Homologies in the colour patterns of the genus Charaxes (Lepidoptera: Nymphalidae)

The phylogenetically and morphologically diverse patterns of Charaxes can be reduced to a simple set of pattern elements which can be homologized throughout the genus. At least five types of correspondence (homologies) exist among pattern elements: those between (1) species, (2) forewing and hindwing, (3) dorsal and ventral wing surface, (4) serial wing-cells, and (5) individual pattern elements within a single wing-cell. Differences in Charaxes colour patterns result from the distortion, elaboration, enlargement, reduction or loss of individual pattern elements. Further variation is often the result of dislocation of pattern elements from their serial homologues in neighbouring wing-cells, and fusion of individual pattern elements to create larger areas of colour. The type of analysis presented in this paper should be broadly applicable within the Lepidoptera and may prove useful in studying the systematics of colour patterns and the evolution of the developmental system that gives rise to them.     

An analysis of the phenotypic effects of certain colour pattern genes in Heliconius (Lepidoptera: Nymphalidae)

The colour patterns of Heliconius butterflies are built up from an array of serially homologous pattern elements known as the nymphalid groundplan. An analysis of the phenotypic effects of ten genetic loci from H. melpomene and H. cydno reveals that each alters the expression either of a single element of the groundplan or of an entire row of serially homologous elements. Five of the ten loci affect the size (or presence/absence) of specific pattern elements, two affect the colour in which a pattern element is expressed, two affect pattern-inducing activity of the wing veins, and one appears to affect an overall threshold for pattern determination. Three of the ten loci have identical effects on homologues of the fore- and hindwing. We show that most of the apparently large and qualitative phenotypic effects of these genes can be readily explained by relatively small and quantitative changes in the dimensions or positions of specific pattern elements.     

Pupal Melanization in Heliconius erato phyllis (Lepidoptera; Nymphalidae): Genetic and Environmental Effects

This paper deals with estimates of heritability and the effect of two different kinds of environment on the melanization of pupae in the butterfly Heliconius erato phyllis. The results for heritability showed greater differences when the offspring were regressed on male or female values for pupal colour. Pupal colour followed a system of discrete scores, from 2 for the light pupae to 5 for the darkest one. Estimate of the heritability (h²) was 0.44 when the average score of the siblings were regressed on the mid-parental value. When regressed on the male parent, h² was larger (0.54), being very low when regressed on the female parent (0.09). Estimate by the analysis of variance was also 0.44 when both male and female sibs were included in the analysis (for male sibs, h²=0.43 and for female sibs, 0.47). To test for the effect of the environment, each brood was divided in three, one being the control, the second subjected to a black environment when reaching the fifth instar and the third to a white environment. Those in the black environment originated dark pupae that scored 5 or 4; for those in the white environment, there was no difference with the controls. Caterpillars when entering the prepupal stage were also subjected to the black treatment (early and late prepupal stage, respectively, for treatments called black A and black B). A significant effect was observed only when early prepupal stage was subjected to the black environment.     

Colour pattern homology and evolution in Vanessa butterflies (Nymphalidae: Nymphalini): eyespot characters

Ocelli are serially repeated colour patterns on the wings of many butterflies. Eyespots are elaborate ocelli that function in predator avoidance and deterrence as well as in mate choice. A phylogenetic approach was used to study ocelli and eyespot evolution in Vanessa butterflies, a genus exhibiting diverse phenotypes among these serial homologs. Forty‐four morphological characters based on eyespot number, arrangement, shape and the number of elements in each eyespot were defined and scored. Ocelli from eight wing cells on the dorsal and ventral surfaces of the forewing and hindwing were evaluated. The evolution of these characters was traced over a phylogeny of Vanessa based on 7750 DNA base pairs from 10 genes. Our reconstruction predicts that the ancestral Vanessa had 5 serially arranged ocelli on all four wing surfaces. The ancestral state on the dorsal forewing and ventral hindwing was ocelli arranged in two heterogeneous groups. On the dorsal hindwing, the ancestral state was either homogenous or ocelli arranged in two heterogeneous groups. On the ventral forewing, we determined that the ancestral state was organized into three heterogeneous groups. In Vanessa, almost all ocelli are individuated and capable of independent evolution relative to other colour patterns except for the ocelli in cells ?1 and 0 on the dorsal and ventral forewings, which appear to be constrained to evolve in parallel. The genus Vanessa is a good model system for the study of serial homology and the interaction of selective forces with developmental architecture to produce diversity in butterfly colour patterns.     

Comparative effects of inbreeding and outbreeding on the ontogeny of Heliconius erato phyllis (Lepidoptera: Nymphalidae)

Inbreeding depression has been reported in various groups of organisms, including insects. Estimates of inbreeding consequences were obtained by comparing 12 life‐history and morphological traits among nine inbred families (F = 0.25) and 16 outbred families (F = 0) of the Neotropical butterfly Heliconius erato phyllis. A Student's t‐test showed statistically significant differences for pupal weight and right forewing area, both in males and in females, between inbred and outbred families. Survival during development, from egg hatching to adulthood, also differed significantly between inbred and outbred families. The average number of haploid lethal equivalents was 0.17 for pupal weight, 0.15 for forewing area and 0.71 for survival from hatching to adulthood. The results of this study confirm that the consequences of inbreeding are more deleterious to life history traits than to morphological ones.     

Molecular evolution of a long wavelength-sensitive opsin in mimetic Heliconius butterflies (Lepidoptera: Nymphalidae)

This study examines the pattern of opsin nucleotide and amino acid substitution among mimetic species 'rings' of Heliconius butterflies that are characterized by divergent wing colour patterns. A long wavelength opsin gene, OPS1 , was sequenced from each of seven species of Heliconius and one species of Dryas (Lepidoptera: Nymphalidae). A parsimony analysis of OPS1 nucleotide and amino acid sequences resulted in a phylogeny that was consistent with that presented by Brower & Egan in 1997, which was based on mitochondrial cytochrome oxidase I and II as well as nuclear wingless genes. Nodes in the OPS1 phylogeny were well supported by bootstrap analysis and decay indices. An analysis of specific sites within the gene indicates that the accumulation of amino acid substitutions has occurred independently of the morphological diversification of Heliconius wing colour patterns. Amino acid substitutions were examined with respect to their location within the opsin protein and their possible interactions with the chromophore and the G-protein. Of the 15 amino acid substitutions identified among the eight species, one nonconservative replacement (A226Q) was identified in a position that may be involved in binding with the G-protein.     

Wing-Click Sounds of Heliconius cydno alithea (Nymphalidae: Heliconiinae) Butterflies

Field-collected Heliconius cydno Doubleday females were observed producing audible wing clicks during encounters between conspecifics in greenhouses in a large insectary during the day and at roosting time. Occasionally, these females also were observed producing sounds in aggressive encounters with females of a close relative, H. erato (L). However, the wing-clicks were not observed subsequently from first-generation adults born in the greenhouses. The sounds were produced in short trains of 3–10 wing-clicks at the rate of 10 clicks/s. The individual clicks had a mean duration of 1.48 ms and a broad frequency spectrum, with a peak near 1075 Hz. This peak lies near the 1200-Hz frequency of maximal sensitivity measured previously for auditory neurons of H. erato. The production of these previously unreported sounds suggests that wing clicks may play a role in both intra- and interspecific communication among Heliconius species.     

Genetic evidence for a sibling species of Heliconius charithonia (Lepidoptera; Nymphalidae)

Heliconius charithonia is a widespread species which, unlike many Heliconius, is non-mimetic and shows little racial differentiation. Only one form, 'peruvianus', which occurs in the dry forest habitats of western Ecuador and Peru, has a distinct and clearly mimetic colour pattern. Here it was shown that H. peruvianus was distinct from H. charithonia bassleri at allozyme loci (D = 0.25 over 22 loci). This differentiation was ten times greater than that between H. charithonia sampled from Ecuador and the Caribbean (D = 0.027) and was consistent with analysis of mitochondrial sequence data (3.4-4% sequence divergence between H. peruvianus and H. charithonia). One individual with a H. peruvianus colour pattern and allozyme genotype was collected in an area where H. charithonia was known to be common, demonstrating that contact between the taxa occurs in western Ecuador. Furthermore, the allozyme genotype of another individual was heterozygous for four of five diagnostic loci and was most likely an F1 hybrid between H. charithonia and H. peruvianus. These data imply that H. charithonia and H. peruvianus are distinct species which hybridize occasionally. This species pair show many similarities with H. erato and H. himera, which are similarly differentiated genetically and also show ecological and colour pattern differences. These species fulfil some of the predictions of both allopatric refugium and parapatric adaptationist models of speciation in the neotropics, suggesting that elements of both hypotheses may be true.     

Adaptive radiation and convergence in subdivisions of the butterfly genus Heliconius (Lepidoptera: Nymphalidae)

The process of adaptive radiation and convergence, usually regarded as a feature of macro-evolution, can be seen in the mimetic colour patterns of the butterflies within the confines of the South American genus Heliconius. This can be shown by dividing the genus into subgroups on the basis of adult, pupal and larval morphology: the theory that the mimicry between species results solely from close systematic relationships is thereby refuted, as members of the same morphological group can display widely divergent mimetic patterns, and conversely mutual mimics may belong to several different morphological groups. Various forms of parallel and convergent evolution are thought to account for the present pattern of mimicry, the process is known to start even before full speciation has taken place. A new subgenus (Neruda) is created to contain three atypical members of the genus.     

Genetic differentiation without mimicry shift in a pair of hybridizing Heliconius species (Lepidoptera: Nymphalidae)

Butterflies in the genus Heliconius have undergone rapid adaptive radiation for warning patterns and mimicry, and are excellent models to study the mechanisms underlying diversification. In Heliconius, mimicry rings typically involve distantly related species, whereas closely related species often join different mimicry rings. Genetic and behavioural studies have n how reproductive isolation in many pairs of Heliconius taxa is largely mediated by natural and sexual selection on wing colour patterns. However, recent studies have uncovered new cases in which pairs of closely related species are near‐perfect mimics of each other. Here, we provide morphometric and genetic evidence for the coexistence of two closely related, hybridizing co‐mimetic species on the eastern slopes of the Andes, H. melpomene amaryllis and H. timareta ssp. nov. , which is described here as H. timareta thelxinoe . A joint analysis of multilocus genotyping and geometric morphometrics of wing shape shows a high level of differentiation between the two species, with only limited gene flow and mixing. Some degree of genetic mixing can be detected, but putative hybrids were rare, only one of 175 specimens being a clear hybrid. In contrast, we found phenotypic differentiation between populations of H. timareta thelxinoe , possibly indicative of strong selection for local mimicry in different communities. In this pair of species, the absence of breakdown of genetic isolation despite near‐identical wing patterns implies that factors other than wing patterns keep the two taxa apart, such as chemical or behavioural signals, or ecological adaptation along a strong altitudinal gradient. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 830–847.     

Hybridization and transgressive exploration of colour pattern and wing morphology in Heliconius butterflies

Hybridization can generate novel phenotypes distinct from those of parental lineages, a phenomenon known as transgressive trait variation. Transgressive phenotypes might negatively or positively affect hybrid fitness, and increase available variation. Closely related species of Heliconius butterflies regularly produce hybrids in nature, and hybridization is thought to play a role in the diversification of novel wing colour patterns despite strong stabilizing selection due to interspecific mimicry. Here, we studied wing phenotypes in first‐ and second‐generation hybrids produced by controlled crosses between either two co‐mimetic species of Heliconius or between two nonmimetic species. We quantified wing size, shape and colour pattern variation and asked whether hybrids displayed transgressive wing phenotypes. Discrete traits underlain by major‐effect loci, such as the presence or absence of colour patches, generate novel phenotypes. For quantitative traits, such as wing shape or subtle colour pattern characters, hybrids only exceed the parental range in specific dimensions of the morphological space. Overall, our study addresses some of the challenges in defining and measuring phenotypic transgression for multivariate traits and our data suggest that the extent to which transgressive trait variation in hybrids contributes to phenotypic diversity depends on the complexity and the genetic architecture of the traits.     

Skipping flights in Ypthima butterflies (Lepidoptera: Nymphalidae)

The skipping flight patterns of three species of Ypthima (Lepidoptera: Nymphalidae) were analyzed using high‐speed video recordings to clarify how wings move and how driving forces are produced. All three species showed a flight pattern that includes a pause that accounts for about 50% of a flap cycle when their wings completely close after each upstroke. The observed pause causes the “skipping” flight trajectory based on the clap–fling mechanism. Pause duration was correlated with upstroke wing motion, suggesting the contribution of the latter to a long pause duration. This is also supported by the temporal relationship between the wing and body motions. The aerodynamic power necessary for the pause flight was calculated for the three species.     

Phylogeography of the Marsh Fritillary Euphydryas aurinia (Lepidoptera: Nymphalidae) in the UK

We sampled extant (and extinct) populations of Euphydryas aurinia to examine the phylogeography of the species in the UK. We were interested in whether the genetic structuring of populations reflects anything other than a single recent post-glacial colonization event. Four hundred base pairs of the mitochondrial Cytochrome b gene were sequenced from individuals from populations throughout the UK, as well as populations in France and Portugal and seven polymorphic allozyme loci resolved. The mean number of allozyme alleles per locus was 4 and isolation by distance was shown not to be a factor in the geographic structuring of genetic diversity either with or without the inclusion of the French data (Mantel statistic Z = 0.015 and 0.112 respectively, P >0.5). Cytochrome b nucleotide diversity (average number of nucleotide differences per site between two sequences) was low overall (0.003, n = 63) but mean cytochrome b gene diversity over all populations was 0.77. The presence of the Portuguese and French haplotype in Scottish populations indicates that the Iberian peninsula was likely to be one glacial refugium for E. aurinia populations. The pattern of mitochondrial DNA found in the UK could be interpreted in one of two ways: (1) two separate colonization events or (2) a single slow colonization event. Allele frequency distributions followed a similar geographical pattern as mitochondrial DNA haplotypes. An AMOVA assigned just 2.68% of allozyme genetic variation to the grouping tested, providing more support for the single colonization event theory.     

Species level taxonomy of the Neotropical hairstreak genus Porthecla (Lepidoptera: Lycaenidae: Theclinae: Eumaeini)

The species level taxonomy of Porthecla is revised. Six previously described species are recognized: P. ravus (Druce 1907); P. barba (Druce 1907); P. dinus (Hewitson 1867); P. porthura (Druce 1907); P. minyia (Hewitson 1867); P. gemma (Druce 1907), and another six new species are proposed: P. forasteira Faynel & Moser n. sp.; P. annette Faynel & Robbins n. sp.; P. johanna Faynel & Robbins n. sp.; P. peruensis Faynel & Moser n. sp.; P. prietoi Faynel & Busby n. sp. and P. willmotti Busby, Faynel & Moser n. sp. For each Porthecla species we present diagnostic characters, images of male and female adults, drawings of male and female genitalia, distribution maps, and notes on habitat and other biological traits. An identification key for males is provided. To stabilize names; lectotypes are designated for Thecla minyia Hewitson 1867, and Thecla gemma Druce 1907. Wing pattern resemblances between Porthecla and other genera are discussed.     

A hybrid zone provides evidence for incipient ecological speciation in Heliconius butterflies

In Heliconius butterflies, it has been proposed that speciation occurs through a combination of divergence in ecological habitat preferences and mimetic colour patterns. Here we test this hypothesis by investigating a parapatric form of the widespread species Heliconius erato. Mendelian (colour patterns) and molecular genetic data permit us to address hypotheses about introgression and genetic differentiation between different populations. Combined analysis of colour pattern, microsatellite loci and mitochondrial DNA showed that Heliconius erato venus and Heliconius erato chestertonii form a bimodal hybrid zone implying partial reproductive isolation. In a sample of 121 individuals collected in sympatry, 25% were hybrids representing a significant deficit of heterozygotes compared to the Hardy-Weinberg expectation. Seven microsatellite loci, analysed for a subset of these individuals, showed marked differentiation between the parental taxa, and unambiguously identified two genotypic clusters concordant with our phenotypic classification of individuals. Mitochondrial DNA analysis showed H. erato venus as a monophyletic group well differentiated from H. erato chestertonii, implying a lack of historical introgression between the populations. Heliconius erato chestertonii is therefore an incipient species that maintains its integrity despite high levels of hybridization. Moreover, H. erato chestertonii is found at higher altitudes than other races of H. erato and has a distinct colour pattern and mimetic relationship. Hence, there are now two examples of parapatric incipient species related to H. erato, H. himera and H. erato chestertonii, both of which are associated with higher altitudes, more arid habitats and distinct mimetic relationships. This implies that parapatric habitat adaptation is a likely cause of speciation in this group.     

蛱蝶翅鳞片的超微结构观察

对我国东北地区典型常见蛱蝶科15属20种蝴蝶翅鳞片的超微结构进行了扫描电镜观察。结果显示：蛱蝶翅鳞片形态上可分为窄叶形、阔叶形和圆叶形3种,鳞片长65～135 μm,宽35～85 μm,间距48～112 μm。蛱蝶翅鳞片的超微结构可分为拱桥形、棋盘形和筛孔形3 种。拱桥形结构和棋盘形结构比较接近,二者与筛孔形结构差异较明显。在已观察的种类中,线蛱蝶属红线蛱蝶翅鳞片上的纵肋突起最小（200 nm×300 nm）,闪蛱蝶属柳紫闪蛱蝶翅鳞片上的纵肋突起最大（590 nm×560 nm）。鳞片具有相似的形状、结构和排列,尤其是同属蝴蝶翅鳞片超微结构的形状和尺寸差异较小,表明它们之间的亲缘关系接近。