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Pieris napi males (left columns) and females (right columns) without (left group of 4 individuals) and with (right group of 4 individuals) filter transparent only to UV. Top row, individuals from the southern part of Finland; bottom row, individuals from the north
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... (n = 10) Ventral (n = 10) Dorsal (n = 6) Ventral (n = 6) North number of pierid species [7], but we noted that the variations in P. napi are not haphazard or random but are ob- viously correlated with the geographic latitude at which the specimens were collected (Fig. 1). When only the dor- sal wing surfaces were observed un- der UV, we found that in 10 of 14 north/south randomly selected pairs of female P. napi examined (approx. 75%), specimens from the northern parts of Finland (near the polar circle: 66830' N) had wings that more strongly reflected UV at both 366 and 254 nm wavelength than those of ...
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... pITD cues is likely to depend on the rise time of the stimulus onset. One might expect that stimuli with a steep onset would provide better pITD cues because of a more precise triggering of action po- tentials. However, stimuli with slowly rising ramps could be advantageous for directional hearing by creating an additional latency difference, Dt (Fig. 1a), between receptor responses from the left and right ear [3,12]. Electrophysiological recordings from auditory receptors in locusts show that ramp-like stimuli produce such a latency gain (visible in the steeper slope of the upper curve in Fig. ...
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... could be advantageous for directional hearing by creating an additional latency difference, Dt (Fig. 1a), between receptor responses from the left and right ear [3,12]. Electrophysiological recordings from auditory receptors in locusts show that ramp-like stimuli produce such a latency gain (visible in the steeper slope of the upper curve in Fig. ...
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... the other hand, these stimuli also lead to an increased temporal jitter of latencies (see standard deviations in Fig. 1b), thereby reducing possible benefits of increased Dt values. In or- der to ascertain how these two oppos- ing effects interact we determined the probabilities for incorrect directional decisions in a Monte-Carlo simulation using the respective distributions of latencies from Fig. 1b and of nine ad- ditional low-frequency receptor ...
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... temporal jitter of latencies (see standard deviations in Fig. 1b), thereby reducing possible benefits of increased Dt values. In or- der to ascertain how these two oppos- ing effects interact we determined the probabilities for incorrect directional decisions in a Monte-Carlo simulation using the respective distributions of latencies from Fig. 1b and of nine ad- ditional low-frequency receptor ...
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Citations
... Since then, our knowledge of UV patterns on the wings of butterflies and moths had expanded to include at least ten families of Lepidoptera [4][5][6], such as Pieridae [7][8][9][10], Nymphalidae [11,12], Riodinidae [13], Lycaenidae [14,15], Lymantriidae [6], and Papilionidae [3,16,17]. ...
... The females of Pieris napi [7,63], Pieris bryoniae [62], as well as other species of Pieridae, such as Eurema candina [38,64], Pieris rapae [33,65], Pieris occidentalis [66], and Belenois zochalia [67], reflect UV light more strongly than their conspecific males-these species thus display different degrees of UV sexual dichromatism. For example, Stella et al. [63] found a 25% higher level of UV reflectance in female Pieris napi than in their conspecific males (Figure 1), while Meyer-Rochow and Järvilehto [4] found a 35-40% difference of UV reflectance in this species. Nevertheless, this phenomenon, that is the females having higher UV reflectance levels than their conspecific males, in Lepidoptera is an exception [1]. ...
... However, males of Pieris napi do not have highly UV-reflective patterns, due mainly to the presence of pterins, which decrease the level of UV reflectance and increase the degree of whiteness (i.e., the level of reflectance in the visible spectrum of light) in this species. Males are under a sexually selective pressure from the females for whiter wing patterns, i.e., patterns with a higher level of whiteness [69][70][71], which is probably why variation in UV reflectance levels in males appears relatively low in comparison to the females of this species [4,63]. It is expected that chemical removal of the pterin pigment on the wings of male Pieris napi would lead to an analogical appearance of UV reflectance as is seen in the females. ...
Ultraviolet (UV) means ‘beyond violet’ (from Latin ‘ultra’, meaning ‘beyond’), whereby violet is the colour with the highest frequencies in the ‘visible’ light spectrum. By ‘visible’ we mean human vision, but, in comparison to many other organisms, human visual perception is rather limited in terms of the wavelengths it can perceive. Still, this is why communication in the UV spectrum is often called hidden, although it most likely plays an important role in communicating various kinds of information among a wide variety of organisms. Since Silberglied’s revolutionary Communication in the Ultraviolet, comprehensive studies on UV signals in a wide list of genera are lacking. This review investigates the significance of UV reflectance (and UV absorption)—a feature often neglected in intra- and interspecific communication studies—mainly in Lepidoptera. Although the text focuses on various butterfly families, links and connections to other animal groups, such as birds, are also discussed in the context of ecology and the evolution of species. The basic mechanisms of UV colouration and factors shaping the characteristics of UV patterns are also discussed in a broad context of lepidopteran communication.
... For instance in green-veined whites (Pieris napi), individuals that inhabit harsher environments reflect more UV light than those from warmer areas, which are more suitable for breeding. Furthermore, the wings of males are less UV-reflective than the wings of females (Meyer-Rochow and Järvilehto 1997;Tuomaala et al. 2012;Stella et al. 2018b). This trend, however, seems to be reversed in species with structural UV colouration. ...
... In context of our results, which suggests that there is a relationship between the environment and a UV pattern expression at least in some of the investigated species, it can be hypothesised that species living in areas where there is more shadow or dense, strongly UV-absorptive vegetation (Silberglied 1979), should have larger UV patterns or that these patterns should cover both fore-and hindwings to fulfil their signalling function. This hypothesis is linked to a proposal by Meyer-Rochow and Järvilehto (1997) who claim that the wings of Pieris rapae individuals from northern regions reflect the UV light more strongly because the percentage of UV irradiation on Earth's surface decreases from equator towards the poles (Herman et al. 1999). Extrapolating from this proposal, however, we should expect butterflies from arid or alpine areas to have larger UV patterns as well because in such areas, there is less grass with a low UV albedo, and sand or other materials with a relatively high UV albedo prevail (Chadyšiene and Girgždys 2008), with the consequence that as the UV albedo increases, contrast between UV iridescent wings and the background declines. ...
It has been suggested that structural ultraviolet (UV) patches on the wings of butterflies play a role in sexual selection. UV patches may be condition-dependent signals of mate quality. In the current study, we investigated associations between the morphological properties of two male wing patterns (one signalling and one non-signalling trait) and between these patterns and various environmental variables in seven species of the genus Gonepteryx (G. rhamni, G. nepalensis, G. maxima, G. amintha, G. aspasia, G. niphonica and G. cleopatra). We collected UV photographs of a total of 320 male specimens and analysed them using geometric morphometrics. Our results show that the shape of UV patches (a signalling trait) is more asymmetric than the wing venation (a non-signalling trait). In both examined traits, however, relationship between the environment and fluctuating asymmetry is significant only in a minority of species. Our results thus do not support the hypothesis that fluctuating asymmetry is a reliable indicator of an individual’s quality, in other words, that UV patches are condition-dependent trait. Examination of correlations between the two investigated shapes and the environment yielded similar results, and while the shape of UV patterns tended to be more strongly associated with the environment than the venation patterns, the correlation reached a level of significance only in a minority of cases. Due to the ambiguity of our findings, we cannot corroborate the hypothesis that UV patches act as biological signals of male quality in Gonepteryx butterflies, which is the case in various other related butterfly species. Finally, we found that UV patches discriminate among various Gonepteryx species better than the venation patterns do, which indicates that UV patches play a role in species recognition. It also suggests that UV patterns could be a useful taxonomic trait.
... Various groups of butterflies have received different amount of attention, probably due to the presence or absence of conspicuous coloration in their species. UV patterns are known to exist in at least ten families of Lepidoptera (Meyer-Rochow 1991, Lyytinen et al. 2004, Obara et al. 2008a) and not only diurnal, but even nocturnal species of Lepidoptera exhibit wing patterns perceptible only in the UV part of the spectrum (Allyn and Downey 1977, Silberglied 1979, Brunton and Majerus 1995, Meyer-Rochow and Järvilehto 1997. In some species, UV patterns serve as a protection against predators (Lyytinen et al. 2004, Olofsson et al. 2010. ...
... Moreover, UV patterns vary in relation to environmental conditions and can therefore signal some properties of the environment where the individual had developed. Temperature, rate of precipitation, and possibly also the level of UV radiation are the most important factors that influence the quality and presence of UV pattern, especially in Pieridae (Meyer-Rochow and Järvilehto 1997, Obara et al. 2008b, Pecháček et al. 2014). In the Coliads, the quality of the pattern also influences the females' choice of sexual partners (Papke et al. 2007). ...
... Brunton et al. (1998) show that UV patterns may have strong phylogenetic signal, but a comprehensive phylogenetic study of the genus Colias is still not available, probably because the most frequently used mitochondrial marker, namely, the Cytochrome Oxidase Subunit I, displays a low or no differentiation between species of the genus (Kramp et al. 2016). Although previous studies have revealed that UV reflectance is associated with some large-scale variables, such as temperature or precipitation, these analyses tended to focus on just one species (Meyer-Rochow and Järvilehto 1997, Pecháček et al. 2014, Stella et al. 2018). This was not the case in our study, since we targeted ecological properties relevant to 106 taxa of the Colias butterflies. ...
Ultraviolet patterns in butterflies have been recognized and studied for many years. They are frequently involved in both intraspecific and interspecific interactions. Only a handful of studies, however, have investigated possible links between ultraviolet (UV) reflectance and ecological properties in some genera of the Lepidoptera as a whole. This study examines the impact of habitat and distribution on UV reflectance patterns on the wings of 106 species and subspecies of Colias butterflies. Based on standardized digital photographs, we performed a multivariate analysis of relations between UV reflectance, preferred habitat (alpine, arctic, dry grasslands, humid, forest, and ubiquitous), and distribution area (Afrotropical, Nearctic, Neotropical, European, Caucaso-Anatolian, boreal Eurasian, Central Asian mountains, northern China and Japan, and northern Oriental region). UV patterns occur more frequently in the male (60 taxa) than in female (25 taxa) Coliads. This difference in presence of UV patterns is used for differentiating between the males and females of a given species or subspecies. Further possible explanations of this phenomenon are also discussed. This study also shows that particular configurations of UV patterns are significantly associated with particular distribution areas. This relation is relatively strong but overall trends remain unclear. Based on the results of this study, it can be concluded that there exists a significant difference in the configuration of UV reflectance between the sexes, and that the configuration of UV reflectance significantly interacts with the geographical distribution of Colias species and subspecies.
... In the absence of microridges, the UV reflectance are caused due to pigments. UV reflectance property is further correlated with geographical latitude in P. napi [36]. Butterflies have spectral sensitivity in UV, blue and green region to use this UV pattern for its daily activity [37]. ...
Butterflies wings possess different types of scales to perform diverse functions. Each
scale has many nano and microstructures, which interferes with light, resulting in
unique coloration for each butterfly. Besides coloration, the arrangement of scales further
helps in giving better survivability. Thus, analysis of wing pattern provides an overall
idea about adaptation and activity of the animal. The current study deciphers the
structure and composition of a wing of a pierid butterfly Catopsilia pomona, which
remains active at 42°C at which temperature all other butterflies face a tougher task for
existence. In order to know the relation between survivability and adaptation in the
wing, we have investigated the structural and physical composition of the wing of C.
pomona under optical spectroscopy (absorption, reflectance and transmittance) along
with microscopy techniques (optical and scanning electron microscopy), which are not
described in earlier studies. The current findings reveal unique structural arrangement
within scales to provide the best fit to the animal in variable temperature.
... This trend, however, varies both within and between the sexes Tuomaala et al., 2012). Furthermore, in comparison with other butterfly species such as Colias eurytheme (Silberglied et al., 1978), the age of P. napi individuals has little effect on their UV reflectance (Meyer-Rochow & Järvilehto, 1997). In the multivoltine P. napi, females follow various heritable strategies associated with mating tactics, which range from strict monandry (i.e., females mate only once) to a high degree of polyandry (Meyer-Rochow, 1999;Wedell et al., 2002;Välimäki & Kaitala, 2006;Kivelä & Välimäki, 2008). ...
... Color polymorphism in butterflies has been extensively studied along geographic and environmental gradients, such as variation across latitude (Hovanitz, 1944), longitude (Obara et al., 2008a), altitude (Tuomaala et al., 2012), level of ultraviolet radiation (Meyer-Rochow & Järvilehto, 1997), temperature, and/or photoperiod (Hazel & West, 1983). Furthermore, ultraviolet coloration of butterflies may also be influenced by the quality of food ingested during their larval development (Knuttel & Fiedler, 2001;Kemp, 2006;Rutowski et al., 2007). ...
... Based on these results, we suggest 2 possible but not necessarily exclusive explanations: First, higher levels of UV reflectance of butterfly wings, which help facilitate mate recognition, may be a way of compensating for low levels of environmental UV radiation in northern areas and lower altitude. At higher latitudes, the sun is lower in the horizon so the UV rays travel a greater distance through UV-absorbing layers of the atmosphere (Meyer-Rochow & Järvilehto 1997, Madronich et al., 1998. We also suggest that in females, UV reflectance is negatively correlated with environmental UV irradiation. ...
The subject of our investigation was the visual features of wing colour with special focus on the UV reflectance in the green-veined white (Pieris napi). Previous studies had concluded that UV reflectance on dorsal wing surfaces is found only in the female P. napi. Based on UV sensitive photography, we analysed a correlation between 12 geographic and environmental factors and UV reflectance patterns on three patches on the forewings of 407 P. napi specimens from the Palaearctic region. Results had shown that females significantly differ from males: they exhibit a 25% higher UV reflectance. To investigate whether and how UV reflectance levels on the forewings and hindwings of both sexes are influenced by the environment, we performed a PCA with several environmental variables. For several variables (in particular, latitude and longitude, mean annual temperature and precipitation, and temperature annual range and altitude), the Generalized linear model (GLM) model revealed a significant correlation in both sexes. This suggests a link between UV reflectance levels and the environment and distribution of P. napi. We found that stronger UV reflectance is associated with generally more hostile environments and concluded that large-scale environmental factors influence the UV reflectance on the forewings of both male and female green-veined white butterflies. This article is protected by copyright. All rights reserved.
... There is a large body of information on sexual communication in butterfl ies in the literature (e.g. Rutowski, 1977;Silberglied, 1977Silberglied, , 1984Meyer-Rochow & Järvilehto, 1997;Rutowski et al., 2001Rutowski et al., , 2007Wiklund, 2003;Kinoshita et al., 2008;Imafuku & Kitamura, 2015). Sexually active male butterfl ies search for mates by fl ying around or by waiting on perches that females can be expected to pass and be easily detected. ...
... Eguchi & Meyer-Rochow, 1983;Meyer-Rochow, 1991;Rutowski et al., 2007). An interesting example of UV signal adaptation is described for the butterfl y Pieris napi (family Pieridae) by Meyer-Rochow & Järvilehto (1997), the dorsal wing surfaces of the females of which at Arctic latitudes exhibit signifi cantly stronger UV refl ectivity than those of conspecifi c females at lower latitudes. They suggest that this above-average refl ectivity may serve to compensate for the reduced UV radiation at Arctic latitudes resulting from the lower angle of the sun, thus enabling Arctic P. napi males to detect these signals, even if the UV-sensitivity of their compound eyes is similar to that of males at lower latitudes. ...
Animals, including human beings, tend to respond more strongly to stimuli that are associated with the highest relative rewards. This applies not only to food rewards but also to reproductive success. In the present review article this issue is discussed for insects in connection with intersexual communication and
flower-visiting behaviour. Implications of the preference for supernormal visual releasing stimuli are examined from a sensory and evolutionary perspective, including a consideration of the choice of potential mates and recognition of the most rewarding flowers.
... at lower latitudes. This indicates that the lower incidence of UV light at high latitudes makes it more difficult for the males there to locate females (Meyer-Rochow & Järvilehto, 1997 ). There is thus evidence for a clear correlation between primary peak positions of spectral sensitivity and spectral reflectance from wing surfaces. ...
The correlation between dorsal wing colours and spectral sensitivity of the compound eyes of 13 species of thecline butterflies, consisting of 8 sexually monomorphic and 5 dimorphic species, was investigated. Spectral reflectance of the dorsal surfaces of the wings was measured using a spectrophotometer and spectral sensitivities using electroretinography. All 13 species examined showed a common basic pattern of spectral sensitivity with a primary peak at a wavelength of 440-460 nm. Detailed analyses of the deviations in sensitivity from the basic pattern revealed a correlation in monomorphic species with conspicuous wing hues, especially in males.
... This trend was observed between the sexes and along latitude among females (UVreflectance increased and long wavelength reflectance decreased toward the north). The higher UV-reflectance of the northern females may increase their visibility to males under the lower sun-angle conditions characteristic of high latitude habitats, as suggested by Meyer-Rochow & Järvilehto (1997). However, because the sexual dimorphism and latitudinal cline in female wing colour was more pronounced in the long wavelength reflectance and degree of melanization than in the UV-reflectance, the role of latitudinal wing colour variation in the communication of P. napi cannot only be based on wing UV-patterns. ...
In butterflies, wing colour may simultaneously be under sexual selection in the context of mating selection and natural selection in the context of thermoregulation. In the present study, we collected mated females of the green‐veined white butterfly (Pieris napi) from locations spanning 960 km of latitude across Fennoscandia, and investigated sex‐specific latitudinal wing colour variation in their offspring raised under identical conditions. We measured wing colour characteristics, including reflectance at wavelengths 300–700 nm and the degree of wing melanization. At all latitudes, females reflected more light in the short wavelengths ( 450 nm), and they were more melanized than males. However, female wing colour varied more with latitude than that of males. Among females, long wavelength reflectance decreased, whereas short wavelength reflectance and melanization increased, towards the north. By contrast, among males, latitudinal variation was found only in the ventral hindwing melanization. These results are consistent with the idea that the balance between natural and sexual selection acting on wing colour changes with latitude differently in males than females. The dark wing colour of females in the north may be a thermoregulatory adaptation, although males may be constrained from evolving the dark dorsal wing colour favoured by natural selection because of constant sexual selection across latitudes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.
... The traps were emptied once a week and all so-called macrolepidopterous species were identified, counted and sexed. As with some butterflies (e.g., Pieris napi: Rochow and Järvilehto, 1997) in some species of moths different colour morphs were noticed and recorded. Identifications were made by the members of the Finnish Lepidopterological Society and the data were fed into the Hertta-database and preserved in separate files for each year at the Finnish Environment Institute. ...
... However, to date no work has directly tested either possibility. Therefore, we sought to characterize both the molecular makeup and optical properties of these scale granules, with the hope that the findings would better inform our understanding of bright pierid wing colours, and the morphological constituents responsible for inter-and intrasexual colour variation found across the clade (Bowden 1977;Meyer-Rochow & Järvilehto 1997;Obara & Majerus 2000). ...
... Such ideas are likely to be useful for understanding the evolution of the pterin-based colour phenotypes investigated here. As spectral data from P. protodice attest (figure 2), males of this species have more highly chromatic, pterin-based wing colours than do their female conspecifics, a pattern which is common across the Pieridae (Makino et al. 1952;Obara & Hidaka 1968;Descimon 1975;Bowden 1977;Meyer-Rochow & Järvilehto 1997;Obara & Majerus 2000). Additionally, previous work has shown that pterin-based sexual dichromatism is important to mating decisions by members of both sexes in P. protodice (Rutowski 1981). ...
A small but growing literature indicates that many animal colours are produced by combinations of structural and pigmentary mechanisms. We investigated one such complex colour phenotype: the highly chromatic wing colours of pierid butterflies including oranges, yellows and patterns which appear white to the human eye, but strongly absorb the ultraviolet (UV) wavelengths visible to butterflies. Pierids produce these bright colours using wing scales that contain collections of minute granules. However, to date, no work has directly characterized the molecular composition or optical properties of these granules. We present results that indicate these granules contain pterin pigments. We also find that pterin granules increase light reflection from single wing scales, such that wing scales containing denser granule arrays reflect more light than those with less dense granule collections. As male wing scales contain more pterin granules than those of females, the sexual dichromatism found in many pierid species can be explained by differences in wing scale pterin deposition. Additionally, the colour pattern elements produced by these pterins are known to be important during mating interactions in a number of pierid species. Therefore, we discuss the potential relevance of our results within the framework of sexual selection and colour signal evolution.
