Biology subjects

Hudson, A. G.

Publications and source records attributed to Hudson, A. G..

5 recordsLinked to original sources

bioRxiv2026

Evolution of novel host-microbiota coupling underlies adaptation to nutrient-scarce environments.

Animals colonizing food-limited environments need to overcome growth constraints by adapting to low, inconsistent nutritional inputs. Comparative studies of surface and cave populations of the Mexican tetra fish species Astyanax mexicanus provide a powerful system to explore evolution to food scarcity. In nutrient-scarce caves, evolved traits such as eye loss and increased fat storage have been shown to conserve energy in cavefish1-3 . However, the role of microbiota-mediated metabolism in sustaining growth and survival under food limitation remains poorly understood. Here, we demonstrate that surface and cave populations distinctly modulate their gut microbiota, with cavefish recruiting microbes whose predicted metabolites specifically promote growth under nutrient-limited conditions. Using microbiota data from three distinct dietary regimes and a fasting treatment, integrated topological data analysis4 and sparse modeling identify sugar and fatty acid degradation pathways coupled with growth in cavefish. Notably, the metabolites of these pathways are beneficial only for cavefish growth, and not for surface fish. Fasting in cavefish led to the recruitment of gut microbes capable of metabolizing aromatic compounds inaccessible to the host, whereas it recruited few microbial associates in surface fish. Our findings indicate that cavefish evolved novel host-microbiota coupling to sustain growth and resilience in their nutrient-scarce niche. We anticipate that our findings will broadly inform studies of evolution under extreme nutritional conditions and provide insights into the role of host-microbiota interactions in resilience to food scarcity at varied time scales.

evolutionary biology↗

bioRxiv2024

Exploring phenotypic diversity: a comparative analysis of cichlid convergence

Convergent evolution of similar phenotypes suggests some predictability in the evolutionary trajectories of organisms, due to strong and repeated selective pressures, and/or developmental constraints. In adaptive radiations, particularly in cichlid fish radiations, convergent phenotypes are commonly found within and across geographical settings. There are some main axes of cichlid morphological diversification. Recurrent changes in body patterns reveal adaption to alternative habitats, and modifications of the trophic apparatus respond to the exploitation of different food resources. Here we compare two Neotropical cichlid assemblages, the Mexican desert cichlid, and the Nicaraguan Midas cichlid, with similar polymorphic body and trophic apparatus patterns despite their independent evolution and evaluate morphological and gene expression convergence and divergence. We found a single morphological axis of differentiation in pharyngeal jaws with equivalent papilliform and molariform morphotypes in both cichlid radiations. In contrast, we found two different axes of differentiation in the shape of the body, defining two alternative limnetic body patterns. Genetic differences between morphotypes seem to be specific to each radiation, with no clear patterns of convergence.

evolutionary biology↗

bioRxiv2021

Epigenetic Divergence during Early Stages of Speciation in an African Crater Lake Cichlid Fish

Epigenetic variation can alter transcription and promote phenotypic divergence between populations facing different environmental challenges. Here we assess the epigenetic basis of diversification during the early stages of speciation. We focus on the extent and functional relevance of DNA methylome divergence between two Astatotilapia calliptera ecomorphs in crater Lake Masoko, southern Tanzania. We report extensive genome-wide methylome divergence between populations linked to key biological processes, including transcriptional activity of ecologically-relevant genes. These include genes involved in steroid metabolism, haemoglobin composition and erythropoiesis, consistent with divergent habitat occupancy of the ecomorphs. Using a common garden experiment, we found that global methylation profiles are rapidly remodelled across generations, but ecomorph-specific differences can be inherited. Collectively, our study suggests an epigenetic contribution to early stages of vertebrate speciation. One sentence summaryInheritance and plasticity of epigenetic divergence characterise early stages of speciation in an incipient cichlid species of an African crater lake.

genomics↗

bioRxiv2019

Ecological speciation in European whitefish is driven by a large-gaped predator

Lake-dwelling fish that form species pairs/flocks characterized by body size divergence are important model systems for speciation research. While several sources of divergent selection have been identified in these systems, their importance for driving the speciation process remains elusive. A major problem is that in retrospect, we cannot distinguish selection pressures that initiated divergence from those acting later in the process. To address this issue, we reconstructed the initial stages of speciation in European whitefish (Coregonus lavaretus) using data from 357 populations of varying age (26-10 000 years). We find that whitefish speciation is driven by a large-growing predator, the northern pike (Esox lucius). Pike initiates divergence by causing a largely plastic differentiation into benthic giants and pelagic dwarfs; ecotypes that will subsequently develop partial reproductive isolation and heritable differences in gill raker number. Using an eco-evolutionary model, we demonstrate how pikes habitat specificity and large gape size are critical for imposing a between-habitat trade-off, causing prey to mature in a safer place or at a safer size. Thereby, we propose a novel mechanism for how predators may cause dwarf/giant speciation in lake-dwelling fish species.

evolutionary biology↗

bioRxiv2018

G-Protein signaling increases germline stem cell activity in Drosophila males in response to multiple rounds of mating

Adult stem cells divide to renew the stem cell pool and replenish specialized cells that are lost due to death or usage. However, little is known about the mechanisms regulating how stem cells adjust to a demand for specialized cells. A failure of the stem cells to respond to this demand can have serious consequences, such as tissue loss, or prolonged recovery post injury. Here, we challenge the male germline stem cells (GSCs) of Drosophila melanogaster for the production of specialized cells using mating experiments. We show that repeated mating reduced the sperm pool and accelerated germline stem cell (GSC) divisions. The increase in GSC divisions depended on the activity of the highly conserved G-proteins. Germline expression of RNA-Interference (RNA-i) constructs against G-proteins or a dominant negative G-protein eliminated the increase in GSC divisions in mated males. Consistent with a role for the G-proteins in the regulation of GSC divisions, RNA-i against seven out of 35 G-protein coupled receptors (GPCRs) within the germline cells also eliminated the capability of males to accelerate their GSC divisions in response to mating. Our data show that GSCs are receptive to GPCR stimulus, potentially through a network of interactions among multiple signaling pathways.

developmental biology↗