Biology subjects

Jarrett, C.

Publications and source records attributed to Jarrett, C..

3 recordsLinked to original sources

bioRxiv2026

Rapid connectivity alterations of thalamic nuclei during initial learning of goal-directed behaviour

The thalamus is essential for learning, dynamically engaging with other subcortical and cerebral cortex regions throughout the learning process. Here, the thalamus serves as a critical connector hub and synchroniser within the thalamocortical system of the brain. However, whilst higher order thalamic nuclei are known to be particularly important for this process, the exact contributions of individual higher order and first order thalamic nuclei, alongside their individual involvement with cortical networks and subcortical regions, remains unexplored within the initial phase of learning. In light of this, we analysed fMRI data obtained within a paradigm which is designed to examine initial learning processes within feedback-driven stimulus-response learning, in order to explore thalamic contributions. We investigated dynamic learning-related functional connectivity alterations between various thalamic nuclei with other subcortical regions and cortical networks. Our results show that the initial phase of learning was associated with: (1) decreasing functional connectivity between thalamic nuclei and frontoparietal and cingulo-opercular networks, (2) increasing functional connectivity between thalamic nuclei with default mode and salience networks, (3) decreasing functional connectivity between thalamic nuclei and the putamen, and (4) decreasing functional connectivity amongst higher order thalamic nuclei. Furthermore (5) these dynamic alterations were associated primarily by mediodorsal thalamus. Altogether, these results indicate that higher order thalamic nuclei play a crucial role within initial learning and in the generation of novel goal-directed behaviour. This was demonstrated through enhanced functional connectivity with selected cortical networks which drive goal-directed behaviour, alongside decreased functional connectivity with striatal regions which drive motor selectivity.

neuroscience↗

bioRxiv2025

Shifting baselines increase the risk of misinterpreting biodiversity trends

Ecological studies quantifying the impact of land-use change on biodiversity may be sensitive to the choice of reference points - or baselines - particularly when sampling across human land-use gradients and other space-for-time comparisons. Much depends on whether the chosen baseline has already undergone shifts in species composition because of hunting, habitat loss and degradation. However, few studies have assessed the influence of shifting baselines on estimates of anthropogenic impacts. Using new survey data from five West African land-use gradients, we examine how habitat patch size and structure influences the estimated impact of land-use change on bird species richness and functional diversity. We show that smaller forests have already lost many forest-dependent birds, particularly those with large body size or specialised ecological niches, leading to reduced estimates of biodiversity loss after deforestation. The steepest biodiversity loss was found in mid-sized forests whereas relatively shallow declines were estimated for the most extensive forests - despite their richer taxonomic and functional diversity. In these larger forest blocks, accurate estimates of biodiversity loss may require longer transects extending beyond the biodiversity shadow caused by the more extensive spillover of forest species into the surrounding landscape, potentially linked to source-sink dynamics. These findings suggest that biodiversity assessments are highly sensitive to baseline selection and transect design, highlighting the risk of underestimating land-use impacts unless shifting baselines are carefully considered.

ecology↗

bioRxiv2024

Food webs can deliver win-win strategies for tropical agroforestry and biodiversity conservation

Balancing biodiversity conservation and agricultural productivity is commonly regarded as a trade-off, but such analyses overlook ecosystem services that functional biodiverse communities provide in agroecosystems, and the possibility that win-win strategies may exist. We developed a dynamic mechanistic community model of the bird-insect food web associated with African cocoa agroforestry, structurally informed by metabarcoding data on bird diets, and fitted to trapping data on species abundances. We used the model to predict equilibrium community composition under varying intensities of shade management and pesticide use. Our results indicate that low-intensity farming favours forest bird species, and potential pollinator abundance, with no increase in pest biomass. Furthermore, using simulations of pesticide application, we found that pesticides do not effectively reduce pest biomass, and result in forest bird extinction. Our mechanistic framework combines the influence of management and the direct and indirect effects of species interactions, and demonstrates that low intensity agriculture may provide a win-win for biodiversity and ecosystem services.

ecology↗