anatomicky moderního člověka s výjimkou subsaharské Afriky a celkový rozsah tohoto přenosu může dosahovat až 20 %. Křížení s neandertálci lidem zřejmě umožnilo snadnější adaptaci na chladnější podmínky eurasijského kontinentu, současně však přineslo i výskyt některých chorob. Překvapení přinesla sekvence aDNA izolovaná z článku prstu nalezeného v Denisově jeskyni na Altaji. Ukázalo se, že tento jedinec patřil k neznámému druhu odlišnému jak od moderních lidí, tak i od neandertálců. I tito hominini přispěli až 6 % svojí DNA do genomu některých současných populací člověka (JV Asie, Oceánie). Podle nejnovějších poznatků byl tok genů mezi homininy středního a mladého paleolitu poměrně složitý, byla např. detekována příměs neandertálské DNA v genomu denisovců, kteří navíc získali další sekvence od dalšího, blíže neurčeného druhu hominina. Posledním příspěvkem paleogenetiky do obrazu naší evoluce je sekvence mitochondriální DNA získaná ze zhruba 400 tisíc let starých fosilních pozůstatků heidelberského člověka (Homo heidelbergensis) ze Sima de los Huesos (Šachty kostí) z krasové oblasti Atapuerca ve Španělsku, která ukazuje na příbuznost tohoto druhu., Molecular genetics entered the arena of anthropology at the end of the 1960s, but only direct analysis of ancient DNA (aDNA) from fossils since the 80s has permitted a better insight into the evolution of our own species. Despite the rapid decomposition of DNA starting immediately after death, molecular geneticists are now able to retrieve and sequence aDNA tens or even hundreds of thousands years old. Paleogenetic studies of ancient humans and their relatives have revealed a rather complex picture of Middle and Upper Pleistocene hominins (Neanderthals, Denisovans, ante-Neanderthals etc.) and gene flow among them. New and exciting findings changing our views of the evolution of our own species are appearing with an accelerating pace., Miloš Macholán., and Obsahuje seznam literatury
he painted lady butterfly (Vanessa cardui) (Lepidoptera: Nymphalidae: Nymphalinae) is well known for its seasonal long-distance migrations and for its dramatic population fluctuations between years. Although parasitism has occasionally been noted as an important mortality factor for this butterfly, no comprehensive study has quantified and compared its parasitoid complexes in different geographical areas or seasons. In 2009, a year when this butterfly was extraordinarily abundant in the western Palaearctic, we assessed the spatial and temporal variation in larval parasitism in central Morocco (late winter and autumn) and north-east Spain (spring and late summer). The primary parasitoids in the complexes comprised a few relatively specialized koinobionts that are a regular and important mortality factor in the host populations. However, there was a strong seasonal variation in the level of parasitism. In Spain percentage parasitism was more than four times higher in late summer than in spring (77.3% vs. 18%), while in Morocco it was five times higher by the end of winter than in the autumn (66.2% vs. 13.2%). In both regions the build up of parasitoid populations occurred after V. cardui had bred in the same general area over successive generations, and this may represent a selective force favouring seasonal migration to enemy-free space., Constanti Stefanescu ... [et al.]., and Obsahuje seznam literatury
Pásemnička sladkovodní (Prostoma graecence) je málo známý, ale běžný vodní živočich. Žije na kamenech a vodních rostlinách v tekoucích i stojatých vodách, především v nižších polohách. Živí se drobnými planktonními a bentickými organismy. Na hlavě má 6 očních skvrn (mladší jedinci 4). Loví pomocí chobotku (proboscis), který obsahuje centrální trn s jedovou žlázou a po stranách 2 - 5 přídatných trnů. Tento orgán je typický pro pásnice (Nemertea)., The ribbon worm Prostoma graecense (Nemertea) is a little known but common water animal. It occurs on stones and plants in running and standing waters, mostly in the lowlands. It is a carnivore feeding on tiny planktonic and benthic animals. P. graecense has 6 black eyespots (young specimens have four) on the top of its head. The eversible proboscis is armed with one central stylet with a poison gland and paired pouches each containing two to five accessory stylets. The proboscis is a typical apparatus of ribbon worms, used for hunting., Jan Špaček., and Obsahuje seznam literatury
In this study we analyzed the inter-specific relationships in assemblages of syrphids at a site in northern Italy in order to determine whether there are patterns in diurnal co-occurrence. We adopted a null model approach and calculated two co-occurrence metrics, the C-score and variance ratio (V-ratio), both for the total catch and of the morning (8:00–13:00) and afternoon (13:00–18:00) catches separately, and for males and females. We recorded discordant species richness, abundance and co-occurrence patterns in the samples collected. Higher species richness and abundance were recorded in the morning, when the assemblage had an aggregated structure, which agrees with previous findings on communities of invertebrate primary consumers. A segregated pattern of co-occurrence was recorded in the afternoon, when fewer species and individuals were collected. The pattern recorded is likely to be caused by a number of factors, such as a greater availability of food in the morning, prevalence of hot and dry conditions in the early afternoon, which are unfavourable for hoverflies, and possibly competition with other pollinators. Our results indicate that restricting community studies to a particular time of day will result in certain species and/or species interactions not being recorded., Manuela D´Amen ... [et al.]., and Obsahuje seznam literatury
1_Urbanisation is an important cause of species extinctions. Although urban water systems are also highly modified, studies on aquatic or semi-aquatic organisms are rare. The aim of this study is to identify the factors that determine species richness of Odonata in 22 Central European cities and along an urban-rural gradient within six of them. With 64 indigenous species in total and an average of 33 species per city, the species richness of Odonata in Central European cities is comparatively high. A generalised linear model indicates that species richness is positively related to city area. Additional predictors are climatic variables (temperature amplitude, sunshine duration and July temperature) and the year last studied. Since most cities are usually located in areas with naturally high habitat heterogeneity, we assume that cities should be naturally rich in dragonflies. The role of city area as a surrogate for habitat and structural richness most likely explains why it is strongly associated with Odonata species richness. The relationship between species richness and the climatic variables probably reflects that Odonata species richness in Central Europe is limited by warm and sunny conditions more than by availability of water. The temporal effect (the year last studied) on species richness is likely to be a consequence of the recent increase in Mediterranean species associated with global warming. Urbanisation clearly has an adverse effect on the species diversity of Odonata. Species richness increases along a gradient from the centre of a city to the rural area and is significantly highest in rural areas. This pattern probably reflects a gradient of increasing habitat quality from the centre of cities to rural areas. Moreover, the number of water bodies is generally very low in the city centres., 2_Based on our results, we make recommendations for increasing the abundance and number of species of dragonflies in cities., Christoph Willigalla, Thomas Farmann., and Obsahuje seznam literatury
We conducted a molecular phylogenetic analysis based on mitochondrial cytochrome oxidase subunit I and nuclear 28S rRNA gene sequences of species of Japanese elmids (23 species from 12 genera) and examined the hind-wings of 24 species in order to determine the incidence of hind-wing degeneration among species and the presence of dimorphic species with respect to hind-wing degeneration. Based on the molecular phylogenetic analysis, we determined that the previously separated winged and wingless species, Stenelmis vulgaris and S. miyamotoi, and Leptelmis gracilis and L. parallela, are two forms of the same species. Of the 24 species whose hind wings were studied, we found apterous (3 species of Zaitzeviaria), brachypterous (2 species of each of Optioservus and Paramacronychus) and dimorphic species (2 species as above) in separate clades of the phylogeny. These were the smallest or medium-sized species. Dimorphic species occurred in mid- to downstream areas and used reeds and wood as substrates. The percentage of species with hind-wing degeneration (wingless or dimorphic) was high among the species (29%) studied compared to the perceived percentage for temperate beetles (<10%). Thus, we found that the degeneration of hind wings has occurred repeatedly in these elmid species. However, we identified only ambiguous habitat and life history correlates of hind-wing degeneration, and the adaptive significance of hind-wing degeneration in these species of elmids remains unclear., Masakazu Hayashi, Simon D. Song, Teiji Sota., and Obsahuje seznam literatury