Biology subjects

Gordus, A. G.

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

8 recordsLinked to original sources

bioRxiv2026

Comparative transcriptomic analysis reveals signatures of selection for orb-weaving behavior in spiders

Spiders (Araneae) are responsible for one of the most captivating and intricate examples of animal architecture in the natural world: the web. But only certain groups of spiders weave the familiar spiral-shaped orb web, and the evolutionary origin of orb-weaving has left arachnologists tangled in a debate for the past decade. Since phylogenetic studies rejected the long-held belief that orb-weavers were monophyletic, two competing hypotheses have emerged: that the cribellate (dry) and ecribellate (sticky) orb webs arose independently and convergently, or that the ability to weave the orb originated with web-spinning common ancestors of all extant orb-weavers and was subsequently lost in many non-orb-weaving descendants. Attempts to reconstruct the ancestral state of the orb web have reached conflicting conclusions as a result of disagreements about the species phylogeny and the definition of orb-weaving. As a potential solution to this phylogenetic impasse, we tested orthologous genes from across the genomes of 98 species of spiders for evidence of both convergent positive selection and relaxed selection corresponding to the orb-weaving phenotype, the patterns that we would expect to be caused by each of the competing hypotheses on the origins of the orb. Using a permutation-based approach, we also compared the odds of gene loss and duplication between orb-weavers and non-orb-weaving spiders and identified genes whose copy number differ significantly between the two phenotypic groups. Through these analyses, we integrate the evolutionary history and genetic basis of orb web-associated traits, providing unique insights into the emergence of complex behavior.

evolutionary biology↗

bioRxiv2025

Unsupervised discovery and predictive sensorimotor transformation of spider prey capture through active vibration sensing

Animals flexibly adjust posture and movement in response to vibrational sensory input to extract information from dynamic environments. While sensorimotor transformations have been extensively studied in visual and somatosensory systems, their structure remains poorly understood in substrate-borne vibration sensing. Here, we combine high-resolution web vibration recordings with fine-scale behavioral tracking in the orb-weaving spider Uloborus diversus to dissect the sensorimotor basis of prey capture. Using unsupervised modeling, we identified discrete behavioral states that structure spider capture sequences, achieving over 83% classification accuracy. We then developed a predictive framework combining a linear-filtered generalized linear model (GLM) with a hidden Markov model (HMM) that robustly forecasts behavioral transitions across diverse prey vibration contexts. Notably, spiders exhibit context-dependent motor transitions--such as crouching and shaking--following decreases in prey vibrational power, consistent with active sensing behaviors that enhance signal detection. Furthermore, spiders reliably turn toward the web radius exhibiting the highest vibration amplitude during prey localization, demonstrating that amplitude alone predicts turning direction. These findings reveal a structured, predictive sensorimotor transformation linking external vibration cues to internal behavioral states. Our results highlight general principles of active sensing and closed-loop control in non-visual invertebrate systems, with broader implications for sensorimotor integration across species.

animal behavior and cognition↗

bioRxiv2025

The Maternal Effect of SKN-1B and DAF-7 on Intergenerational Pathogen Avoidance Learning in C. elegans.

Parental health strongly influences the development of embryos, and can ultimately influence behavior post-birth. When exposed to pathogenic Pseudomonas aeruginosa (PA14), C. elegans produces a robust immune response, as well as a learned behavior to avoid PA14 in the future. This learned avoidance of PA14 can be inherited by the F1 generation. An important trigger of the worms immune response to infection is the Nrf2 homologue, SKN-1. We find that the SKN-1B isoform strongly influences the intergenerational inheritance of PA14 avoidance in F1 animals via DAF-7 (TGF-{beta}) signaling from ASI. Functional SKN-1B is required in both the P0 and F1 generations to facilitate F1 avoidance of PA14 due to parental exposure. While inherited avoidance of PA14 was not observed in F2+ generations, the single generation learning investigated here may provide a parallel pathway to improve the fitness of F1 animals in a dynamic environment.

neuroscience↗

bioRxiv2025

Nonlinear integration of sensory and motor inputs by a single neuron in C. elegans.

Context is important for sensory integration. Rather than simply considering sensory information independently, the brain integrates this information to inform behavior, however identifying this property at the single-neuron level is not trivial. In Caenorhabditis elegans, the paired interneurons AIBL and AIBR (AIB) have a compartmentalized organization of presynapses along its singular process. Sensory and sensory interneurons primarily synapse along the proximal process, while motor and motor interneurons synapse along the distal process. Since this neuron has graded potentials, the simplest model for AIB integration is simply a convolution of its presynaptic inputs. Through a series of experiments to manipulate sensory and motor input onto AIB, we find that while AIB activity is primarily a convolution of motor inputs, its sensory responses are not integrated independently. Instead, the gain in sensory input is a function of the temporal dynamics of motor input. Sensory information is reinforced when it matches the expected behavioral response. We find this property is also observed in other whole-brain datasets. Context-dependent behavioral responses to sensory input is well-documented. Here, we show this property can be localized to single neurons in the worm nervous system. This integration property likely plays an important role in context-dependent decision-making, as well as the highly variable dynamics of the worm nervous system.

neuroscience↗

bioRxiv2024

A three-dimensional immunofluorescence atlas of the brain of the hackled-orb weaver spider, Uloborus diversus.

Spider orb-web building is a captivating, rare example of animal construction, whose neural underpinnings remain undiscovered. We created a three-dimensional atlas for the hackled orb-weaver, Uloborus diversus, based on immunostaining for the presynaptic component, synapsin, in whole-mounted spider synganglia. Whereas spider neuroanatomy has thus far been most comprehensively studied in cursorial species, this optically-sectioned atlas contributes a continuous, finely resolved model of the central nervous system of an orb-web building spider. Aligned to this volume, we examined the expression patterns of neuronal populations representing many of the classical neurotransmitters and neuromodulators (GABA, Acetylcholine, Serotonin, Octopamine/Tyramine), as well as a subset of neuropeptides (AllatostatinA, Crustacean Cardioactive Peptide (CCAP), FMRFamide, Proctolin) - detailing immunoreactivity in an unbiased fashion throughout the synganglion to reveal co-expression in known structures (such as the arcuate body), as well as novel neuropils not readily apparent in prior spider research, including the tonsillar neuropil as well as a potential protocerebral bridge. These structures provide targets for future functional studies, and taken together could represent a spider equivalent of the central complex, contributing to behaviors such as web-building.

neuroscience↗

bioRxiv2024

An optogenetic assay for the dauer decision in Caenorhabditis elegans

The dauer decision in Caenorhabditis elegans is a critical developmental decision that ensures survival under harsh environmental conditions. Factors such as temperature, food availability, and pheromone strongly influence the decision to enter and exit dauer. Traditional assays that assess the dauer decision are often confounded by the influence of pheromones from the population, which are often dynamic and highly variable. To mitigate this issue, we developed a simple, single-housing assay for dauer quantification that is compatible with optogenetics. We show that insulin-like peptides (ILPs) from ASJ and other neurons strongly influence the decision to exit dauer, and that ASJ activity can be manipulated with optogenetics to influence the dauer decision in a temporally precise manner.

neuroscience↗

bioRxiv2022

Chromosome-level genome and the identification of sex chromosomes in Uloborus diversus

The orb-web is a remarkable example of animal architecture that is observed in families of spiders that diverged over 200 million years ago. While several genomes exist for Araneid orb-weavers, none exist for other orb-weaving families, hampering efforts to investigate the genetic basis of this complex behavior. Here we present a chromosome-level genome assembly for the cribellate orb-weaving spider Uloborus diversus. The assembly reinforces evidence of an ancient arachnid genome duplication and identifies complete open reading frames for every class of spidroin gene, which encode the proteins that are the key structural components of spider silks. We identified the two X chromosomes for U. diversus and identify candidate sex-determining genes. This chromosome-level assembly will be a valuable resource for evolutionary research into the origins of orb-weaving, spidroin evolution, chromosomal rearrangement, and chromosomal sex-determination in spiders.

genomics↗

bioRxiv2021

Distinct movement patterns generate stages of spider web-building

The geometric complexity and stereotypy of spider webs have long generated interest in their algorithmic origin. Like other examples of animal architecture, web construction is the result of several assembly phases that are driven by distinct behavioral stages coordinated to build a successful structure. Manual observations have revealed a range of sensory cues and movement patterns used during web construction, but methods to systematically quantify the dynamics of these sensorimotor patterns are lacking. Here, we apply an analytical pipeline to quantify web-making behavior of the orb-weaver Uloborus diversus. Position tracking revealed stereotyped stages of construction that could occur in typical or atypical progressions across individuals. Using an unsupervised clustering approach, we identified general and stage-specific leg movements. A Hierarchical Hidden Markov Model revealed that stages of web-building are characterized by stereotyped sequences of actions largely shared across individuals, regardless of whether these stages progress in a typical or atypical fashion. Web stages could be predicted based on action-sequences alone, revealing that web-stages are a physical manifestation of underlying behavioral phases. HighlightsO_LISpider centroid trajectories indicate stereotyped progression of web-building stages. C_LIO_LIUnsupervised movement clustering reveals a shared set of movements which correspond to previously defined behaviors that define web-making across individuals. C_LIO_LIStages of web-building use both stage-specific and non-specific behaviors. C_LIO_LIStereotyped and distinct action sequences are predictive of stages of web-building. C_LI

animal behavior and cognition↗