Ectoparasite presence and brood size manipulation interact to accelerate telomere shortening in nestling jackdaws

Early‐life conditions impact fitness, but whether the combined effect of extrinsic stressors is additive or synergistic is not well known. This is a major knowledge gap because exposure to multiple stressors is frequent. Telomere dynamics may be instrumental when testing how stressors interact because many factors affect telomere shortening, and telomere shortening predicts survival. We evaluated the effect of manipulated brood size and natural infestation by the carnid fly Carnus hemapterus on nestling growth and telomere shortening of wild jackdaws (Corvus monedula). Telomere length, measured in blood using TRF, shortened on average by 264 bp, and on average, Carnus infection induced more telomere shortening. Further analyses showed that in enlarged broods, nestlings' telomeres shortened more when parasitized, while in reduced broods there was no effect of infection on telomere shortening. We conclude that there is a synergistic effect of number of siblings and Carnus infection on telomere shortening rate: blood‐sucking parasites may negatively impact telomeres by increasing cell proliferation and/or physiological stress, and coping with infection may be less successful in enlarged broods with increased sibling competition. Larger nestlings had shorter telomeres independent of age, brood manipulation or infection. Growth was independent of infestation but in enlarged broods, nestlings were lighter at fledging. Our findings indicate that (i) evaluating consequences of early‐life environmental conditions in isolation may not yield a full picture due to synergistic effects, and (ii) effects of environmental conditions may be cryptic, for example, on telomeres, with fitness consequences expressed beyond the temporal framework of the study

Social effects on age-related and sex-specific immune cell profiles in a wild mammal

Evidence for age-related changes in innate and adaptive immune responses is increasing in wild populations. Such changes have been linked to fitness, and knowledge of the factors driving immune response variation is important for understanding the evolution of immunity. Age-related changes in immune profiles may be owing to factors such as immune system development, sex-specific behaviour and responses to environmental conditions. Social environments may also contribute to variation in immunological responses, for example, through transmission of pathogens and stress arising from resource and mate competition. Yet, the impact of the social environment on age-related changes in immune cell profiles is currently understudied in the wild. Here, we tested the relationship between leukocyte cell composition (proportion of neutrophils and lymphocytes [innate and adaptive immunity, respectively] that were lymphocytes) and age, sex and group size in a wild population of European badgers (Meles meles). We found that the proportion of lymphocytes in early life was greater in males in smaller groups compared to larger groups, but with a faster age-related decline in smaller groups. By contrast, the proportion of lymphocytes in females was not significantly related to age or group size. Our results provide evidence of sex-specific age-related changes in immune cell profiles in a wild mammal, which are influenced by the social environment

Assessing the Effects of Climate on Host-Parasite Interactions: A Comparative Study of European Birds and Their Parasites

[Background] Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals. [Methodology/Principal Finding] Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas. We investigated whether change in abundance and prevalence of parasites was related to change in body condition, reproduction and population size of hosts. We conducted analyses based on the entire dataset, but also on a restricted dataset with intervals between study years being 5–15 years. Parasite abundance increased over time when restricting the analyses to datasets with an interval of 5–15 years, with no significant effect of changes in temperature at the time of breeding among study sites. Changes in host body condition and clutch size were related to change in temperature between first and second study year. In addition, changes in clutch size, brood size and body condition of hosts were correlated with change in abundance of parasites. Finally, changes in population size of hosts were not significantly related to changes in abundance of parasites or their prevalence. [Conclusions/Significance] Climate change is associated with a general increase in parasite abundance. Variation in laying date depended on locality and was associated with latitude while body condition of hosts was associated with a change in temperature. Because clutch size, brood size and body condition were associated with change in parasitism, these results suggest that parasites, perhaps mediated through the indirect effects of temperature, may affect fecundity and condition of their hosts. The conclusions were particularly in accordance with predictions when the restricted dataset with intervals of 5–15 years was used, suggesting that short intervals may bias findings.The Academy of Finland is acknowledged for a grant to TE (project 8119367) and EK (project 250709). PLP was supported by a research grant (TE_291/2010) offered by the Romanian Ministry of Education and Science. T. Szép received funding from OTKA K69068 and JT from OTKA 75618. JMP was supported by a JAE grant from Consejo Superior de Investigaciones Científicas. SM-JM, FdL-AM, JF, JJS and FV were respectively supported by projects CGL2009-09439, CGL2012-36665, CGL2009- 11445, CGL2010-19233-C03-01 and CGL2008-00562 by the Spanish Ministry of Science and Innovation and FEDER and project EVITAR by the Spanish Ministry of Health. FV was also supported by the European Regional Development Fund. MACT was funded by a predoctoral FPU grant from the Spanish Ministry of Education (AP20043713). PM was supported by grant from the Polish Ministry of Science and Higher Education (project 2P04F07030), and the Foundation for Polish Science

Hemoparasites and immunological parameters in Snow Bunting (Plectrophenax nivalis) nestlings

Knowledge on hemoparasites and immunological parameters in wild birds with Arctic distribution is limited. In this study, we chose the Snow Bunting (Plectrophenax nivalis) as model species to address this issue. Using nestlings, we aimed at (i) detecting hemoparasites with vector-borne transmission (via microscopic and molecular methods) and nest-dwelling ectoparasites and at (ii) exploring the relationship between several immunological parameters and parasitism. Nestlings were infected by Lankesterella parasites but hemoparasites of the genera Plasmodium, Haemoproteus, Leucocytozoon, Trypanosoma, Hepatozoon or Babesia were not found. This result may indicate the lack of suitable dipteran vectors or the inability of haemosporidians to reproduce in the Arctic region. Inflammation in response to the phytohaemagglutinin (PHA) injection was negatively related to infection by Lankesterella and positively related to weight gain in nestlings. The number of leukocytes and IgG level were not related to infection or PHA response, although the relationship between IgG level and PHA immune response was marginally significant. Besides, nestlings reared in mite-infected nests showed higher IgG level than those reared in mite-free nests. Taken together, (i) the positive relationship between PHA response/weight gain and PHA response/IgG level could reflect the nestlings’ nutritional status; and (ii) the higher IgG level in nestlings reared in mite-infected nests may be the result of a specific immune response to mite antigens. Different parasites may alter distinct immunological parameters in birds breeding under extreme weather conditions.This work has been funded by project CTM2010-11387 of the Ministry of Science and Innovation (Spain). The fieldwork was carried out with the support of the Group of research of Prof. Arne Moksnes of the Norwegian University of Science and Technology.Peer Reviewe

Individual Quality and Extra-Pair Paternity in the Blue Tit: Sexy Males Bear the Costs

Adaptive explanations for the evolution of extra-pair paternity (EPP) suggest that females seek extra-pair copulations with high quality males. Still, the link between ornamentation, individual quality, and paternity remains unclear. Moreover, honest signaling is essential when explaining EPP because it is needed for sexual selection to occur; yet, it is understudied in multiple ornaments. Because blue tits (Cyanistes caeruleus) show variable color expression in several plumage patches, we tested: (i) over two seasons, whether males in better condition, more ornamented and less infected by blood parasites gain EPP and have higher reproductive success, and (ii) over three seasons, whether mating patterns affect color change. Males with more saturated yellow feathers, brighter tails, and in better condition had higher reproductive success in one of the seasons. Contrary to expectation, in another season, males that gained EPP were parasitized by blood parasites, suggesting increased vector exposure during extra-pair copulations. Our results for two seasons show that males siring more extra-pair young were older and grew brighter cheek or tail feathers for the following season. Despite the increased mating costs, in socially monogamous avian systems, high quality males incur in EPP without compromising traits that may be under sexual selection.This study was funded by projects CGL2012-40026-C02-01 and CGL2012-40026-C02-02 from the MEC (Ministerio de Economía y Competitividad). E.P.B. was supported by a JAE grant from the Spanish National Research Council (CSIC)

Colour change in a structural ornament is related to individual quality, parasites and mating patterns in the blue tit

Carry-over effects refer to processes that occur in one season and influence fitness in the following. In birds, two costly activities, namely reproduction and moult, are restricted to a small time window, and sometimes overlap. Thus, colour in newly moulted feathers is likely to be affected by the costs of reproduction. Using models of bird vision we investigated male colour change in a free-living population of blue tits (Cyanistes caeruleus) in three sampling occasions: spring 1, winter and spring 2. We related crown, tail, breast and cheek feather colouration after the moult (winter) to the intensity of infections by blood parasites during reproduction (spring 1). In the following spring (spring 2), we explored mating patterns with respect to changes in feather colour (springs 1 vs. 2). Males that were less intensely infected by the malaria parasite Plasmodium while breeding showed purer white cheek feathers in winter, which may indicate higher feather quality. Increased brightness in the white cheek was associated with better body condition during reproduction. In the following season, males with brighter cheeks paired with females that had noticeably brighter cheek patches compared to the male’s previous mate. These results suggest that the conditions experienced during reproduction are likely to affect moult and thus feather colouration, at least in the white patch. High quality individuals may allocate resources efficiently during reproduction increasing future reproductive success through variation in mating patterns. Carry-over effects from reproduction might extend not only to the non-breeding phase, but also to the following breeding season.This study was funded by projects CGL2012-40026-C02-01 and CGL2012-40026-C02-02 from the MEC (Ministerio de Economia y Competitividad).Peer Reviewe

Comprobación de un nuevo método para reducir la infección por ectoparásitos en cajas-nido

[EN] In wild bird populations nestlings are commonly infested by ectoparasites. The effects that ectoparasites exert on host fitness usually become evident after the complete elimination of parasites or a substantial reduction in their abundance. Among the most common elimination methods in ecological studies, the use of chemical insecticides is traditionally preferred. However, the application of several doses is usually needed because the efficiency of insecticides decreases over time. This results in increasing toxicity effects and disturbance of both parents and nestlings. In the present study, we tested the efficacy of Inesfly, a new insecticidal paint. Inesfly acts by releasing active water-soluble compounds progressively over a period, therefore having a longer-lasting effect than other insecticides. By applying this insecticidal paint inside nest-boxes used by blue tits Cyanistes caeruleus during the breeding season, we investigated its effect on the abundance of blackfly (Simuliidae), biting midge (Culicidae), flea (Ceratophyllidae), mite (Dermanyssidae) and blowfly (Calliphoridae) larvae. The insecticide significantly reduced the abundance of Protocalliphora azurea blowflies, while other parasites remained unaffected. Our results show that Inesfly was ineffective against ectoparasites infesting blue tit nest-boxes, blowflies excepted, at least at the dose applied. Finally, no negative effects on nestlings were reported following the use of this insecticide.[ES] En las poblaciones naturales de aves los polluelos son comúnmente infectados por ectoparásitos. Los efectos que estos ectoparásitos tienen en la eficacia biológica del hospedador se hacen evidentes después de la eliminación completa o de la reducción substancial de su abundancia. Entre los métodos más utilizados, la aplicación de insecticidas es el preferido tradicionalmente. Sin embargo, debido a que la eficacia del insecticida disminuye a lo largo del tiempo, generalmente se necesita la aplicación de varias dosis. Esto resulta en un aumento de la toxicidad y molestias en la reproducción tanto para los padres como para los polluelos. En este estudio, hemos probado la eficacia de un nuevo insecticida (Inesfly). Inesfly actúa mediante la liberación progresiva de compuestos activos solubles en agua, por lo tanto teniendo un efecto a largo plazo comparado con insecticidas anteriores. Mediante la aplicación experimental de este insecticida en forma de pintura dentro de las cajas nido de una población de herrerillo común Cyanistes caeruleus durante la época reproductora, investigamos su efecto en la abundancia de mosca negra (Simuliidae), jején (Culicidae), pulga (Ceratophyllidae), ácaro (Dermanyssidae) y larva de mosca azul (Calliphoridae). El insecticida redujo significativamente la abundancia de la mosca azul Protocalliphora azurea, mientras que la de otros parásitos no se vio afectada. Nuestros resultados muestran que Inesfly no fue efectivo con respecto a los ectoparásitos que infectan las cajas nido de herrerillos excepto para la mosca azul, al menos en la dosis aplicada. Finalmente, no se observaron efectos negativos en los polluelos después de la aplicación de este insecticida.This study was funded by project CGL2012-40026-C02-01 from the Ministerio de Ciencia e Innovación. Rodrigo Megía was supported by Ministerio de Ciencia e Innovación FPI grants.Peer Reviewe

Eggshell pigmentation in the blue tit: male quality matters

Many passerines lay protoporphyrin-pigmented eggs, and the degree of spotting seems to be related to female condition and environmental characteristics. However, most studies have ignored the relationship between the male’s quality and eggshell pigmentation. Because ornaments can act as honest indicators of individual quality, spottiness could be related to the parents’ feather colouration. Using models of bird vision, we investigated whether male and female ornamentation explained variation in spotting coverage in a free-living population of blue tits (Cyanistes caeruleus). We also explored the associations between other important individual characteristics (i.e. the pair’s infection status) and spotting coverage. Females that laid more pigmented eggs suffered from higher parasitaemia by the blood parasite Leucocytozoon and had smaller clutches, more saturated yellow breast feathers and reduced body mass. Male plumage colour and infection status explained a higher percentage of the variation in eggshell pigmentation than female characteristics. Males that had more saturated white cheeks and less saturated yellow breasts and were more intensely infected by the parasite Haemoproteus and less by Plasmodium attended nests with more spotted eggs. Additionally, these males were younger and more likely to father extra-pair offspring. These results, although observational, suggest that male attractiveness, male age, extra-pair paternity and parasitic infections could be important determinants of eggshell pigmentation. Males in poorer condition might have provided less food to laying females, which in turn laid more pigmented eggs and were also in poor condition. Alternatively, increased eggshell pigmentation could result from female differential allocation or breeding in low-quality territories.This study was funded by projects CGL2012-40026-C02-01 to SM and CGL2012-40026-C02-02 to JM from the MEC (Ministerio de Economia y Competitividad). EPB was supported by a JAE grant from the Spanish National Research Council (CSIC).Peer Reviewe

Early‐life seasonal, weather and social effects on telomere length in a wild mammal

Early-life environmental conditions can provide a source of individual variation in life-history strategies and senescence patterns. Conditions experienced in early life can be quantified by measuring telomere length, which can act as a biomarker of survival probability in some species. Here, we investigate whether seasonal changes, weather conditions, and group size are associated with early-life and/or early-adulthood telomere length in a wild population of European badgers (Meles meles). We found substantial intra-annual changes in telomere length during the first three years of life (both between and within individuals), with shorter telomere lengths in the winter following the first spring and a trend for longer telomere lengths in the second spring compared to the first winter. In terms of weather conditions, cubs born in warmer, wetter springs with low rainfall variability had longer early-life (3–12 months old) telomere lengths. Additionally, cubs born in groups with more cubs had marginally longer early-life telomeres, providing no evidence of resource constraint from cub competition. We also found that our previously documented positive association between early-life telomere length and cub survival probability remained when social and weather variables were included. Finally, after sexual maturity, in early adulthood (i.e. 12–36 months) we found no significant association between same-sex adult group size and telomere length (i.e. no effect of intra-sexual competition). Overall, we show that controlling for seasonal effects, which are linked to food availability and foraging success, is important in telomere length analyses, and that variation in telomere length in badgers reflects early-life conditions and also predicts first year cub survival

Repeated measures ANOVAs with laying date, clutch size, brood size, body condition and population density of hosts in two separate study years as within subjects factors and locality identity, host identity, latitude, interval in years and temperature change (°C/year) as between subjects factors.

<p>Each effect was estimated in separates models. P-values smaller than 0.05 are shown in bold.</p