Wing Dimorphisms and the Evolution of Migratory Polymorphisms among the Insecta

Many species of insects exhibit wing dimorphism, one morph havingfully developed wings and the other morph having reduced wingsand being incapable of flight. These wing dimorphisms providevisible manifestations of migratory polymorphisms. Since wingedindividuals do not, in principle, have to fly, the existenceof forms with reduced wings suggests that there is a tradeoffbetween flight capability and other fitness components. Comparisonsof the life histories of the fully winged and wing reduced morphsdemonstrate that this tradeoff is most commonly expressed asa decrease in the age of first reproduction and increased fecundityin the morph with reduced wings. Given these tradeoffs, theevolution of wing dimorphism will depend upon its genetic basis,including correlations with other life history components. Areview of the recent literature suggests that the heritabilityof wing morphology is high, and we suggest that this high heritabilitycould be maintained, in part, by antagonistic pleiotropy. In dimorphic species, the winged morph is generally consideredto be the migrant form. However, there are significant correlations,both within and among species, between the proportion of wingedindividuals, the proportion of winged individuals with functionalflight muscles, and the flight propensity of those individuals.This suggests that the proportion of winged individuals andthe propensity of the winged morph to migrate are intimatelyconnected at both the physiological and population level. Therefore,the study of the evolution of wing dimorphism is important notonly in its own right but also as a model of how migratory propensityevolves in monomorphically winged species.     

Updating the knowledge of assassin bug cockroaches (Blattodea: Blaberidae: Paranauphoeta Brunner von Wattenwyl): Species from China and taxonomic changes

The investigation into the cockroach genus Paranauphoeta Brunner von Wattenwyl is insufficient, and there is a lack of taxonomic documentation of this genus from China. Recently, the authors obtained some newly collected specimens which facilitated this study. In this paper the generalized morphology of Paranauphoeta is interpreted in detail, particularly for the male phallic complex, which is illustrated as a whole rather than in pieces. The taxonomy of Paranauphoeta species from China is revised. One out of four species recorded from China, P. indica Saussure & Zehntner, is removed; instead, P. kirby nom. nov. is recorded from China. Together with three new species described in this paper, namely, P. anulata sp. nov. , P. brachyptera sp. nov. and P. lineola sp. nov. , a total of seven Paranauphoeta species are now known to occur in China, whose habitus photos are provided. The new species confirm that this genus is wing‐polymorphic. Male structures, if available, are illustrated. Female structures and oothecae, of which knowledge is limited in this genus and also in cockroach taxonomy, are illustrated or documented, respectively. A key to and a distribution map of the Paranauphoeta species from China are provided. In addition, P. atra Shelford nom. rev. , P. sinica Bey‐Bienko stat. nov. and P. vietnamensis Anisyutkin stat. nov. are regarded as valid separate species.     

Butterfly wing patterns

This paper integrates genetical studies of variation in the wing patterns of Lepidoptera with experimental investigations of developmental mechanisms. Research on the tropical butterfly,Bicyclus anynana, is described. This work includes artificial selection of lines with different patterns of wing eyespots followed by grafting experiments on the lines to examine the phenotypic and genetic differences in terms of developmental mechanisms. The results are used to show how constraints on the evolution of this wing pattern may be related to the developmental organisation. The eyespot pattrn can be envisaged as a set of developmental homologues; a common developmental mechanism is associated with a quantitative genetic system involving high genetic correlations. However, individual genes which influence only subsets of the eyespots, thus uncoupling the interdependence of the eyespots, may be important in evolutionary change. The postulated evolutionary constraints are illustrated with respect to differences in wing pattern found among other species ofBicyclus.     

Development of a wingless morph in the ladybird beetle, Adalia bipunctata

SUMMARY Many taxa of winged insects have independently lost the ability to fly and often possess reduced wings. Species exhibiting natural variation in wing morphology provide opportunities to investigate the genetics and developmental processes underlying the evolution of alternative wing morphs. Although many wing dimorphic species of beetles are known, the underlying mechanisms of variation are not well understood in this insect order. Here, we examine wing development of wild type and natural wingless morphs of the two-spot ladybird beetle, Adalia bipunctata . We show that both pairs of wings are distally truncated in the wingless adults. A laboratory population of the wingless morph displays heritable variation in the degree of wing truncation, reflecting reduced growth of the larval wing discs. The coexistence of variable wingless morphs supports the idea that typical monomorphic wingless insects may be the result of a gradual evolution of wing loss. Gene expression patterns in wing discs suggest that the conserved gene network controlling wing development in wild-type Adalia is disrupted in the dorsoventral patterning pathway in the wingless morphs. Previous research on several species of ant has revealed that the anteroposterior wing patterning pathway is disrupted in wingless workers. Future investigations should confirm whether interruptions in both taxa are limited to the patterning pathways found thus far, or whether there are also shared interruption points. Nevertheless, our results highlight that diverse mechanisms of development are likely to underlie the evolution of wingless insects.     

Elements of butterfly wing patterns

The color patterns on the wings of butterflies are unique among animal color patterns in that the elements that make up the overall pattern are individuated. Unlike the spots and stripes of vertebrate color patterns, the elements of butterfly wing patterns have identities that can be traced from species to species, and typically across genera and families. Because of this identity it is possible to recognize homologies among pattern elements and to study their evolution and diversification. Individuated pattern elements evolved from non-individuated precursors by compartmentalization of the wing into areas that became developmentally autonomous with respect to color pattern formation. Developmental compartmentalization led to the evolution of serially repeated elements and the emergence of serial homology. In these compartments, serial homologues were able to acquire site-specific developmental regulation and this, in turn, allowed them to diverge morphologically. Compartmentalization of the wing also reduced the developmental correlation among pattern elements. The release from this developmental constraint, we believe, enabled the great evolutionary radiation of butterfly wing patterns. During pattern evolution, the same set of individual pattern elements is arranged in novel ways to produce species-specific patterns, including such adaptations as mimicry and camouflage.     

Preliminary study of wing interference patterns (WIPs) in some species of soft scale (Hemiptera,Sternorrhyncha, Coccoidea,Coccidae)

The fore wings of scale insect males possess reduced venation compared with other insects and the homologies of remaining veins are controversial. The hind wings are reduced to hamulohalterae. When adult males are prepared using the standard methods adopted to females and nymphs, i.e. using KOH to clear the specimens, the wings become damaged or deformed, an so these structures are not usually described or illustrated in publications. The present study used dry males belonging to seven species of the family Coccidae to check the presence of stable, structural colour patterns of the wings. The visibility of the wing interference patterns (WIP), discovered in Hymenoptera and Diptera species, is affected by the way the insects display their wings against various backgrounds with different light properties. This frequently occurring taxonomically specific pattern is caused by uneven membrane thickness and hair placement, and also is stabilized and reinforced by microstructures of the wing, such as membrane corrugations and the shape of cells. The semitransparent scale insect’s fore wings possess WIPs and they are taxonomically specific. It is very possible that WIPs will be an additional and helpful trait for the identification of species, which in case of males specimens is quite difficult, because recent coccidology is based almost entirely on the morphology of adult females.     

Leinendera achaeta sp. n., a new species of robber fly from Brazil (Diptera,Asilidae, Asilinae)

The third species of the Neotropical genus Leinendera Carrera, 1945, Leinendera achaeta sp. n., is described from Rio Grande do Sul state, Brazil. The habitus, wing and male terminalia are described and illustrated, and a key to the three Brazilian species is provided.     

Wing colors based on arrangement of the multilayer structure of wing scales in lycaenid butterflies (Insecta: Lepidoptera)

Male wing colors and wing scale morphology were examined for three species of lycaenid butterflies: Chrysozephyrus ataxus, Favonius cognatus and F. jezoensis. Measurement of spectral reflectance on the wing surface with a spectrophotometer revealed species‐specific reflection spectra, with one or two peaks in the ultraviolet and/or green ranges. Observations of wing scales using an optical microscope revealed that light was reflected from the inter‐ridge regions, where transmission electron microscopy revealed a multilayer structure. Based on the multilayer dimensions obtained, three models were devised and compared to explain the measured reflectance spectrum. The results showed that the best fit is a model in which thicknesses of thin films of the multilayer system are not constant and air spaces between cuticle layers are more or less packed with cuticle spacers. This suggests that the specific wing colors of the species examined are produced by the species‐specific arrangement of the multilayer structure of wing scales.     

PRIZES FOR ESSAYS

Mendelsohn, J. M., Kemp, A. C, Biggs, H. C, Biggs, R. &; Brown, C.J. 1989. Wing areas, wing loadings and wing spans of 66 species of African raptors. Ostrich 60:35-42.

The paper provides data on the wing areas of 855 birds of 66 species and wing spans of 918 individuals of 58 species of African raptors. Two measures of wing loading were calculated for those individuals that were weighed. Wing, secondary and ulnar lengths are used to derive an index of wing area which explains 98,8% of the variation in the mean wing areas of 46 species. A regression, derived from this relationship, can be used to estimate wing areas from the three linear measurements, all of which can be taken on museum specimens. Similarly, an index, using the sum of wing and ulnar lengths accounts for 99,5% of the variation in the mean wing spans of 36 species. The wing dimensions of males and females, and adults and juveniles are compared in several species. For those species with adequate samples of measurements of wing area, body mass and wing span, the cost of flapping flight can be estimated with confidence.     

Discrimination of Eubazus (Hymenoptera, Braconidae) sibling species using geometric morphometrics analysis of wing venation

Abstract.  Complexes of sibling and cryptic species are encountered frequently in parasitic Hymenoptera. Geometric morphometrics is a useful tool to detect minimal morphological variations, which often are undetectable by traditional morphological studies and even by classical morphometric approaches. We applied geometric morphometrics to wing venation to assess a complex case of sibling species in the genus Eubazus (Hymenoptera, Braconidae), parasitoids of conifer bark weevils of the genus Pissodes (Coleoptera, Curculionidae). The results and methods were compared with previous taxonomic studies on the same species, involving classical multivariate morphometrics, isoenzyme analyses, cross-mating experiments and biological observations. Geometric morphometrics confirmed the previous division into four distinct species. However, this approach enabled the four species to be separated simultaneously, with a reliability of 98.6% for well-classified females and 93.1% for males. A similar result in previous studies was obtained only by combining isoenzyme analyses and several canonical variate analyses, including many morphometric characters. Furthermore, measurements of wing venation were less time-consuming, more reliable and required less prior knowledge of braconid taxonomy than the measurements needed for the classical morphometrics methods. Geometric morphometrics was used also to test the effect of host species on wing shape. Several female populations of Eubazus semirugosus originating from three different Pissodes spp. were compared. Significant differences were found in wing shape between conspecific Eubazus from different host species. The results are discussed in relation to reproductive isolation and genetic flow between the four species.     

Discovery of the genus Crinoedischia in the Middle Permian of France (Insecta: Orthoptera)

New orthopteran Crinoedischia lapeyriei sp. nov. is described and illustrated from the Middle Permian (Guadalupian) of Lodève Basin in southern France. The new species is separated from the Lower Permian (Artinskian) Crinoedischia species by differences in wing venation pattern such as long ScP with anterior branches, RA with prominent distal branches, and MA ending with three branches. The significance and parallels of entomofaunas between Salagou and Wellington formations (Lodève, Elmo, Midco) are briefly discussed.     

Does ultraviolet reflectance accentuate a sexually selected signal in terns?

Unlike the majority birds that replace their primaries once each year, most Sterna terns practice an unusual repeated wing molt, wherein a variable number of inner primaries are replaced twice or even three times in a single year. This seemingly redundant replacement of the primaries may serve as a sexually selected indicator of quality in that terns may evaluate potential mates based on the number of primaries they were able to replace twice or three times prior to the breeding season. To evaluate the potential of repeated molt as a social signal, we compared light-reflectance curves and photon catches for new (twice-molted) and old (once-molted) primaries in three species of terns. We observed that old feathers reflected considerably less light across all wavelengths and found that in two of the three species examined the ultraviolet reflectance was disproportionably reduced in old feathers relative to the reduction in visible reflectance. Thus, the UV component of coloration in tern wing feathers may accentuate the difference between the new feathers generated by repeated wing molt and older, more worn feathers, thereby reinforcing a sexually selected signal of quality.     

Temperature shapes the costs,benefits and geographic diversification of sexual coloration in a dragonfly

The environment shapes the evolution of secondary sexual traits by determining how their costs and benefits vary across the landscape. Given the thermal properties of dark coloration generally, temperature should crucially influence the costs, benefits and geographic diversification of many secondary sexual colour patterns. We tested this hypothesis using sexually selected wing coloration in a dragonfly. We find that greater wing coloration heats males – the magnitude of which improves flight performance under cool conditions but dramatically reduces it under warm conditions. In a colder region of the species’ range, behavioural observations of a wild population show that these thermal effects translate into greater territorial acquisition on thermally variable days. Finally, geo‐referenced photographs taken by citizen scientists reveal that this sexually selected wing coloration is dramatically reduced in the hottest portions of the species’ range. Collectively, our results underscore temperature's capacity to promote and constrain the evolution of sexual coloration.     

Selective predation on wing morphology in sympatric damselflies

Although predation is thought to affect species divergence, the effects of predator-mediated natural selection on species divergence and in nonadaptive radiations have seldom been studied. Wing melanization in Calopteryx damselflies has important functions in sexual selection and interspecific interactions and in species recognition. The genus Calopteryx and other damselfly genera have also been put forward as examples of radiations driven by sexual selection. We show that avian predation strongly affects natural selection on wing morphology and male wing melanization in two congeneric and sympatric species of this genus (Calopteryx splendens and Calopteryx virgo). Predation risk was almost three times higher for C. virgo, which has an exaggerated degree of wing melanization, than it was for the less exaggerated, sympatric congener C. splendens. Selective predation on the exaggerated species C. virgo favored a reduction and redistribution of the wing melanin patch. There was evidence for nonlinear selection involving wing patch size, wing patch darkness, and wing length and width in C. splendens but weaker nonlinear selection on the same trait combinations in C. virgo. Selective predation could interfere with species divergence by sexual selection and may thus indirectly affect male interspecific interactions, reproductive isolation, and species coexistence in this genus.     

Drosophila wing melanin patterns form by vein-dependent elaboration of enzymatic prepatterns

BACKGROUND: Animal melanin patterns are involved in diverse aspects of their ecology, from thermoregulation to mimicry. Many theoretical models have simulated pigment patterning, but little is known about the developmental mechanisms of color pattern formation. In Drosophila melanogaster, several genes are known to be necessary for cuticular melanization, but the involvement of these genes in melanin pattern evolution is unknown. We have taken a genetic approach to elucidate the developmental mechanisms underlying melanin pattern formation in various drosophilids. RESULTS: We show that, in D. melanogaster, tyrosine hydroxylase (TH) and dopa decarboxylase (DDC) are required for melanin synthesis. Ectopic expression of TH, but not DDC, alone was sufficient to cause ectopic melanin patterns in the wing. Thus, changes in the level of expression of a single gene can result in a new level of melanization. The ontogeny of this ectopic melanization resembled that found in Drosophila species bearing wing melanin patterns and in D. melanogaster ebony mutants. Importantly, we discovered that in D. melanogaster and three other Drosophila species these wing melanin patterns are dependent upon and shaped by the circulation patterns of hemolymph in the wing veins. CONCLUSIONS: Complex wing melanin patterns are determined by two distinct developmental mechanisms. Spatial prepatterns of enzymatic activity are established late in wing development. Then, in newly eclosed adults, melanin precursors gradually diffuse out from wing veins and are oxidized into dark brown or black melanin. Both the prepatterning and hemolymph-supplied components of this system can change during evolution to produce color pattern diversity.     

Geometric morphometric analysis of Eysarcoris guttiger,E.annamita and E.ventralis (Hemiptera: Pentatomidae)

The genus Eysarcoris can be easily distinguished from other genera through the two spots in the basal angle of the scutellum.Nevertheless,Eysarcoris species show complex variances.Geometric morphometric methods have been increasingly applied to distinguish species and to define the boundary of genera among insects.In the present study,geometric morphometric approach was firstly employed to evaluate the shape variation of three characters (fore wing,hind wing and pygophore) of E.guttiger,E.annamita and E.ventralis using E.aeneus as outgroup to ascertain whether this approach is a reliable method for the taxonomy of Eysarcoris.Analysis was conducted on the landmarks of the three characters of these species.Multivariate regression of procrustes coordinates against centroid size was conducted to test the presence of allometry.Principal component analysis (PCA),canonical variate analysis (CVA)and cluster analysis were utilized to describe variations in shapes among the studied species.For all of the three characters,though PCA analysis showed some overlap among species,p-values for procrustes distance and mahalanobis distance were all less than 0.0001.The distribution of the three studied species corresponds with their species status.This study demonstrates that the geometric morphometrics of both the fore wing and the hind wing might represent a possible tool for the identification of species within this genus.     

浙江西闪岛三突多足摇蚊亚属一新种（双翅目：摇蚊科）

记述采自浙江省西闪岛的三突多足摇蚊亚属1新种：杯状三突多足摇蚊Polypedilum (Tripodura) cypellum sp. nov.。该新种与哈氏三突多足摇蚊P. (T.) harteni Andersen & Mendes, 2010相似,区别于本亚属其它已知种的主要特征是具高脚杯状的上附器。文中提供了雄成虫的翅、前足胫节端部、生殖节、上附器等特征图。     

Revision of genus Argyrophenga (Lepidoptera: Satyridae)

Abstract

The endemic New Zealand genus Argyrophenga Doubleday is revised. The genus is shown to consist of three species, antipodum Doubleday, harrisi n.sp., and janitae n.sp. Wing pattern, wing coloration, and male genitalia of all species are described and illustrated. Keys to species are given for both sexes. Taxonomic conclusions are supported by biometric and distributional data. Flight behaviour is described. A brief comparison is made between Argyrophenga and the other endemic New Zealand satyrid genera.     

Wing structure and polymorphism in minute scavenger beetles (Coleoptera,Latridiidae)

The main structural elements of the hind wing in 56 species of the family Latridiidae (Coleoptera) are analyzed. In macropterous forms, wing venation is reduced to 3 modified veins. 10 areas of sclerotization of the wing membrane are distinguished. Three forms with different degrees of wing reduction are revealed: the brachypterous, the micropterous, and the apterous form. Among 56 species examined, 40 are represented only by the macropterous form; 2, 3, 5, and 6 species, by macropterous and brachypterous, macropterous and micropterous, micropterous, and apterous forms, respectively.