Biology subjects

Faucher, R.

Publications and source records attributed to Faucher, R..

4 recordsLinked to original sources

bioRxiv2026

Macroevolutionary consequences of twin neck innovations in deep-sea dragonfishes

The origin of novel phenotypes can influence access to new ecological resources, which may have positive, neutral, or negative effects on subsequent phenotypic diversification. In this study, we tested the macroevolutionary consequences of a pair of putative functional innovations occurring in deep-sea fishes of the order Stomiiformes. Integrating phylogenetic comparative methods, micro-CT scans, and external body measurements, we recover a mosaic of diversification trends associated with these innovations. We found some evidence for elevated evolutionary rates in tooth morphology associated with the predatory dragonfishes, which possess a gap between their vertebral column and skull that exposes the notochord and enables neck-like flexibility. However, a second novelty building upon the first, a functional neck joint enabling extreme cranial kinesis, was linked to faster rates of skull evolution. Our results suggest that innovations that help shift ecological roles and overcome functional constraints related to those roles, like gape-limitation in prey depauperate habitats, may play an important role in promoting phenotypic diversification. This work builds on a growing body of evidence highlighting how the deep sea promotes phenotypic diversity, generating the extreme forms that are celebrated by scientists and the public alike.

evolutionary biology↗

bioRxiv2026

Ecological axes of skull diversification in a massive 1 vertebrate radiation

Eupercarian spiny-rayed fishes are one of the largest vertebrate radiations, rivaling mammals and occupying nearly every aquatic habitat. We present a densely sampled, time-calibrated phylogenomic framework for Eupercaria, supporting a revised classification, combined with the largest cranial phenomics dataset for fishes. Habitat and trophic ecology make independent, complementary contributions to skull shape. Most species cluster around a conserved generalized architecture, the Percomorph Pile, from which one clade of pufferfishes, anglerfishes, butterflyfishes, and surgeonfishes repeatedly invaded novel morphospace; exceptionally high rates on its deep branches indicate that rapid skull evolution arose early in this clade. Freshwater lineages converge on the ancestral condition, reflecting late arrival into systems occupied by older otophysans, whereas durophages show the greatest disparity and converge on derived forms. Cranial diversity was partitioned among subclades during the Cretaceous and later within them across the Cenozoic, showing that clade-level differences in evolutionary rates and ecological opportunity jointly shaped skull diversification.

evolutionary biology↗

bioRxiv2026

Gut microbiome connectivity drives mass host colonization and buffers against antibiotic-induced collapse

Microbial dispersal continually shapes gut microbiomes, seeding communities during assembly and replenishing them after perturbation. Dispersals effect depends on its strength: low dispersal introduces stochasticity and drives divergence, whereas high dispersal increases mixing and promotes convergence. Although this pattern manifests across host-microbe systems, the mechanism by which dispersal alters colonization dynamics to generate such contrasting outcomes remains unclear. Identifying factors that toggle these dualistic effects is essential for predicting and controlling gut microbiome assembly and stability. We addressed this problem in gnotobiotic larval zebrafish, which is a tractable vertebrate model that enables experimental control and quantification of gut bacterial dispersal. To dissect the roles of dispersal, we defined the relationship between inoculation dose and colonization frequency for a model Vibrio cholerae isolate under different dispersal regimes. Strikingly, a dose yielding only 50% colonization in isolated hosts--the CD50--produced nearly universal colonization during co-housing, despite identical host and bacterial densities. Measurements of intestinal growth, carrying capacity, shedding, and environmental persistence were used to construct a quantitative colonization-dispersal model that explained the basis for this shift in colonization outcomes. At the CD50, colonization is inherently probabilistic, but once the first hosts become colonized, they reseed the environment and amplify secondary exposures, creating a feedback loop that rapidly transforms individual-level stochasticity into widespread colonization. We further show that this feedback operates in complex microbiomes, where larger host groups--with more opportunities for recolonization--buffer communities against antibiotic-induced collapse. Together, our findings demonstrate that dispersal regimes are not fixed but dynamically shift as hosts become increasingly connected. By revealing how dispersal and interhost transmission drive mass colonization and stabilize gut communities, our work identifies microbiome connectivity as a central mechanism governing gut microbial assembly and resilience.

microbiology↗

bioRxiv2023

Phylogenomics reveals the deep ocean as an accelerator for evolutionary diversification in anglerfishes

Colonization of a novel habitat is often followed by radiation in the wake of ecological opportunity. Alternatively, some habitats should be inherently more constraining than others if the challenges of that environment have few evolutionary solutions. We examined the push-and-pull of these factors on evolution following habitat transitions, using anglerfishes (Lophiiformes) as a model. Deep-sea fishes are notoriously difficult to study, and poor sampling has limited progress thus far. Here we present a new phylogeny of anglerfishes with unprecedented taxonomic sampling (1,092 loci and 40% of species), combined with three-dimensional phenotypic data from museum specimens obtained with micro-CT scanning. We use these datasets to examine the tempo and mode of phenotypic and lineage diversification using phylogenetic comparative methods, comparing lineages in shallow and deep benthic versus bathypelagic habitats. Our results show that anglerfishes represent a surprising case where the bathypelagic lineage has greater taxonomic and phenotypic diversity than coastal benthic relatives. This defies expectations based on ecological principles since the bathypelagic zone is the most homogeneous habitat on Earth. Deep-sea anglerfishes experienced rapid lineage diversification concomitant with colonization of the bathypelagic zone from a continental slope ancestor. They display the highest body, skull and jaw shape disparity across lophiiforms. In contrast, reef-associated taxa show strong constraints on shape and low evolutionary rates, contradicting patterns suggested by other shallow marine fishes. We found that Lophiiformes as a whole evolved under an early burst model with subclades occupying distinct body shapes. We further discuss to what extent the bathypelagic clade is a secondary adaptive radiation, or if its diversity can be explained by non-adaptive processes.

evolutionary biology↗