Biology subjects

de la Hera, I.

Publications and source records attributed to de la Hera, I..

5 recordsLinked to original sources

bioRxiv2024

Delayed post-juvenile moult in malaria-infected European blackcaps

Parasites have their strongest impact on fitness when host defences limit the quantity of resources available for other critical life-history stages, such as development, breeding or migration. One greatly neglected stage that could be altered by parasites is the post-juvenile moult (PJM) of birds, through which inexperienced yearlings replace their weak and fast-generated juvenile feathers by adult-like feathers. The earlier juvenile birds complete PJM, the earlier they will be prepared to withstand forthcoming adverse conditions, especially if they migrate short after moulting. We used data from 435 juvenile European blackcaps (Sylvia atricapilla) sampled during three years in 26 localities spanning the wide range of environmental conditions across Iberian Spain to test whether haemosporidian infections (presence and abundance in blood of parasites of the genera Haemoproteus, Plasmodium and Leucocytozoon) were related to delayed PJM. Controlling for body condition, sex, year and date of capture, infected blackcaps (single-infected or coinfected) had lower moult scores indicative of delayed moult, especially when birds had Plasmodium infections or higher intensity of Haemoproteus parasites. Our results broaden the range of fitness costs that haemosporidian parasites may have on birds, as delayed plumage maturation prolongs the period during which juvenile birds lack a fully functional plumage.

ecology↗

bioRxiv2022

Partitioning variance in a signaling trade-off under sexual selection reveals among-individual covariance in trait allocation

Understanding the evolution of traits subject to trade-offs is challenging because phenotypes can (co)vary at both the among- and within-individual levels. Among-individual covariation indicates consistent, possibly genetic, differences in how individuals resolve the trade-off, while within-individual covariation indicates trait plasticity. There is also the potential for consistent among-individual differences in behavioral plasticity, although this has rarely been investigated. We studied the sources of (co)variance in two characteristics of an acoustic advertisement signal that trade off with one another and are under sexual selection in the gray treefrog, Hyla chrysoscelis: call duration and call rate. We recorded males on multiple nights calling spontaneously and in response to playbacks simulating different competition levels. Call duration, call rate, and their product, call effort, were all repeatable both within and across social contexts. Call duration and call rate covaried negatively, and the largest covariance was at the among-individual level. There was extensive plasticity in calling with changes in social competition, and we found some evidence for among-individual variance in call rate plasticity. The significant negative among-individual covariance in trait values is perpendicular to the primary direction of sexual selection in this species, indicating potential limits on the response to selection.

animal behavior and cognition↗

bioRxiv2021

Inhibitory control performance is repeatable across years and contexts in a wild bird population

Inhibitory control is one of several cognitive mechanisms required for self-regulation, decision making and attention towards tasks. Linked to a variety of maladaptive behaviours in humans, inhibitory control is expected to influence behavioural plasticity in animals in the context of foraging, social interaction, or responses to sudden changes in the environment. One widely used cognitive assay, the detour task, putatively tests inhibitory control. In this task, subjects must avoid impulsively touching transparent barriers positioned in front of food, and instead access the food by an alternative but known route. Recently it has been suggested that the detour task is unreliable and measures factors unrelated to inhibitory control, including motivation, previous experience and persistence. Consequently, there is growing uncertainty as to whether this task leads to erroneous interpretations about animal cognition and its links with socio-ecological traits. To address these outstanding concerns, we designed a variant of the detour task for wild great tits (Parus major) and deployed it at the nesting site of the same individuals across two spring seasons. This approach eliminated the use of food rewards, limited social confounds, and maximised motivation. We compared task performance in the wild with their performance in captivity when tested using the classical cylinder detour task during the non-breeding season. Task performance was temporally and contextually repeatable, and none of the confounds had any significant effect on performance, nor did they drive any of the observed repeatable differences among individuals. These results support the hypothesis that our assays captured intrinsic differences in inhibitory control. Instead of throwing the detour task out with the bathwater, we suggest confounds are likely system and experimental-design specific, and that assays for this potentially fundamental but largely overlooked source of behavioural plasticity in animal populations, should be validated and refined for each study system.

animal behavior and cognition↗

bioRxiv2020

No evidence for cross-contextual consistency in spatial learning and behavioural flexibility in a passerine

Although the evolution of cognitive differences among species has long been of interest in ecology, whether natural selection acts on cognitive processes within populations has only begun to receive similar attention. One of the key challenges is to understand how consistently cognitive traits within any one domain are expressed over time and across different contexts, as this has direct implications for the way in which selection might act on this variation. Animal studies typically measure a cognitive domain using only one task in one context, and assume that this captures the likely expression of that domain in different contexts. This deficit is not surprising because, from an ecologists perspective, cognitive tasks are notoriously laborious to employ, and for design reasons most tasks can only be deployed in a specific context. Thus our knowledge of whether individual differences in cognitive abilities are consistent across contexts is limited. Using a wild population of great tits (Parus major) we characterised consistency of two cognitive abilities, each in two different contexts: 1) spatial learning at two different spatial scales, and 2) behavioural flexibility as both performance in a detour reaching task and reversal learning in a spatial task. We found no evidence of a correlation between the two spatial learning speeds, or between the two measures of behavioural flexibility. This suggests that cognitive performance is highly plastic and sensitive to differences across tasks, or that variants of these well-known tasks may tap into different combinations of both cognitive and non-cognitive mechanisms, or that they simply do not adequately measure each putative cognitive domain. Our results highlight the challenges of developing standardised cognitive assays to explain natural behaviour and to understand the selective consequences of that variation.

animal behavior and cognition↗

bioRxiv2019

Diet-induced changes to host gut microbiota are linked to foraging innovation in a wild bird.

The microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.

ecology↗