Biology subjects

Ronco, F.

Publications and source records attributed to Ronco, F..

5 recordsLinked to original sources

bioRxiv2025

African Cichlid Lake Radiations Recapitulate Riverine Axial Morphologies Through Repeated Exploration of Morphospace

Macroevolutionary theory predicts that adaptive radiations are characterised by early bursts of trait evolution followed by rate slowdowns as ecological niches are filled. However, these dynamics are rarely detected within individual clades. Here, we test whether this discrepancy arises from limited temporal sampling by comparing replicated adaptive radiations of African cichlids spanning distinct evolutionary timescales. We show that the net rates of vertebral count evolution are inversely correlated with radiation age, consistent with early burst dynamics. However, we do not detect this pattern within the individual systems. We also find evidence of changes to the underlying processes that generate disparity across the timescale of adaptive radiation, signalled by increasing importance of phylogenetic signal with radiation age. This suggests that early phenotypic expansion is both rapid and phylogenetically unstructured, but that stabilising dynamics emerge on longer timescales, amid declining rates. Despite rapid phenotypic diversification, lacustrine lineages occupy only a subset of the broader morphospace of riverine taxa, suggesting that diversification over short timescales is constrained and may largely resample the variation already present in older lineages. Our results provide strong evidence for shifting evolutionary dynamics through time in adaptive radiations, and that the apparent rarity of early-burst signals in comparative analyses may partly reflect limited statistical power due to narrow temporal sampling.

evolutionary biology↗

bioRxiv2024

Adaptive cellular evolution in the intestinal tracts of hyperdiverse African cichlid fishes

Adaptations related to how nutrients are acquired and processed play a central role in the colonization of novel ecological niches and, therefore, in organismal diversification. While the evolution of feeding structures has been studied extensively in this context, the nature of dietary adaptations in the digestive tract remains largely unexplored. Here, we investigate the cellular and molecular basis of dietary adaptations in the massive radiation of cichlid fishes in Lake Tanganyika using comprehensive single-cell transcriptomic data derived from the intestines of 24 endemic cichlid species with distinct habitats and diets. We show that, at the cellular level, dietary adaptations are primarily driven by anterior enterocytes, and that both the relative abundance and gene expression profiles of these cells have evolved in response to rapid dietary specializations. These dietary adaptations are driven by rapidly evolving cell population-specific genes, suggesting that alterations in epithelial cell specification programs and molecular makeup promote ecological diversification.

evolutionary biology↗

bioRxiv2023

Host adaptive radiation is associated with rapid virus diversification and cross-species transmission in African cichlid fishes

Adaptive radiations are generated through a complex interplay of biotic and abiotic factors. Although adaptive radiations have been widely studied in the context of animal and plant evolution, little is known about how they impact the evolution of the viruses that infect these hosts, which in turn may provide insights into the drivers of disease emergence. We examined how the rapid adaptive radiation of the African cichlid fishes of Lake Tanganyika over the last 10 million years has shaped the diversity and evolution of the viruses they carry. Through metatranscriptomic analysis we identified 121 vertebrate-associated viruses among various tissue types that fell into 13 RNA and 4 DNA virus groups. Host-switching was commonplace, particularly within the Astroviridae, Metahepadnavirus, Nackednavirus, Picornaviridae, and Hepacivirus groups, occurring more frequently than in other fish communities. A time-calibrated phylogeny revealed that hepacivirus evolution was not constant throughout the cichlid radiation, but accelerated 2-3 million years ago, coinciding with a period of rapid cichlid diversification and niche packing in Lake Tanganyika, thereby providing more closely related hosts for viral infection. These data show that African cichlids contain a complex interacting pool of virus diversity, likely reflecting their close genetic relationships that lowers the barriers to cross-species virus transmission.

evolutionary biology↗

bioRxiv2020

Dynamics of sex chromosome evolution in a rapid radiation of cichlid fishes

Sex is a fundamental trait that is determined, depending on the species, by different environmental and/or genetic factors, including various types of sex chromosomes. While the functioning and emergence of sex chromosomes have been explored in species scattered across the eukaryotic tree of life, little is known about tempo and mode of sex chromosome evolution in closely related species. Here, we examine the dynamics of sex chromosome evolution in an archetypical example of adaptive radiation, the cichlid fishes of African Lake Tanganyika. Through inspection of male and female genomes from 244 cichlid taxa and the analysis of transcriptomes from 66 taxa, we identify signatures of sex chromosomes in 79 taxa, involving 12 different linkage groups. We estimate that Tanganyikan cichlids have the highest rates of sex chromosome turnover and heterogamety transitions known to date. We further show that the recruitment of chromosomes as sex chromosomes is not at random and that some chromosomes have convergently emerged as sex chromosomes in cichlids, which provides empirical support to the "limited options" hypothesis of sex chromosome evolution.

evolutionary biology↗

bioRxiv2020

Structural manipulations of a shelter resource reveal underlying preference functions in a shell-dwelling cichlid fish

Many animals can modify the environments in which they live, thereby changing the selection pressures they experience. A common example of such niche-construction is the use, creation, or modification of environmental resources for use as nests or shelters. Because these resources often have correlated structural elements, it can be difficult to disentangle the relative contribution of these elements to resource choice, and the preference functions underlying niche-construction behaviour remain hidden. Here, we present an experimental paradigm that uses 3D-scanning, -modelling, and -printing to create replicas of structures that differ with respect to key structural attributes. We show that a niche-constructing, shelldwelling cichlid fish, Neolamprologus multifasciatus, has strong open-ended preference functions for exaggerated shell replicas. Fish preferred shells that were fully intact and either enlarged, lengthened, or had widened apertures. Shell intactness was the most important structural attribute, followed by shell length, then aperture width. We disentangle the relative roles of different shell attributes, which are tightly correlated in the wild, but nevertheless differentially influence shelter choice and therefore niche construction in this species. We highlight the broad utility of our approach when compared to more traditional methods (e.g. two-choice tasks) for studying animal decision-making in a range of contexts.

evolutionary biology↗