Butterfly Pattern Research Articles

ESS emergence pattern of male butterflies in stochastic environments

The evolutionarily stable (or ESS) emergence schedule for males of univoltine butterflies is analysed in an environment in which the female emergence schedule fluctuates stochastically between years. The ESS emergence curve, computed using the mutant invadability criterion, is shown to be the one that maximizes mean logarithmic lifetime mating success in the population in which it dominates. If males have accurate information about the female emergence schedule within each year, their emergence curve would evolve to the one predicted by a deterministic game model. The male emergence curve would then shift between years, closely following year to year changes in the female emergence pattern. If, instead, males have uncertainty about the female emergence schedule, the ESS male emergence curve becomes broader than the one predicted by the deterministic game model and will not track the between-year fluctuation of female emergence well. In a special case, we show how the between-year variation of mean emergence date, the variance of emergence date, the sexual difference in mean emergence dates (protandry) and the between-year correlation of mean emergence dates of both sexes should change with the degree of accuracy of information available to males.

Shear microscopy of the "butterfly pattern" in polymer mixtures.

The concentration fluctuations induced in a semidilute polymer solution by shear flow are directly visualized for the first time. The spatial structure of the ``butterfly pattern'' observed by light scattering is elucidated, being the result of hydrodynamic rippling waves which have a distribution of tilt angles. The minimal tilt angle depends on shear rate in a power law fashion, causing the butterfly to almost close upon itself at high shear rates. The concentration waves have a time scale related to a shear rate \ensuremath{\gamma}\ifmmode \dot{}\else \.{}\fi{}\ensuremath{\sim}1 ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$ and periodicity \ensuremath{\lambda}\ensuremath{\sim}10 \ensuremath{\mu}m, indicating a link to reptation processes.

Symmetry systems and compartments in Lepidopteran wings: the evolution of a patterning mechanism

ABSTRACT The wing patterns of butterflies are made up of an array of discrete pattern elements. Wing patterns evolve through changes in the size, shape and color of these pattern elements. The pattern elements are arranged in several parallel symmetry systems that develop independently from one another. The wing is further compartmentalized for color pattern formation by the wing veins. Pattern development in these compartments is largely independent from that in adjacent compartments. This two-fold compartmentalization of the color pattern (by symmetry systems and wing veins) has resulted in an extremely flexible developmental system that allows each pattern element to vary and evolve independently, without the burden of correlated evolution in other elements. The lack of developmental constraints on pattern evolution may explain why butterflies have diverged so dramatically in their color patterns, and why accurate mimicry has evolved so frequently. This flexible developmental system appears to have evolved from the convergence of two ancient patterning systems that the butterflies inherited from their ancestors. Mapping of various pattern types onto a phylogeny of the Lepidoptera indicates that symmetry systems evolved in several steps from simple spotting patterns. Initially all such patterns were developmentally identical but each became individuated in the immediate ancestors of the butterflies. Compartmentalization by wing veins is found in all Lepidoptera and their sister group the Trichoptera, but affects primarily the ripple patterns that form the background upon which spotting patterns and symmetry systems develop. These background pattern are determined earlier in ontogeny than are the symmetry systems, and the compartmentalization mechanism is presumably no longer active when the latter develop. It appears that both individuation of symmetry systems and compartmentalization by the wing veins began at or near the wing margin. Only the butterflies and their immediate ancestors evolved a pattern formation mechanism that combines the development of a regular array of well-differentiated symmetry systems with the mechanism that compartmentalizes the wing with respect to color pattern formation. The result was an uncoupling of symmetry system development in each wing cell. This, together with the individuation of symmetry systems, yielded an essentially mosaic developmental system of unprecedented permutational flexibility that enabled the great radiation of butterfly wing patterns.

Strain induced fluctuations in polymer networks, melts and gels (butterfly patterns)

We present several examples of an unexpected behaviour, occurring in different types of polymer networks (permanent or temporary) containing either small or large proportions of mobile species. The spatial fluctuations of local concentration of the mobile probes appear (through neutron scattering experiments) to be anisotropically enhanced (essentially parallel to the elongation axis) when the samples are uniaxially stretched. This behaviour may arise either from an anisotropic enhancement of the thermal fluctuations under strain or from the revealing of «quenched» large scale heterogeneities. It has not been possible yet to decide which of these rather different explanations is the more satisfactory

PHENOTYPIC CORRELATION STRUCTURE AMONG ELEMENTS OF THE COLOR PATTERN IN PRECIS COENIA (LEPIDOPTERA: NYMPHALIDAE).

The component parts of butterfly wing patterns are arranged in sets of serially homologous pattern elements, repeated from wing cell to wing cell. Measurements were made on the sizes and positions of these elements on two successive, independent, sets of specimens in order to elucidate the phenotypic correlation structure among pattern elements. That portion of the correlation between measures due to overall size variation was accounted for through two alternate methods: multiple regression on two vein length measures, which represent wing size, and a Wright-style factor analysis. The sizes of pattern elements belonging to a homologous series were found to be significantly correlated whereas those of non-homologous elements varied independently. The degree of correlation among homologs varied, and, in the case of eyespot sizes, appeared to be inversely related to the degree of their morphological divergence. Although not correlated in size, the positions of non-homologous elements that lie within the same wing cell are moderately correlated. The results support current developmental models for the ontogeny of butterfly color pattern.

The distribution of radiolabeled pigment precursors in the wing patterns of nymphalid butterflies

The distribution of radiolabeled pigment precursors in the wing patterns of nymphalid butterflies

“Butterfly” Light Scattering Pattern in Shear-Enhanced Concentration Fluctuations in Polymer Solutions and Anomaly at High Shear Rates

The effects of simple shear flow on concentration fluctuations in semidilute solutions of high molecular weight polystyrene are investigated by the flow light scattering method. The shear-rate (\(\dot{\gamma}\) ) dependence of scattering was found to fall into four regimes: Regime I at \(\dot{\gamma} \dot{\gamma}_{c}\), \(\dot{\gamma}_{c}\) being the critical shear rate for the shear-enhanced concentration fluctuations. In Regime II, a unique butterfly-type scattering pattern with a dark streak perpendicular to the flow direction appears. The intensity parallel to the flow increases by about 100 times with increasing \(\dot{\gamma}\) . In Regime III at higher shear rates, the intensity increase with \(\dot{\gamma}\) tends to saturate, and finally in Regime IV at even higher shear rates, the intensity further increases and the butterfly pattern changes into a two-point pattern elong...

Normal and shear strain distributions of the equine third metacarpal during locomotion: Characterizing bone's functional milieu

The study elucidates the applicability of stabiolomety in evaluating floor sitting modes and characterizing the center of pressure (CoP) displacement patterns of women in sitting. The measurement included quantifying the stabilometric dimensions while women (N=10) seated on the piezoelectric force platform in different modes—such as squatting, left leg crossed, right leg vertically bent at knee, and vice versa, both legs bent at knee without pelvic support, legs extended and locked at knee, sideways sitting with legs folded. The principal component analysis of 10 CoP dimensions yielded three-component model, describing (1) the size, radius, and range of the CoP oscillation, (2) the trajectory (trace) length and velocity of CoP displacement, and (3) the directional CoP displacement, such as anterio-posterior (AP) and medio-lateral (ML) displacements. Detailed one-way repeated measures ANOVA showed that the sitting modes had discernable effects on the amplitude deviations as well as velocity parameters derived from CoP co-ordinates. The extending of legs caused the body to move largely in the AP direction, and also markedly influenced the CoP trajectory length as well as the velocity of CoP displacements, indicating greater instability in the postures. Knee bent modes as well as sideways sitting resulted in larger ML excursion of CoP. Squatting with both legs crossed had equilateral AP and ML CoP displacement with least velocity of displacement, and identified as a more stable floor seated posture. Eleven envelopes of CoP trace patterns were characterized in terms of ML, AP, centralized, diffused, and multi-centric CoP movement from its barycenter. The CoP trace patterns did not indicate one pattern—one posture relationship; however, the centralized CoP displacement was most prevalent in squatting as well as sideways sitting postures. The diffused nature of displacement was dominant in knee bent postures. The ML butterfly and AP patterns were evenly present in extended legs, locked at knee postures and in without pelvic support knee bent posture. The first of the kind study reflects a broadened scope of stabilometry in profiling functional measures of postural balance of women in floor sitting modes.The postural stability/instability is a crucial concern to mitigate risk potentials of spinal and musculo-skeletal injuries at workplaces. The stabilometry is a promising approach to ascertain and characterize women's floor sitting modes, for neurological, orthopedic, and ergonomics applications.

Butterfly Eye-spots and Corneal Reflections

The wings of the order Lepidoptera (butterflies and moths) demonstrate many interesting optical principles. Within the 165,000 species identified to date are combinations of colours and patterns that would impress the most sophisticated of art critics. The patterns and colours are achieved by the precise placement of both pigmented and non-pigmented scales which take advantage of light absorption, diffraction and scattering. For example, the colour white in the centre of the pattern in Fig. 1 is from light scattering, produced by air spaces within the scales, whereas the brilliant iridescent blues of the wings of the Morpho peleides are due to light diffraction. Of all the fascinating aspects of the butterfly patterns, that of the 'eye-spot' entices me most as an ophthalmologist. Experiments using birds and butterflies with eye-spots have demonstrated that when the peacock butterfly, Nymphalis io, suddenly displays its eye-spots by raising its hindwings and retracting the fore wings, attacking birds draw back. When the eye spot pattern is rubbed off the butterfly wings by the experimenter, the birds attack and eat the butterflies [1, 2]. One of the interesting subtleties of the eye-spot is

Latitudinal patterns in the size of European butterflies

The importance of seasonality in shaping latitudinal size patterns was investigated in 16 species of lycaenine and satyrine butterflies with distributions in Sweden and continental Europe. Species without shifts in voltinism within the study area generally displayed clear size clines, increasing in size from north to south within Sweden. These species were also larger in continental Europe than in Sweden. In northern temperate areas a linear model for mean size at different latitudes seems to be a reasonable approximation for most species in this category. The size patterns for three species with shifts from univoltinism to bivoltinism at latitudes within Sweden were more reminiscent of the “saw‐tooth”‐pattern predicted by theory for such cases. The results suggest that size patterns in European butterflies to a large extent is governed by the length of the favorable season at different latitudes, affecting selection for development time and size. Altitude and drought also affect the effective season length and may amplify or complicate latitudinal patterns.

Seasonal Polyphenism in Wing-Melanin Pattern and Thermoregulatory Adaptation in Pieris Butterflies

We examine the hypothesis that seasonal polyphenism (response to larval photo- period and/or temperature) in adult wing-melanic pattern of pierine butterflies is adaptive for thermoregulation in seasonally varying thermal conditions. Previous functional analyses demon- strate how changes in different wing-melanic characters can affect thermoregulatory perfor- mance of Pietis (Pontia) occidentalis in warm and cool thermal environments. We develop qualitative predictions about the polyphenic response of these characters to larval photoperiod and/or temperature that would improve thermoregulatory performance in seasonally varying thermal environments. Laboratory experiments in which full sibling families of P. occidentalis were split into long day, warm temperature and short day, cool temperature rearing treatments demonstrated significant agreement between the predicted and observed polyphenic responses for both males and females. The thermoregulatory model failed to predict correctly the observed polyphenic response of melanic characters in the basal and discal cell region of the dorsal forewing. Some melanic characters not expected to affect thermoregulatory performance also showed significant polyphenic responses to rearing environment. Norms of reaction revealed significant differences among families in the polyphenic response of melanic pattern. The ab- sence of significant family correlations in melanic character values across larval environments suggests that the polyphenic expression of melanic pattern in different seasonal environments is not strongly constrained genetically. Analyses of field samples suggest that much of the seasonal variation in melanic pattern observed in the field is the result of polyphenic response to larval-rearing environment. Comparisons of the thermoregulatory behavior and polyphenic response between pierine butterflies (family Pieridae, subfamily Pierinae) and their sister group (subfamily Coliadinae) suggest that seasonal polyphenism in pierines is adaptive for thermoregu- lation and involves both the ventral and dorsal wing surfaces.

Differences in ultraviolet wing patterns in the New Zealand lycaenid butterfliesLycaena salustius,L. rauparaha, andL. feredayias a likely isolating mechanism

Abstract The dorsal and ventral surfaces of fore- and hind wings in Lycaena salustius, L. rauparaha, and L. feredayi were examined under visible and ultraviolet (UV) light. Differences between the males and females of all three species, invisible to the human eye, appear under UV-radiation. Males of L. salustius exhibit extensive UV-reflecting regions on the dorsal sides of both wing pairs. On female L. salustius, these UV-reflecting areas are reduced to tiny submarginal spots. Males and females of both L. rauparaha and L. feredayi are UV-absorbing. Scales examined under the scanning electron microscope confirmed the correlation between scale-ultrastructure and UV-reflectance or absorbance known from other butterflies. The geographical distribution of the sexually UV-dichromatic L. salustius and either the UV-absorbing L. rauparaha or L. feredayi (rarely both) overlap, and the latter two are not found together on their own. Therefore I suggest that the UV-pattern is an isolating mechanism, similar to the ...

Butterfly Patterns: an Anomaly Common to the Neutron Scattering Spectra of Elongated Rubbers, Melts and Gels:

AbstractA totally unexpected phenomenon has been observed for the first time a few years ago when studying, by small angle neutron scattering, rubbery networks containing a small proportion of uncrosslinked labelled (deuterated) chains [1].When such a system is elongated, the scattered intensity strongly increases with the extension ratio λ for q vectors parallel to the stretching direction (and for low q values). Conversely, in the direction perpendicular to the elongation axis, the scattered intensity slightly decreases at low q for small extension ratios and then remains approximately constant when λ is further increased. The changes which are observed occur therefore in a direction opposite to the “conventional” one, i.e. that corresponding to chains effectively linked by at least two chemical junctions to the network and thus oriented on an average along the direction of stretching.

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.

Ferromagnetic resonance of single-crystal YIG/GGG/YIG layers (abstract)

We report on the microwave properties of single crystal of YIG/GGG/YIG grown in (11̄0) layers. The YIG layers were sufficiently thin so that single-domain ferromagnetic resonance (FMR) was observed. FMR fields were measured as a function of field direction, magnitude, and frequency. Bulk magnetic parameters were deduced from FMR and VSM measurements. For the YIG layer next to the GGG substrate, we measured 4πM(1)eff =1750 G, 2K(1)l/M =−82 Oe, K(1)u =0, and for the other layer 4πM(2)eff =1256 G, 2K(2)1/M=−82 Oe, 2K(2)u/M =50 Oe, g=2.025, where 4πM(i)eff (i=1,2) is the sum of the saturation magnetization and uniaxial magnetic anisotropy field normal to the film plane, and K(i)l and K(i)u (i=1,2) are cubic and in-plane uniaxial anistropy energies, respectively. FMR measurements at low fields show typical ‘‘butterfly’’ variations1 of FMR fields versus frequency for H, the magnetic field parallel to either 〈110〉 or 〈100〉 axis. However, a new butterfly pattern was also observed for the magnetic field parallel to the 〈111〉 axis. This new result is intrinsic to layered structure and not to single-layer excitations. We explain this data in terms of nonuniform distribution of strain in the two YIG layers and misalignment between the magnetization direction in the two YIG layers in zero field. For a reverse field of −2 Oe the misalignment is total and equal to 180°

Ferromagnetic resonance of single-crystal YIG/gadolinium gallium garnet/YIG layers

We report on the microwave properties of single-crystal YIG/gadolinium gallium garnet/YIG grown in (110) layers, where YIG is yttrium iron garnet. The YIG layers were sufficiently thin so that single domain ferromagnetic resonance (FMR) was observed. FMR fields were measured as a function of field direction and magnitude and frequency. Bulk magnetic parameters deduced from FMR and vibrating-sample magnetometer measurements agree with published values. In addition, FMR measurements at low fields show typical ‘‘butterfly’’ variations of the FMR fields with a frequency for H, the magnetic field, parallel to either the 〈100〉 or 〈110〉 axis. However, a new butterfly pattern was also observed for the magnetic field parallel to the 〈111〉 axis. This result is intrinsic to layered structures and not to single layer excitations. We attribute this new result to nonuniform distribution of strain in the two YIG layers, and as a consequence, we predict that magnetostatic fringe fields from edges are sufficient to induce spin-flop magnetic configurations in single-crystal YIG double layers.

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

The colour patterns of Heliconius butterflies are composed from a relatively simple set of pattern elements whose homologues are recognizable throughout the genus. Although Heliconius colour patterns look quite different from those of most nymphalids, these pattern elements are seen to derive from the generalized nymphalid groundplan. The differences arise primarily from the loss or positional shift of certain pattern elements, a high degree of fusion between individual pattern elements, and, in the forewing, asymmetries of the pattern elements relative to the wing-cell midline. The scheme of homologies we present is consistent with what is currently known about the comparative morphology and developmental physiology of colour pattern formation in Lepidoptera, and provides a framework for the interpretation of developmental, evolutionary and genetic studies in Heliconius.

Emergence patterns in male checkerspot butterflies: Testing theory in the field

Recent theoretical models predicting the emergence patterns of male butterflies are tested with extensive field data. Previous models suggest that at evolutionary equilibrium the curve of male emergence will be truncated; no males will emerge after a certain date during the flight season. No truncation of male emergence was found for Euphydryas editha in 10 years of detailed mark-recapture data in a homogeneous habitat. In general, a poor fit between theoretical and observed emergence patterns was found, suggesting that the models do not provide useful insights to the natural situation. Possible reasons for this failure are discussed.

DISSECTING CORRELATED CHARACTERS: ADAPTIVE ASPECTS OF PHENOTYPIC COVARIATION IN MELANIZATION PATTERN OF PIERIS BUTTERFLIES.

In this study we address the question of how much of the covariation among phenotypic characters observed in natural populations is adaptive. We examine covariation among a set of phenotypic characters that describe the wing-melanization pattern of Pieris butterflies. Previous functional analyses of thermoregulatory performance allow us to predict a priori whether and how different wing melanic characters should be correlated. We quantify and analyze the variation in the wing-melanization pattern within species for a series of Pieris populations from relatively cool environments in North America and compare these results with the predictions based on our adaptive hypothesis. We consider adaptive covariation both for biogeographic variation among populations and for seasonal polyphenism (phenotypic plasticity) within populations. Our hypothesis correctly predicts many of the qualitative features of covariation in melanization among major regions of the wings, at the level of biogeographic variation among populations, for both males and females of Pieris occidentalis. When within-population variation is considered, agreement with the adaptive predictions varies considerably in different populations for both P. occidentalis and P. napi males and females. Agreement for P. napi, particularly the females, is generally poorer than for P. occidentalis. In both species, there is a consistent difference in melanization pattern between alpine and arctic sites; this difference is discussed in relation to the differences in the radiative environment between these two types of "cold" habitats. Our results suggest that some important aspects of phenotypic correlation among wing melanic characters in Pieris are adaptive. We emphasize the important distinction between covariation and co-occurrence of characters, and we discuss these results in relation to the extensive biogeographic variation and phenotypic plasticity (seasonal polyphenism) in Pieris wing-melanization patterns.

Comparative Thermoregulation of Four Montane Butterflies of Different Mass

In this field study, I examine whether body mass affects flight behavior and thoracic temperature ($T_{th}$) in butterflies from a relatively cool environment (3,100 m high in the Sierra Nevada of California). Comparisons are made with thermoregulatory patterns of butterflies from other habitats and are discussed in terms of male mating strategies. The smallest (.023 g) butterflies examined (males ofAgriades glandon) spent 94% of the time in the morning basking and 6% flying. Near noon, they spent only 25% of the time perched (basking). Agriades glandon did not regulate a stable $T_{th}$. Instead, these small butterflies prolonged flight duration by storing heat prior to flight; the $T_{th}$ was on the average 9.2 C higher at takeoff than at landing. Almost all A. glandon basked dorsally near midday. However, a large percentage, 30% in the morning and 60% in the evening, basked laterally. Heating rates in the field were indistinguishable between lateral and dorsal basking positions in recently killed A. g...