Publications

2026

1. Land sharing or land sparing? Implications for farmland birds of conservation concern in France

   Adélie Erard, Ottmar Cronie, Raphaël Lachièze-Rey, and 1 more author

   Landscape Ecology, Aug 2026

   Abs DOI

   Purpose: Farmland bird populations have experienced widespread declines across Europe, raising urgent questions about how agricultural landscapes should be structured to reconcile biodiversity conservation and food production. Land sparing and land sharing represent two contrasting strategies, yet empirical evidence remains mixed. Objectives: We aim to quantify responses of bird communities along a land sharing–sparing gradient and identify which landscape management strategies best support different ecological groups. Methods: Using the French Breeding Bird Survey, we analyzed 810 locations monitored between 2001–2024. A land sharing–sparing gradient was quantified using forest area, agricultural heterogeneity, and landscape diversity indices. Bird counts were modeled with negative binomial spatio-temporal Bayesian models (INLA), incorporating climate, spatial random fields, and temporal autocorrelation. Results: Forest specialists responded positively to greater forest area, supporting land sparing. Generalists benefited from higher agricultural heterogeneity, consistent with land sharing. Unexpectedly, farmland specialists did not benefit from increased heterogeneity, and conservation-priority farmland species showed negative associations with natural elements. Conclusion: No single land-use strategy maximizes abundance across all bird groups. Land sparing favors forest specialists and conservation-priority species, while land sharing benefits generalists. Context-dependent landscape planning and customized agricultural practices are essential.

2024

1. Opening the species box: what parsimonious microscopic models of speciation have to say about macroevolution

   Élisa Couvert, François Bienvenu, Jean-Jil Duchamps, and 4 more authors

   Journal of Evolutionary Biology, Oct 2024

   Abs DOI

   In the last two decades, lineage-based models of diversification, where species are viewed as particles that can divide (speciate) or die (become extinct) at rates depending on some evolving trait, have been very popular tools to study macroevolutionary processes. Here, we argue that this approach cannot be used to break down the inner workings of species diversification and that “opening the species box” is necessary to understand the causes of macroevolution, but that too detailed speciation models also fail to make robust macroevolutionary predictions. We set up a general framework for parsimonious models of speciation that rely on a minimal number of mechanistic principles: (a) reproductive isolation is caused by excessive dissimilarity between genotypes; (b) dissimilarity results from a balance between differentiation processes and homogenizing processes; and (c) dissimilarity can feed back on these processes by decelerating homogenization. We classify such models according to the main homogenizing process: (a) clonal evolution models (ecological drift), (b) models of genetic isolation (gene flow), and (c) models of isolation by distance (spatial drift). We review these models and their specific predictions on macroscopic variables such as species abundances, speciation rates, interfertility relationships, or phylogenetic tree structure. We propose new avenues of research by displaying conceptual questions remaining to be solved and new models to address them: the failure of speciation at secondary contact, the feedback of dissimilarity on homogenization, and the emergence in space of breeding barriers.