https://hdl.handle.net/10481/31070 2026-04-03T18:20:26Z https://hdl.handle.net/10481/111988 Factors determining the timing of host response towards parasitic eggs: a meta-analytical approach Huertas Gómez, José Ignacio; Honza, Marcel; Ruiz-Raya, Francisco; Soler Cruz, Manuel; Samas, Peter Egg rejection is the most widespread defence strategy used by hosts of avian brood parasites to mitigate the fitness costs imposed by parasitism. Although the timing of this response (that is the latency between parasitism and egg rejection) is a critical component of host defences, the variation in rejection latency across different brood parasite–host systems remains poorly understood. Here, a meta-analysis of experimental studies on egg rejection was conducted to identify the key predictors of rejection latency. Results showed that hosts from sympatric populations, where parasites are present, tend to reject eggs more rapidly than hosts from allopatric populations. Egg characteristics strongly influenced response timing: mimetic eggs were ejected later; similarly sized eggs showed the longest latencies and smaller eggs were rejected most quickly. In addition, higher rejection rates were associated with shorter latencies. The duration of nest monitoring also showed a significant effect on measured latency, highlighting a major methodological factor that can bias latency estimates. Our findings indicate that the characteristics known to trigger egg rejection also shape its timing and emphasize the need for methodological standardization (particularly in nest monitoring protocols) to accurately assess egg-rejection behaviours. This work provides new insights into the proximate and ultimate factors driving the timing of host responses in avian brood parasite systems. https://hdl.handle.net/10481/111403 Interactions between urbanization, malaria infection and avian cloacal microbiome Garrigós, Marta; Jiménez-Peñuela, Jéssica; Saavedra, Irene; Veiga, Jesús; García-López, María José; Garrido Escudero, Mario; Ruiz-López, María José; Figuerola, Jordi; Moreno-Indias, Isabel; Martínez de la Puente, Josué Urbanization, a major component of global change, has drastically modified the landscape, and is generally associated with biodiversity loss. Pollutants and low-quality food resources, among other urban stressors, can alter the physiology of urban-dwelling birds, ultimately affecting their interactions with other organisms, including pathogens and symbiotic microorganisms. The house sparrow (Passer domesticus) is one of the most common passerine species closely associated with anthropized environments. Here, we explored the association between the level of habitat urbanization, avian malaria infection (Plasmodium and Haemoproteus are grouped together in this study) and their combined effects on the composition of the cloacal microbiome of wild house sparrows. Urban birds showed a lower parasite prevalence than those from natural and rural habitats. In addition, the association between avian malaria infection and avian cloacal bacterial-microbiome composition depended on the habitat type. In natural habitats, infected birds showed a nearly significant increase in bacterial richness and significant differences in the relative abundance of various taxa, compared to uninfected individuals. In contrast, infection status was not associated with any microbiome parameter in birds from rural and urban habitats. In conclusion, habitat type is associated with avian malaria prevalence in house sparrows and may modulate the relationship between parasite infection and the bacterial composition of avian cloacal microbiome. https://hdl.handle.net/10481/111399 A riddle wrapped in an enigma: parasitic lice as clues to the evolutionary puzzle of Sapayoa (Aves) Soto-Patiño, Juliana; Doña Reguera, Jorge; Johnson, Kevin P. Parasites can provide powerful insights into host evolution and biogeography. The bird Sapayoa aenigma, the only Neotropical member of the otherwise Old World clade Eurylaimides, has long puzzled ornithologists due to its phylogenetic placement and uncertain biogeographic origin. We investigated the evolutionary origin of a chewing louse in the genus Myrsidea found on Sapayoa. Using genome-wide data from 91 Myrsidea specimens from oscine, suboscine and non-passerine hosts, we reconstructed a global phylogeny to evaluate hypotheses about the origin of Sapayoa and its parasite. Phylogenomic, molecular dating and cophylogenetic analyses support a scenario in which the Myrsidea lineage on Sapayoa originated outside the Neotropics and was acquired via host-switching from an Old World oscine. The parasite’s divergence time (24.4–17.9 Ma) postdates the split between Sapayoa and other Eurylaimides, ruling out strict codivergence. Ancestral host reconstruction supports an oscine origin and Old World acquisition, and biogeographic analysis also indicates Old World origins, though with uncertainty in the exact region. These findings support a co-dispersal scenario in which Sapayoa acquired its parasite in the Old World and brought it to the Neotropics. Our study highlights the value of parasites as complementary tools for disentangling complex evolutionary and biogeographic histories. A Spanish translation is available in the electronic supplementary material. https://hdl.handle.net/10481/111296 Condition- and parasite- dependent expression of a male-like trait in a female bird Martínez Padilla, Jesús; Vergara, Pablo; Pérez-Rodríguez, Lorenzo; Casas Arenas, Fabián; Ludwig, Sonja; Haines, Jessica; Zeineddine, M.; Redpath, Steve In many species, females display brightly coloured and elaborate traits similar to those that males use in intra- and inter-sexual selection processes. These female characters are sometimes related to fitness, and might function as secondary sexual characteristics that have evolved through sexual selection. Here, we used descriptive data from 674 females in 10 populations and an experimental removal of Trichostrongylus tenuis parasites in four populations, to examine the effects of season, age, condition, and parasites on the size of supraorbital combs displayed by female red grouse Lagopus lagopus scoticus. We found that comb size (i) was greater during the breeding than the non-breeding season, (ii) was greater in adult than in young females, (iii) was positively correlated with body condition, and (iv) negatively correlated with parasite abundance. Experimentally, we showed that comb size increased proportionally to the number of worms removed after parasite dosing. Our findings provide a better understanding of proximate mechanisms behind the expression of a male-like trait in females, and we discuss its possible function as a female ornament. This study was funded by a Natural Environment Research Council grant (NE/D014352/1). https://hdl.handle.net/10481/111294 Local differences in habitat selection by great bustards Otis tarda in changing agricultural landscapes: implications for farmland bird conservation López-Jamar, Juan; Casas Arenas, Fabián; Díaz, Mario; Morales, Manuel B. Local changes in land use can influence patterns of habitat selection by farmland birds, thus biasing predictions of population responses to land use changes based on wildlife-habitat or niche modelling. This study, based in arable farmland in south-central Spain, determined whether habitat selection (use of agricultural habitats and the distance to roads, tracks and buildings) by Great Bustards Otis tarda varied between two nearby areas with differing land uses. The western sector has experienced a process of land abandonment and infrastructure development linked to an airport project that started in 1998 and finished in 2009, while the eastern sector maintains extensive dry farmland systems. Great Bustards avoided ploughed fields and selected short- and long-term fallows. Selection of fallows was more intensive in the sector suffering recent land-use changes, where these substrates were more abundant. Great Bustards were distributed further from roads, paths and buildings than would be expected if individual birds selected habitats at random. Avoidance of infrastructure was strongest in the area suffering recent land-use changes. Local patterns of habitat selection seemed to change in relation to agricultural abandonment and infrastructure development. Consequently, conservation measures based on knowledge of broad patterns of habitat use and selection such as agri-environmental schemes may fail to ensure steppe bird conservation locally if such local effects are overlooked. Specifically, schemes should include landscape-scale restrictions on the development and use of infrastructure (roads, tracks and buildings). Analyses of the patterns and causes of local and regional changes in habitat selection are essential to conserve populations of endangered farmland birds. This work is a contribution to the project EASY (Evaluating current European Agri-environment Schemes to quantify and improve nature conservation efforts in agricultural landscapes), financed by the V Framework Program of the EU (www.dow.wau.nl/natcons/NP/EASY) and to the project AGRIPOPES of the European Science Foundation.