BUSCADOR RECOLECTA

The role of plumage ornamentation as a signal of parasite infection is a key issue in the evolution of animal behaviour. Despite the undeniable role of host–parasite interactions in sexual selection, it is still unclear how parasites influence the variance in the expression of females displaying multiple ornaments. Here, by taking advantage of a long-term and individual-based, monitored population of pied flycatchers, Ficedula hypoleuca, in a Mediterranean area, we investigated the variation in the expression of wing patch (size) and forehead patch (occurrence and size) in relation to infections with haemosporidian parasites in breeding adult females. Haemosporidian infection was related to wing patch size, and this association varied in direction and magnitude depending on the origin of birds (locally born versus immigrant) and the type of breeding habitat (oakwood versus pine plantation). Specifically, differences in wing patch size were most evident among immigrant females breeding in the pine plantation, with noninfected females expressing larger wing patches than infected ones. Regarding the forehead patch, its occurrence was also modulated by haemosporidian infection through two-way interactions with bird origin (lower occurrence in locally born females) and breeding habitat type (lower occurrence among infected than uninfected females in the oakwood, whereas the opposite was true in the pine plantation). Only bird age predicted forehead patch size. Therefore, in addition to haemosporidian infection, the expression of these ornaments was related to extrinsic (breeding habitat) and intrinsic (age, origin) factors, which suggests the existence of trade-offs between physiological responses to infection and the expression of secondary sexual traits. Overall, our results suggest that plumage ornaments provide independent and reliable information on the haemosporidian infection status of female pied flycatchers., This research was supported by projects CGL2006-07481/BOS (to J. C. Senar), CGL2009-10652 (to J. C. Senar), CGL2011-29694 (to J. Potti) and CGL2014- 55969-P (to F. Valera) from the Spanish Ministry of Education and project PAC05-006-2 (to J. A. Dávila) from Universidad de Castilla-La Mancha (UCLM, Spain). During writing, E.G.B. was supported by a Margarita Salas Contract financed by the European Union-NextGenerationEU and the Recovery, Transformation and Resilience Plan (Spanish Ministry of Universities). C.C. was supported by the grant ref. RYC2021-033977-I funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. J.M. was supported by a postdoctoral researcher contract for scientific excellence under the Plan Propio de I+D+i of the Universidad de Castilla – La Mancha (UCLM). D.C. was supported by a Talent Attraction fellowship from the Autonomous Community of Madrid (CAM), Spain (2022-T1_AMB-24025) and the project PID2022-141763NA-I00, funded by MCIN/AEI (https://doi.org/10.13039/501100011033)., Funding for open access charge: Universidad de Granada / CBUA., Peer reviewed

Temporal changes in environmental conditions may play a major role in the year-to-year variation in fitness consequences of behaviours. Identifying environmental drivers of such variation is crucial to understand the evolutionary trajectories of behaviours in natural contexts. However, our understanding of how environmental variation influences behaviours in the wild remains limited. Using data collected over 14 breeding seasons from a collared flycatcher (Ficedula albicollis) population, we examined the effect of environmental variation on the relationship between survival and risk-taking behaviour, a highly variable behavioural trait with great evolutionary and ecological significance. Specifically, using annual recapture probability as a proxy of survival, we evaluated the specific effect of predation pressure, food availability, and mean temperature on the relationship between annual recapture probability and risk-taking behaviour (measured as flight initiation distance [FID]). We found a negative trend, as the relationship between annual recapture probability and FID decreased over the study years and changed from positive to negative. Specifically, in the early years of the study, risk-avoiding individuals exhibited a higher annual recapture probability, whereas in the later years, risk-avoiders had a lower annual recapture probability. However, we did not find evidence that any of the considered environmental factors mediated the variation in the relationship between survival and risk-taking behaviour., K-115970/Hungarian National Research, Development and Innovation Office
CGL2015-70639-P/Ministry of Economy and Competitiveness in Spain
Eötvös Loránd University
PID2019-104835GB-I00/ARAID Foundation and the Ministry of Science and Innovation
2019-353/Hungarian Academy of Sciences, Peer reviewed

The study of host–parasite co-evolution is a central topic in evolutionary ecology. However, research is still fragmented and the extent to which parasites influence host life history is debated. One reason for this incomplete picture is the frequent omission of environmental conditions in studies analyzing host–parasite dynamics, which may influence the exposure to or effects of parasitism. To contribute to elucidating the largely unresolved question of how environmental conditions are related to the prevalence and intensity of infestation and their impact on hosts, we took advantage of 25 years of monitoring of a breeding population of pied flycatchers, Ficedula hypoleuca, in a Mediterranean area of central Spain. We investigated the influence of temperature and precipitation during the nestling stage at a local scale on the intensity of blowfly (Protocalliphora azurea) parasitism during the nestling stage. In addition, we explored the mediating effect of extrinsic and intrinsic factors and blowfly parasitism on breeding success (production of fledglings) and offspring quality (nestling mass on day 13). The prevalence and intensity of blowfly parasitism were associated with different intrinsic (host breeding date, brood size) and extrinsic (breeding habitat, mean temperature) factors. Specifically, higher average temperatures during the nestling phase were associated with lower intensities of parasitism, which may be explained by changes in blowflies’ activity or larval developmental success. In contrast, no relationship was found between the prevalence of parasitism and any of the environmental variables evaluated. Hosts that experienced high parasitism intensities in their broods produced more fledglings as temperature increased, suggesting that physiological responses to severe parasitism during nestling development might be enhanced in warmer conditions. The weight of fledglings was, however, unrelated to the interactive effect of parasitism intensity and environmental conditions. Overall, our results highlight the temperature dependence of parasite–host interactions and the importance of considering multiple fitness indicators and climate-mediated effects to understand their complex implications for avian fitness and population dynamics., This research received support from projects CGL2006-07481/BOS (to J.C. Senar), CGL2009-10652 (to J.C. Senar), CGL2011-29694 (to J. Potti), and CGL2014-55969-P (to F. Valera) from the Spanish Ministry of Education, as well as project PAC05-006-2 (to J.A. Dávila) from the Universidad de Castilla-La Mancha (Spain). During the writing process, E.G.B. was supported by a Margarita Salas Contract financed by the European Union-NextGenerationEU and the Recovery, Transformation, and Resilience Plan (Spanish Ministry of Universities). D.C. received support through a Talent Attraction fellowship from the Autonomous Community of Madrid (CAM), Spain (2022-T1_AMB-24025), and the projects PID2022-141763NA-I00, CGL2015-70639-P, and PID2019-104835GB-I00, funded by MCIN/AEI (doi: 10.13039/501100011033). C.C. was supported by the grant ref. RYC2021-033977-I funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. J.M.P. was supported by the ARAID Foundation. Funding for open access charge: Universidad de Granada/CBUA., Peer reviewed

The major histocompatibility complex (MHC) plays a critical role in the immune response against pathogens. Its high polymorphism is thought to be mainly the consequence of host-pathogen co-evolution, but elucidating the mechanism(s) driving MHC evolution remains challenging for natural populations. We investigated the diversity of MHC class II genes in a wild population of pied flycatchers Ficedula hypoleuca and tested its associations with two key components of individual fitness: lifetime reproductive success and survival. Among 180 breeding adults in our study population, we found 182 unique MHC class II exon 2 alleles. The alleles showed a strong signal of positive selection and grouped into nine functional supertypes based on physicochemical properties at the inferred antigen-binding sites. Three supertypes were found in > 98% of the sampled individuals, indicating that they are nearly fixed in the population. We found no rare supertypes in the population, as all supertypes were present in > 70% of individuals. Three supertypes were related to different components of individual fitness: two were associated with lower offspring production over time, while the third was positively associated with survival. Overall, the substantial allelic and functional diversity and the relationship between specific supertypes and fitness are in accordance with the notion that balancing selection maintains MHC class II diversity in the study population, possibly with fluctuating selection as the underlying mechanism. The absence of rare supertypes in the population suggests that the balancing selection is not driven by rare-allele advantage., This work was supported by projects PAC05-006-2, CGL2006-07481/BOS from the Ministerio de Ciencia e Innovación, Spain. Most recently this work has been supported by the Comunidad Autónoma de Madrid (CAM), Spain (project: 2022-T1_AMB-24025 to DC) and the Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación, MCIN/ AEI/10.13039/501100011033 (project: PID2022-141763NA-I00 to DC). D.C. received support from a CAM Talent Attraction grant associated with project 2022-T1_AMB-24025. C.C. was supported by the grant ref. RYC2021-033977-I funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. JR was funded by the Swedish Research Council grant 2020-06488., Peer reviewed

The major histocompatibility complex (MHC) plays a critical role in the immune response against pathogens. Its high polymorphism is thought to be mainly the consequence of host-pathogen co-evolution, but elucidating the mechanism(s) driving MHC evolution remains challenging for natural populations. We investigated the diversity of MHC class II genes in a wild population of pied flycatchers Ficedula hypoleuca, and tested its associations with two key components of individual fitness: lifetime reproductive success and survival. Among 180 breeding adults in our study population, we found 182 unique MHC class II exon 2 alleles. The alleles showed a strong signal of positive selection and grouped into 9 functional supertypes based on physicochemical properties at the inferred antigen-binding sites. Three supertypes were found in > 98% of the sampled individuals, indicating that they are nearly fixed in the population. We found no rare supertypes in the population, as all supertypes were present in >70% of individuals. Three supertypes were related to different components of individual fitness: two were associated with lower offspring production over time, while the third was positively associated with survival. Overall, the substantial allelic and functional diversity and the relationship between specific supertypes and fitness is in accordance with the notion that balancing selection maintains MHC class II diversity in the study population, possibly with fluctuating selection as the underlying mechanism. The absence of rare supertypes in the population suggests that the balancing selection is not driven by rare-allele advantage., Comunidad de Madrid : 2022-T1_AMB-24025, Beca Atracción de Talento de la Comunidad de Madrid; Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación : PID2022-141763NA-I00, Proyectos de Generación de Conocimiento, Peer reviewed

Population genetics is an invaluable tool for studying and conserving scarcely researched and elusive threatened species. The Chaco eagle (Buteogallus coronatus) is one of the rarest and most severely threatened raptors in the Neotropical region, and due to its elusiveness, many aspects of the species’ life history, with important conservation implications, remain mostly unknown. Here, relying primarily on non-invasive DNA sampling at a large spatio-temporal scale, we investigate the reproductive strategies of the Chaco eagle. Over twelve years (2002–2014), we collected 87 moulted feathers from territorial individuals and blood samples from 32 nestlings at 30 nesting sites distributed across a large region (approximately 30,000 km2) of semiarid habitats in Argentina. A primary aim was to elucidate whether this species breeds on a two-year cycle basis, a crucial but still unclear aspect of its life history since, if confirmed, this delay would impose a significant limitation on the lifetime productivity of Chaco eagles across its entire range. We also investigated the occurrence of pair substitutions and territory changes between reproductive events, factors likely intertwined with adult mortality rates and anthropogenic pressures. We found conclusive evidence that eagles may breed annually. In addition, our data suggest that the replacement of a pair member and/or the breeding dispersal to another territory (up to 30 km away) is not uncommon in the species, presumably due to human-related mortality. These spatial patterns of breeding territory selection and breeding dispersal have never been described for large eagles in the Neotropics and highlight the potential ecological consequences of human pressure on this keystone species. Overall, these findings bear direct implications for the demographic dynamics, management, and conservation strategies of the Chaco eagle., DC was supported by a CONICET postdoctoral fellowship, a Talent attraction program from the Autonomous Community of Madrid, Spain (ref: 2022-T1/AMB-24025) and the project PID2022–141763NA-I00 funded by MCIN/AEI/10.13039/501100011033. This study was funded by the Facultad de Ciencias Exactas y Naturales - UNLPam (Argentina), The Peregrine Fund (USA) and the Agencia Española de Cooperación Internacional para el Desarrollo (AECID, Spain), Peer reviewed

Natal dispersal is a key life history trait determining fitness and driving population dynamics, genetic structure, and species distributions. Despite existing evidence that not all phenotypes are equally likely to successfully establish in new areas, the mechanistic underpinnings of natal dispersal remain poorly understood. The propensity to disperse into a new environment can be favoured by a high degree of phenotypic plasticity, which facilitates local adaptation and may be achieved via epigenetic mechanisms, which modify gene expression and enable rapid phenotypic changes. Epigenetic processes occur in particular genomic regions—DNA methylation on CpG sites in vertebrates—and thus individual genomes may differ in their capacity to be modified epigenetically. This ‘Epigenetic potential’ (EP) may represent the range of phenotypic plasticity attainable by an individual and be a key determinant of successful settlement in novel areas. We investigated the association between EP—quantified as the number of genome-wide CpG variants—and natal dispersal propensity in a long-term study population of Pied flycatchers (Ficedula hypoleuca) monitored since colonisation of a new habitat 35 years ago. We tested this association at three levels, comparing EP between: (i) individuals dispersing between and within habitat patches; (ii) immigrants to the population and locally born individuals; and (iii) individuals from first (comprising colonisers or their direct descendants) and later generations of the population (consisting of locally born individuals, which did not show natal dispersal between habitat patches). Results show a significant, positive association between EP and dispersal propensity in comparisons (i)—only in females—and (iii), but not (ii). Furthermore, CpG variants were non-randomly distributed across the genome, suggesting species- and/or population-specific CpGs being more frequent in promoters and exons. Our findings point to EP playing a role in dispersal propensity at spatial and temporal scales, supporting the idea that epigenetically driven phenotypic plasticity facilitates dispersal and environmental coping in free-living birds., B.J. was funded by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 101027784. M.T. was supported by an Adaptive Life Scholarship awarded by the University of Groningen. M.R. was funded by a FRIPRIO Research Council Norway Grant (Project Number: 314866) and by a start-up grant at the University of Nottingham. C.C. received support from the MCIN/AEI/10.13039/501100011033 and the European Union Next Generation EU/PRTR through contracts no. FJC2018-038412-I and RYC2021-033977-I. D.C. was supported by a Talent Attraction fellowship from the Autonomous Community of Madrid (CAM), Spain (2022-T1_AMB-24025) and the project PID2022/141763NA-100, funded by MCIN/AEI/10.13039/501100011033. J.C.D. was supported by a Margarita Salas postdoctoral fellowship (MS2022 call) provided by the Spanish Ministry of Science, Innovation and Universities (Next Generation EU funds) and Universidad de Castilla- La Mancha (Spain). J.T.G also benefited from the support of Research Project ref. 022-GRIN-34462, funded by the University of Castilla-La Mancha and the Fondo Europeo de Desarrollo Regional (FEDER). Fieldwork was funded by I + D National Plan Projects of the Spanish Ministry of Economy, Industry and Competitiveness (PID2019-104835GB-I00 and PID2022-138133NB-100), co-funded by European Regional Development Fund FEDER, EU., Peer reviewed