Cherkaoui, S. I. | Search bioRxiv

bioRxiv2026

A novel lineage of Chilomastix mesnili in wild Moroccan Barbary macaques (Macaca sylvanus)

Chilomastix spp. are flagellated protists found in the intestines of a broad range of hosts. They are generally non-pathogenic and have been little studied, especially using molecular techniques, and significant taxonomic uncertainty regarding the host specificity of lineages remains. As part of a study of intestinal microbial communities of wild Barbary macaques (Macaca sylvanus) from Morocco, we mined 50 faecal metagenomic sequence libraries and found 11 rRNA sequences matching Chilomastix. Compared to published 18S rRNA sequences, the Barbary macaque Chilomastix sequences formed a well-supported clade distinct from human-derived C. mesnili ST1 from Indonesia. The macaque Chilomastix sequences cluster with a single pig-derived isolate and two sequences from Japanese macaques (Macaca fuscata). This indicates that M. sylvanus harbours a lineage of Chilomastix distinct from the common human strain of C. mesnili and geographically widespread. We were also able to reconstruct the complete rDNA operon from this lineage.

evolutionary biology↗

bioRxiv2021

Genomic bases of insularity and ecological divergence in barn owls (Tyto alba) of the Canary Islands

Islands, and the particular organisms that populate them, have long fascinated biologists. Due to their isolation, islands offer unique opportunities to study the effect of neutral and adaptive mechanisms in determining genomic and phenotypical divergence. In the Canary Islands, an archipelago rich in endemics, the barn owl (Tyto alba) is thought to have diverged into a subspecies (T. a. gracilirostris) on the eastern islands, Fuerteventura and Lanzarote. Taking advantage of 40 whole-genomes and modern population genomics tools, we provide the first look at the origin and genetic makeup of barn owls of this archipelago. We show that the Canaries hold diverse, long-standing and monophyletic populations with a neat distinction of gene pools from the different islands. Using new method, less sensitive to structure than classical FST, to detect regions involved in local adaptation to the insular environment, we identified a haplotype-like region likely under positive selection in all Canaries individuals. Genes in this region suggest morphological adaptations to insularity. In the eastern islands, where the subspecies T. a. gracilirostris is present, genomic traces of selection pinpoint signs of locally adapted body proportions and blood pressure, consistent with the smaller size of this population living in a hot arid climate. In turn, genomic regions under selection in the western barn owls from Tenerife showed an enrichment in genes linked to hypoxia, a potential response to inhabiting a small island with a marked altitudinal gradient. Our results illustrate the interplay of neutral and adaptive forces in shaping divergence and early onset speciation.

evolutionary biology↗