Antioxidant supplementation during early development reduces parasite load but does not affect sexual ornament expression in adult ring-necked pheasants Phasianus colchicus

ArticleCopyright © 2012 The Authors. Functional Ecology © 2012 British Ecological Society1. The ‘parasite-mediated sexual selection’ (PMSS) hypothesis predicts that exaggerated male ornamentation could provide a signal to females of a males ability to resist parasites. Empirical tests of the PMSS have been largely equivocal, however, which may be because most have not considered the role of early life-history effects. 2. Many sexually-selected traits are carotenoid-based. Allocation of dietary-derived carotenoids to sexual ornaments may trade-off with allocation to pro-inflammatory immune response and/or antioxidant functions, mediated by the oxidative status of individuals. Exposure to parasites can increase oxidative stress, so under this scenario sexually-selected traits indicate ability to resist oxidative stress rather than ability to resist parasites per se. Such life-history trade-offs, mediated by oxidative status of individuals, are particularly acute during growth and development. 3. Here we use ring-necked pheasants, Phasianus colchicus, a strongly sexually-selected species, to test whether supplementation with dietary antioxidants (vitamin E) can mitigate the effects of early exposure to parasites (the nematode, Heterakis gallinarum), via alteration of the oxidative status of individuals, and positively affect the expression of sexual ornaments at adulthood. 4. We found that vitamin E mediated the effect of early exposure to parasites on levels of oxidative damage at 8 weeks of age and reduced the parasite load of individuals at adulthood as predicted. However, the expression of sexual ornaments, immune function, and growth were unaffected by either early vitamin E supplementation or manipulation of parasite load. In contrast to the predictions of the PMSS hypothesis the intensity of sexual ornament expression was not related to either parasite load or oxidative status of individuals (current or long-term). Consequently there was no evidence that the expression of sexual ornaments provided information on the ability of males to resist infection from parasites.NERCRoyal Societ

Habitat correlates of Eurasian woodcock Scolopax rusticola abundance in a declining resident population

In Europe, woodland bird populations have been declining since at least the 1970s, and in Britain, around one third of woodland bird species have undergone declines over this period. Habitat change has been highlighted as a possible cause, but for some species clear evidence of this is lacking owing to an incomplete knowledge of the species’ habitat requirements. Here, we analyse national data to explain the variation in abundance of a declining woodland bird, the Eurasian Woodcock. A nationwide, species-specific survey of breeding Woodcock was conducted in 2003 and 2013 at 807 and 823 randomly selected 1-km squares respectively. The counts were compared with a range of landscape-scale habitat variables as well as local habitat measures recorded by surveyors, using generalised linear mixed models. Habitat variables were measured at a variety of spatial scales using ring buffers, although our analyses show that strong collinearity between scales hinders interpretation. At large landscape scales, breeding Woodcock abundance was correlated with total woodland area and the way this interacted with woodland type. Woodcock were more abundant in woods containing a more heterogeneous mix of woodland habitat types and in woods further from urban areas. On a smaller spatial scale, Woodcock were less likely to be found at sites dominated by beech Fagus spp. and more likely to occur in woods containing birch Betula spp. The Woodcock’s association with large, heterogeneous woods and the apparent attractiveness of certain woodland types present the most relevant topics for future research into the role of habitat change in long-term declines

Summary review and synthesis: Effects on habitats and wildlife of the release and management of pheasants and red-legged partridges on UK lowland shoots

This is the final version. Available on open access from the Nordic Council for Wildlife Research via the DOI in this recordThis review examines 128 items of primary and other literature to provide an insight into current knowledge of the effects of pheasant and red-legged partridge releasing and associated management for shooting on habitats and wildlife in the UK. It summarizes key findings and uses them to define sub-topic sections for which the effects are classified as positive, neutral or negative. This forms the basis of a numerical synthesis of effects and some overall conclusions. Fifty-four directly related studies were identified, which defined 25 sub-topics or effects. A mix of positive, neutral and negative ecological consequences of releasing are described, for which the corresponding number of sub-topics approximately balance each other. Positive effects are usually a consequence of gamebird management activities, most negative effects are caused by the released birds themselves. The different spatial scales at which effects are likely to operate are identified, for example effects on generalist predators or of gamecrops occur at the landscape scale, while many habitat effects have a local impact. Some local negative effects have relatively straightforward management solutions for example, by identifying and avoiding especially sensitive sites when locating release pens. The synthesis identifies seven negative effects associated with the increasing scale of releasing. Several positive effects are linked to economic considerations and are more likely to have greater impact at larger shoots. Pheasants released into woodland have more direct local effects than partridge releases on farmland. The framework of sub-sections could be used as the basis for a more complex synthesis or weighted analysis for a particular set of ecological priorities. The review findings should be interpreted as representing a median type of shoot in terms of size and adherence to good practice over recent decades. They increase the awareness of potential conflicts, highlighting the need for best practice and what factors to consider for mitigation

Caenorhabditis elegans SMA-10/LRIG Is a Conserved Transmembrane Protein that Enhances Bone Morphogenetic Protein Signaling

Bone morphogenetic protein (BMP) pathways control an array of developmental and homeostatic events, and must themselves be exquisitely controlled. Here, we identify Caenorhabditis elegans SMA-10 as a positive extracellular regulator of BMP–like receptor signaling. SMA-10 acts genetically in a BMP–like (Sma/Mab) pathway between the ligand DBL-1 and its receptors SMA-6 and DAF-4. We cloned sma-10 and show that it has fifteen leucine-rich repeats and three immunoglobulin-like domains, hallmarks of an LRIG subfamily of transmembrane proteins. SMA-10 is required in the hypodermis, where the core Sma/Mab signaling components function. We demonstrate functional conservation of LRIGs by rescuing sma-10(lf) animals with the Drosophila ortholog lambik, showing that SMA-10 physically binds the DBL-1 receptors SMA-6 and DAF-4 and enhances signaling in vitro. This interaction is evolutionarily conserved, evidenced by LRIG1 binding to vertebrate receptors. We propose a new role for LRIG family members: the positive regulation of BMP signaling by binding both Type I and Type II receptors

Effects of Supplementary Feeding on the Breeding Ecology of the Buff-Throated Partridge in a Tibetan Sacred Site, China

Our goal was to document effects of year-round supplemental feeding on breeding ecology of the Buff-throated Partridge, Tetraophasis szechenyii, within a Tibetan sacred site. We evaluated effects of supplemental feeding used as religious/cultural practices which could potentially aid conservation of endangered phasianids. We compared fed breeding groups to neighboring nonfed groups. Fed groups initiated first clutches significantly earlier than nonfed groups. Earlier laying groups within fed and nonfed groups showed significantly lower hatching rates than later groups; however, fed groups showed significantly higher hatching rates than nonfed groups laying in the same period. Earlier laying increased opportunities to renest. All six fed groups with clutch failures renested compared to only one of five nonfed groups with clutch failures. Fed female breeders showed significantly greater investment in their young with larger clutches and larger eggs, which likely increased survivability of early hatchlings. We observed no predation on birds at feeding sites and recorded only four cases of predation on incubating females, which showed no detectable difference between fed and nonfed groups. Ground-nesting birds typically face high risks of predation. Ten of the 48 groups nested in trees, which occurs in few phasianid species. Tree nests showed significantly higher hatching rates compared to ground nests; however, we found no significant difference in tree nesting between fed and nonfed groups. This partridge is one of four gallinaceous species with cooperative breeding. Breeding groups with helpers had significantly greater reproductive success than single pairs, and fed female breeders with helpers laid bigger eggs than single pairs. Comparing annual reproductive output per group, fed groups not only produced significantly more independent young (≥150 days post-hatching), their young hatched significantly earlier, which likely have greater reproductive value over later hatched young of nonfed groups. Supplemental feeding year-round is likely what enabled the successes of the fed partridges

Effects of tick Ixodes ricinus infestation on pheasant Phasianus colchicus breeding success and survival

In some parts of Britain, pheasants Phasianus colchicus are infested by Ixodes ricinus ticks in the spring and summer. The effects of experimental reduction of tick infestation levels on the breeding success and survival of reared female pheasants were studied on two estates in southern England during 1995-1997. Females were radio-tagged and half of the birds, selected at random, were fitted with a slow-release acaricide, which substantially reduced their tick burdens. Clutch survival was significantly higher for treated females throughout the three-year study period, and hence more chicks were hatched by treated females (3.30 ± 0.86) than by control females (0.70 ± 0.36), even though treated and control birds produced the same numbers of clutches and eggs. During April-July, the female survival rate was significantly higher for acaricide-treated birds, showing an improvement of 10-15% over that of control birds each year. While these impacts will be of minor importance where annual pheasant releasing takes place to supplement autumn stocks for shooting, they might reduce the potential harvest on estates with wild pheasants or on those aiming to re-establish self-sustaining naturalised populations