Biology subjects

Hendry, A.

Publications and source records attributed to Hendry, A..

9 recordsLinked to original sources

bioRxiv2026

Among-population variation in the threespine stickleback ( Gasterosteus aculeatus ) liver metabolome: effects of ancestry and environment

Untargeted metabolomics offers a powerful lens for quantifying high-dimensional phenotypic variation within and among species in nature, but has yet to be widely adopted in evolutionary ecology. Some important initial questions are whether metabolome composition differs among populations, and to what extent such variation is genetic or plastic. Here, we use untargeted liquid chromatography tandem mass spectrometry to characterize the relative abundance of 5,939 molecular features of the threespine stickleback (Gasterosteus aculeatus) liver metabolome. Native lake populations differ in metabolome composition, reflecting effects of sex, size, geography, and population ecotype (benthic versus limnetic). Stickleback from these lakes were translocated to found new populations in nine recently fishless lakes, permuting fish ecotypes across benthic and limnetic lake habitats. Several generations later, metabolomes in these experimental populations reflect effects both of their genetic ancestry (e.g., taurocholic acid, a cholane steroid bile acid, was elevated in limnetic-ancestries), as well as their present habitat (e.g., acylcarnitines). Additionally, ecotypes transplanted into a habitat to which they were maladapted exhibited a distinctive metabolomic profile. We conclude that stickleback exhibit both heritable and plastic among-population differences in liver metabolome, which could represent an important phenotypic basis of rapid evolution, population divergence, and perhaps local adaptation.

Molecular Biology↗

bioRxiv2025

Hybridization but minimal introgression: ecologically-based divergent selection maintains a steep hybrid zone in parapatric stickleback fish

Steep hybrid zones provide key insights into the mechanisms of speciation by reflecting incomplete reproductive isolation between diverging populations. However, the specific reproductive barriers preventing the fusion of such populations generally remain unclear, particularly the role of ecologically-based divergent selection. To address the latter, we here investigate a steep hybrid zone between lake and stream ecotypes of threespine stickleback fish inhabiting contiguous habitats within a single watershed. Given the spatial proximity of these habitats and the systems postglacial age, historical allopatry is unlikely to have contributed to the evolution of reproductive isolation. Using individual whole-genome sequencing from clinal sampling sites, we find that hybridization occurs within a narrow zone - just a few hundred meters long - at the transition between lake and stream habitat. Individuals in this contact zone exhibit strongly bimodal genome-wide ancestry, with a rapid shift toward the stream ecotypes genomic background, consistent with strong selection against lake-derived alleles in the stream habitat. Individual-based simulations tailored to this system demonstrate that divergent ecological selection alone can maintain the observed sharp cline, and illustrate the sustained antagonism between gene flow and selection near the habitat transition. Our findings underscore the power of ecological divergence to generate and maintain reproductive isolation, even in the absence of historical separation, and motivate further empirical work on the ecological underpinnings of steep hybrid zones.

evolutionary biology↗

bioRxiv2024

Destabilized host-parasite dynamics in newly founded populations

When species disperse into previously unoccupied habitats, new populations encounter unfamiliar species interactions such as altered parasite loads. Theory predicts that newly founded populations should exhibit destabilized eco-evolutionary fluctuations in infection rates and immune traits. However, to understand founder effects biologists typically rely on retrospective studies of range expansions, missing early-generation infection dynamics. To remedy this, we experimentally founded whole-lake populations of threespine stickleback. Infection rates were temporally stable in native source lakes. In contrast, newly founded populations exhibit destabilized host-parasite dynamics: high starting infection rates led to increases in a heritable immune trait (peritoneal fibrosis), suppressing infection rates. The resulting temporal auto-correlation between infection and immunity suggest that newly founded populations can exhibit rapid host-parasite eco-evolutionary dynamics.

evolutionary biology↗

bioRxiv2022

Gut Enterochromaffin Cells are Critical Drivers of Visceral Pain and Anxiety

Gastrointestinal (GI) discomfort is a hallmark of most gut disorders and represents a significant component of chronic visceral pain 1. For the growing population afflicted by irritable bowel syndrome (IBS), GI hypersensitivity and pain persist long after signs of tissue injury have resolved 2. IBS also exhibits a strong sex bias afflicting women three-fold more than men 1. Identifying the molecules, cells, and circuits that mediate both the acute and persistent phases of visceral pain is a critical first step in understanding how environmental and endogenous factors produce long-term changes in the nervous system or associated tissues to engender chronic pain syndromes 3,4. Enterochromaffin (EC) cells within the gut epithelium are exceedingly rare sensory neuroendocrine cells that detect and transduce noxious stimuli to nearby nerve endings via serotonin. Here, we manipulate murine EC cell activity using genetic strategies to ascertain their contributions to visceral pain. We show that acute EC cell activation is sufficient to elicit hypersensitivity to gut distension and necessary for the sensitizing actions of isovalerate, a bacterially derived short-chain fatty acid irritant associated with inflammatory GI disorders. Remarkably, prolonged EC cell activation by itself is sufficient to produce persistent visceral hypersensitivity, even in the absence of an instigating inflammatory episode. Perturbing the activity of these rare EC cells led to a marked increase in anxiety-like behaviors that normalized after blocking serotonergic signaling. Sex differences were also observed accross a range of assays indicating that females have a higher baseline visceral sensitivity. Our findings validate a critical role for EC cell-mucosal afferent signaling in acute and persistent GI pain while highlighting mechanistically defined genetic models for studying visceral hypersensitivity, sex differences, and associated behaviors.

physiology↗

bioRxiv2020

A nonsense mutation in TFEC is the likely cause of the recessive piebald phenotype in ball pythons ( Python regius)

Captive-bred ball pythons (Python regius) represent a powerful model system for studying the genetic basis of colour variation and Mendelian phenotypes in vertebrates. Although hundreds of Mendelian phenotypes (colour morphs) affecting colouration and patterning have been described for ball pythons, the genes causing these colour morphs remain unknown. Here, we used crowdsourcing of samples from commercial ball python breeders to investigate the genetic basis of a classic phenotype found in the pet trade, the piebald [characterized by dorsolateral patches of unpigmented (white) skin]. We used whole-genome sequencing of pooled samples followed by population genetic methods to delineate the genomic region containing the causal gene. We identified TFEC of the MIT-family of transcription factors as a candidate gene. Functional annotation of SNPs identified a nonsense mutation in TFEC, which we conclude is the likely causal variant for the piebald phenotype. Our work shows that ball python colour morphs have the potential to be an excellent model system for studying the genetic basis of pigment variation in vertebrates, and highlights how collaborations with commercial breeders can accelerate discoveries.

genomics↗

bioRxiv2019

Dynamic coupling of cochlear inner hair cell intrinsic Ca2+ action potentials to Ca2+ signaling of non-sensory cells

The relationship between Ca2+ action potential (AP) activity in immature inner hair cells (IHCs) and the spontaneous ATP-dependent intercellular Ca2+ signaling in cochlear non-sensory cells (NSCs) of the greater epithelial ridge (GER) is unclear. Here, we determined that IHCs fired asynchronous Ca2+ APs also in the absence of Ca2+ activity in the GER. Patch clamp recordings from IHCs isolated from the rest of the sensory epithelium confirmed that this firing activity is an intrinsic property of immature IHCs. However, frequency, correlation index and burst duration of IHC APs increased significantly during Ca2+ wave propagation in NSCs, and depended on wave extension in the GER. Furthermore, IHC depolarization under whole cell patch clamp conditions triggered Ca2+ signals in nearby NSCs with a delay that was proportional to the distance from the stimulated IHC. Thus the immature mammalian cochlea supports bidirectional exchange of Ca2+ signals between IHCs and NSCs.\n\nIMPACT STATEMENTIn inner hair cells of the developing mammalian cochlea, Ca2+ action potentials are both intrinsic and bidirectionally coupled to the ATP-dependent Ca2+ signaling of the surrounding non-sensory cells.

developmental biology↗

bioRxiv2018

Six percent loss of genetic variation in wild populations since the industrial revolution

Genetic variation underpins population fitness and adaptive potential1,2. Thus it plays a key role in any species probability of long-term persistence, particularly under global climate change. Genetic variation can be lost in a single generation but its replenishment may take hundreds of generations3. For that reason safeguarding genetic variation is considered fundamental to maintaining biodiversity, and is an Aichi Target for 20204. As human activities are driving declines in many wild populations5, genetic variation is also likely declining. However the magnitude of ongoing genetic variation loss has not been assessed, despite its importance. Here we show a 6% decline in within-population genetic variation of wild organisms since the industrial revolution. The erosion of genetic variation has been most severe for island species, with an 18% average decline. We also identified several key taxonomic and geographic information gaps that must be urgently addressed. Our results are consistent with single time-point meta-analyses that indicated genetic variation is likely declining 6,7. However, our results represent the first confirmation of a global decline, and estimate of the magnitude of the genetic variation lost from wild populations.

genetics↗

bioRxiv2018

Ecosystem tipping points in an evolving world

There is growing concern over tipping points arising in ecosystems due to the crossing of environmental thresholds. Tipping points lead to strong and possibly irreversible shifts between alternative ecosystem states incurring high societal costs. Traits are central to the feedbacks that maintain alternative ecosystem states, as they govern the responses of populations to environmental change that could stabilize or destabilize ecosystem states. However, we know little about how evolutionary changes in trait distributions over time affect the occurrence of tipping points, and even less about how big scale ecological shifts reciprocally interact with trait dynamics. We argue that interactions between ecological and evolutionary processes should be taken into account for understanding the balance of feedbacks governing tipping points in nature.

ecology↗

bioRxiv2018

Spontaneous and coordinated Ca2+ activity of cochlear sensory and non-sensory cells drives the maturation of OHC afferent innervation

Outer hair cells (OHCs) are highly specialized sensory cells conferring the fine tuning and high sensitivity of the mammalian cochlea to acoustic stimuli. Here, by genetically manipulating spontaneous Ca2+ signalling in vivo, through a period of early postnatal development, we find that the refinement of OHC afferent innervation is regulated by complementary spontaneous Ca2+ signals originating in OHCs and non-sensory cells. OHCs fire spontaneous Ca2+ spikes during a narrow period of immature development. Simultaneously, waves of Ca2+ activity in the non-sensory greater epithelial ridge act, via ATP-induced activation of P2X receptors, to synchronize OHC firing, resulting in the refinement of their afferent innervation. In the absence of connexin channels Ca2+ waves are impaired, leading to a reduction in the number of ribbon synapses and afferent fibres on OHCs. We propose that the correct maturation of the afferent connectivity in OHCs requires experience-independent Ca2+ signals from sensory and non-sensory cells.

neuroscience↗