Biology subjects

Westerman, E. L.

Publications and source records attributed to Westerman, E. L..

16 recordsLinked to original sources

bioRxiv2026

Proteomic consequences of male mate preference learning and female phenotype in the butterfly Bicyclus anynana

Mate preference learning, where individuals use past social experience to choose mates, is prevalent in many species. Yet its consequences on reproductive investment, and whether individuals differentially invest in reproduction based on their learned perception of the mates phenotype, are unknown. We addressed these questions using the butterfly Bicyclus anynana, where males acquire individual preferences for artificially painted 0-UV dorsal hindwing spotted (DHSN) females, who then lay more eggs. We measured the spermatophore proteins transferred by naive and experienced males to females manipulated to have preferred (0-DHSN) and unpreferred (2-DHSN) wing patterns. Using data independent acquisition (DIA), we identified 2144 proteins in the B. anynana spermatophore transferred to the female during mating. Experienced males that mated with preferred and unpreferred females had more differentially abundant (DA) proteins in their spermatophores that have functions in circadian rhythms, oogenesis, and neural signalling than naive males. Proteins associated with oogenesis were DA in spermatophores transferred to preferred females, which may contribute to why preferred females lay more eggs. Overall, our study provides evidence for the role of experience-induced behavioural plasticity in tailoring male ejaculates in butterflies and identifies proteins that influence female physiology and behaviours which directly affect the pairs overall reproductive fitness.

animal behavior and cognition↗

bioRxiv2026

The gene yellow influences aversive mate preference learning in a butterfly

Reproductive isolation is a central driver of speciation and can be reinforced by both innate mate preferences and mate preference learning. Pigmentation genes are strong candidates for pleiotropic effects on these processes because they shape visual traits used in mate choice and may also influence neural function, yet their role in learning is poorly understood. Here, we test whether the pigmentation gene yellow affects innate mate preference and aversive mate preference learning in female Bicyclus anynana, and whether these effects are associated with changes in brain dopamine levels. Using CRISPR-Cas9, we knocked out the yellow gene, developed a mutant line, and tested the mate preferences and mate preference learning ability of mutant females compared to wild-type (WT) females. We find that loss of yellow does not alter assortative mating based on pigmentation or disrupt innate visual or olfactory preferences. In contrast, loss of yellow does influence learning ability, as mutant females failed to modify mate preference following aversive premating experience, indicating an impairment in aversive learning. Despite yellows role in the melanin biosynthesis pathway, brain dopamine levels remain unchanged in mutant females relative to WT females. These findings identify yellow as a pleiotropic gene influencing both pigmentation and aversive mate preference learning, providing evidence that pigmentation genes can shape behavioral processes important for reproductive isolation and speciation. Significance statementPigmentation genes are best known for controlling color patterns, but they may also influence behavior through shared neural pathways. Here, we show that the pigmentation gene yellow is required for aversive mate preference learning in the butterfly Bicyclus anynana. Females lacking yellow retain normal innate visual and olfactory mate preferences but fail to learn to avoid previously unattractive mates. Surprisingly, this learning deficit is not associated with altered dopamine levels, suggesting that downstream neural signaling pathways are involved instead. These findings identify a gene that influences both pigmentation and learned mate preference, providing evidence that pigmentation genes can shape behavioral processes important for reproductive isolation and speciation.

animal behavior and cognition↗

bioRxiv2026

Neurotranscriptomic signatures of natural variation in mate preference learning in two subspecies of Heliconius melpomene butterflies

Many animals change their behavior in response to social experiences by learning. Although social learning is adaptive, not all individuals learn. In Heliconius melpomene, H. m. malleti males respond to 2-day prior failed copulation experience by decreasing courtship, whereas H. m. rosina males do not. Here, we explore the transcriptomic differences in both the neural (brain) and sensory (eyes, antennae) tissues underlying this natural diversity in male aversive mate-preference learning. While the transcriptomic profiles of the two subspecies are inherently different across all three tissues, we found the greatest difference between the good (H. m. malleti), and bad (H. m. rosina) mate-preference learners in the brain, followed by the sensory tissues. Known learning genes and Gene Ontology terms were associated with differences in mate-preference learning, suggesting conserved learning pathways across animals. Genes within putative magic loci associated with colors, odors, and locomotion, were also differentially expressed between H. m. malleti and H. m. rosina, suggesting multimodal sensory processing may drive behavioral variance in these two subspecies. Overall, our study identifies genetic underpinnings for differences in preference learning, both in neural processing and sensory tissues. Selection on these genes/networks could result in preference learning-induced reinforcement, leading to reproductive isolation and speciation.

evolutionary biology↗

bioRxiv2024

Female Olfactory Sensitivity is Temporally Asynchronous with Male Courtship in a Butterfly

Signal efficacy is crucial to communicative behaviours. To be effective, a signal once broadcast must be capable of being received and interpreted by a receiver or receivers. In addition to maximizing the amount that a signal stimulates receptive organs, optimally the timing of when a signal is broadcast would synchronize with a receivers peak receptivity. Here, we investigated whether peak timing of male courtship, which includes release of a pheromone required for copulation to occur, is synchronized with female pheromone sensitivity in the butterfly Bicyclus anynana (Lepidoptera: Nymphalidae). To do this, we performed behavioural and electrophysiological assays at dawn, noon, and dusk. We also investigated the circadian rhythmicity of antennae gene expression by performing RNA-Sequencing on antennal tissues collected at dawn, noon and dusk. We found that although males court most often near dusk, females are more sensitive to odorants in the morning. Furthermore, antennae exhibited differential and diurnally rhythmic expression of odorant receptors and genes associated with learning and sexual receptivity, as well as gene ontology (GO) terms related to fatty acid metabolism and trehalose biosynthesis, supporting our circadian electrophysiological results. Previous literature indicates females form both positive and negative mate preference associations with male pheromones in the morning, regardless of whether males court females. Thus, this asynchrony may enable female B. anynana to learn mate preferences before they are courted by conspecific (or potentially heterospecific) males. SummaryMale Bicyclus anynana butterflies court more at dusk while females are more sensitive to odorants in the morning. Patterns of antenna gene expression also suggest circadian rhythmicity of odorant sensitivity.

animal behavior and cognition↗

bioRxiv2024

Synchronous seasonal plasticity in colouration, behaviour, and visual gene expression in a wild butterfly population

Phenotypic plasticity allows many animals to quickly respond to seasonal changes in their environment. Seasonal changes to physiological systems, such as sensory systems, may explain other more obvious changes in behaviour, often working synergistically with changes in morphology. Here we investigate if there are covarying seasonal changes to morphology, behaviour, and the visual system in the seasonally plastic butterfly Junonia coenia. To describe when seasonal wing patterns occur at our field sites in the central United States and for analysis of gene expression in eye tissue, we collected animals throughout the summer and fall in 2018, 2019, 2020, and 2021. For the first three years we also visited field sites to observe behaviour during focal watches and point counts throughout the flight period. We found that more J. coenia exhibit seasonal dark wing patterns in September and October compared to butterflies collected in previous months. This change in wing pattern correlates to an increase in basking behaviour. Eye tissues of dark fall animals and lighter summer animals exhibit different patterns of gene expression, including clock genes and genes involved in eye pigment synthesis. Subsequent analysis of monthly variation in opsin gene expression in eye tissues confirmed that opsin genes are not differentially expressed throughout the year, though period gene expression is higher in the fall, and females have higher blue opsin gene expression than males. This concurrent seasonal shift in colouration, behaviour, and underlying visual physiology indicates that J. coenia undergoes a complex shift in phenotype that encompasses more than simple changes to thermoregulation.

animal behavior and cognition↗

bioRxiv2024

Asynchronous temporal variance in learning behaviour and neural gene expression in a butterfly

Mate preference learning, including imprinting-like learning, is pervasive across animal taxa, and can affect the selection and maintenance of certain phenotypes. However, not much is known about the temporal dynamics behind imprinting-like learning, or the genetic underpinnings underlying it. To uncover the temporal dynamics of imprinting-like learning, from both a behavioural and transcriptional perspective, we conducted learning and RNA-Seq time series using the butterfly Bicyclus anynana, a species where both sexes learn mate preferences. We exposed females to an unfamiliar, unpreferred male phenotype (4-spotted male) for five different exposure (training) periods, ranging from 30 minutes to three hours, and recorded their choice between the preferred, familiar male phenotype (2-spotted) and 4-spotted males in mate choice trials conducted two days after training. We also assessed differential gene expression of naive females and females exposed to trainer males for these same five exposure periods, to identify temporal patterns in gene expression associated with learning. While we found that the longest exposure had the strongest effect on preference learning, we did not observe a linear effect of exposure time on learning. We also show that the highest peak of differentially expressed genes (DEGs) was after one hour of exposure. While a number of genes were uniquely DE at each time point, one gene, associated with transcription initiation, was differentially expressed during learning across all five time points. We observed a similar decreasing trend in both gene expression and learned response after 1.5 hours of exposure, offering new insights to possible attention and forgetting mechanisms. Therefore, our results indicate that both gene expression and learning are temporally dynamic, and not linear through time. They also highlight the role of transcription in mate preference learning and memory formation in Lepidoptera, and illustrate that imprinting-like learning may exhibit similar molecular temporal dynamics as associative learning.

animal behavior and cognition↗

bioRxiv2023

Behavioural changes in aposematic Heliconius melpomene butterflies in response to their predatory bird calls

Prey-predator interactions have resulted in the evolution of many anti-predatory traits. One of them is the ability for prey to listen to predators and avoid them. Although prey anti-predatory behavioural responses to predator auditory cues are well described in a wide range of taxa, studies on whether butterflies change their behaviours in response to their predatory calls are lacking. Heliconius butterflies are unpalatable and form Mullerian mimicry rings as morphological defence strategies against their bird predators. Like many other butterflies in the Nymphalidae family, Heliconius butterflies possess auditory organs, which are hypothesized to have evolved to assist with predator detection. Here we test whether Heliconius melpomene change their behaviour in response to their predatory bird calls by observing the behaviour of male and female H. m. plessini exposed to calls of Heliconius avian predators: rufous-tailed jacamar, migratory Eastern kingbird, and resident tropical kingbird. We also exposed them to the calls of the toco toucan, a frugivorous bird as a control bird call, and an amplified greenhouse background noise as a noise control. We found that individuals changed their behaviour in response to jacamar calls only. Males increased their walking and fluttering behaviour, while females did not change their behaviour during the playback of the jacamar call. Intersexual behaviours like courtship, copulation, and abdomen lifting did not change in response to bird calls. Our findings suggest that despite having primary predatory defences like toxicity and being in a mimicry ring, H. m. plessini butterflies changed their behaviour in response to predator calls. Furthermore, this response was predator specific, as H. m. plesseni did not respond to either the Eastern kingbird or the tropic kingbird calls. This suggests that Heliconius butterflies may be able to differentiate predatory calls, and potentially the birds associated with those calls. HighlightsO_LIMany prey animals change their behaviour in response to their predators calls. C_LIO_LIWhether butterflies alter behaviour in response to bird predator calls is unknown. C_LIO_LIWe show that Heliconius melpomene change behaviour in response to jacamar calls. C_LIO_LIMales increased walking and fluttering, but did not alter courting behaviour. C_LIO_LIH. melpomene did not respond to predatory Eastern kingbird or tropical kingbird calls. C_LI

animal behavior and cognition↗

bioRxiv2023

One size does not fit all: Family specific differences in seasonal patterns of abundance and behavior in butterfly communities

Animal communities can undergo seasonal shifts in assemblage, responding to changes in their environment. Animal behavior can also shift due to seasonal environmental variation, with the potential to shape ecosystems. However, it is unclear if similar environmental factors and time scales affect both abundance and behavior. We examined how butterfly abundance and behavior change seasonally in temperate prairies and a butterfly garden, and if the factors driving variation differ between taxonomic families. We conducted monthly abundance surveys year-round and biweekly abundance and behavior surveys during the summer and fall, in 2017-2021 and 2018-2020 respectively. We also determined how ambient light, temperature, precipitation, and time of year interact to affect butterfly abundance and behavior. We found increased temperature and light levels correlate with increases in general butterfly abundance. Unlike the greater community, Lycaenidae abundance decreased as weekly precipitation increased, and Papilionidae abundance did not respond to changes in environmental factors. Only Nymphalidae changed behavior in response to environmental factors, increasing thermoregulatory behaviors as temperature and light levels decreased. These results indicate that lineages may differ in their sensitivity to environmental factors, which could result in disproportionate changes in their abundances in response to future climate change and anthropogenic-driven disturbance.

ecology↗

bioRxiv2022

A learning experience elicits sex-dependent neurogenomic responses in Bicyclus anynana butterflies

Sexually dimorphic behavior is pervasive across animals, with males and females exhibiting different mate selection, parental care, foraging, dispersal, and territorial strategies. However, the genetic underpinnings of sexually dimorphic behaviors are poorly understood. Here we investigate gene networks and expression patterns associated with sexually dimorphic imprinting-like learning in the butterfly Bicyclus anynana. In this species, both males and females learn visual preferences, but learn preferences for different traits and use different signals as salient, unconditioned cues. To identify genes and gene networks associated with this behavior, we examined gene expression profiles of the brains and eyes of male and female butterflies immediately post training and compared them to the same tissues of naive individuals. We found more differentially expressed genes and a greater number of significant gene networks in the eye, indicating a role of the peripheral nervous system in visual imprinting-like learning. Females had higher chemoreceptor expression levels than males, supporting the hypothesized sexual dimorphic use of chemical cues during the learning process. In addition, genes that influence B. anynana wing patterns (sexual ornaments), such as invected, spalt, and apterous, were also differentially expressed in the brain and eye, suggesting that these genes may influence both sexual ornaments and the preferences for these ornaments. Our results indicate dynamic and sex-specific responses to social scenario in both the peripheral and central nervous systems and highlight the potential role of wing patterning genes in mate preference and learning across the Lepidoptera.

animal behavior and cognition↗

bioRxiv2022

Genetic and peripheral visual system changes underlie evolving butterfly mate preference

Many studies have linked genetic variation to behavior, but less is known about how that variation alters the neural circuits that drive behavior. We investigated the genetic and neurobiological basis of courtship preference variation in Heliconius butterflies, which use vision to identify appropriate mates based on wing color patterns. We found that Heliconius cydno preference variation was strongly associated with genetic variation and differential expression of senseless-2, a gene predominantly expressed in the eye. Further measurements of photoreceptor sensitivities revealed differences in inter-photoreceptor inhibition of ultraviolet-sensitive cells corresponding to courtship preference variation. Our results reveal a genetic basis for preference/cue co-evolution, suggest a link between sens-2 and visual system variation, and support the idea that changing peripheral neural computations can significantly alter essential behaviors. SummaryGenetic and expression variation of senseless-2 and inter-photoreceptor inhibition predict visual mate preference in a clade of diverse butterflies.

evolutionary biology↗

bioRxiv2022

Sex-limited diversification of the eye in Heliconius butterflies

Butterflies have evolved an immense diversity in eye organization to support a range of vision-based behaviors including courtship, oviposition, and foraging. This diversity has been surveyed extensively across the butterfly phylogeny, and here we take a complementary approach to characterize the eye within a group of closely related Heliconius butterflies. Using a combination of immunostaining for different opsins and eyeshine for determining the distribution of light-filtering screening pigments, we identified several sexually dimorphic features of eye organization where male eyes varied and female eyes did not. Ultraviolet (UV) sensitive photoreceptors varied in which of two UV opsins were expressed, including co-expression of both within single photoreceptors, and these differences were consistent with a role in courtship and conspecific identification. Additional differences across species and sex included the distribution of three ommatidial types defined by the expression pattern of UV and blue opsins, the distribution of a red screening pigment, and which ommatidial types expressed the red screening pigment. We hypothesize that female eyes are optimized for a dimorphic behavior such as oviposition, while male eyes adapt to other selective pressures such as the local light environment.

neuroscience↗

bioRxiv2021

Evolutionary history limits species' ability to match color sensitivity to available habitat light

The spectrum of light that an animal sees - from ultraviolet to far red light - is governed by the number and wavelength sensitivity of a family of retinal proteins called opsins. It has been hypothesized that the spectrum of light available in an environment influences the range of colors that a species has evolved to see. However, invertebrates and vertebrates use phylogenetically distinct opsins in their retinae, and it remains unclear whether these distinct opsins influence what animals see, or how they adapt to their light environments. Systematically utilizing published visual sensitivity data from across animal phyla, we found that terrestrial animals are more sensitive to shorter and longer wavelengths of light than aquatic animals, and that invertebrates are more sensitive to shorter wavelengths of light than vertebrates. Controlling for phylogeny removes the effects of habitat and lineage on visual sensitivity. Closed and open habitat terrestrial species have similar spectral sensitivities when comparing across the Metazoa, and deep water animals are more sensitive to shorter wavelengths of light than shallow water animals. Our results suggest that animals do adapt to their light environment, however the invertebrate-vertebrate evolutionary divergence has limited the degree to which animals can perform visual tuning.

evolutionary biology↗

bioRxiv2020

Ontogenetic changes in sensory gene expression in Bicyclus anynana butterflies

Animal behavior is largely driven by the information that animals are able to extract and process from their environment. However, the function and organization of sensory systems often change throughout ontogeny, particularly in animals that undergo indirect development. As an initial step toward investigating these ontogenetic changes at the molecular level, we characterized the sensory gene repertoire and examined the expression profiles of genes linked to vision and chemosensation in two life stages of an insect that undertakes a dramatic metamorphosis, the butterfly Bicyclus anynana. Using RNA-seq, we compared gene expression in the heads of late fifth instar larvae and newly-eclosed adults that were reared under identical conditions. Over 50% of all expressed genes were differentially expressed between the two developmental stages, with 4,046 genes upregulated in larval heads and 4,402 genes upregulated in adult heads. In larvae, upregulated vision-related genes were biased toward those involved with eye development, while phototransduction genes dominated the vision genes that were upregulated in adults. Moreover, the majority of the chemosensory genes we identified in the B. anynana genome were differentially expressed between larvae and adults, several of which share homology with genes linked to pheromone detection, host plant recognition, and foraging in other species of Lepidoptera. These results reveal promising candidates for furthering our understanding of sensory processing and behavior in the disparate developmental stages of butterflies and other animals that undergo metamorphosis.

genomics↗

bioRxiv2020

Wing-pattern-specific effects of experience on mating behavior in Heliconius melpomene butterflies

Many animals have the ability to learn, and some taxa have shown learned mate preference. This learning may be important for speciation in some species. The butterfly Heliconius melpomene is a model system for several areas of research, including hybridization, mate selection, and speciation, partially due to its widespread diversity of wing patterns. It remains unclear whether these butterflies can learn to prefer certain mates and if social experience shapes realized mating preferences. Here we test whether previous experience with a female influences male mate preference for two different H. melpomene subspecies, H. m. malleti and H. m. rosina. We conducted no-choice behavioral assays to determine if latency to court and whether males courted (vs no courtship) differed between naive males and males with previous exposure to a young, sexually mature, virgin female. To test whether assortative courtship preference is learned in H. melpomene, males were either paired with a female who shared their phenotype or one who did not. Naive H. m. malletti males courted assortatively, while naive H.m. rosina males did not. Experienced H. m. malleti males reduced their courting relative to naive males, suggesting that social experience with a sexually mature female that does not result in copulation may be perceived as a negative experience. In contrast, experienced H. m. rosina males exhibited similar courting rates to naive H. m. rosina males. Our results suggest that social experience can influence male mating behavior in H. melpomene and that behavioral plasticity may differ across populations in this species.

animal behavior and cognition↗

bioRxiv2019

Multiple loci control eyespot number variation on the hindwings of Bicyclus anynana butterflies

The underlying genetic changes that regulate the appearance and disappearance of repeated traits, or serial homologs, remain poorly understood. One hypothesis is that variation in genomic regions flanking master regulatory genes, also known as input-output genes, controls variation in trait number, making the locus of evolution almost predictable. Other hypotheses implicate genetic variation in up-stream or downstream loci of master control genes. Here, we use the butterfly Bicyclus anynana, a species which exhibits natural variation in eyespot number on the dorsal hindwing, to test these two hypotheses. We first estimated the heritability of dorsal hindwing eyespot number by breeding multiple butterfly families differing in eyespot number, and regressing eyespot number of offspring on mid-parent values. We then estimated the number and identity of independent genetic loci contributing to eyespot number variation by performing a genome-wide association study with restriction site-associated DNA Sequencing (RAD-seq) from multiple individuals varying in number of eyespots sampled across a freely breeding lab population. We found that dorsal hindwing eyespot number has a moderately high heritability of approximately 0.50. In addition, multiple loci near previously identified genes involved in eyespot development display high association with dorsal hindwing eyespot number, suggesting that homolog number variation is likely determined by regulatory changes at multiple loci that build the trait and not by variation at single master regulators or input-output genes.\n\nData accessibilityThe Bicyclus anynana PstI RAD-tag sequencing data is available via the Genbank BioProject PRJNA509697. Genotype VCF files will be made available through Figshare upon acceptance.

genetics↗

bioRxiv2018

Career Choice, Gender, and Mentor Impact: Results of the U.S. National Postdoc Survey

The postdoctoral community is an essential component of the academic and scientific workforce. As economic and political pressures impacting these enterprises continue to change, the postdoc experience has evolved from short, focused periods of training into often multidisciplinary, extended positions with less clear outcomes. As efforts are underway to amend U.S. federally funded research policies, the paucity of postdoc data has made evaluating the impact of policy recommendations challenging. Here we present comprehensive survey results from over 7,600 postdocs based at 351 academic and non-academic U.S. institutions in 2016. In addition to demographic and salary information, we present multivariate analyses on the factors that influence postdoc career plans and mentorship satisfaction in this population. We further analyze gender dynamics and expose wage disparities and career choice differences. Academic research positions remain the predominant career choice of postdocs in the U.S., although unequally between postdocs based on gender and residency status. Receiving mentorship training during the postdoctoral period has a large, positive effect on postdoc mentorship satisfaction. Strikingly, the quality of and satisfaction with postdoc mentorship appears to also heavily influence career choice. The data presented here are the most comprehensive data on the U.S. postdoc population to date. These results provide an evidence basis for informing government and institutional policies, and establish a critical cornerstone for quantifying the effects of future legislation aimed at the academic and scientific workforce.

scientific communication and education↗