Biology subjects

Romeo, D.

Publications and source records attributed to Romeo, D..

6 recordsLinked to original sources

bioRxiv2026

Early-Life Exposure to Warming Enhances Sea Urchin Heatwave Tolerance but Fails under Extreme Stress

The exposure to environmental stressors early in life can shape organisms to express more tolerant phenotypes to the same conditions during adulthood, a process called developmental plasticity. However, this acquired acclimation ability might depend on the intensity of the stimulus perceived later in life. Here, we took advantage of a purple sea urchin Paracentrotus lividus population developed at abnormally high sea temperature in the proximity of a power plant to test the limits of their developmentally acquired plasticity to increased water temperature. We simulated two marine heatwaves, a category I (moderate) and IV (extreme), and exposed the power plant population as well as a naive population developed in natural sea conditions. We measured their respiration rate and molecular responses to these two heatwaves. Regardless of the population of origin, sea urchins exposed to heatwaves showed higher oxygen consumption, indicating an increase in metabolic rates. At the molecular level, the biggest difference between the two populations was found following the moderate heatwave. Compared to the developmentally acclimated sea urchins, the naive population expressed genes coding for proteins with stress response, chromatin remodeling and RNA splicing functions, while suppressing immune response, revealing that developmental exposures can aid in priming the responses of adults to moderate temperature increases. However, a stronger heatwave leveled the differences between the two populations, with sea urchins from both locations expressing genes involved in proteostasis and detoxification. Nevertheless, regardless of the simulated marine heatwave intensity, sea urchins from the naive population always showed enrichment of the spliceosome pathway compared to power plant urchins, which activated immune response genes instead, reflecting fundamentally different thermal stress-coping strategies shaped by their developmental environments. Overall, our results demonstrate the critical yet context-dependent role of developmental plasticity in shaping the resilience of marine ectotherms to climate change.

evolutionary biology↗

bioRxiv2025

Molecular drivers of mutualistic association between anemone and anemonefish

The anemone-anemonefish mutualism is one of the most iconic in the marine environment. While the evolution of this mutualistic relationship has contributed to the ecological success of both partners, the underlying molecular processes that establish and maintain it remain poorly understood, particularly how anemonefish tolerate anemone venom. Here we explored the transcriptional dynamics in the anemonefish Amphiprion clarkii and its host anemone Entacmaea quadricolor 48 hours after association to identify the molecular underpinnings of their mutualistic relationship. Upon acclimation with an anemone, anemonefish showed differential regulation of sensory perception and memory genes in key brain regions, indicating activation of neural pathways that may facilitate host recognition and mutualism establishment. In the fishs skin, altered expression of genes involved in neurotransmitter release, cytoskeleton organization, and venom receptor proteins points to mechanisms of resistance to anemone venom. This resistance is particularly remarkable since anemone hosting fish exhibited increased expression of genes encoding mechanoreceptors, venom proteins, and ion channels involved in nematocyst discharge, indicating the anemone does indeed mount an active response to their mutualistic partner. Overall, our results highlight the complex interplay of molecular events in both species that play a pivotal role in establishing this mutualistic relationship.

genomics↗

bioRxiv2025

Interspecific variation in cleaning behaviour and honesty among cleaner wrasses

Mutualism is an interspecific interaction in which both partners gain a net fitness benefit. However, mutualisms are vulnerable to conflict because one partner may increase its benefits at the others expense (cheating). In coral reef cleaning mutualisms, cleaner fishes may cheat by feeding on client mucus rather than ectoparasites, imposing costs on clients and potentially destabilising cooperation. Here, using a standardised experimental framework, we examined cheating behaviour, measured via client jolts as a proxy, in four dedicated (relying on cleaning for sustenance) and three non-dedicated (opportunistic) cleaner fish using an interaction test with three client types (predatory, visitor and resident), and the bystander test, to evaluate potential behavioural changes in the presence of a bystander. When exposed to the same standardised social stimuli, dedicated cleaners responded differently across species, showing pronounced interspecific variation in both interaction time and client jolt frequency, whereas non-dedicated cleaners showed broadly uniform behavioural profiles with rare client jolts. Although captive interactions produced generally lower jolt rates than those typically reported in the wild, cleaner responses still differed across client types, suggesting context-dependent shifts in investment and exploitation with client identity. Bystander effects were weak overall; however, Labroides bicolor significantly reduced jolt expression when a bystander was present, suggesting that reputation-related adjustment may be species-specific. These findings highlight the capacity of cleaner species to respond differently to the same social environment, revealing species-specific behavioural strategies with potential consequences for mutualism stability and the selective pressures shaping cooperation-exploitation trade-offs.

animal behavior and cognition↗

bioRxiv2024

Neural Mechanisms of Mutualistic Fish Cleaning Behaviour: a Study in the Wild

One crucial interaction for the health of fish communities in coral reefs is performed by the cleaner fish by removing ectoparasites and other particles from the body of other fish, so called clients. Studying the underlying mechanisms of this behaviour is essential to understanding how species react to social stimuli and defining the drivers of mutualism. Here, we pinpoint the neural molecular mechanisms in the cleaning behaviour of Labroides dimidiatus in the wild through an in-situ interaction experiment at a coral reef in New Caledonia. Five cleaners and clients (Abudefduf saxatilis) were placed into underwater aquaria to interact, while five were not presented with a client. The brain transcriptomes revealed 291 differentially expressed genes in cleaners that were interacting with a client. Among these genes, grin2d, npy, slc6a3 and immediate early genes (fosb; fosl1; nr4a1) were related to learning and memory, glutamate and dopamine pathways, which confirm molecular pathways observed in laboratory studies. However, a new potential mechanism was found with npy (Neuropeptide Y) as a driver of feeding behaviour. These results show that in-situ experiments are essential for corroborating interpretations inferred from experiments in captivity and identify drivers of interspecific interactions.

animal behavior and cognition↗

bioRxiv2024

Cleaner gobies can solve a biological market task when the correct cue is larger

Animal cognition is deeply influenced by interactions with the environment. A notable example of sophisticated cognition in the animal kingdom is described by the mutualistic relationship between cleaner fish and clients, where decision-making processes play a pivotal role in partner choice and fish survival. In this context, while extensive research has explored the cognition of the cleaner wrasse Labroides dimidiatus, its Caribbean counterparts, Elacatinus spp., have been comparatively inadequately evaluated. In this study, we used plexiglass plates as surrogates for clients and assessed the ability of cleaner gobies, Elacatinus oceanops, to solve a biological market task where prioritising an ephemeral food plate over a permanent one would double the food reward. We varied cue-based decision-making using both ecologically relevant cues (plate size and colour) and non-relevant ones (presentation side). Additionally, we tested their capacity for reversal learning, an indicator of complex cognitive abilities. Notably, cleaner gobies were able to solve the biological markets task when the distinguishing cue was a larger plate size. Given that these gobies tend to prioritise larger predatory clients in nature, our results align with their natural inclination. Furthermore, considering these gobies were bred in captivity and never experienced cleaning interactions in their lifetime, our data might suggest that their intrinsic cognitive abilities are shaped by evolutionary pressures rooted in their ecological roles. In essence, even in the absence of direct ecological interactions, innate cognitive abilities in cleaner gobies seem to be deeply influenced by evolutionary forces tied to their natural ecological functions. However, their inability to solve the same task involving other cues, may be influenced by factors such as captivity-reared fish or limitations in the experimental design. Further research, including wild individuals, is essential to elucidate the cognitive abilities of the studied species and its implications in the ecological context and evolutionary history.

animal behavior and cognition↗

bioRxiv2022

Long non-coding RNA as environmental regulator in a non-model fish

The majority of the transcribed genome does not have coding potential but is composed of non-coding transcripts that are involved in transcriptional and post-transcriptional regulation of protein-coding genes. Regulation of gene expression is important in determining the response of organisms to changes in the environment, and therefore their persistence as population or species under global change. However, long non-coding RNAs (lncRNAs) are scarcely studied especially in non-model organisms due to the lack of a reliable pipeline for their accurate identification and annotation. Here, we present a pipeline which uses a combination of alignment-dependent and independent methods for the identification of conserved and species-specific lncRNAs from RNA-Seq data. Validation of this pipeline was performed using existing RNA-Seq data from Acanthochromis polyacanthus brain tissue, identifying a total of 4,728 lncRNAs across the genome, the majority of which (3,272) are intergenic. To investigate the possible implications of these intergenic lncRNAs (lincRNAs), we estimated the expression changes of lincRNAs and coding genes in response to ocean acidification. We found lincRNAs which neighbour or possibly trans-regulate differentially expressed coding genes related to pH regulation, neural signal transduction and ion transport, which are known to be important in the response to ocean acidification in fish. Overall, this pipeline enables the use of existing RNA sequencing data to reveal additional underlying molecular mechanisms involved in the response to environmental changes by integrating the study of lncRNAs with gene expression.

molecular biology↗