Biology subjects

Mugue, N.

Publications and source records attributed to Mugue, N..

4 recordsLinked to original sources

bioRxiv2024

Selection of different parameters to study epistatic effect between heat shock and slightly deleterious mutations in the most fragile stage of embryogenesis Cyprinus carpio L.

The primary genetic challenge encountered in artificial populations lies in the strong genetic drift, which leads to the accumulation of numerous slightly deleterious mutations across the genome. Such mutations diminish the adaptability of the entire population. The objective of this project involves the investigation and implementation of genetic selection methods within cultivated fish populations such Cyprinus carpio L. In order to maintain a high level of genome quality in productive species, we conducted a proof-of-principle experiment employing stress-induced strong purifying selection. This selection process is based on negative epistasis and effectively eliminates organisms carrying an excess of deleterious variants. The first step involves the creation of mutant and intact groups of fish. To obtain mutant groups, we treated male gametes with the ENU mutagen, which primarily induces single-nucleotide substitutions uniformly throughout the genome, thereby imitating natural mutations. This methodology is paramount for the accurate interpretation of experimental outcomes. Notably, temperature stands as a pivotal factor influencing the embryonic development of fish. Therefore, we subjected the embryos to a diverse range of temperatures and varied the duration of exposure during critical stages of embryogenesis. Through meticulous examination, we ascertained that the stage most susceptible to screening purposes is the 22-somite pair stage, occurring at a temperature of 38{degrees}C, with a 40-minute exposure period. We suppose, this comprehensive approach can be applied to improve the quality of the gene pool within domestic fish populations, ultimately enhancing the economic efficacy of fish farms. The future prospects of this method encompass its potential application to various species.

ecology↗

bioRxiv2022

Epigenetic variations are landmarks of freshwater adaptation in threespine sticklebacks

For evolutionary biology, the phenotypic consequences of epigenetic variations and their potential contribution to adaptation and diversification are pressing issues. Marine and freshwater sticklebacks represent an ideal model for studying both genetic and epigenetic components of phenotypic plasticity that allow fish to inhabit water with different salinity. Here, we applied single-cell genomics (scRNA-seq and scATAC-seq) and whole-genome bisulfite sequencing to characterize intercellular variability in transcription, the abundance of open chromatin regions, and CpG methylation level in gills of marine and freshwater stickleback morphs. We found little difference in overall transcriptional variance between the morphs but observed significant changes in chromatin openness variance. In addition, genomic divergence islands (DIs) coincided with regions of increased methylation entropy in freshwater fish. Moreover, analysis of transcription factor binding sites within DIs revealed that [C]TCF motifs around marker SNPs were significantly enriched within the region. Altogether, our data show that increased epigenetic variance accompanies the adaptation of marine sticklebacks to freshwater.

evolutionary biology↗

bioRxiv2021

Adaptive radiation and burst speciation of hillstream cyprinid fish in African river

Adaptive radiation of fishes was long thought to be possible only in lacustrine environments. Recently, several studies have shown that also riverine and stream environments provide the ecological opportunity for adaptive radiation. In this study, we report on a riverine adaptive radiation of six ecomorphs of cyprinid hillstream fishes of the genus Garra in a river located in the Ethiopian Highlands in East Africa. Garra are predominantly highly specialized algae-scrapers with a wide distribution ranging from Southeastern Asia to Western Africa. However, adaptive phenotypic diversification in mouth type, sucking disc morphology, gut length and body shape have been found among these new species in a single Ethiopian river. Moreover, we found two novel phenotypes of Garra ( thick-lipped and predatory) that were not described before in this species-rich genus (>160 species). Mitochondrial and genome-wide data suggest monophyletic, intra-basin evolution of Garra phenotypic diversity with signatures of gene flow from other local populations. Although sympatric ecomorphs are genetically distinct and can be considered to being young species as suggested by genome-wide SNP data, mtDNA was unable to identify any genetic structure suggesting a recent and rapid speciation event. Furthermore, we found evidence for a hybrid origin of the novel thick-lipped phenotype, as being the result of the hybridization of two other sympatrically occurring species. Here we highlight how, driven by ecological opportunity, an ancestral trophically highly specialized lineage is likely to have rapidly adaptively radiated in a riverine environment, and that this radiation was promoted by the evolution of novel feeding strategies.

evolutionary biology↗

bioRxiv2018

Adaptive radiation of barbs of the genus Labeobarbus (Cyprinidae) in the East African river

Large African barbs of the genus Labeobarbus are widely distributed in African freshwaters, and exhibit profound phenotypic plasticity that could be a prerequisite for adaptive radiation. Using morphological, molecular, and stable isotope analyses, we investigated whether an adaptive radiation has occurred in a riverine assemblage of the L. gananensis complex. This complex is composed of six phenotypically distinct sympatric forms inhabiting the Genale River (Ethiopian highlands, East Africa). Of the six forms, five were divergent in their mouth morphology, corresponding to generalized, lipped, scraping (two forms) and large-mouthed phenotypes. Stable isotope analysis revealed differences in 15N and 13C among these forms, representing different foraging strategies (omnivorous, scraping and piscivorous). Phylogenetic analysis of two mtDNA markers confirmed the monophyly of L. gananensis, suggesting an intra-riverine radiation. However, the Genale assemblage appears to have originated through a combination of allopatric and sympatric events. Some of the specialized forms within this drainage originated independently from the local generalized forms in three different river regions within local mini-flocks composed of two to three sympatric forms. Our study shows that adaptive radiation in rivers can be enhanced by a combination of sympatric speciation and temporal geographic isolation, leading to local sympatric speciation followed by migration.

evolutionary biology↗