Search results for " zoology"
showing 10 items of 2242 documents
<p><strong>Towards resolving a problem of the identity of the <em>Aethus</em> species (Hemiptera: Heteroptera: Cydnidae) occu…
2014
The genus Aethus in Cambodia is known only from a single species collected in the 1950s that was originally identified as A. indicus. However, what was regarded as A. indicus in the Oriental and Australian regions appeared to consist of three sibling species, recognizable only on the basis of male genital structures, i.e., A. philippinensis, A. pseudindicus, and true A. indicus. To date, the lack of males representing this genus from Cambodia made it impossible to verify which species actually occur in this country. The present study, based on eight males collected at the same locality in Cambodia where the specimens were originally identified as A. indicus more than 50 years ago (i.e., Sie…
Temporal variation in reproductive allocation in a shield bug Elasmostethus interstinctus
1996
We investigated changes in the reproductive output and the effect of female phenotype on reproductive parameters in a shield bug Elasmostethus interstinctus (L.) (Heteroptera: Acanthosomatidae) over the whole reproductive period. At the beginning and the middle of the reproductive period eggs were smaller than at the end of the period. Clutch mass and number of eggs per clutch decreased in laying sequence, first clutches being much larger than any of the later ones. Lifetime fecundity correlated positively with female size: large females produced more eggs and lived longer than small ones. Egg size did not vary with female size. Offspring survival until adulthood increased with egg weight. …
Why are wasps so intimidating: field experiments on hunting dragonflies (Odonata: Aeshna grandis)
2003
Abstract The mechanisms of aposematism (unprofitability of prey combined with a conspicuous signal) have mainly been studied with reference to vertebrate predators, especially birds. We investigated whether dragonflies, Aeshna grandis, avoid attacking wasps, Vespula norwegica, which are an unprofitable group of prey for most predators. As a control we used flies that were painted either black or with yellow and black stripes. The dragonflies showed greater aversion to wasps than to flies. Black-and-yellow-striped flies were avoided more than black ones, suggesting that aposematic coloration on a harmless fly provides a selective advantage against invertebrate predators. There was no signifi…
Larval trematode infections in freshwater gastropods from the Albufera Natural Park in Spain
1998
AbstractMalacological samplings were made from January 1994 to December 1996 in the Albufera Natural Park (Valencia, Spain) to trace the dynamics of molluscan populations and the prevalence and intensity of infection by larval trematodes. A total of 10,533 freshwater gastropods belonging to seven species (Lymnaea auricularia, L. truncatula, L. palustris, L. peregra, Bithynia tentaculata, Physa acuta and Gyraulus chinensis) was examined, and 110 (1.04%) were found to harbour some of the nine distinguishable types of cercariae, namely four echinostome cercariae (Hypoderaeum conoideum, Echinoparyphium recurvatum, Euparyphium albuferensis, and Echinostoma sp.), four furcocercous cercariae, and …
Habitat Differences and Variability in the Lek Mating System of Black Grouse
1996
Spatially fixed territoriality has been regarded to be a general feature in lek mating systems. In the absence of territories, however, the nature of leks may change remarkably. We compared leks of black grouse in areas, where territoriality was governed by habitat characteristics. On ice-covered lakes, where the lekking ground was homogeneous and offered no landmarks by which the displaying males would be able to recognize territory boundaries, the male aggregations were mobile. 'Classical' leks on bogs, however, were stable. It also appeared that on mobile leks, as compared to stable leks, the opportunities for females to choose their mates were reduced. The distribution of mating success…
Restrictive mate choice criteria cause age-specific inbreeding in female black grouse, Tetrao tetrix
2012
Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to kinship. This suggests that the risks of inbreeding may be small because passive mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk. Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an individual’s life span, but in the lek-breeding black grouse, inbreeding increases with female age. To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null models of random mate choice ranging from complete randomness to more biologically realistic…
Fluctuating asymmetry and copulation success in lekking black grouse
1997
Abstract In lekking black grouse, Tetrao tetrix males at the centre of the leks obtain more copulations than males at the edges. We found that males with territories at the edge of the lek obtained fewer matings and also have the most asymmetric tarsi. However, when considering the tail ornament (the lyre) no correlation between asymmetry and mating success was found. Although females are unlikely to select males on the basis of tarsus symmetry, asymmetry in this trait may reflect male condition. We suggest that males in poor condition, as reflected by higher levels of fluctuating asymmetry in the tarsi, do not achieve central positions on the lek arena. This would account for the lower suc…
Egg and embryo proteins in European newts (genus Triturus) and their taxonomic potential
1987
AbstractPolyacrylamide disc electrophoresis was carried out on water soluble proteins of eggs and embryos of Triturus alpestris, T. boscai, T. cristatus, T. helveticus, T. marmoratus and T. vulgaris. "Major bands" and "minor bands" were defined and species specific phenotyps are described. The patterns of major bands proved to be rather constant during embryonic development up to approximately stage 30 (stretched tailbud stage). The method as used in this study is considered to be practical and relevant for diagnostic studies on Triturus species.
Effect of Willow TitPoecile montanusalarm calls on attack rates by Pygmy OwlsGlaucidium passerinum
2013
One suggested anti-predator function of alarm calls is to deliver a message to a predator that it has been detected. Moreover, giving the alarm call could provide a signal to the predator that capturing the individual giving the alarm is more difficult than capturing its silent group members, as the caller is probably the most aware of the predator's location. In an aviary experiment using stuffed dummy Willow Tits Poecile montanus, we assessed whether an authentic alarm call given by Willow Tit affected Pygmy Owl Glaucidium passerinum prey preference. In the experiment, the Owls attacked only the ‘silent’ dummy individuals, suggesting that alarm calling could offer direct fitness benefits …
UV reflecting vole scent marks attract a passerine, the great grey shrike Lanius excubitor
2002
Diurnal raptors have been shown to use ultraviolet vision and UV-reflecting vole scent marks to find suitable hunting areas. We studied if a passerine species, the great grey shrike Lanius excubitor that uses voles as its primary food, may also detect prey-patches in the same way. We conducted a laboratory experiment with ten shrikes. Each individual shrike had four options to choose from: (1) scent marks with UV light, (2) scent marks without UV light, (3) clean arena with UV light, and (4) clean arena without UV light. The birds preferred the scent-marked arena with UV light as measured by the number of scans and the time spent above it. Therefore, we suggest that great grey shrike probab…