Search results for "Dati"
showing 10 items of 8549 documents
Fire benefits flower beetles in a Mediterranean ecosystem
2018
Despite the abundance of plants that benefit from fire in Mediterranean ecosystems, little is known about the possible presence of fire-favoured insects (other than bark beetles). For two years we sampled invertebrates after two large wildfires in eastern Spain and demonstrate that two flower beetle species, Protaetia morio and P. oblonga (Cetoniidae), show a pyrophilous behaviour. These beetles were much more numerous after the fires than in unburnt plots around the fire perimeter; in addition, these species tended to increase in number with the distance from the fire perimeter and with fire recurrence, especially P. morio. These results were maintained for the two postfire years sampled. …
Immune activation increases susceptibility to oxidative tissue damage in Zebra Finches.
2006
Summary 1The innate immune response involves the production of highly reactive molecules (reactive oxygen and nitrogen species, ROS and RNS). These toxic compounds can effectively destroy invading pathogens but can also, non-specifically, target host cells. Tissue damage caused by ROS and RNS can be substantial if the inflammatory response is overactive, potentially inducing a so-called immunopathology. 2In this study, we induced an inflammatory response in Zebra Finches by the way of a LPS injection (lipopolysaccharide of the cell wall of Escherichia coli), using as a control a group of birds injected with saline (phosphate-buffered saline). Body mass was measured both before and 24 h afte…
Survival cost of an early immune soliciting in nature.
2009
8 pages; International audience; If immune functions confer obvious benefits to hosts, life-history theory assumes that they also induce costs, leading to trade-offs between immunity and other fitness components. However, whether substantial fitness costs are associated with immune systems in the wild is debatable, as numerous factors may influence the costs and benefits associated with immune activation. Here, we explore the survival cost of immune deployment in postfledging birds. We injected Eurasian collared dove nestlings (Streptopelia decaocto) with antigens from Escherichia coli, and examined whether this immune challenge affected survival after fledging. To assess survival, birds we…
Do carotenoid-based sexual traits signal the availability of non-pigmentary antioxidants?
2006
SUMMARY Carotenoid-based signals are thought to be indicators of male quality because they must be obtained from the diet and might thus indicate the ability of individuals to gather high-quality food. However, carotenoids are also known to have important physiological functions as immunoenhancers and antioxidants, and, as such, carotenoid-based sexual traits have also been suggested to reflect the health and antioxidant status of their bearers. This last idea is based on the hypothesis that carotenoids that are allocated to sexual signals are no longer available for the detoxification system. Recently, this hypothesis has been challenged on the grounds that the antioxidant activity is not …
Variation in predation risk and vole feeding behaviour: a field test of the risk allocation hypothesis.
2003
Many prey animals experience temporal variation in the risk of predation and therefore face the problem of allocating their time between antipredator efforts and other activities like feeding and breeding. We investigated time allocation of prey animals that balanced predation risk and feeding opportunities. The predation risk allocation hypothesis predicts that animals should forage more in low- than in high-risk situations and that this difference should increase with an increasing attack ratio (i.e. difference between low- and high-risk situations) and proportion of time spent at high risk. To test these predictions we conducted a field test using bank voles ( Clethrionomys glareolus) as…
Habitat Preference of German Mantis religiosa Populations (Mantodea: Mantidae) and Implications for Conservation.
2015
In Germany, the thermophilic European mantid ( Mantis religiosa L.) is endangered. Here, we study habitat requirements during its life, and discuss the applicability of the two conservation measures grazing and mowing to this insect species . At two study sites in south-western Germany, which were each subject to one of these measures, we recorded structural and climatic conditions within different microhabitats. We also conducted capture–mark–recapture studies for adult M. religiosa , and mapped adult roosting, oothecae deposition, egg hatching, and imaginal molting in microhabitats over two vegetation periods. In order to assess microhabitat preference of M. religiosa during its life, and…
Elevated oxidative stress in pied flycatcher nestlings of eumelanic foster fathers under low rearing temperatures
2019
Striking variation in melanin coloration within natural populations is likely due to the different fitness outcomes of alternative phenotypes in varying environmental conditions. There are two types of melanin: eumelanins yield blackish hues, whereas pheomelanins yield reddish hues. The production of eumelanins requires low levels of glutathione (GSH), which is the most important intracellular antioxidant, whereas the production of pheomelanins requires high levels of GSH. We investigated the oxidative status of male pied flycatchers (Ficedula hypoleuca) with different degrees of melanin coloration under different temperatures during the nestling period. Moreover, we assessed the oxidative …
Skylarks trade size and energy content in weed seeds to maximize total ingested lipid biomass
2014
International audience; tThe trade-off between forage quality and quantity has been particularly studied in herbivore organisms,but much less for seed eating animals, in particular seed-eating birds which constitute the bulk of win-tering passerines in European farmlands. The skylark is one of the commonest farmland birds in winter,mainly feeding on seeds. We focus on weed seeds for conservation and management purposes. Weedseeds form the bulk of the diet of skylarks during winter period, and although this is still a matter fordiscussion, weed seed predation by granivorous has been suggested as an alternative to herbicides usedto regulate weed populations in arable crops. Our objectives wer…
Egalitarian mixed-species bird groups enhance winter survival of subordinate group members but only in high-quality forests
2020
AbstractOnly dominant individuals have unrestricted access to contested resources in group-living animals. In birds, subordinates with restricted access to resources may respond to intragroup contests by acquiring extra body reserves to avoid periods of food shortage. In turn, higher body mass reduces agility and increases predation and mortality risk to subordinates. Birds often live in hierarchically organized mixed-species groups, in which heterospecific individuals are considered to substitute for conspecifics as protection against predators at a significantly reduced competition cost. Crested tits (Lophophanes cristatus) and willow tits (Poecile montanus) form mixed-species groups duri…
Genetic correlation between resistance to oxidative stress and reproductive life span in a bird species.
2010
Evolutionary theories propose that aging is the result of a trade-off between self-maintenance and reproduction, and oxidative stress may play a crucial role in such a trade-off. Phenotypic manipulations have revealed that a high investment in reproduction leads to a decline in the organism's resistance to oxidative stress, which could in turn accelerate aging. Here, by using quantitative genetic analyses as a tool to disentangle genetic effects from phenotypic variances, the relationship between resistance to oxidative stress at sexual maturity and two key reproductive life-history traits (i.e., number of breeding events during life and age at last reproduction) was analyzed in cross-foste…