Puchýřka útlá (Coleanthus subtilis) je vysoce ekologicky specializovaný druh jednoleté trávy (čeleď lipnicovité - Poaceae), rostoucí ve vodních nádržích a tocích po dočasném poklesu vodní hladiny. Přežít na stanovištích, která často podléhají rychlým a nečekaným změnám, jí napomáhá řada adaptací, např. velmi krátký vývojový cyklus (5-7 týdnů) a jeho proměnlivost v závislosti na konkrétních podmínkách prostředí, drobná, snadno šiřitelná semena a tvorba dlouhodobé semenné banky. Je rozšířena na třech kontinentech, avšak nejvíce lokalit je známo z rybníků v České republice, zejména v jihočeských rybničních pánvích a na Českomoravské vrchovině. Vedle příznivé kombinace přírodních faktorů (klima, geologická stavba) se za velkou koncentrací lokalit na našem území nepochybně skrývá pozoruhodná synchronizace životního cyklu puchýřky s po staletí se opakujícím hospodářským cyklem chovu kapra., Coleanthus subtilis, a highly ecologically specialised annual grass species (Poaceae), grows in water bodies and watercourses after a temporary decrease of water level, and shows a range of adaptations to this habitat subjected to fast and unexpected changes (e.g., short life cycle, phenotypic plasticity, small, easily dispersible seeds, long-term soil seed bank). The highest number of sites is known from the Czech Republic (especially South Bohemian fishpond basins and the Bohemian-Moravian Uplands). Besides natural factors (climate, geology), the remarkable synchronisation of Moss Grass life cycle with the farming cycle of Common Carp (Cyprinus carpio) is undoubtedly the reason for its disjunct distribution., Kateřina Šumberová, Michal Ducháček., and Obsahuje seznam literatury
1_Intraguild predation (IGP) and cannibalism occur in the field and could affect the dominance structure of guilds of coccinellid species. The exotic biological control agent Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is now well established in most areas of Northern and Central Italy, but it is unclear what effect this species could have on native dominant and non-dominant coccinellids with which it co-occurs. In order to predict the trophic interactions in coccinellid guilds and the likely effect of H. axyridis, the incidence of IGP and cannibalism among the following six species were evaluated under laboratory conditions: H. axyridis, three native dominant species, Adalia bipunctata (L.), Oenopia conglobata (L.) and Coccinella septempunctata L. and two native non-dominant species, Platynaspis luteorubra (Goeze) and Scymnus apetzi (Mulsant). Unfed and fed fourth instar larvae of the above species were paired in an experimental arena and the incidence of predation recorded over a period of 24 h. In absence of aphids, the survival probabilities (SP) of A. bipunctata and O. conglobata were lowest when paired with either C. septempunctata or H. axyridis (< 0.20 SP after 24 h). The SP of C. septempunctata was similar if paired with either a conspecific larva or H. axyridis (< 0.34 SP after 24 h) and that of H. axyridis was reduced similarly if paired with either a conspecific larva or C. septempunctata (> 0.71 SP after 24 h). The SP of P. luteorubra was lower when paired with A. bipunctata and C. septempunctata (< 0.07 SP after 24 h) than with other species and that of S. apetzi was greatly reduced when paired with all the dominant and exotic species (< 0.27 SP after 24h)., 2_In presence of aphids no predatory events occurred in most combinations. H. axyridis acted as a strong predator of native dominant and non-dominant coccinellids when the aphids are scarce. We did not find any evidence, however, that the incidence of IGP among exotic and native species is higher than either IGP or cannibalism in native species. The likelihood of IGP occurring in the field is discussed., Gabriele Rondoni, Andrea Onofri, Carlo Ricci., and Obsahuje seznam literatury
K lalokoploutvým rybám lze vysledovat původ nejstarších čtvernožců (tetrapodů). Přestože dnes přežívají jen dva druhy rodu latimerie (Latimeria), v minulosti tyto ryby představovaly poměrně úspěšnou skupinu vodních obratlovců. Článek popisuje hlavní znaky jednotlivých skupin a jejich minulost., Fossil lobe-finned fishes can be traced as direct ancestors of the first terrestrial tetrapods. Although two species of one genus (coelacanths Latimeria chalumnae and L. menadoensis) have survived to these days, the lobe-finned fishes formed a successful group of aquatic vertebrates in the past. The main features and history of their subgroups are described., and Tomáš Přikryl.
The theory of life history evolution generally predicts a negative across-environment correlation between development time and size at maturity in response to variations in environmental quality. Deviations from this pattern occur under specific circumstances. In particular, organisms may mature both early and at a small size when (1) some ultimate change (e.g. time constraint, resource exhaustion) in the environment precludes further growth, or (2) when there are predictable among-environment differences in mortality rates. The first scenario is frequently documented in insects but evidence for the second possibility is scarce. Here we report a crowding-induced plastic response resulting in a clear positive across-environment correlation between final weight and development time in a geometrid moth. The response was apparent during the entire larval period and in the last larval instar. Crowding also led to increased growth rates. As outbreaks have not been reported for this species it is unlikely that early pupation is a response to anticipated food shortage. Instead, we suggest that crowded larvae may perceive a higher risk of predation, perhaps because they are unable to distinguish conspecifics from potential predators. A possibility for a plastic increase in growth rate implies that the uncrowded larvae grow at submaximal rates, which indicates a cost of high growth rate., Helen Vellau, Toomas Tammaru., and Obsahuje seznam literatury
Morphology of mature larvae of two Central European species of Scydmaenus Latreille is described and illustrated: S. (s. str.) tarsatus Müller & Kunze and S. (Cholerus) hellwigii (Herbst). Inaccuracies in previous descriptions of S. tarsatus are discussed and the following combination of characters is defined as diagnostic for Scydmaenus: epicranial sutures reaching posteromedian margins of antennal insertions; presence of a single pair of stemmata and epicranial supraantennal pits; anterior row of subtriangular teeth on epipharynx; mandibles falciform and without mesal teeth; antennomere 3 rudimentary; antennal sensory appendage subconical and asymmetrical; maxilla with galea and lacinia; labium strongly constricted between mentum and prementum; thoracic tergites undivided along midline; head capsule, thoracic tergites, laterotergites and abdominal segments except sternite 1 densely setose; thoracic sternites and abdominal sternite1 largely asetose; and lack of urogomphi. We also describe the feeding behaviour of immature S. tarsatus and demonstrate for the first time that Scydmaeninae larvae can feed on live springtails and not armoured mites. In the introduction we provide a summary of the literature on all hitherto known preimaginal stages of Scydmaeninae., Pawel Jaloszynski, Aleksandra Kilian., and Obsahuje seznam literatury
In Europe there are only a few species of the syrphid fly Microdon, which live in the nests of various genera of ants. For most of these rare flies, details of their biology, larval behaviour and relationships with their hosts are still not yet well known. In this paper we present data on the life cycle, feeding behaviour and growth pattern of Microdon myrmicae, a social parasite of Myrmica ants and compare it with two species of Maculinea butterflies similarly parasitizing Myrmica ant colonies. M. myrmicae has three larval instars and overwinters as a third instar. Eggs and 1st instar larvae are ignored by ants, which indicate that they are “chemically insignificant”. 2nd and 3rd instar larvae feed on small ant brood. M.myrmicae larvae grow rapidly from May to July and later in the year the host colony only serves as shelter for overwintering. Like Maculinea alcon, larvae of M. myrmicae are numerous in Myrmica nests and more numerous than those of Maculinea teleius. Since the larvae of Microdon feed on an abundance of young ant brood, they experience low level of scramble competition and although many may develop in an ant’s nest they have probably little effect on host colony fitness., Magdalena Witek ... [et al.]., and Obsahuje seznam literatury
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