Biology subjects

Biondi, G.

Publications and source records attributed to Biondi, G..

3 recordsLinked to original sources

bioRxiv2026

Vegetation and fires under climate change: a Mediterranean modelled case study from central Italy

Wildfire regimes in Mediterranean landscapes are undergoing significant changes due to the combined effects of land-use transitions and climate change. In particular, land abandonment increased fuel availability, the expansion of the wildland-urban interface increased ignition frequency, while climate change increases the chances of fire-weather conditions and reduces vegetation recovery capacity. This study presents a modelling framework to investigate the coupled dynamics of fire and vegetation under different fire regimes scenarios, using a case study in central Italy (Monte Pisano). The approach integrates two cellular automata models for vegetation dynamics (Batllori et al., 2017) and for fire-spread (PROPAGATOR; Trucchia et al., 2020). The vegetation model represents succession among six functional classes, including grasslands, shrubs, and trees with different fire-response strategies (seeders and resprouters), while explicitly accounting for post-fire recovery processes. The model was calibrated for the area using historical fire perimeters and vegetation maps over 40 years. Fire spread is simulated probabilistically using PROPAGATOR, driven by fuel types, topography, and weather conditions. A stochastic coupling was implemented by sampling fuel classes from vegetation composition, and by feeding simulated burned areas back into the vegetation model, thus enabling dynamic fire-vegetation feedback. Future wildfire scenarios are constructed by linking ignition probability to fire-weather conditions derived from historical reanalysis data (1981-2023). Extreme fire events are defined based on thresholds of wind speed and fuel moisture, and their probability of occurrence is varied across scenarios to represent increasing climate-driven risk. Simulations are performed over a 100-year horizon starting from current vegetation conditions. Results show that, in the absence of fire, vegetation dynamics lead to dominance of late-successional, fire-resilient species (resprouters). This is particularly evident for low probabilities of extreme fire events, with fire impacts diminishing over time as landscapes become less flammable. However, increasing the frequency of extreme fire conditions resulted in persistent disturbance, maintaining higher proportions of shrubs and early successional vegetation, and sustaining elevated burned areas over time. Overall, the study shows that coupling fire spread and vegetation dynamics provides a useful framework for exploring long-term ecosystem trajectories under climate change. The results highlight the critical role of extreme fire events in shaping landscape resilience and suggest that future management strategies should account for fire-vegetation feedbacks to support more stable and less fire-prone ecosystems.

ecology↗

bioRxiv2024

The Circadian Neuropeptide PDF has Sexually Dimorphic Effects on Activity Rhythms

The circadian system regulates the timing of multiple molecular, physiological, metabolic, and behavioral phenomena. In Drosophila, as in other species, most of the research on how the timekeeping system in the brain controls the timing of behavioral outputs has been conducted in males, or sex has not been included as a biological variable. A critical set of circadian pacemaker neurons in Drosophila release the neuropeptide pigment-dispersing factor (PDF), which functions as a key output factor in the network with complex effects on other clock neurons. Lack of Pdf or its receptor, PdfR, results in most flies displaying arrhythmicity in activity-rest cycles under constant conditions. However, our results show that female circadian rhythms are less affected by mutations in both Pdf and PdfR. Crispr-Cas9-mediated mutagenesis of Pdf, specifically in ventral lateral neurons (LNvs), also has a greater effect on male rhythms. We tested the influence of M-cells on the circadian network and showed that speeding up the molecular clock specifically in M-cells led to sexually dimorphic phenotypes, with a more pronounced effect on male rhythmic behavior. Our results suggest that the female circadian system is more resilient to manipulations of M-cells and the PDF pathway, suggesting that circadian timekeeping is more distributed across the clock neuron network in females.

neuroscience↗

bioRxiv2023

The Drosophila Circadian Clock Gene Cycle Controls Development of Clock Neurons

Daily behavioral and physiological rhythms are controlled by the brains circadian timekeeping system, a synchronized network of neurons that maintains endogenous molecular oscillations. These oscillations are based on transcriptional feedback loops of clock genes, which in Drosophila include the transcriptional activators Clock (Clk) and cycle (cyc). While the mechanisms underlying this molecular clock are very well characterized, the roles that the core clock genes play in neuronal physiology and development are much less understood. The Drosophila timekeeping center is composed of [~]150 clock neurons, among which the four small ventral lateral neurons (sLNvs) are the most dominant pacemakers under constant conditions. Here, we show that downregulating the clock gene cyc specifically in the Pdf-expressing neurons prevents leads to decreased fasciculation both in larval and adult brains. This effect is due to a developmental role of cyc, as both knocking down cyc or expressing a dominant negative form of cyc exclusively during development lead to defasciculation phenotypes in adult clock neurons. Clk downregulation also leads to developmental effects on sLNv morphology, although cyc and Clk manipulations produce distinct phenotypes. Our results reveal a non-circadian role for cyc, shedding light on the additional functions of circadian clock genes in the development of the nervous system.

neuroscience↗