Biology subjects

Caro, S. P.

Publications and source records attributed to Caro, S. P..

4 recordsLinked to original sources

bioRxiv2024

Tit wit: environmental and genetic drivers of cognitive variation along an urbanization gradient

Cognitive abilities can promote acclimation and adaptation to life in cities. However, the genetic versus environmental drivers of cognition have rarely been studied in the wild and there exists a major gap concerning the role of cognition in adaptation to novel urban contexts. To address this, we evaluate cognitive variation in wild great tits (Parus major; N = 393) along an urban gradient, and decipher the genetic basis of this variation using a combination of a common garden experiment, quantitative genetic analyses, and genome-wide association studies. Specifically, we measure inhibitory control abilities which affect how animals respond to novel resources and challenges. We find that wild urban and forest tits do not clearly differ in inhibitory control performance (number of errors or the latency to escape) during a motor detour task; a result that was consistent in birds from urban and forest origins reared in a common garden (N = 73). Cognitive performance was repeatable (R = 0.35 - 0.38) and showed low to moderate heritability in the wild (h2= 0.16 - 0.28 using social and genomic pedigrees). We identified five SNPs that were significantly associated with the number of errors during the task, explaining 21% of the cognitive variation. These SNPs are linked to genes related to serotonergic and dopaminergic systems that are known to play important roles in cognition. Altogether, our study finds limited evidence that inhibitory control abilities have evolved under novel urban contexts, yet reveals a genetic basis of this cognitive trait in great tits.

animal behavior and cognition↗

bioRxiv2024

The city and forest bird flock together in a common garden: genetic and environmental effects drive urban phenotypic divergence

Urban phenotypic divergences are documented across diverse taxa, but the underlying genetic and environmental drivers behind these phenotypic changes are unknown in most wild urban systems. We conduct a common garden experiment using great tit (Parus major) eggs collected along an urbanization gradient to: 1) determine whether documented morphological, physiological, and behavioural shifts in wild urban great tits are maintained in birds from urban and forest origins reared in a common garden (N = 73) and 2) evaluate how different sources of genetic, early maternal investment, and later environmental variation contributed to trait variation in the experiment. In line with the phenotypic divergence in the wild, common garden birds from urban origins had faster breath rates (i.e., higher stress response) and were smaller than birds from forest origins, while wild differences in aggression and exploration were not maintained in the experiment. Differences between individuals (genetic and environmentally induced) explained the most trait variation, while variation among foster nests and captive social groups was limited. Our results provide trait-specific evidence of evolution in an urban species where genetic change likely underlies urban differences in morphology and stress physiology, but that urban behavioural divergences are more strongly driven by plasticity.

evolutionary biology↗

bioRxiv2024

Continent-wide drivers of spatial synchrony in age structure across wild great tit populations

Spatio-temporal variation in age structure influences population dynamics, yet we have limited understanding of the spatial scale at which its fluctuations are synchronised between populations. Using 32 great tit populations, spanning 3200km and >130,000 birds across 67 years, we quantify spatial synchrony in breeding age structure and its drivers. We show that larger clutch sizes, colder winters and summers, and larger beech crops lead to younger populations. We report distant-dependent spatial synchrony of age structure, which is maintained at approximately 650km. Despite covariation with age structure, reproductive and environmental variables do not influence the scale of synchrony, except for a moderate effect of beech masting. We suggest that local ecological and density-dependent dynamics impact how environmental variation interacts with age structure, influencing estimates of the environments effect on spatial synchrony. Our analyses demonstrate the operation of synchrony in age structure over large scales, with implications for age-dependent demography in populations.

ecology↗

bioRxiv2023

Developing oak buds produce volatile emissions in response to herbivory by freshly hatched caterpillars

Plant responses to damage by insectivorous herbivores is well documented in mature leaves. The resulting herbivore-induced plant volatiles (HIPVs) protect the plant by attracting carnivorous arthropods and even some insectivorous vertebrates, to parasitize or consume the plant invaders. However, very little is known about plant production of HIPVs in developing buds, particularly when herbivorous insects are too small to be considered a prey item. It is additionally unclear whether plants respond differently to generalist and specialist chewing insects that overlap in distribution. Therefore, we compared HIPV production of Downy oak (Quercus pubescens Willd.) buds infested with freshly hatched caterpillars of Tortrix viridana (specialist) and Operophtera brumata (generalist), against uninfested buds. Of the compounds identified in both years of the experiment, we found that (Z)-hex-3-enyl acetate, (E)-{beta}-ocimene, acetophenone, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), methyl salicylate, -copaene, -humulene, (E)-caryophyllene, and (E,E)--farnesene were higher in infested buds compared to controls. We found no difference in HIPV production between the specialist and the generalist herbivores. Production of HIPVs was also associated with leaf damage, with higher HIPV production in more severely attacked buds. Thus, our study shows that oak trees already start responding to insect herbivory before leaves are developed, by producing compounds similar to those found in damaged mature leaves. Future work should focus on how Downy oak may benefit from initiating alarm cues at a time when carnivorous arthropods and insectivorous vertebrates are unable to use herbivorous insects as host or food.

ecology↗