Biology subjects

Ponti, R.

Publications and source records attributed to Ponti, R..

3 recordsLinked to original sources

bioRxiv2026

Predation and the Evolution of Island Bird Plumage Colouration: Experimental Insights from Island and Mainland Environments

Islands serve as natural laboratories for exploring evolutionary processes, often fostering unique species through their isolation and distinct ecological conditions. These environments present opportunities to study how a range of selective pressures shape biodiversity. Bird plumage colouration is one trait that has shown to consistently change in island populations, and predation has been hypothesized to influence these differences. While animals often face a trade-off between signalling to conspecifics and avoiding detection by predators, the role of predation in shaping conspicuousness remains underexplored experimentally. In this study, we asked how predation pressure differs between insular and mainland habitats, and whether predation risk covaries with conspicuousness of male and female birds across environments. In a field experiment, we investigated predation rates using 3D-printed models painted to represent both sexes of 12 bird species from three archipelagos (Madeira, Azores, and Canary Islands) and their closest mainland relatives. These models were deployed in the species natural environments to measure hit rates (a proxy for predation risk), accounting for factors that influence prey detectability, such as colour of the models, background contrast, and vegetation. We found that models on the islands experienced less hits compared to those on the mainland, while sexual dichromatic models were more likely to be dislodged on the mainland. In addition, for mainland sites, increased chromatic contrast correlated with a higher probability of dislodgment, suggesting that more conspicuous models were more likely to be hit. These results highlight that while predation constrains conspicuousness, other ecological and evolutionary factors likely drive the reduced plumage colouration observed in island birds. Our research offers experimental insights into how predation interacts with conspicuous traits in shaping plumage colouration in birds.

evolutionary biology↗

bioRxiv2023

Age-related spatial ecology of Audouin's gull during the non-breeding season

Relationships between individuals age and the movement ecology and habitat preference of long-lived migratory birds still remain understudied. According to the exploration-refinement hypothesis it is thought that adults would select better and more productive areas for foraging than inexperienced juvenile birds would do. Additionally, age-related differences in migratory patterns and exploited habitats could be explained by the attempt to avoid competition between juveniles and adults. Here, we explored the differences in the migratory patterns, habitat selection and foraging behaviour between juvenile and adult Audouins gulls (Ichthyaetus audouinii), a species listed as vulnerable by the IUCN. We captured 9 juveniles and 8 adults in the colony of San Pedro (SE Spain) and equipped them with high-resolution 5-min programmed GPS to track their postnuptial/first migration and non-breeding destinations. First, juveniles tended to migrate longer distances than adults did. Second, the time spent foraging between age groups did not differ. Third, freshwater masses constituted an essential habitat during the non-breeding season for both juveniles and adults. Fourth, we found that adults used a greater variety of habitats than juveniles did, but adults positively select foraging habitats despite the low availability while juveniles do not. Finally, repeatability in habitat use of individuals of the same age was rather low. We provided evidence of age-related differences in migratory patterns and habitat exploitation during the non-breeding period in a migratory seabird which can be explained by the avoidance of competition between adults and juveniles and the greater experience in foraging performance that adults have in comparison with juveniles.

ecology↗

bioRxiv2019

Mitochondrial substitution rates estimation for molecular clock analyses in modern birds based on full mitochondrial genomes

Abstractti Mitochondrial DNA (mtDNA) is a very popular resource in the study of evolutionary processes in birds, and especially to infer divergence times between lineages. These inferences rely on rates of substitution in the mtDNA genes that, ideally, are specific for the studied taxa. But as such values are often unavailable many studies fixed rate values generalised from other studies, such as the popular "standard molecular clock". However the validity of these universal rates across all bird lineages and for the different mtDNA has been severely questioned. Thus, we here performed the most comprehensive calibration of the mtDNA molecular clock in birds, with the inclusion of complete mitochondrial genomes for 622 bird species and 25 reliable fossil calibrations. The results show variation in the rates between lineages and especially between markers, contradicting the universality of the standard clock. Moreover, we provide especific rates for every mtDNA marker (except D-loop) in each of the sampled avian orders, which should help improve future estimations of divergence times between bird species or populations.

evolutionary biology↗