Článek se zabývá taxonomií, reprodukční biologií, fylogenetikou, fylogeografií a introdukční historií ryb rodu karas (Carassius). Článek poskytuje souhrn poznatků, které jsou značně komplikované a spojené s jedinečným způsobem rozmnožování, definicí druhu a nepřesným chápáním biologie a systematiky těchto ryb v minulosti. Celá problematika je ještě daleko od svého kompletního vyřešení, ale současný pohled nám může pomoci v lepší péči o vodní prostředí., This article deals with the taxonomy, reproductive biology, phylogenetics, phylogeography and introduction history of the fishes of the genus Carassius. It summarizes findings associated with their unique mode of reproduction, challenging species delimitation and insufficient understanding of the biology and systematics of these fishes in the past. Deeper insight into the biology of Prussian Carp (Carassius gibelio) will require more research, but the available results can improve our understanding and management of the aquatic environment., Lukáš Kalous., 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.
Heterospecific hybrids often suffer from a lowered fitness relative to parental species. Contextdependent intrinsic costs of hybridization are partially due to a malfunction in cell biochemical machinery that affects metabolic rates at the organismal level. This study examines whether heterospecific hybridization influences the metabolic costs of maintenance in F1 hybrids between closely related newts, Triturus carnifex and T. dobrogicus. When controlled for body size, oxygen consumption in hybrid newts was 59-76 % higher than in the parental species. This suggests that high standard metabolic rates in hybrids may contribute to thecosts of hybridization in newts.
Příspěvek popisuje velmi neobvyklý nález mloka skvrnitého (Salamandra salamandra), který byl zaznamenán ve výšce 2 m nad zemí šplhající po kmeni vzhůru. Z literatury je sice známo vyhlížení samic samci z vyvýšených míst, ale tento nález je velmi odlišný. Důvod tohoto výjimečného chování je neznámý., The species is usually encountered on the ground, stones or lying wood not too high above ground. However, I found one individual climbing up a tree at a height of two metres. Unfortunately, nothing is known of the motives behind this unusual behaviour., and Antonín Krása.
Polyploidie je důležitým evolučním mechanismem přispívajícím k biodiverzitě současných ryb a také významným nástrojem v akvakultuře. Tento článek podává přehled o mechanismech vzniku polyploidie a o kauzálním vztahu mezi hybridizačními událostmi a zvýšením stupně ploidie. Uvádí rovněž příklady využití specifických vlastností polyploidů v akvakultuře., Polyploidy is an important evolutionary mechanism contributing to the biodiversity of extant fishes, and it also represents a notable tool in aquaculture. This paper reviews the mechanisms by means of which polyploidy arises and the causal relationship between hybridisation events and elevation of the ploidy level. Utilization of specific traits of polyploids in aquaculture is also discussed., Martin Flajšhans, Petr Ráb., and Obsahuje seznam literatury
Acanthocephalus lutzi (Hamann, 1891) is proposed to be transferred to the genus Pseudoacanthocephalus Petrochenko, 1956 based on the type material from Rhinella marina (L.) from Brazil and recently collected material from R. arenarum (Hensel) from Argentina. Pseudoacanthocephalus is characterised by the following features: a cylindrical trunk without spines, a cylindrical proboscis, testes in tandem, a compact cluster of cement glands, a nearly terminal male genital pore, a ventral and sub-terminal female genital pore, and egg without polar prolongations, containing a holoechinate acanthor. Pseudoacanthocephalus lutzi comb. n. has a proboscis armature of 14-18 longitudinal rows of 5-8 hooks each, with all roots formed by a posteriorly directed longitudinal spatulate sheet having a central rib, and an inconspicuous sheet directed anteriorly; a variable number (4, 5 or 6) of cement glands; a cerebral ganglion located near the base of the proboscis receptacle; digitiform to claviform lemnisci, as long as, or slightly shorter or slightly longer than the proboscis receptacle; a sigmoid-shaped posterior end in males; an egg with a conspicuous fibrillar coat; and one of the larval hooks more robust and different in shape than the others. Additionally, the type material of Acanthocephalus saopaulensis Smales, 2007 from Rhinella icterica (Spix) from Brazil and a paratype of A. caspanensis Fernández et Ibarra Vidal, 1992 from R. spinulosa (Wiegmann) from Chile were studied. Acanthocephalus saopaulensis is considered conspecific with P. lutzi and A. caspanensis is transferred to Pseudoacanthocephalus because it possesses all the characters of the genus mentioned above. The use of characters such as egg morphology and host ecology for distinguishing Acanthocephalus from Pseudoacanthocephalus is also discussed.
To investigate time- and spatial related variations in the composition of otter Lutra lutra diet, a total of 838 faecal samples was collected in the upper catchment of the Agri River (Basilicata region, southern Italy), and analysed. Data were split up according to the four seasons and between the main river and three of its tributaries. Fish and amphibians formed the bulk of otter diet, their consumption being inversely correlated. Trophic niche breadth was positively correlated with the frequency of occurrence of fish, whilst it was negatively correlated to that of amphibians and the altitude of the sampling stations. The frequency of consumption of fish did not vary through the year, whilst amphibians were mainly eaten during their hibernation and breeding period. Otter diet along the four main rivers differed significantly, the species being mainly piscivorous on the main river, whilst relying on alternative food resources on its tributaries, where habitat features or human interference reduced fish abundance. Fish availability seems to represent the main factor determining the composition and diversity of otter diet.
Research in freshwater ecology has traditionally focused on water courses or large still waters. However, ponds support proportionately high levels of biodiversity relative to other inland waters in Europe, and foraging by Eurasian otter Lutra lutra (L., 1758) could have considerable impacts on species composition in these small water bodies. The aim of the present study was to analyse otter spraints around ponds during two contrasting seasons (winter and spring) in north Norfolk (eastern England), where both otter and ponds are of particular conservation concern. Spraint density, prey diversity and the consumption of river-associated species were higher in spring than winter. In both seasons, birds were the most important prey category as ingested biomass. European eel Anguilla anguilla (L., 1758) and amphibians, specifically common frog Rana temporaria L., 1758 and common toad Bufo bufo (L., 1758), were more consumed in spring, whereas northern pike Esox lucius L., 1758 and tench Tinca tinca (L., 1758) were taken in winter. Non-native common carp Cyprinus carpio L., 1758 was important in both seasons, whereas threatened native crucian carp Carassius carassius (L., 1758) was a minor prey item. Massive kills of common toad, which involved a new handling technique for predation on this species, were observed mainly in spring. The study demonstrated otters to display great plasticity in foraging behaviour and contributes to the
understanding of otter predatory pressure on pond biodiversity, with implications for landscape management.
Článek o vývoji vztahu akvaristiky a vědeckého výzkumu je zaměřen především na aspekty taxonomie, etologie a rozmnožování. Stručně jsou zmíněny počátky akvaristiky stojící na základech tehdejší vědy, a uvedena jména významných osobností, které ovlivnily vývoj chovu ozdobných ryb. Je zdůrazněn termín akvariologie, zavedený pro multidisciplinární vědecké základy akvaristiky., This article deals with the mutual relations between the aquarium hobby and scientific research, especially with respect to taxonomy, ethology and breeding. The beginnings of aquaristics, based on earlier scientific sources, are mentioned, and leading figures pioneering the developments in keeping tropical fish are also introduced. The term aquariology, applied to the multidisciplinary scientific basis of ornamental fish farming, is highlighted., Jindřich Novák., and Obsahuje seznam literatury
Understanding the diets of predators, prey selection and their impact on prey populations is pivotal to investigations on the ecology of predator and prey species. In this study, we observed a hand-reared European otter (Lutra lutra) foraging in the wild, in order to identify the type of prey captured by the predator. The study was carried out between March and June 2001 in a diverse range of natural otter habitats in Białowieża Forest (NE Poland). We found that tadpoles represented an important part of the otter's diet in June, when their frequency of occurrence and biomass reached 38% and 11%, respectively. During spring, tadpoles were less common than other types of prey, such as adult amphibians, fish, or aquatic Coleoptera. Otter diet varied among months and there were differences in the main prey type captured among water body types. Our results highlight the need to develop methods that enable the identification of tadpoles and other cryptic seasonal food items in riparian predator diets.