Climate features that influence life cycles, notably severity, seasonality, unpredictability and variability, are summarized for different polar zones. The zones differ widely in these factors and how they are combined. For example, seasonality is markedly reduced by oceanic influences in the Subantarctic. Information about the life cycles of Arctic and Antarctic arthropods is reviewed to assess the relative contributions of flexibility and programming to life cycles in polar regions. A wide range of life cycles occurs in polar arthropods and, when whole life cycles are considered, fixed or programmed elements are well represented, in contrast to some recent opinions that emphasize the prevalence of flexible or opportunistic responses. Programmed responses ale especially common for controlling the appearance of stages that are sensitive to adverse conditions, such as the reproductive adult. The relative contribution of flexibility and programming to different life cycles is correlated with taxonomic affinity (which establishes the general lifecycle framework for a species), and with climatic zone, the habitats of immature and adult stages, and food., Hugh V. Danks, and Lit
This paper describes previously unreported lateral cuticle splits occurring during the moulting of larvae of the leaf-miners Pachyschelus laevigatus (Say, 1839) (Coleoptera: Buprestidae) and Cameraria sp. (Lepidoptera: Gracillariidae). In these species the cuticle does not split dorsally during the larval/larval moults as in most insects, but laterally, thus permitting the larva to leave its exuviae sideways rather than vertically. This previously overlooked phenomenon is hypothesized to have evolved independently in both taxa and is an adaptation to life in the vertically limited space of their mines and, therefore, might be found in other organisms confined to similar conditions. The exuvial split in the larva to pupa moult of Cameraria sp. taking place inside a relatively tick and firm cocoon is, however, of the regular dorso-medial type, and, therefore, two different successive types of moult occur within a single ontogenesis. For comparative purposes the common dorsal exuvial split is described and illustrated for the leaf-mining larvae of Profenusa alumna (Hymenoptera: Tenthredinidae), Sumitrosis rosea (Coleoptera: Chrysomelidae) and the free-living Satonius fui (Coleoptera: Torridincolidae)., Vasily V. Grebennikov., and Obsahuje seznam literatury
Competition is a major force organizing ant communities and results in co-occurring species evolving different strategies for foraging and use of space. Territorial species, as top dominants exclude each other, while shaping the local ant communities both qualitatively and quantitatively. In this study we examined how two territorial species, Formica polyctena and Lasius fuliginosus, can coexist in adjacent territories over long periods of time, and whether they affect co-occurring species of ants in different ways. Field observations in the absence and in the presence of baits were carried out around a L. fuliginosus nest complex surrounded by a polydomous F. polyctena colony in S Finland in 2007–2009. Both species controlled their territories, but were affected by changes in the abundance of the other species and the distance from L. fuliginosus’ main nest. They did not have the same effect on the subordinate species in the absence of baits, but the abundance of Myrmica spp. recorded at baits was negatively affected by both of the territorial species. The preferences of the different species for the artificial food sources differed: L. fuliginosus and F. polyctena preferred tuna to honey and Myrmica spp. honey to tuna. More individuals of the subordinate species were recorded in the territory of F. polyctena than of L. fuliginosus, although conflicts with this territorial species were also recorded. During the three years of the study almost no overlaps in the territories of the two territorial species were recorded, and there were mostly minor shifts in the boundaries of the territories. Differences between the two territorial species in their use of space and competitive effects ensured their coexistence at this particular site in Finland., Wojciech Czechowski ... [et al.]., and Obsahuje seznam literatury
Luňáci rodu Milvus jsou v současné době objektem studia ornitologických taxonomů (v současnosti se rozlišují čtyři druhy), věnuje se jim pozornost z hlediska evoluční historie, udivováni jsme poznatky z jejich sociálního života a velké úsilí je zaměřeno na jejich ochranu. Překvapivě početné jsou případy mezidruhové hybridizace mezi sympatricky (na stejném území) se vyskytujícími luňáky červenými (M. milvus) a luňáky hnědými (M. migrans). V článku je přiblížen aktuální pohled na taxonomii luňáků v globálním kontextu a detailně popíšeme průběh hnízdění smíšených párů luňáka červeného a luňáka hnědého, které se nám poprvé v přírodě podařilo zaznamenat v letech 1995 a 1996 na Slovensku a r. 2013 také v České republice., At present, four valid species are recognized within the genus Milvus. Red Kites (M. milvus) and Black Kites (M. migrans migrans) occur sympatrically in Slovakia and the Czech Republic. One mixed pair of kites (a Red Kite female and Black Kite male) nested successfully in Slovakia in 1995 and 1996 (with three and two young, respectively). Another mixed pair of kites (a Red Kite female and Black Kite male) nested successfully in the Czech Republic in 2013. Two young fledged from the nest, the third one was killed by a Goshawk (Accipiter gentilis) during the nesting period. These reports represent the first cases of inter-specific hybridization of kites in these two countries. Moreover, an indication of cooperative nesting was observed in the Czech Republic., Ivan Literát, Hynek Matušík, Peter Rác., and Obsahuje seznam literatury
Chovu malých jihoamerických cichlid rodů Laetacara a Nannacara se mohou věnovat i akvaristé, kteří své zálibě nemohou vyčlenit ve svém domově příliš velký prostor. Velkoryse pojaté akvaristické zázemí není v tomto případu nezbytné. Tyto rybky se starají o své potomstvo velmi starostlivě, takže lze při rozmnožování pozorovat různé projevy rodičovské péče., South American cichlids of the genera Laetacara and Nannacara can be bred also by aquarists without an elaborate aquarium equipment. These little fish look after their offspring very carefully, so various displays of parent care can be observed., and Jaroslav Eliáš.
Males in many beetles show horn or mandible dimorphism. The stag beetle Dorcus rectus was assumed to have dimorphic males, but in this species there are not two but three visually distinct mandibular phenotypes. The aim of this study is to determine if the three phenotypes represent an allometric trimorphism in this species by studying the scaling relationship between body length and mandible length in 148 adult males and 31 adult females. The relationship was fitted using the following four statistical models; a simple line, a logistic curve, a continuous segmented line and a discontinuous line. The best-fitting model for the males was a discontinuous line with two break points and that for the females a simple line. The male data was also well fitted by a logistic curve. The discontinuous linear model divided the males into three groups that were in good agreement with the three phenotypes. These results suggest that a subtle allometric trimorphism possibly exists in males of this species. Small males of this species have no distinct teeth on their mandibles, whereas small males of D. striatipennis and D. curvidens, which are closely related to D. rectus, have a pair of distinct teeth on their mandibles. The phylogenetic relationship of these Dorcus species suggests that the trimorphism in D. rectus may have arisen through the loss of teeth in small males., Yutaka Iguchi., and Obsahuje seznam literatury