RESUMO
Wedell and Kemp ([2024]. Examined the importance of female sexual preferences for male UV reflectance on offspring viability and the evolution of male traits in the butterfly Eurema hecabe. Female preferences were found to have multiple consequences, including increased trait value, higher offspring viability, and reduced mutational load. These findings highlight that female sexual preferences for specific male traits can also have further consequences for individual fitness and evolution of specific morphological characteristics.
Assuntos
Evolução Biológica , Borboletas , Aptidão Genética , Preferência de Acasalamento Animal , Animais , Borboletas/genética , Borboletas/fisiologia , Feminino , Masculino , Seleção Sexual , Raios UltravioletaRESUMO
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 sapho subclade of the classical adaptive radiation of Heliconius butterflies. Heliconius butterflies generally have 21 chromosomes with very high synteny. However, the five Heliconius species in the sapho subclade show large variation in chromosome number ranging from 21 to 60. We find that the W chromosome is fused with chromosome 4 in all of them. Two sister species pairs show subsequent fusions between the W and chromosomes 9 or 14, respectively. These 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 short-read resequencing to detect genomic signatures of fusion events between sex chromosomes and autosomes even when sex chromosomes are not explicitly assembled.
Assuntos
Borboletas , Evolução Molecular , Cromossomos Sexuais , Animais , Borboletas/genética , Cromossomos Sexuais/genética , Feminino , Masculino , Filogenia , Genômica/métodos , Sintenia , Cromossomos de Insetos/genética , Genoma de InsetoRESUMO
When populations experience different sensory conditions, natural selection may favor sensory system divergence, affecting peripheral structures and/or downstream neural pathways. We characterized the outer eye morphology of sympatric Heliconius butterflies from different forest types and their first-generation reciprocal hybrids to test for adaptive visual system divergence and hybrid disruption. In Panama, Heliconius cydno occurs in closed forests, whereas Heliconius melpomene resides at the forest edge. Among wild individuals, H. cydno has larger eyes than H. melpomene, and there are heritable, habitat-associated differences in the visual brain structures that exceed neutral divergence expectations. Notably, hybrids have intermediate neural phenotypes, suggesting disruption. To test for similar effects in the visual periphery, we reared both species and their hybrids in common garden conditions. We confirm that H. cydno has larger eyes and provide new evidence that this is driven by selection. Hybrid eye morphology is more H. melpomene-like despite body size being intermediate, contrasting with neural trait intermediacy. Overall, our results suggest that eye morphology differences between H. cydno and H. melpomene are adaptive and that hybrids may suffer fitness costs due to a mismatch between the peripheral visual structures and previously described neural traits that could affect visual performance.
Assuntos
Borboletas , Seleção Genética , Simpatria , Animais , Borboletas/anatomia & histologia , Borboletas/genética , Borboletas/fisiologia , Olho/anatomia & histologia , Panamá , Feminino , Masculino , Hibridização GenéticaRESUMO
Butterfly eyespots are wing patterns reminiscent of vertebrate eyes, formed by concentric rings of contrastingly coloured scales. Eyespots are usually located close to the wing margin and often regarded as the single most conspicuous pattern element of butterfly wing colour displays. Recent efforts to understand the processes involved in the formation of eyespots have been driven mainly by evo-devo approaches focused on model species. However, patterns of change implied by phylogenetic relationships can also inform hypotheses about the underlying developmental mechanisms associated with the formation or disappearance of eyespots, and the limits of phenotypic diversity occurring in nature. Here we present a combined evidence phylogenetic hypothesis for the genus Eunica, a prominent member of diverse Neotropical butterfly communities, that features notable variation among species in eyespot patterns on the ventral hind wing surface. The data matrix consists of one mitochondrial gene region (COI), four nuclear gene regions (GAPDH, RPS5, EF1a and Wingless) and 68 morphological characters. A combined cladistic analysis with all the characters concatenated produced a single most parsimonious tree that, although fully resolved, includes many nodes with modest branch support. The phylogenetic hypothesis presented corroborates a previously proposed morphological trend leading to the loss of eyespots, together with an increase in the size of the conserved eyespots, relative to outgroup taxa. Furthermore, wing colour pattern dimorphism and the presence of androconia suggest that the most remarkable instances of sexual dimorphism are present in the species of Eunica with the most derived eyespot patterns, and are in most cases accompanied by autapomorphic combinations of scent scales and "hair pencils". We discuss natural and sexual selection as potential adaptive explanations for dorsal and ventral wing patterns.
Assuntos
Borboletas , Animais , Filogenia , Borboletas/genética , Borboletas/anatomia & histologia , Caracteres Sexuais , Pigmentação/genética , Asas de Animais/anatomia & histologiaRESUMO
Monarch butterflies (Danaus plexippus) are well studied for their annual long-distance migration from as far north as Canada to their overwintering grounds in Central Mexico. At the end of the cold season, monarchs start to repopulate North America through short-distance migration over the course of multiple generations. Interestingly, some populations in various tropical and subtropical islands do not migrate and exhibit heritable differences in wing shape and size, most likely an adaptation to island life. Less is known about forewing differences between long- and short-distance migrants in relation to island populations. Given their different migratory behaviors, we hypothesized that these differences would be reflected in wing morphology. To test this, we analyzed forewing shape and size of three different groups: nonmigratory, lesser migratory (migrate short-distances), and migratory (migrate long-distances) individuals. Significant differences in shape appear in all groups using geometric morphometrics. As variation found between migratory and lesser migrants has been shown to be caused by phenotypic plasticity, and lesser migrants develop intermediate forewing shapes between migratory and nonmigratory individuals, we suggest that genetic assimilation might be an important mechanism to explain the heritable variation found between migratory and nonmigratory populations. Additionally, our research confirms previous studies which show that forewing size is significantly smaller in nonmigratory populations when compared to both migratory phenotypes. Finally, we found sexual dimorphism in forewing shape in all three groups, but for size in nonmigratory populations only. This might have been caused by reduced constraints on forewing size in nonmigratory populations.
Assuntos
Borboletas , Asas de Animais , Animais , Migração Animal , Borboletas/genética , México , Asas de Animais/anatomia & histologiaRESUMO
The taxonomy of the South American metalmark butterflies of the genus Alesa Doubleday, 1847 is reviewed. A new taxonomic arrangement for Alesa is supported after the analysis of about 600 specimens, including the recognition of two new species, described herein, A. juliae sp. nov. and A. mariae sp. nov.. Alesa negra Röber, 1931, so far recognized as a junior subjective synonym of A. telephae (Boisduval, 1836), is here recognized as a valid species (stat. rev.) and A. amethystina Gallard & Fernandez, 2015 as a junior subjective synonym (syn. nov.) of A. negra, and A. fournierae Lathy, 1958 is recognized as a junior subjective synonym (syn. nov.) of A. amesis (Cramer, 1777). Neotypes are designated for Papilio amesis Cramer, 1777, Erycina prema Godart, [1824] and Mimocastinia egeria Biedermann, 1936. Lectotypes are designated for Erycina priolas Godart, [1824], Eurybia telephae Boisduval, 1836, A. smaragdifera Westwood, 1851, A. lipara Bates, 1868, A. hemiurga Bates, 1868, A. thelydrias Bates, 1868, and Mimocastnia rothschildi Seitz, 1913. Three previously established species groups are here supported by morphological characters including the following species, "prema group": A. prema, A. esmeralda Salazar & Constantino, 2007, A. beneluzi Gallard & Fernandez, 2015, A. rothschildi and A. juliae sp. nov.; "telephae group": A. telephae, A. humilis Brévignon, 2015, A. negra stat. rev. and A. suzana Ahrenholz & Hall, 2010; and "amesis group": A. amesis, A. mariae sp. nov., A. lipara Bates, 1867, A. hemiurga Bates, 1867 and A. thelydrias Bates, 1867. Adults and their genitalia are illustrated for all species available to examination. The main diagnostic characters used to distinguish the species belonging to the "amesis group" are illustrated, and pictures of adults images in situ and distribution maps are provided. Additionally, all species are diagnosed and discussed based on their morphology.
Assuntos
Distribuição Animal , Borboletas , Animais , Borboletas/anatomia & histologia , Borboletas/genética , Genitália/anatomia & histologia , América do SulRESUMO
Euryades corethrus is a Troidini butterfly (Papilionidae, Papilioninae), endemic to grasslands in southern Brazil, Uruguay, Argentina and Paraguay. Formerly abundant, nowadays it is in the Red list of endangered species for those areas. During its larval stage, it feeds on Aristolochia spp, commonly found in southern grasslands. These native grassland areas are diminishing, being converted to crops and pastures, causing habitat loss for Aristolochia and E. corethrus. This study aimed to assess the genetic diversity, population structure and demographic history of E. corethrus. We sampled eight populations from Rio Grande do Sul, Brazil and based on Cytochrome Oxidase subunit I (COI) molecular marker, our results suggest a low genetic variability between populations, presence of gene flow and, consequently, lack of population structure. A single maternally inherited-genetic marker is insufficient for population-level decisions, but barcoding is a useful tool during early stages of population investigation, bringing out genomic diversity patterns within the target species. Those populations likely faced a bottleneck followed by a rapid expansion during the last glaciation and subsequent stabilization in effective population size. Habitat loss is a threat, which might cause isolation, loss of genetic variability and, ultimately, extinction of E. corethrus if no habitat conservation policy is adopted.
Assuntos
Aristolochia , Borboletas , Animais , Borboletas/genética , Pradaria , Larva , ArgentinaRESUMO
Habitat fragmentation and ecosystem changes have the potential to affect animal populations in different ways. To effectively monitor these changes, biomonitoring tools have been developed and applied to detect changes in population structure and/or individual traits that reflect such changes. Fluctuating asymmetry (FA) represents random deviations from perfect symmetry in bilateral traits from perfect symmetry in response to genetic and/or environmental stresses. In this study, we evaluated the use of FA as a tool to monitor stress caused by forest fragmentation and edge formation, using the tropical butterfly M. helenor (Nymphalidae) as a model species. We collected adult butterflies from three fragments of Atlantic Forest in Brazil encompassing both edge and interior habitats. Four wing traits (wing length, wing width, ocelli area, and ocelli diameter) were evaluated. Butterflies captured at edge sites exhibited higher FA values for wing length and wing width compared to those captured at interior sites, whereas traits related to ocelli did not show differences between the two habitat types. Our results suggest that the differences in abiotic and biotic conditions between forest interior and edges can act as a source of stress, impacting the symmetry of flight-related traits. On the other hand, as ocelli are crucial for butterfly camouflage and counter-predator strategies, our results indicate that this trait may be more conserved. By employing FA, we identified trait-specific responses to habitat fragmentation, thus suggesting its potential as a biomarker for environmental stress that can be used in butterflies to monitor habitat quality and change.
Assuntos
Borboletas , Ecossistema , Animais , Borboletas/genética , Florestas , Asas de Animais , FenótipoRESUMO
Little is known about the extent to which species use homologous regulatory architectures to achieve phenotypic convergence. By characterizing chromatin accessibility and gene expression in developing wing tissues, we compared the regulatory architecture of convergence between a pair of mimetic butterfly species. Although a handful of color pattern genes are known to be involved in their convergence, our data suggest that different mutational paths underlie the integration of these genes into wing pattern development. This is supported by a large fraction of accessible chromatin being exclusive to each species, including the de novo lineage-specific evolution of a modular optix enhancer. These findings may be explained by a high level of developmental drift and evolutionary contingency that occurs during the independent evolution of mimicry.
Assuntos
Evolução Biológica , Mimetismo Biológico , Borboletas , Montagem e Desmontagem da Cromatina , Asas de Animais , Animais , Mimetismo Biológico/genética , Borboletas/anatomia & histologia , Borboletas/genética , Borboletas/crescimento & desenvolvimento , Pigmentação/genética , Asas de Animais/anatomia & histologia , Asas de Animais/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Elementos Facilitadores GenéticosRESUMO
Despite insertions and deletions being the most common structural variants (SVs) found across genomes, not much is known about how much these SVs vary within populations and between closely related species, nor their significance in evolution. To address these questions, we characterized the evolution of indel SVs using genome assemblies of three closely related Heliconius butterfly species. Over the relatively short evolutionary timescales investigated, up to 18.0% of the genome was composed of indels between two haplotypes of an individual Heliconius charithonia butterfly and up to 62.7% included lineage-specific SVs between the genomes of the most distant species (11 Mya). Lineage-specific sequences were mostly characterized as transposable elements (TEs) inserted at random throughout the genome and their overall distribution was similarly affected by linked selection as single nucleotide substitutions. Using chromatin accessibility profiles (i.e., ATAC-seq) of head tissue in caterpillars to identify sequences with potential cis-regulatory function, we found that out of the 31,066 identified differences in chromatin accessibility between species, 30.4% were within lineage-specific SVs and 9.4% were characterized as TE insertions. These TE insertions were localized closer to gene transcription start sites than expected at random and were enriched for sites with significant resemblance to several transcription factor binding sites with known function in neuron development in Drosophila We also identified 24 TE insertions with head-specific chromatin accessibility. Our results show high rates of structural genome evolution that were previously overlooked in comparative genomic studies and suggest a high potential for structural variation to serve as raw material for adaptive evolution.