Perinatal variation and covariation of oxidative status and telomere length in yellow-legged gull chicks.

The perinatal period is critical to survival and performance of many organisms. In birds, rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status, with potentially negative consequences on physiology mediated by oxidative stress. In addition, telomere length (TL) undergoes reduction during birds' early life, partly depending on oxidative status. However, relatively few studies have focused specifically on the changes in oxidative status and TL that occur immediately after hatching. In this study of the yellow-legged gull Larus michahellis, we found that chicks undergo a marked increase in plasma total antioxidant capacity and a marked decrease in the concentration of pro-oxidant molecules during the first days after hatching. In addition, TL in erythrocytes decreased by 1 standard deviation over the 4 days post-hatching. Body mass and tarsus length covaried with total antioxidant capacity and concentration of pro-oxidants in a complex way, that partly depended on sex and laying order, suggesting that oxidative status can affect growth. Moreover, TL positively covaried with the concentration of pro-oxidant molecules, possibly because retention of high concentrations of pro-oxidant molecules results from mechanisms of prevention of their negative effects, including reduction in TL. Thus, this study shows that chicks undergo marked variation in oxidative status, which predicts growth and subsequent TL, prompting for more studies of the perinatal changes in the critical post-hatching stages

High-ranking alleviates male local competition in lek mating systems

Territoriality entails demanding social interactions with competing individuals, typically males. Variation in quality of males can be predicted to affect the spatial arrangement of territories. We present a model aimed at understanding the spatial properties of territories on leks, where the presence of a hierarchy in a population of males leads to the clustering of individuals around high-ranking \u2018hotshot\u2019 males. The hierarchy results in a decrease in the number of nearest neighbors interacting directly with high-ranking males, with potential socio-sexual benefits for such males

Begging and parental care in relation to offspring need and condition in the barn swallow (Hirundo rustica)

Parents are selected to maximize their fitness by allocating care among their progeny in relation to the differential reproductive value of offspring. Nestlings have been hypothesized to signal need for parental care reliably through their begging behavior, but offspring condition as reflected by their reproductive value may likewise affect begging and hence provisioning. We assessed the relative importance of need and condition in determining begging behavior and feeding rate of nestling barn swallows (Hirundo rustica) through short-term starvation, a challenge to their immune system with a foreign antigen negatively affecting condition, and brood size manipulation. Food deprivation but not condition or brood size manipulation increased nestling begging rate. Parents fed offspring depending on both need and condition but only when feeding broods that were reduced or of normal size. In enlarged broods, offspring received less food per capita than in reduced broods, and parents did not discriminate among nestlings relative to their need or condition. Thus, nestlings signal their need by increased solicitation. Parents allocate food to offspring dependent on both need and condition, with these effects depending on parental workload as determined by experimental brood size

A chemotaxonomic investigation on Vitis vinifera1. Within-cultivar population analysis

The extent of variability for storage protein subunits as well as the isozymes of AcP, EST and PGM was evaluated by isoelectric focusing on a large number of individual self-pollinated seeds from cvs Chardonnay, Sangiovese and Traminer. Extracts from 35 randomly selected kernels gave reproducible protein patterns and may thus be taken as representative of the average genetic make-up in a given biotype

Elevated frequency of abnormalities in barn swallows from Chernobyl

Ever since the Chernobyl accident in 1986, that contaminated vast areas in surrounding countries with radiation, abnormalities and birth defects have been reported in human populations. Recently, several studies suggested that the elevated frequency of such abnormalities can be attributed to poverty and stress in affected human populations. Here, we present long-term results for a free-living population of barn swallows, Hirundo rustica, demonstrating the presence of 11 morphological abnormalities in populations around Chernobyl, but much less frequently in an uncontaminated Ukrainian control population and three more distant control populations. The presence of these abnormalities in barn swallows is associated with reduced viability. These findings demonstrate a link between morphological abnormalities and radiation in an animal population that cannot be attributed to poverty and stress. The most parsimonious hypothesis for abnormalities in animal and human populations alike is that the effects are caused by the same underlying cause, viz. radiation derived from the Chernobyl accident

Parasites and biological invasions : do helminths play a role in facilitating grey squirrel (Sciurus carolinensis) settlement and in its competition with native red squirrel (Sciurus vulgaris)?

AIM: Several studies have shown that parasites can play an important role in biological invasions (Dunn AM, 2009, Adv Parasitol, 68: 161-184), mainly via two different processes. First, during the invasion process, alien species often lose part of their parasite community with a positive impact on their population growth and consequently on their settlement and spread (\u201cparasite release hypothesis", Torchin ME et al 2003, Nature, 421: 628-630). Second, parasites may mediate the impact of invasive species on native taxa ("parasite-mediated competition", Hudson P and Greenman J, 1998, Trends Ecol Evol, 13:387-390), introducing in the environment novel parasites to which native species are more susceptible or increasing the abundances of local parasite acting as additional reservoir (Tompkins DM, 2001 Parasitology, 1999: 187-193). Since 1948, the Eastern grey squirrel (Sciurus carolinensis), a North-American alien species, has been repeatedly introduced in Italy, causing local extinction of the native Eurasian red squirrel (Sciurus vulgaris), mainly through exploitation competition for food (Martinoli A et al, 2010, Hystrix It J Mamm, 21: 127-136). Our purpose is to explore gastro-intestinal helminth communities of grey and red squirrels in Italy in order to investigate the role of parasites in the settlement of the alien species and in its interaction with native one. In particular, we want to test two independent hypothesis: the parasite release and the parasite-mediated competition MATERIAL AND METHODS: We have sampled 8 populations (4 grey-only, 3 red-only and 1 red-grey area) in Piedmont and Lombardy by capturing both species with standard live-trapping techniques. Grey squirrels were euthanized immediately after capture, while red squirrels were marked and released after samples collection. Grey squirrels were then dissected and their intestinal content examined using standard parasitological techniques. For red squirrels, we performed coprological analysis and tape tests to obtain indirect information on their gastro-intestinal parasites. To provide a check-list of red squirrel parasites, we also dissected several roadkills collected from different sites in Northern Italy. RESULTS: We dissected 142 grey squirrels in which we identified four different species of gastro-intestinal nematodes: Strongyloides robustus, Trichostrongylus calcaratus, Trichuris muris and Aonchotheca annulosa (prevalence: 74%, 13%, 6% and 2%, respectively). The species richness we observed is lower compared to what is reported for grey squirrel in their native range (Raush R and Tiner JD, 1948, Am Midl Nat, 39: 728-747). S. robustus is a parasite common and abundant in North-American squirrels (Bartlett CM, 1995, Folia Parasit, 42:102-114), but never recorded in Europe until now, thus likely brought here by grey squirrels during the invasion process. On the contrary, T. calcaratus, T. muris and A. annulosa should be considered as non-specific or accidental species, the latter two acquired by the grey squirrel here in Europe. As regards red squirrels, coprological analysis, tape tests and 26 roadkills collected in red-only areas have shown the presence of only one nematode, Rodentoxyuris sciuri (prevalence: 96%), typical of this species and already recorded in red squirrels in Europe (Hugot JP et al, 1996, Int J Parasitol, 26: 147-149). On the other hand, in red-grey areas, coprological analysis and roadkills examination have shown the presence of S. robustus in red squirrels, suggesting parasite transmission from the grey squirrel to the native species. CONCLUSION: Our results lend support to the parasite release hypothesis, as grey squirrels in Italy are missing several helminths species usually present in North-America. Moreover, the lack of species-specific parasites is suggested by the presence of some accidental species, probably exploiting vacant niches. Concerning parasite-mediated competition, we found that S. robustus can be transmitted to the red squirrel, but so far we haven't found any evidence of helminths spillover from red to grey squirrel. To confirm that S. robustus actually plays a role in grey squirrel impact on the native species, further investigation on the pathogenic effect of this nematode on red squirrels is needed

Large-scale spatial distribution of breeding Barn Swallows Hirundo rustica in relation to cattle farming

Capsule: The information on the spatial distribution of cattle farming stored in public bovine computerized databases can predict the distribution and abundance of breeding Barn Swallow Hirundo rustica L. across Europe. Aims: To develop and validate models of habitat factors which account for the distribution of breeding Barn Swallow colonies. Results: The models were based on data on the distribution of cattle farming provided by the public Bovine Computerized Database of the Regione Lombardia (northern Italy). Cattle distribution was a strong predictor of presence and size of Barn Swallow colonies as well as of the number of swallow colonies in a municipality. The models were robust and passed a cross-validation procedure and were used to estimate the spatial distribution of about 116,000 breeding pairs in awide area (8695 km(2)) of the low Po plain of northern Italy in 2001. Conclusions: Bovine computerized databases are mandatory in all European Union (EU) countries according to the EU Regulation (CE) 1760/2000. They may serve as a basis for wide scale modelling of the distribution and abundance of breeding Barn Swallow in Europe

Antioxidant Defenses Predict Long-Term Survival in a Passerine Bird

Normal and pathological processes entail the production of oxidative substances that can damage biological molecules and harm physiological functions. Organisms have evolved complex mechanisms of antioxidant defense, and any imbalance between oxidative challenge and antioxidant protection can depress fitness components and accelerate senescence. While the role of oxidative stress in pathogenesis and aging has been studied intensively in humans and model animal species under laboratory conditions, there is a dearth of knowledge on its role in shaping life-histories of animals under natural selection regimes. Yet, given the pervasive nature and likely fitness consequences of oxidative damage, it can be expected that the need to secure efficient antioxidant protection is powerful in molding the evolutionary ecology of animals. Here, we test whether overall antioxidant defense varies with age and predicts long-term survival, using a wild population of a migratory passerine bird, the barn swallow (Hirundo rustica), as a model.Plasma antioxidant capacity (AOC) of breeding individuals was measured using standard protocols and annual survival was monitored over five years (2006-2010) on a large sample of selection episodes. AOC did not covary with age in longitudinal analyses after discounting the effect of selection. AOC positively predicted annual survival independently of sex. Individuals were highly consistent in their relative levels of AOC, implying the existence of additive genetic variance and/or environmental (including early maternal) components consistently acting through their lives.Using longitudinal data we showed that high levels of antioxidant protection positively predict long-term survival in a wild animal population. Present results are therefore novel in disclosing a role for antioxidant protection in determining survival under natural conditions, strongly demanding for more longitudinal eco-physiological studies of life-histories in relation to oxidative stress in wild populations

Sex-Related Effects of an Immune Challenge on Growth and Begging Behavior of Barn Swallow Nestlings

Parent-offspring conflicts lead the offspring to evolve reliable signals of individual quality, including parasite burden, which may allow parents to adaptively modulate investment in the progeny. Sex-related variation in offspring reproductive value, however, may entail differential investment in sons and daughters. Here, we experimentally manipulated offspring condition in the barn swallow (Hirundo rustica) by subjecting nestlings to an immune challenge (injection with bacterial lipopolysaccharide, LPS) that simulates a bacterial infection, and assessed the effects on growth, feather quality, expression of morphological (gape coloration) and behavioral (posture) begging displays involved in parent-offspring communication, as well as on food allocation by parents. Compared to sham-injected controls, LPS-treated chicks suffered a depression of body mass and a reduction of palate color saturation. In addition, LPS treatment resulted in lower feather quality, with an increase in the occurrence of fault bars on wing feathers. The color of beak flanges, feather growth and the intensity of postural begging were affected by LPS treatment only in females, suggesting that chicks of either sex are differently susceptible to the immune challenge. However, irrespective of the effects of LPS, parents equally allocated food among control and challenged offspring both under normal food provisioning and after a short period of food deprivation of the chicks. These results indicate that bacterial infection and the associated immune response entail different costs to offspring of either sex, but a decrease in nestling conditions does not affect parental care allocation, possibly because the barn swallow adopts a brood-survival strategy. Finally, we showed that physiological stress induced by pathogens impairs plumage quality, a previously neglected major negative impact of bacterial infection which could severely affect fitness, particularly among long-distance migratory birds