Biology subjects

Salazar, C.

Publications and source records attributed to Salazar, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Adaptation in the eye and brain contributes to species divergence in visual perception in Heliconius butterflies

Sensory systems mediate the interaction between organisms and their environment, but how complex sensory pathways evolve and relate to variation in perception and behavior across ecological contexts, remains poorly understood, especially for terrestrial taxa. Here, we investigate whole-visual-system adaptation in Heliconius erato butterflies. Using continent-wide sampling, we demonstrate that within H. erato, facet count significantly decreased with increasing elevation. Common-garden rearing of low-elevation H. erato populations from Ecuador and their high-elevation sister species, H. himera, showed that eye and brain morphology are heritable, and comparisons to genomic measures of divergence indicates that this variation is due to divergent selection. Parallel comparisons from Colombia involving H. chestertonii (high elevation) and H. erato venus (low elevation) further revealed that eye and brain morphology can evolve as independent, decoupled traits. For both locations, differences in visual acuity correlated with variation in facet count. We also observed parallel evolution of spectral sensitivity, with independent high-elevation populations having fewer red-reflecting lateral filtering pigments. To experimentally link visual system morphology to behavior, we assessed visual acuity in second-generation H. erato cyrbia-H. himera hybrids. Overall, acuity was influenced by facet count, and when analyzed together with brain morphology, by a positive interaction between facet count and optic lobe volume, demonstrating that structural investment in the eye and neural expansion combine to maximize visual perception. This work shows that visual adaptation is a multi-layered process whereby sensory traits can evolve independently under localized ecological pressures, but evolution across the visual pathway contributes to refinements in behavioral performance.

evolutionary biology↗

bioRxiv2026

Rapid speciation in Harlequin Toads (Anura: Bufonidae) endemic to the Sierra Nevada de Santa Marta

The Neotropical genus Atelopus has experienced a drastic population decline in recent decades. Despite this, a knowledge gap remains regarding the conservation genetic status, phylogeography, and demographic history of most of its species, especially those endemic to areas with limited access like the Sierra Nevada de Santa Marta in Colombia. In this genomic study, we inferred phylogenetic relationships, demographic history, and gene flow among four endemic Atelopus morphospecies in the Sierra Nevada de Santa Marta-SNSM. Additionally, we compared the effective population size (Ne) estimates with the available population census data. NextRAD was used to obtain genomic data from 95 individuals collected at five sites in the SNSM and two in the Colombian Pacific (outgroup). The morphospecies recently diverged in a scenario without gene flow and were recovered as monophyletic. Their phylogenetic relationships were discordant, which is attributed to the presence of incomplete lineage sorting-ILS, which would also explain their shared ancestry among them. The lack of gene flow as well as the recent divergence times given by demography suggests a recent and rapid speciation. However, the reproductive isolation mechanisms that promote or maintain the species boundaries in this group remain unknown and require further investigation. We suggest that this process may have been influenced by the complex topography of the SNSM, traits such as high philopatry, low dispersal ability, and behavioral factors such as habitat preference or to factors related to genetic architecture that influenced the rapid formation of reproductive barriers among populations. Additionally, a pattern of population decline was observed around 200.000 years ago, with recent increases in three morphospecies. Despite the reduction in effective population size, no signs of inbreeding were detected. However, for A. laetissimus, the only species surveyed, the estimated value of Ne and its implications should be interpreted with caution. Ultimately, our findings reveal an evolutionary history shaped by a burst of diversification and abrupt reproductive isolation, highlighting how the resulting endemism and restricted genetic connectivity shape the unique evolutionary trajectory and vulnerability of this threatened montane species. Significance StatementThe mechanisms driving rapid speciation in montane ecosystems remain a central question in evolutionary biology. This study provides crucial genomic insights into the diversification of four endemic Atelopus species in an isolated Neotropical massif. We reveal a compelling evolutionary scenario where species diverge rapidly in absence of gene flow. This rapid speciation was likely facilitated by complex topography, environmental heterogeneity, and ecological and behavioral differences among species. Nevertheless, the evolutionary processes that limited gene flow among SNSM species have not yet been identified.

evolutionary biology↗

bioRxiv2026

Ecological divergence and post-eclosion brain development shape visual performance during Heliconius speciation

Sensory adaptation is increasingly recognized as a key driver of ecological speciation, but how visual system divergence is coordinated across development, and how this translates into behavioral differences, remains poorly understood. The butterfly Heliconius cydno, which inhabits closed-canopy forests, has larger eyes and greater investment in visual brain centers than its sympatric close-relative H. melpomene, which occupies more open forest-edge habitats, suggesting divergent ecological selection on the visual system. However, the behavioral consequences of these visual adaptations, their developmental trajectories, and whether they break down in hybrids is unknown. To address these questions, we combined ecological field data with behavioral assays and deep-learning-assisted segmentation of neuroanatomy. Visual acuity - the ability to resolve spatial detail - was higher in H. cydno, consistent with its greater ommatidia number, but also increased with age in both species despite no change in external eye morphology. These improvements coincided with the onset of male courtship and female oviposition, suggesting that early adult neurodevelopment shapes visual performance and may support the demands of reproduction. Brain morphology showed species-specific trajectories of post-eclosion optic lobe growth that broadly paralleled increases in acuity and were accompanied by ongoing neurogenesis in the adult optic lobes. While hybrids exhibited intermediate visual acuity, relationships among different components of the visual system were disrupted in hybrids. Together, these results show that ommatidia number alone cannot explain variation in visual acuity, and highlight how coordinated sensory evolution, and its breakdown in hybrids, may contribute to divergence during the early stages of speciation. Significance StatementAdaptation of sensory systems is increasingly recognized as a key driver of species formation, but it is unclear how these systems develop and shape behavioral differences. Using closely related Heliconius butterflies adapted to different light environments, we show that visual acuity improves during early adulthood through neural development, despite no change in eye structure. This maturation coincides with the onset of reproductive behaviors and is accompanied by growth and neurogenesis in visual brain regions. In hybrids, coordination among sensory traits breaks down, resulting in intermediate visual performance. These results show that sensory development is critical for behavioral adaptation and suggest that its integration contributes to the maintenance of species boundaries.

evolutionary biology↗

bioRxiv2026

Comprehensive drug efficacy data for mucinous ovarian carcinoma using a novel and extensive biobank of patient-derived organoid models

Mucinous Ovarian Carcinoma (MOC) is a rare ovarian cancer histological subtype with distinct pathology, genomics and clinical outcomes compared to other epithelial ovarian cancers. Accordingly, there is little evidence to guide clinical care, particularly in the use of systemic therapies, and the field has lacked informative and diverse pre-clinical models. We developed MOC-specific methods for generating tumour organoids with a success rate of 70% for long-term cultured lines (n=19). Organoid lines were developed from localised, advanced and recurrent tumours, including from biopsy tissue, and represent diverse genomic features not previously captured by existing cell lines. The organoid lines were highly similar to the tumours of origin for genomic and immunohistochemical markers. Screening using a panel of 11 chemotherapy agents highlighted resistance to standard-of-care agents such as carboplatin. Gastrointestinal cancer chemotherapy agents and their combination regimens lacked activity. Paclitaxel was often highly potent at low doses but failed to kill all cells. However, less frequently used drugs such as gemcitabine, topotecan and doxorubicin inhibited many of the lines more effectively than paclitaxel. Available, but non-standard of care, chemotherapy agents should be considered for clinical management of MOC. This is the largest (by [~]10 fold) cohort of fully characterised patient-derived MOC organoid lines described and the first with extensive drug screening data affording an opportunity for drug discovery and screening for personalised treatment.

cancer biology↗

bioRxiv2025

Genetic parallelism underpins convergent mimicry coloration across Lepidoptera

Convergent evolution, the repeated evolution of similar phenotypes in response to the same selective pressures across multiple lineages, is widespread in nature. The extent to which the same genetic mechanisms contribute to convergent evolution could reveal whether the pathway towards these optimal endpoints is flexible or constrained to follow a particular route. Although mimicry of aposematic colour patterns is well known in Lepidoptera, our knowledge of the genetic basis of these convergent patterns is mostly restricted to a few closely-related species. Here we study the genetic basis of mimicry across seven species of Ithomiini and Heliconius butterflies and a day-flying Chetone moth, representing lineages that diverged between [~]1-120 Mya, each presenting similar colour pattern switches. In all the butterfly species, the genetic variants most strongly associated with convergent colour pattern switches are similarly located in non-coding regions near the genes ivory and optix. Colour pattern variation in the moth is associated with a [~]1 Mb inversion around ivory paralleling the supergene architecture of the co-mimic Heliconius numata. In contrast to previous studies in Heliconius, there is limited evidence of alleles shared by means of hybridization in convergence among closely-related ithomiine species. Repeated parallel evolution of regulatory switches via reuse of the same two genes suggests that convergent colour pattern evolution is highly constrained, even across large evolutionary timescales.

evolutionary biology↗

bioRxiv2025

Gene loss associated with plasticity-first evolution in Heliconius butterflies

Phenotypic plasticity occurs when a genotype can produce more than one phenotype under different environmental conditions. Genetic accommodation allows plastic phenotypes to be tuned to new environments and eventually to even be lost. The colourful and toxic Heliconiini butterflies have biochemical plasticity - they either sequester their cyanogenic glucosides (CG) from their larval hostplant or biosynthesize them when compounds for sequestration are not available. Here, we trace the evolution of CG biosynthesis in Heliconiini butterflies, a fundamental component of this biochemical plasticity. We first reconstructed the evolutionary history of biochemical plasticity in Heliconiini butterflies using chemical data from over 700 individuals, demonstrating that plasticity was ancestral in the tribe and further lost in a few clades, such as the Sapho clade that only sequester CGs. In lepidopterans, CG biosynthesis has been fully characterized in the moth Zygaena filipendulae, and is composed of CYP405A2, CYP332A3, and UGT33A1. Thus, we CRISPR-edited the gene CYP405 in Heliconius erato, and confirmed that CYP405-knockout caterpillars do not biosynthesize CGs. We identified the CYP405s and CYP332s in other lepidopterans and found that both genes were independently co-opted into CG biosynthesis in the Heliconiinae butterflies and Zygaena moths. Most lepidopterans have a CYP332, but CYP405 is mostly restricted to butterflies and has been duplicated in all Heliconius species. Although several CYP405 copies were found in the Sapho clade, they lack structurally important P450 domains, which explain they loss of biochemical plasticity via specialization in CG sequestration. Our findings represent one of the few examples of plasticity-first evolution in which the genetic mechanisms associated with its accommodation/assimilation are known.

evolutionary biology↗

bioRxiv2024

Programming the elongation of mammalian cell aggregates with synthetic gene circuits

A key goal of synthetic morphogenesis is the identification and implementation of methods to control morphogenesis. One line of research is the use of synthetic genetic circuits guiding the self-organization of cell ensembles. This approach has led to several recent successes, including control of cellular rearrangements in 3D via control of cell-cell adhesion by user-designed artificial genetic circuits. However, the methods employed to reach such achievements can still be optimized along three lines: identification of circuits happens by hand, 3D structures are spherical, and effectors are limited to cell-cell adhesion. Here we show the identification, in a computational framework, of genetic circuits for volumetric axial elongation via control of proliferation, tissue fluidity, and cell-cell signaling. We then seek to implement this design in mammalian cell aggregates in vitro. We start by identifying effectors to control tissue growth and fluidity in vitro. We then combine these new modules to construct complete circuits that control cell behaviors of interest in space and time, resulting in measurable tissue deformation along an axis that depends on the engineered signaling modules. Finally, we contextualize in vitro and in silico implementations within a unified morphospace to suggest further elaboration of this initial family of circuits towards more robust programmed axial elongation. These results and integrated in vitro/in silico pipeline demonstrate a promising method for designing, screening, and implementing synthetic genetic circuits of morphogenesis, opening the way to the programming of various user-defined tissue shapes.

synthetic biology↗

bioRxiv2024

Genomics of Neotropical biodiversity indicators: two butterfly radiations with rampant chromosomal rearrangements and hybridisation

A major question in evolutionary biology is what drives the diversification of lineages. Rapid, recent radiations are ideal systems for addressing how new species arise because they still show key morphological and ecological adaptations associated with speciation. While most studied recent radiations have evolved in an insular environment, less research has been carried out on continental radiations with complex species interactions. Melinaea and Mechanitis butterflies (Nymphalidae: Ithomiini) have rapidly radiated in the Neotropics. They are classical models for Amazonian biogeography and colour pattern mimicry and have been proposed as biodiversity indicators. We generated reference genomes for five species of each genus, and whole-genome resequencing data of most species and subspecies covering a wide geographic range to assess phylogeographic relationships, patterns of hybridisation and chromosomal rearrangements. Our data help resolve the classification of these taxonomically challenging butterflies and reveal very high diversification rates. We find rampant evidence of historical hybridisation and putative hybrid species in both radiations, which may have facilitated their rapid diversification. Moreover, dozens of chromosomal fusions and fissions were identified between congeneric species, and even some within species. We conclude that interactions between geography, hybridisation and chromosomal rearrangements have contributed to these two rapid radiations in the highly diverse Neotropical region. We suggest that rapid radiations may be spurred by repeated periods of geographic isolation during Pleistocene climate oscillations, combined with lineage-specific rapid accumulation of incompatibilities during allopatric phases, followed by secondary contact with some gene exchange. Significance StatementUnderstanding factors contributing to rapid speciation is a key aim of evolutionary biology. Here we focus on two rapid radiations of Neotropical butterflies. Our genomic data with broad taxonomic and geographic coverage reveal rampant hybridisation and chromosomal rearrangements, each likely contributing to the high diversification rates. Our study highlights the use of genomic data to resolve taxonomically challenging species groups and elucidate drivers of diversification in rapid radiations. We show that for biodiversity hotspots with recent radiations, barcoding is insufficient to characterise species richness due to gene flow and recent speciation. The taxonomic implications of both introgression and karyotype diversity for species delimitation are important to consider during monitoring and management of biodiversity in these vulnerable habitats.

evolutionary biology↗

bioRxiv2024

Sensory weighting reflects changing patterns of visual investment during ecological divergence in Heliconius butterflies.

Integrating information across sensory modalities enables animals to orchestrate a wide range of complex behaviours. The relative importance placed on one sensory modality over another reflects the reliability of cues in a particular environment and corresponding differences in neural investment. As populations diverge across environmental gradients, the reliability of sensory cues may shift, favouring divergence in neural investment and the weight given to different sensory modalities. During their divergence across closed-forest and forest-edge habitats, closely related butterflies Heliconius cydno and H. melpomene evolved distinct brain morphologies, with the former investing more in vision. Quantitative genetic analyses suggest selection drove these changes, but their behavioural effects remain uncertain. We hypothesised that divergent neural investment may alter sensory weighting. We trained individuals in an associative learning experiment using multimodal colour and odour cues. When positively rewarded stimuli were presented in conflict pairing positively trained colour with negatively trained odour, and vice-versa, H. cydno favoured visual cues more strongly than H. melpomene. Hence, differences in sensory weighting may evolve early during divergence and are predicted by patterns of neural investment. These findings, alongside other examples, imply that differences in sensory weighting stem from divergent investment as adaptations to local sensory environments.

evolutionary biology↗

bioRxiv2023

Divergent warning patterns influence male and female mating behaviours in a tropical butterfly

Traits under divergent ecological selection that also function during mating can be important in maintaining species boundaries. Few studies have considered mutual mate choice, where both males and females base mating decisions on the same trait. We investigated the contribution of visual preference to assortative mating between an aposematic butterfly Heliconius cydno and its sympatric relative H. melpomene. Wing colouration in Heliconius butterflies evolved as a warning signal but also functions as a mating cue. We predicted that both sexes of H. cydno contributed to assortative mating by exhibiting visual preference towards conspecific wing colouration. We analysed published and new data from preference experiments, in which males were presented with conspecific and H. melpomene females. We also recorded female responses and mating outcomes in choice experiments, involving conspecific males with either the original white or artificially painted red forewing bands. Both sexes of H. cydno responded more positively towards the conspecific colouration, yet male colouration did not predict mating outcomes in female choice experiments. As courtships are initiated by males in butterflies, our findings suggest that female visual preference might be of secondary importance in preventing gene flow between H. cydno and H. melpomene.

animal behavior and cognition↗

bioRxiv2023

Adaptive introgression of a visual preference gene

Visual preferences are important drivers of mate choice and sexual selection, but little is known of how they evolve at the genetic level. Here we take advantage of the diversity of bright warning patterns displayed by Heliconius butterflies, which are also used during mate choice. We show that two Heliconius species have evolved the same visual mating preferences for females with red patterns by exchanging genetic material through hybridization. Extensive behavioral experiments reveal that male preferences are associated with a genomic region of increased admixture between these two species. Variation in neural expression of regucalcin1, located within this introgressed region, correlates with visual preference across populations, and disruption of regucalcin1 with CRISPR/Cas9 impairs courtship towards conspecific females, proving a direct link between gene and behavior. Our results support a role for hybridization during behavioral evolution, and show how visually-guided behaviors contributing to adaptation and speciation are encoded within the genome.

evolutionary biology↗

bioRxiv2023

Parallel shifts in flight-height associated with altitude across incipient Heliconius species

Vertical gradients in microclimate, resource availability and interspecific interactions are thought to underly stratification patterns in tropical insect communities. However, only a few studies have explored the adaptive significance of vertical space use during early population divergence. We analysed flight-height variation across speciation events in Heliconius butterflies representing parallel instances of divergence between low and high-altitude populations. We measured flight-height in wild H. erato venus and H. chestertonii, lowland and mountain specialists respectively, and found that H. chestertonii consistently flies at a lower height. We compared these data with previously published results for H. e. cyrbia and H. himera, the latter of which flies lower and, like H. chestertonii, recently colonised high-altitude, dry forests. We show that these repeated trends largely result from shared patterns of selection across equivalent environments, producing parallel trait-shifts in H. himera and H. chestertonii. Although our results imply a signature of local adaptation, we did not find an association between resource distribution and flight-height in H. e. venus and H. chestertonii. We discuss how this pattern may be explained by variation in forest structure and microclimate. Overall, our findings underscore the importance of behavioural adjustments during early divergence mediated by altitude-shifts.

evolutionary biology↗

bioRxiv2023

Sex chromosome - autosome fusions in Heliconius butterflies

Sex chromosomes are evolutionarily labile in many animals and sometimes fuse with autosomes, creating so-called neo-sex chromosomes. Fusions between sex chromosomes and autosomes have been proposed to reduce sexual conflict and to promote adaptation and reproductive isolation among species. Recently, advances in genomics have fuelled the discovery of such fusions across the tree of life. Here, we discovered multiple fusions leading to neo-sex chromosomes in the sara/sapho clade of the classical adaptive radiation of Heliconius butterflies. Heliconius butterflies generally have 21 chromosomes with very high synteny. However, the five species in the sapho subclade show large variation in chromosome number ranging from 21 to 60. We found that the W chromosome is fused with chromosome 4 in all of them. Two sister species pairs showed subsequent fusions between the W and chromosomes 9 or 14, respectively. These sequential fusions between autosomes and sex chromosomes make Heliconius butterflies an ideal system for studying the role of neo-sex chromosomes in adaptive radiations and the degeneration of sex chromosomes over time. Our findings emphasize the capability of WGS technology to detect neo-sex chromosomes even when sex chromosomes are not explicitly assembled. Author SummaryFusions between sex chromosomes and autosomes are thought to have the potential to resolve sexual conflict and enhance local adaptation or reproductive isolation between species. Here, we discovered such fusions in Heliconius butterflies. Heliconius butterflies mostly have a very stable karyotype with 21 chromosomes and high synteny across species. However, the five species in the sapho subclade have up to 60 chromosomes, suggesting that they have undergone many chromosomal fissions. We document that in addition to the fissions, the sapho subclade also showed multiple fusions between the female-specific sex chromosome (W) and autosomes. We found a W-4 fusion shared by all five species and additional W fusions with chromosomes 9 and 14 shared by two species each. Even though in many sapho subclade species the autosomes have undergone fissions, the chromosomes fused with the W represent the full-length autosomes, as seen in other Heliconius species, suggesting that fusing to the W protected them from fissions. Our study reveals the power of short-read sequencing to discover neo-sex chromosomes and showcases Heliconius butterflies as a promising system for studying the causes and consequences of sex chromosome evolution.

evolutionary biology↗

bioRxiv2022

Does sexual conflict contribute to the evolution of novel warning patterns?

Why warning patterns are so diverse is an enduring evolutionary puzzle. Because predators associate particular patterns with unpleasant experiences, an individuals predation risk should decrease as the local density of its warning pattern increases, promoting pattern monomorphism. Distasteful Heliconius butterflies are known for their diversity of warning patterns. Here, we explore whether interlocus sexual conflict can contribute to their diversification. Male Heliconius use warning patterns as mating cues, but mated females may suffer costs if this leads to harassment, favoring novel patterns. Using simulations, we show that drift alone is unlikely to cause pattern diversification, but that sexual conflict can assist such process. We also find that genetic architecture influences the evolution of male preferences, which track changes in warning pattern due to sexual selection. When male attraction imposes costs on females, this affects the speed at which novel pattern alleles increase. In two experiments, females laid fewer eggs with males present. However, although males in one experiment showed less interest in females with manipulated patterns, we found no evidence that female coloration mitigates sex-specific costs. Overall, male attraction to conspecific warning patterns may impose an unrecognized cost on Heliconius females, but further work is required to determine this experimentally.

evolutionary biology↗

bioRxiv2021

Repeated genetic adaptation to high altitude in two tropical butterflies

Repeated evolution can provide insight into the mechanisms that facilitate adaptation to novel or changing environments. Here we study adaptation to high altitude in two divergent tropical butterflies, H. erato and H. melpomene, which have repeatedly and independently adapted to high elevations on either side of the Andean mountains. We sequenced 518 whole genomes from elevational transects and found many regions under selection at high altitude, with repeated genetic differentiation across multiple replicates, including allopatric comparisons. In contrast, there is little molecular parallelism between H. erato and H. melpomene. With a further 85 whole genomes of five close relatives, we find that a large proportion divergent regions have arisen from standing variation and putative adaptive introgression from high-altitude specialist species. Taken together our study supports a key role of standing genetic variation and gene flow from pre-adapted species in promoting parallel genetic local adaptation to the environment.

evolutionary biology↗

bioRxiv2021

Supergene formation is associated with a major shift in genome-wide patterns of diversity in a butterfly

Selection shapes genetic diversity around target mutations, yet little is known about how selection on specific loci affects the genetic trajectories of populations, including their genome-wide patterns of diversity and demographic responses. Here we study the patterns of genetic variation and geographic structure in a neotropical butterfly, Heliconius numata, and its closely related allies in the so-called melpomene-silvaniform clade. H. numata is known to have evolved an inversion supergene which controls variation in wing patterns involved in mimicry associations with distinct groups of co-mimics whereas it is associated to disassortative mate preferences and heterozygote advantage at this locus. We contrasted patterns of genetic diversity and structure 1) among extant polymorphic and monomorphic populations of H. numata, 2) between H. numata and its close relatives, and 3) between ancestral lineages. We show that H. numata populations which carry the inversions as a balanced polymorphism show markedly distinct patterns of diversity compared to all other taxa. They show the highest genetic diversity and effective population size estimates in the entire clade, as well as a low level of geographic structure and isolation by distance across the entire Amazon basin. By contrast, monomorphic populations of H. numata as well as its sister species and their ancestral lineages all show lower effective population sizes and genetic diversity, and higher levels of geographical structure across the continent. One hypothesis is that the large effective population size of polymorphic populations could be caused by the shift to a regime of balancing selection due to the genetic load and disassortative preferences associated with inversions. Testing this hypothesis with forward simulations supported the observation of increased diversity in populations with the supergene. Our results are consistent with the hypothesis that the formation of the supergene triggered a change in gene flow, causing a general increase in genetic diversity and the homogenisation of genomes at the continental scale.

evolutionary biology↗

bioRxiv2021

The CATP-8/P5A-type ATPase functions in multiple pathways during neuronal patterning

The assembly of neuronal circuits involves the migrations of neurons from their place of birth to their final location in the nervous system, as well as the coordinated growth and patterning of axons and dendrites. In screens for genes required for patterning of the nervous system, we identified the catp-8/P5A-ATPase as an important regulator of neural patterning. P5A-ATPases are part of the P-type ATPases, a family of proteins known to serve a conserved function as transporters of ions, lipids and polyamines in unicellular eukaryotes, plants, and humans. While the function of many P-type ATPases is relatively well understood, the function of P5A-ATPases in metazoans remained elusive. We show here, that the Caenorhabditis elegans ortholog catp-8/P5A-ATPase is required for specific aspects of nervous system development. Specifically, the catp-8/P5A-ATPase serves functions in shaping the elaborately sculpted dendritic trees of somatosensory PVD neurons. Moreover, catp-8/P5A-ATPase is required for axonal guidance and repulsion at the midline, as well as embryonic and postembryonic neuronal migrations. Interestingly, not all axons at the midline require catp-8/P5A-ATPase, although the axons run in the same fascicles and navigate the same space. Similarly, not all neuronal migrations require catp-8/P5A-ATPase. A CATP-8/P5A-ATPase reporter is localized to the ER in most if not all tissues and catp-8/P5A-ATPase can function both cell-autonomously and non-autonomously to regulate neuronal development. Genetic analyses establish that catp-8/P5A-ATPase can function in multiple pathways, including the Menorin pathway, previously shown to control dendritic patterning in PVD, and Wnt signaling, which functions to control neuronal migrations. Lastly, we show that catp-8/P5A-ATPase is required for localizing select transmembrane proteins necessary for dendrite morphogenesis. Collectively, our studies suggest that catp-8/P5A-ATPase serves diverse, yet specific roles in different genetic pathways, and may be involved in the regulation or localization of transmembrane proteins to specific subcellular compartments. AUTHOR SUMMARYP-type ATPases are a large family of transporters that are conserved from unicellular eukaryotes and plants to metazoans. Structurally and functionally, they fall into five subfamilies, P1 to P5, of which the latter is further divided into P5A and P5B-type ATPases. Unlike for other P-type ATPases, no mutant phenotypes for the P5A-type ATPases have been described in metazoans. Here, we show that the catp-8/P5A-ATPase in the nematode Caenorhabditis elegans is involved in multiple aspects of neuronal patterning, including neuronal migrations as well as axon guidance and dendrite patterning. A functional fluorescent reporter fusion shows the CATP-8/P5A-ATPase is expressed in most, if not all, tissues in the endoplasmic reticulum and catp-8 can function both in neurons and surrounding tissues from where it orchestrates neuronal development. Genetically, catp-8 acts in multiple pathways during these processes, including the Wnt signaling and the Menorin pathway. Imaging studies suggest that the catp-8/P5A-ATPase is necessary for proper localization of cell-surface transmembrane molecules to dendrites of sensory neurons, but likely not for their trafficking. In summary, we propose that CATP-8/P5A-ATPase serves a function in the ER during development of select neurons, by localizing certain transmembrane, and possibly, secreted proteins

developmental biology↗

bioRxiv2020

Light environment influences mating behaviours during the early stages of divergence in tropical butterflies

Species divergence is facilitated when traits under divergent selection also act as mating cues. Fluctuations in sensory conditions can alter signal perception independently of adaptation to contrasting sensory environments, but how this fine scale variation affects behavioural isolation has received less attention, especially in terrestrial organisms. The warning patterns of Heliconius butterflies are under selection for aposematism and act as mating cues. Using computer vision, we extracted behavioural data from 1481 hours of video footage for 387 individuals. We show that the putative hybrid species H. heurippa and its close relative H. timareta linaresi differ in their response to divergent warning patterns, and that these differences are strengthened with increased local illuminance. Trials with live individuals reveal low-level assortative mating that are sufficiently explained by differences in visual attraction. Finally, results from hybrid butterflies are consistent with linkage between a major warning pattern gene and the corresponding behaviour, though the differences in behaviour we observe are unlikely to cause rapid reproductive isolation as predicted under a model of hybrid trait speciation. Overall, our results highlight that the role of ecological mating cues for behavioural isolation may depend on the immediate sensory conditions during which they are displayed to conspecifics.

evolutionary biology↗