Biology subjects

Chave-Lucas, A.

Publications and source records attributed to Chave-Lucas, A..

3 recordsLinked to original sources

bioRxiv2026

Microbial eco-evolutionary dynamics of decomposition and dormancy

Soil microorganisms regulate a major component of the terrestrial carbon cycle, yet predictions of soil carbon stocks and fluxes often neglect microbial life-history adaptation. To fill this gap, we develop a spatially and stage-structured eco-evolutionary model in which active and dormant microbes move between favorable microsites and an unfavorable bulk soil matrix; decompose organic carbon through costly exoenzyme production; and evolve both exoenzyme investment and entry into dormancy. The model shows that dormancy expands the ecological conditions under which microbial populations persist and has a non-monotonic effect on soil carbon stocks. Adaptive dormancy is shaped by opposing selection in microsites, where inactivity carries an opportunity cost, and in the matrix, where dormancy protects cells from mortality. When dormancy and exoenzyme production jointly evolve, the traits may increase together under high microbial mobility, but often evolve in opposite directions because both carry survival benefits in the matrix. These eco-evolutionary feedbacks can either amplify or attenuate soil carbon fluxes to the atmosphere, depending on soil structure, microbial movement, and dormancy costs. Our results suggest that incorporating microbial life-history evolution into soil carbon models is essential for predicting soil carbon feedbacks to climate.

ecology↗

bioRxiv2026

Spatial heterogeneity shapes microbial eco-evolutionary dynamics of soil carbon

The study of reciprocal influences between ecological and evolutionary processes has advanced considerably, yet integration between evolutionary biology and ecosystem-level ecology remains limited. Here we contribute to this integration by advancing the theory of eco-evolutionary feedbacks between soil microbial adaptation and soil-atmosphere carbon fluxes in a warming climate. We develop a spatially structured model of soil organic matter decomposition that represents microbial populations in microsites embedded in a bulk-soil matrix and focuses on exoenzyme production as a key resource-acquisition trait. The evolutionarily adapted investment in exoenzyme production is shaped by opposing selective forces: negative selection within microsites, where lower-investing mutants exploit exoenzymes as public goods, and positive selection in the soil matrix, where exoenzyme production directly benefits individual cells. Microsite density emerges as a critical determinant of microbial adaptation to warming and its consequences for soil carbon loss. Even small changes in microsite density across a threshold can reverse the ecosystem-level effect of adaptation, from buffering to amplifying carbon loss. High microsite density generally promotes buffering, whereas low microsite density has little effect in cool ecosystems but can strongly amplify carbon loss in warm ecosystems, especially when microbial mobility is low. These results identify soil spatial structure at microsite scale as a key mediator of microbial evolutionary adaptation and soil carbon-climate feedback under global environmental change, with implications for quantitatively improving Earth system models.

ecology↗

bioRxiv2026

Rapid speciation in small populations challenges the dominance of ecological speciation

Speciation - the process by which two lineages become reproductively isolated - plays a key role in the emergence and maintenance of biodiversity. Yet, our understanding of the time it takes for speciation to occur, and of the microevolutionary processes that influence this tempo, remains limited. Here, we thoroughly characterize how population size, mutation rate, local adaptation and migration are expected to influence the duration of speciation, as well as the shape of the "grey zone" of speciation. We show that the relationship between population size and speciation time is indicative of the speciation mode, as faster speciation in smaller populations only occurs in the case of non-ecological speciation. Leveraging genomic estimates of population size and speciation duration across 196 pairs of plant species, we uncover a positive association between population size and speciation duration. Taken together, these results challenge the view that ecological speciation is the source of much of species diversity.

evolutionary biology↗