Biology subjects

Figuerola, J.

Publications and source records attributed to Figuerola, J..

5 recordsLinked to original sources

bioRxiv2026

Ecotypes, Wolbachia, and urbanization shape Culex pipiens population structure in a West Nile virus hotspot

Culex pipiens is a major vector of West Nile Virus (WNV) in Europe and has a complex evolutionary history that has been linked to the probability of WNV spillover to humans. Here, we present a population genomic analysis of Cx. pipiens from a WNV hotspot in southwestern Spain. Whole-genome sequencing of 217 individuals from 24 localities revealed that population structure is mainly shaped by the coexistence of pipiens and molestus ecotypes. Despite clustering, genome-wide divergence between ecotypes was low, consistent with shared ancestral variation. Furthermore, Wolbachia infection was heterogeneous across the study area, where some Culex pipiens pipiens remain uninfected. We also identified three new polymorphic chromosomal inversions on chromosomes 1 and 3 that segregate independently. Although inversions did not underlie ecotypic differentiation, they were enriched for genes involved in olfaction and insecticide resistance pathways, suggesting potential adaptive and epidemiological relevance. Distance-based redundancy analyses showed that ecotype identity explained the largest fraction of genetic variance, with additional contributions from Wolbachia infection, habitat type (urban versus rural) and geographic distance. These results reveal that partial ecotypic differentiation, symbiont infection, and habitat interact to shape population structure in Cx. pipiens, with implications for vector ecology and disease transmission.

genomics↗

bioRxiv2025

Falcons use wind assistance and remote islands to mitigate risk during ocean-crossings

Wind conditions play a major role in determining how birds negotiate ecological barriers during long-distance migration. Migrants typically minimize flights over barriers in opposing winds, while crossing the same barriers directly in supportive winds. Nevertheless, even in supportive conditions, barrier-crossings likely involve a number of risk-mitigating behaviors, including the use of stepping stones. We aimed to understand how seasonal ocean-crossings of Eleonoras falcons (Falco eleonorae) compare in terms of wind support and flight effort, and whether falcons use islands to cross safely in variable wind conditions. To do this we combined GPS-tracking data from 19 individuals over a decade (2012-2022) with wind data from an atmospheric reanalysis model. Despite major differences in wind support, falcons achieved similar ground speeds in both seasons. That is because falcons reduce instantaneous flight effort by flying at lower airspeeds in supportive spring winds (31.5 {+/-} 6.0 km h-1) than in adverse autumn winds (47.4 {+/-} 9.3 km h-1). Overall, it took falcons twice as many flight hours to complete the spring crossings that were 40% greater in terms of air distance compared to autumn crossings. Islands were more frequently used during spring crossings (57.9% individuals in spring vs 21.1% in autumn), and the probability of a falcon using an island significantly increased with weaker wind support in spring (but not in autumn). While wind support partially offsets the extra distance flown over the ocean in spring, isolated islands offer emergency stop-over opportunities when Eleonoras falcons experience relatively weak wind support during protracted ocean crossings.

animal behavior and cognition↗

bioRxiv2023

Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species

Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constraints symbiont populations. We parameterized metabolic theory equations to predict how bird species body size and the body size of their feather mites relate to mite abundance according to four potential energy (microbial abundance, uropygial gland size) and space constraints (wing area, number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance from 26,604 birds of 106 passerine species, using phylogenetic modelling and quantile regression. Feather mite populations were strongly constrained by host space (number of feather barbs) and not energy. Moreover, feather mite species body size was unrelated to their abundance or to the body size of their host species. We discuss the implications of our results for our understanding of the bird-feather mite system and for symbiont abundance in general.

ecology↗

bioRxiv2023

Two avian Plasmodium species trigger different transcriptional responses on their vector Culex pipiens

Malaria is a mosquito-borne disease caused by protozoans of the genus Plasmodium that affects both humans and wildlife. The fitness consequences of infections by avian malaria are well known in birds, however, little information exists on its impact on mosquitoes. Here we study how Culex pipiens mosquitoes transcriptionally respond to infection by two different Plasmodium species, P. relictum and P. cathemerium, differing in their virulence (mortality rate) and transmissibility (parasite presence in exposed mosquitoes saliva). We study the mosquito response to the infection at three critical stages of parasite development: formation of ookinetes at 24 hours post-infection (hpi), the release of sporozoites into the hemocoel at 10 days post-infection (dpi), and storage of sporozoites in the salivary glands at 21dpi. For each time point, we characterized the gene expression of mosquitoes infected with each P. relictum and P. cathemerium and mosquitoes fed on an uninfected bird and, subsequently, compared their transcriptomic responses. Differential gene expression analysis showed most of the transcriptomic changes occurred during the early infection stage (24 hpi), especially when comparing P. relictum and P. cathemerium infected mosquitoes. Differentially expressed genes in mosquitoes infected with each species were related mainly to the immune response, trypsin, and other serine-proteases metabolism. We conclude that these differences in response may partly play a role in the differential virulence and transmissibility previously observed in P. relictum and P. cathemerium in Cx. pipiens.

genomics↗

bioRxiv2016

Unexpected diversity in socially synchronized rhythms of shorebirds

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment1-4. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions1,5, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators6-10. Individuals can temporally segregate their daily activities (e.g. prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (e.g. group foraging, communal defence, pairs reproducing or caring for offspring)6-9,11. The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood5-7,9. Here, we address this in the context of biparental care, a particularly sensitive phase of social synchronization12 where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally-incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parents incubation bout varied from 1 - 19 hours, while period length-the time in which a parents probability to incubate cycles once between its highest and lowest value - varied from 6 - 43 hours. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity5-7,9. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.

animal behavior and cognition↗