Search results for "SYSTEMATICS"
showing 10 items of 6702 documents
Predation by signal crayfishPacifastacus leniusculuson fish eggs and its consequences for coregonid recruitment
2015
The character and magnitude of predation by the invasive, ectothermic Pacifastacus leniusculus, a crayfish widely introduced to Europe and Japan from North America, on the eggs of coregonid fishes, vendace Coregonus albula and whitefish Coregonus lavaretus were examined by experimentation, modelling and field data. The present results showed that P. leniusculus has the potential to be very efficient predator of fish eggs under winter conditions, but the predation by P. leniusculus did not significantly decrease production of coregonid larvae during the years with a high P. leniusculus population in the study lake. Hence, the mortality caused by the novel invertebrate predator appeared to co…
Color-assortative mating in a color-polymorphic lacertid lizard
2013
Color polymorphisms are common in lizards, which provide an excellent model system to study their evolution and adaptive function. The lacertid genus Podarcis is particularly interesting because it comprises several polymorphic species. Previous studies with lacertid lizards have tried to explain the maintenance of color polymorphisms by correlational selection between color morphs and several phenotypic traits. Particular attention has been paid to their putative role as signals reflecting alternative reproductive strategies under frequency-dependent selection, but the relationship between mating patterns and color polymorphism has not been previously considered. In this study, we use long…
Preliminary health screening and possible pathogen determination in aBufo bufo(Linnaeus, 1758) (Amphibia: Bufonidae) population
2010
The population of the common toad, Bufo bufo, on Jersey (Channel Islands, UK) has undergone a marked decline over recent years. Hypothesized causes for this decline include land use change, pollution, climate change and predation. We examined the carcasses of 97 wild adult common toads for gastrointestinal and pulmonary helminths. In addition, 31 adult toad carcasses were examined for the presence of ranavirus infection, and 212 wild common toads were examined for the presence of infection with the fungus Batrachochytrium dendrobatidis. Three nematode species Rhabdias bufonis, Aplectana macintoshii and Oswaldocruzia filiformis, and one species of cestode, Nematotaenia dispar, were identifie…
The joint emergence of group competition and within-group cooperation
2015
Abstract Between-group conflict and within-group cooperation can be seen as two sides of the same coin, coevolving in a group-structured population. There is strong support for between-group competition facilitating the evolution of human cooperative tendencies, yet our understanding of how competition arises is less clear. We show that groups of randomly assembled individuals spontaneously engage in costly group competition, and that decisions promoting between-group conflict are associated with high levels of within-group cooperation. Remarkably, when groups were given the possibility to compete against other groups, net earnings for individuals were higher than when groups were not allow…
Taxonomic clarification in W-Mediterranean Androcymbium (Colchicaceae): A. wyssianum sunk in the synonymy of A.gramineum and A.europaeum restored
2010
Abstract Hoyo A. del & Pedrola-Monfort J.: Taxonomic clarification in W Mediterranean Androcymbium (Colchicaceae): A. wyssianum sunk in the synonymy of A. gramineum and A. europaeum restored. — Willdenowia 40: 47–53. — Online ISSN 1868-6397. — © 2010 BGBM Berlin-Dahlem. doi:10.3372/wi.40.40103 (available via http://dx.doi.org/) Capsule dehiscence has been used as a diagnostic character for W Mediterranean species of Androcymbium. Depending on the state of capsule maturity, the character, however, can be ambiguous in herbarium material. Based on morphological, phenological and cpDNA characters it is shown that misinterpretation of the capsule as indehiscent in the type material of A. gramine…
Small Scale Geographical Variation in Plumage Colour of Pied Flycatcher Males
1997
Ecology -94". A cruise report. Swedish Polar Research Secretariat, Stockholm, pp. 311-316. Lundgren, B., Hedenstr6m, A. and Pettersson, J. 1995. Correlation between some body components and visible fat index in the Willow Warbler Phylloscopus trochilus (L.). Ornis Svecica 5: 75-79. Pettersson, J. and Hasselquist, D. 1985. Fat deposition and migration capacity of Robins Erithacus rubecula and Goldcrests Regulus regulus at Ottenby, Sweden. Ring. & Migr. 6: 66-76. Piersma, T., Bruinzeel, L., Drent, R., Kersten, M., Van der Meer, J. and Wiersma, P. 1996. Variability in basal metabolic rate of a long-distance migrant shorebird (Red Knot, Calidris canutus), reflects shifts in organ sizes. Physiol…
Evolutionary processes in a continental island system: molecular phylogeography of the Aegean Nigella arvensis alliance (Ranunculaceae) inferred from…
2005
Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of past fragmentation, dispersal, and genetic drift on taxon diversification. We used phylogeographical (nested clade) and population genetic analyses to elucidate the relative roles of these processes in the evolutionary history of the Aegean Nigella arvensis alliance (= ‘coenospecies’). We surveyed chloroplast DNA (cpDNA) variation in 455 individuals from 47 populations (nine taxa) of the alliance throughout its core range in the Aegean Archipelago and surrounding mainland areas of Greece and Turkey. The study revealed the presence of three major lineages, with largely nonove…
Modelling drift of pelagic offspring: the importance of egg surveys in providing a realistic model initialization
2015
Abstract Having valid information about the location and dynamics of biological processes is important for coastal management. In this context modelling, the pelagic drift of early life stages has been shown to be an important tool for understanding the spatial scale of population dynamics in marine systems. Often simulated particles are released in hypothetical quantities at assumed spawning grounds with no or few field data to guide the model parametrization. In this study, we combine high-resolution field data and state-of-the-art oceanographic modelling and use a probabilistic approach to construct kernel density distributions of the dispersal of pelagic fish eggs. Specifically, the pot…
Habitat Preferences for Territory Selection by the Endangered Eastern Iberian Reed BuntingEmberiza Schoeniclus witherbyi
2014
Summary. Given the 80% decline of the eastern Iberian reed bunting Emberiza schoeniclus witherbyi breeding population in recent decades, our aim was to identify the habitat components selected during territory establishment and to characterise the vegetation features that are positively or negatively selected at the territory scale. GLMM were used to explain the occurrence of territories in 11 wetlands. Fourteen variables with four vegetation dominance categories were analysed with respect to habitat composition, while occupancy of seven vegetation classes and 12 reed structural parameters were analysed with respect to habitat structure. The proportion of reed-cattails (Typha) measured by t…
First record of an established marbled crayfish Procambarus virginalis (Lyko, 2017) population in Estonia
2019
Invasive marbled crayfish Procambarus virginalis (Lyko, 2017) is spreading alarmingly fast across European countries and beyond. Early maturation, parthenogenetic reproduction mode and high growth rate contribute to a high potential invasiveness. Marbled crayfish can pose severe effects on native communities impacting the native crayfish populations being carrier of the crayfish plague disease caused by Aphanomyces astaci. Here we report the first record of marbled crayfish in Estonia. In total, 104 individuals were found in the artificially warm outflow channel of the cooling system of Balti Power Plant, entering to the water reservoir of the River Narva. Molecular analyses confirmed the m…