Visual features of the wing color, with special reference to the UV (ultraviolet) color, of the British subspecies of the cabbage butterfly, Pieris rapae rapae and its mating behavior were investigated. Both sexes of the British subspecies were found to lack UV color and differed only slightly in color in the visible color range, with female wings more yellowish. It follows that they show only slight sexual dimorphism in wing color. It was shown that the initial mate recognition was mediated visually, based on the wing color. Males discriminated between the sexes visually, but only marginally and were occasionally observed to approach other males mistakenly. The resting males approached by female-searching males displayed a flutter response, deterring the approaching males from attempting to copulate with them; i.e. it functioned as “mechanical isolation mechanism” against maladaptive copulatory attempts between males. The results are discussed in terms of the comparative ethology of the mating behavior with that of the Japanese subspecies. It is suggested that the British subspecies is ancestral to the Japanese subspecies.
In many species of butterfly, males take the initiative in mating behavior. They fly in search of females in appropriate areas, and when they encounter females, they approach them. This initial phase of mating behavior, or initial recognition of potential mates, is mediated visually, female wing color patterns playing an important role (Tinbergen et al., 1942; Crane, 1955; Magnus, 1958; Obara and Hidaka, 1968; Obara, 1970; Wago and Unno, 1976; Rutowski, 1977a, 1978,1981; Silberglied and Taylor, 1978). However, chemosensory stimuli are required for mating behavior to proceed beyond this initial stage. (Tinbergen et al., 1942; Magnus, 1958; Brower et al., 1965; Rutowski, 1977b; Wago, 1978a,b). It has been established that in many species of butterflies, final mate recognition of females by males is usually chemosensory.
Males of the Japanese cabbage butterfly, Pieris rapae crucivora, fly over cabbage fields searching for females (Obara and Hidaka, 1968). Female wing color plays an essential role in eliciting a mating response from males. In this subspecies UV colors are present on the wings of females, but not males, i.e. males and females are strikingly sexually dimorphic in the UV spectrum (Obara, 1970). Initial, and final mate recognition as well, by the male P. rapae crucivora is entirely dependent upon visual cues, the female wing color including UV color as an essential component (Obara, 1970). Males can discriminate females from males, even when these are sealed in an impermeable transparent film (Saran wrap), thereby preventing chemosensory stimuli (Obara, unpublished).
Preliminary observations of museum material suggested that the sexual dimorphism for UV wing color of P. rapae crucivora is not present in the British subspecies of the cabbage butterfly, Pieris rapae rapae. In this subspecies, females have no UV color. These observations raise some interesting questions. For instance, how do British males recognize mates? Is presence or absence of female UV wing color the ancestral state?
In the present study, we aimed first to determine whether the preliminary observations in respect of female UV color, mentioned above, are true. Second, we observed the mating behaviors of British subspecies and carried out experiments to determine how British males recognize mates.
MATERIALS AND METHODS
Butterflies used for UV color examination were derived from British (Cambridge area in UK) larvae raised to adulthood in the laboratory. Recently eclosed butterflies were killed by freezing and carefully set to minimize physical damage to the wings. Male butterflies for behavioral observation were derived from the Cambridge stocks, or were freshly collected around Cambridge.
To compare the visual features of the wing color between the sexes, a female and a male were examined in two ways: photographic examination and reflectance spectrometric analysis.
For the visible color examinations of the wings, 4 male specimens with similar wing color appearance and 4 female specimens likewise with similar wing color appearance were photographed under normal sun light, using color print film (Fuji Super G Ace 400). For the ultra violet color examinations the same specimens were photo graphed using the monochromatic film (Fujifilm Neopan SS) through a UV filter (Hoya UV36) following procedures described by Obara and Hidaka (1968). This filter is transparent to light with wavelengths from ca 300 to 400 nm with a transparency peak at 360 nm. Thereafter, the UV reflectance characteristics of butterflies were assessed using a spectrophotometer (Shimadu UV-260, Integral Sphere Attachment ISR-260). For this assessment, a 5mm×5mm section from the middle, distal part of the hind wings was carefully excised (see circles in Fig. 1) and placed in the cassette of the spectrophotometer, which assesses the percentage of light of specific wavelengths (at 4 nm increments) that is reflected from the specimen. Only the ventral surfaces, and the dorsal surfaces for comparison, of the hind wing samples were assessed as it is this surface that females expose to searching males and which, in the Japanese subspecies, functions as a visual releaser.
Initial observations were intended to provide a general view of the mating behavior of British subspecies. Attention was paid to determination of which sex initiates mating behavior, and to the detailed behaviors of males and females during courtship. Data from these observations were compared with similar, previously published details of the courtship and copulatory behavior of the Japanese sub-species (Obara, 1970).
As a result of the initial behavioral observations, we examined which body parts of the female attracts males and elicits male mating behavior. The wings of females were cut away from the body, and left and right fore-and hind-wings were stuck together basally, in the posture assumed by a resting butterfly (wing dummy). The head, thorax and abdomen from which the wings had been removed, were retained as an integral unit (naked dummy). The wing dummy was placed vertically on the 20cm×25cm Stigrofoam board covered with a black cloth, 15cm distant from the naked dummy. Observations were made of whether males were attracted to the wing dummy or the naked dummy, or both.
To determine whether a male could distinguish between a female and a male and recognize the former as a mate, female and male wing dummies were presented together to searching males. In this experiment 6 male wing dummies with similar wing color appearance and 6 female wing dummies likewise with similar wing color appearance were used. A female and a male wing dummy were placed 15cm apart, in resting posture with the wings closed, on cabbage leaves (termed exposed specimens). The positions of the male and female wing dummies were reversed every 15 min to exclude possible local positional effects.
In a separate experiment designed to examine whether chemo-sensory stimuli have a role in the recognition of females by British male, single female and male wing dummies were placed 15cm apart on a 20cm×25cm transparent vinyl chloride board, framed thinly with wood. The wing dummies were then sealed with a transparent kitchen wrap film (Saran wrap:Asahi-Chemical Industry Co., Ltd.) (termed sealed specimens). The wood frame was attached to prevent the film wrap from being distorted by the specimens, so as not to cause diffused reflection. Transparent rather than black opaque board was used because we found that the film wrap acted as a mirror when set against the black board, causing unexpected artefacts when approaching males saw their own reflections. The transparent board with sealed wing dummies was placed vertically amongst cabbage plants.
The experiments were carried out in a 3m×3m×2m net cage erected outside at the Department of Genetics Field Station of Cambridge University in Cambridge, U.K. More than 70 males were released into the cage.
In these experiments the numbers of males that approached, came into contact with, and attempted to mate with, dummies of various types were recorded.
1. Visual features of the wings
Brisish male and female can be distinguished readily from the markings on the dorsal surface of the forewings, for while females have two black spots on this surface, males only have one (Fig. 1A). Males have two black spots on the ventral surface of the forewing, and the posterior of these, which corresponds in position to the second black spot of females, can be discerned in males on close examination. This is in contrast to Japanese subspecies, in which both sexes have two black spots (Fig. 1A). In addition, British females generally have darker coloration on the proximal and anterior edge of the forewing than do males.
On the other hand, the ventral wing surfaces of the two sexes differed only slightly in color, with female wings more yellowish. This was true both for the hindwing and anterior edge of the forewing that are exposed by females when at rest and so have the potential to be seen and used as sensory cues by males seeking mating partners, if males use visual cues to identify females. Given only a slight sexual dimorphism of resting individuals of the British subspecies in the human-visible spectrum, visual discrimination of the sexes, by males, on the basis of human-visible wavelengths, seems difficult.
This same conclusion appears applicable for UV color. The wings of British females reflect little UV light (Fig. 1b), although close observation of the UV photograph suggests very weak UV reflectance by the dorsal surface of the forewing.
Spectrophotometric measurements are consistent with the photographic results. The dorsal surface of male and female hind wings have slightly different reflectances in the ca 440 – 530 nm wavelength range, reflectance from the male being slightly stronger, as suggested by the photographs in Fig. 1b (Fig. 2A). The ventral surfaces of the hindwings of the two sexes have very similar reflectance characteristics(Fig. 2B).
In summary, British subspecies appears to exhibit only slight visible sexual dimorphism in human-visible wavelength, but scarce in UV wavelength.
2. Mating behavior
The mating behavior of the British subspecies is essentially the same as that of the Japanese subspecies. Males initiate mating behavior, flying in search of females and approaching and attempting to copulate with those they find. Virgin females respond to male mating behavior by assuming a resting posture with the wings closed, while previously mated females reject males by assuming a mate refusal posture with wings open and depressed, and abdomen erect. Females maintain this posture as long as flying males remain in close proximity (Obara, 1964).
The “flutter response”, previously described for the Japanese subspecies (Obara and Hidaka, 1964), was also observed in the British subspecies. This response involves rapid wing fluttering by resting males in response to approaches by flying males. The total of 36 approaches by the female-searching males to the resting males were all followed by the flutter responses by the latter. All of the female-searching males were then observed to fly away following brief behavioral interactions with the resting males, without copulatory attempt.
In the experiment with the naked dummies and wing dummies, 37 males were observed to approach the wing dummies and 31 of them to contact the wing dummies. Twenty-two of the latter displayed attempted copulation to the wing dummies. No males, on the other hand, were observed to approach the naked dummies.
In the experiment using the exposed specimen, 42 males approached the female specimen, whereas 28 males approached the male specimen (Fig. 3). Of the 42 males that approached the female specimen, 39 (93%) males made contact with the specimen. Similarly, 25 of the 28 (89%) males that approached the male specimen did so. The difference between the two sexes is only marginally significant for approach and contact with the p values of 0.12 and 0.10 (Two-tailed binominal test), respectively.
Twenty-two of 42 (52%) males that approached females proceeded to attempt copulation with the female specimen, while 12 of 28 (43%) males that approached males attempted copulation with the male specimen. Here again difference in the proportions for the two sexes is only marginally significant (Two-tailed binominal test, p=0.12). Once the approach has been made, a male is not significantly more likely to attempt to copulate with a female wing dummy than with a male wing dummy (χ2 test, p >0.25).
Similar behaviors were observed for the sealed specimen (Fig. 4). Thirty-eight males approached the female specimen and 26 males approached the male specimen. Most males proceeded to make contact with the specimens they approached (for females, 37 (97%); for males, 25 (96%)). The difference between the two sexes is not significant with the p value, 0.17 for approach and 0.16 for contact (Two-tailed binominal test). Only five (13%) males that approached the female specimen attempted to copulate with it and none of the males that approached the male specimen attempted copulation with it. Some males appeared to try to alight on the film wrap covering the specimen. However, this seemed difficult as the smooth film, when positioned vertically, gives little hold for the tarsal claws.
1. Sexual dimorphism and mate recognition
The results of the experiments with the female wing and naked dummies revealed that in British subspecies, as in Japanese subspecies, it is the female wings, not the female body itself, that attracts males and elicits their mating behavior. Furthermore, the results of the exposed and sealed wing dummy experiments showed that visual, rather than tactile nor chemosensory, cues from the female wings prompt male's mating behavior;i.e. the initial mate recognition is mediated visually(Fig. 3 and 4).
The results of the experiment with wing dummies demonstrated that the ventral surface of the female wings are sufficient in eliciting mating behavior from males. As in the Japanese subspecies, British female keeps their wings closed in a resting position when found by a conspecific male. In such a posture the exposed wing parts of the female are the ventral anterior edge plus the apex of the forewing (fw-VA) and the whole ventral surface of the hind wings (hw-WV). Thus the hw-WV comprises most of the wing area exposed to males and probably plays the critical role in their initial mate recognition.
The present study revealed only slight sexual dimorphism for the wing color in the fw-VA or the hw-WV, in human visible spectra, but little in UV spectra (Fig. 1). The similar appearance between the sexes was apparent both when specimens were viewed by eye, and when they were subjected to spectrophotometric analysis (Fig. 2). The very slight difference in the ventral surfaces of female wing compared to male wings in UV (Fig. 1), is in sharp contrast to the differences seen in Japanese subspecies, in which female, but not male, ventral wing surfaces reflect UV strongly (Fig. 1;Obara and Hidaka, 1968; Obara, 1970).
The difference in wing color sexual dimorphism between the two subspecies explains why males of the two subspecies have different mating behaviors. For British males using visual cues to recognize mates, sexual discrimination must be difficult due to only a slightly appreciable optical wing dimorphism and a proportion of males will be expected to mistakenly make copulatory approaches to conspecific males. This was shown to be the case in the present observation. On the other hand, in Japanese subspecies with distinct sexual dimorphism in the UV wing color, virtually no males (one out of 107 males) approached conspecific male wing dummies when single male and female dummies are juxtaposed 20 cm apart (Obara, 1970).
How, then, is final mate recognition achieved by the British males? In cases when a male approached conspecific resting males, no copulatory attempts occured because the resting male displayed the flutter response. This effectively prevented the approaching male from landing beside the resting male, which is a prerequisite for a male to attempt copulation. It follows that the flutter response of resting males plays an important role in the mate recognition when female-searching males approach; i.e. the flutter response functions as a “mechanical isolation mechanism” against mating interaction between males.
2. Flutter response
Ohtani and Yamamoto (1980) suggested that the flutter response by a male in copula functions to dispell males who approach and attempt to copulate with the female in copula. They presented, however, no explanation for the flutter response displayed by males not in copula. Obara and Hidaka (1964) reported that the flutter response serves no apparent purpose to the males who elicit it nor to the males who perform it. The flutter response thus seems functionless and overt benefit will accrue to neither of the males.
This discussion allows speculation on which of the two subspecies is evolutionarily ancestral to the other. It is improbable that the flutter response has evolved in the Japanese subspecies independently, due to the costs to both female-searching males and resting males, with no overt benefit accruing. On the other hand, for the British subspecies with little sexual dimorphism, the flutter response may have been critically necessary for mate recognition by the male. It may also have been beneficial to males by increasing the temporal and energetic efficiency of their mate-search. Once the UV color cue become available for mate recognition in the Japanese subspecies, however, the flutter response would have been superfluous in mate recognition.
Based on this discussion we conceived no necessary behavioral-ecological factors that would have promoted the evolution of the flutter response in the Japanese subspecies, whereas the flutter response should have been favoured by natural selection in the British subspecies. Consequently it may be possible that the flutter response probably evolved first in the British subspecies as a mate recognition or “mechanical isolation mechanism” between males and that it has remained in the Japanese subspecies as a rudimental behavior with no overt function. If so, this may be evidence for the hypothesis that the British subspecies, P. r. rapae is ancestral to Japanese subspecies, P. r. crucivora and consequently that the absence of female UV wing color is the ancestral state.
We are grateful to Dr. Y. Katoh for the reflectance assessment of the butterfly wings. This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Sports and Culture of Japan (09041151).
Kwa mfano, rangi ya mabawa ya aina ya Pieris rapae, ambayo ni aina ya kipekee ya kipepeo, na tabia yake ya kuoa. Wanaume na wanawake wa aina zote mbili za ndege wa Uingereza hawakupatikana kuwa na rangi ya UV na walitofautiana kidogo tu katika rangi katika safu ya rangi inayoonekana, na mabawa ya wanawake yalikuwa na rangi ya manjano zaidi. Kwa hiyo, wao huonyesha tofauti ndogo tu ya jinsia katika rangi ya mabawa yao. Ilionyeshwa kwamba utambuzi wa kwanza wa mwenzi ulifanywa kwa njia ya kuona, kulingana na rangi ya mabawa. Wanaume walitofautisha kati ya jinsia kwa macho, lakini kwa kiasi kidogo tu na mara kwa mara walionekana wakikaribia wanaume wengine kwa makosa. Wanaume waliopumzika waliofikiwa na wanaume wa kike wanaotafuta walionyesha majibu ya flutter, kuzuia wanaume wanaokaribia kutoka kujaribu kuungana nao; yaani. ilifanya kazi kama "mbinu ya kutengwa ya mitambo" dhidi ya majaribio ya kupanda kati ya wanaume. Matokeo ni kujadiliwa katika suala la ethology kulinganisha ya tabia ya kuoa na ile ya aina ndogo ya Kijapani. Inasemekana kwamba spishi ndogo ya Uingereza ni babu wa spishi ndogo ya Kijapani. Katika spishi nyingi za vipepeo, wanaume ndio huongoza katika mazoea ya kujamiiana. Wao huruka wakitafuta wanawake katika maeneo yanayofaa, na wanapokutana na wanawake, wanawakaribia. Katika hatua hii ya kwanza ya tabia ya kuoa, au utambuzi wa awali wa wenzi wa uwezekano, ni mediated visually, wanawake mrengo rangi mifumo kucheza jukumu muhimu (Tinbergen et al., 1942; Crane, 1955; Magnus, 1977; Obara na Hidaka, 1968; Obara, 1970; Wago na Unno, 1976; Rutowski, 1978; Silberg, 1978; na Taylor, 1978). Hata hivyo, vichocheo vya kemosensory vinahitajika ili tabia ya kuchangamana iendelee zaidi ya hatua hii ya awali. (Tinbergen et al., 1942; Magnus, 1958; Brower et al., 1965; Rutowski, 1977b; Wago, 1978a, b). Imethibitishwa kwamba katika spishi nyingi za vipepeo, utambuzi wa mwisho wa wanawake na wanaume kwa kawaida ni wa kemosensory. Ndege aina ya Pieris rapae crucivora wanazunguka mashamba ya kabichi wakitafuta ndege wa kike. Rangi ya mabawa ya wanawake huchangia sana kuchochea wanaume wafanye ngono. Katika aina hii ya rangi ya UV iko kwenye mabawa ya wanawake, lakini si wanaume, yaani. Wanaume na wanawake ni ya kushangaza kijinsia dimorphic katika UV spectrum (Obara, 1970). Ugunduzi wa kwanza na wa mwisho wa mwenzi na P. rapae crucivora ya kiume unategemea kabisa ishara za kuona, rangi ya mrengo wa kike ikiwa ni pamoja na rangi ya UV kama sehemu muhimu. Wanaume wanaweza kutofautisha wanawake kutoka kwa wanaume, hata wakati hawa wamefungwa katika filamu ya uwazi isiyoweza kupenya (Saran wrap), na hivyo kuzuia vichocheo vya chemosensory (Obara, haijachapishwa). Uchunguzi wa awali wa vifaa vya makumbusho ulionyesha kwamba dimorphism ya kijinsia kwa rangi ya mrengo wa UV ya P. rapae crucivora haipo katika aina ndogo ya Uingereza ya kipepeo cha kabichi, Pieris rapae. Katika spishi hii ndogo, wanawake hawana rangi ya UV. Maelezo hayo yanazusha maswali fulani yenye kupendeza. Kwa mfano, wanaume wa Uingereza hutambuaje wenzi wao? Je, uwepo au kutokuwepo kwa rangi ya mabawa ya UV ya kike ni hali ya mababu? Katika utafiti huu, tulilenga kwanza kuamua kama uchunguzi wa awali kuhusiana na rangi ya UV ya wanawake, zilizotajwa hapo juu, ni kweli. Kwa upande mwingine, uchunguzi wa tabia ya kuoa ya spishi ndogo za Uingereza ulionyesha jinsi wanaume wa Uingereza wanavyoweza kutambua wenzi wao. Vipande vya nyuki vilivyotumiwa katika uchunguzi wa rangi ya UV vilitokana na mabuu ya Uingereza (eneo la Cambridge nchini Uingereza) yaliyofufuliwa hadi kuwa watu wazima katika maabara. Vipepeo waliozaliwa hivi karibuni waliuawa kwa kufungia na kuweka kwa uangalifu ili kupunguza uharibifu wa mabawa. Vipepeo wa kiume kwa ajili ya uchunguzi wa tabia walikuwa inayotokana na hisa Cambridge, au walikuwa freshly zilizokusanywa karibu Cambridge. Ili kulinganisha rangi ya mabawa ya ndege, wanawake na wanaume walichunguzwa kwa njia mbili: uchunguzi wa picha na uchambuzi wa spectrometry ya kutafakari. Kwa ajili ya uchunguzi wa rangi ya kuonekana ya mabawa, sampuli nne za kiume na rangi ya mabawa ya kuonekana na sampuli nne za kike na rangi ya mabawa ya kuonekana zilipigwa picha chini ya mwanga wa jua wa kawaida, kwa kutumia filamu ya rangi ya rangi (Fuji Super G Ace 400). Kwa ajili ya uchunguzi wa rangi ya ultraviolet, sampuli hizo zilipigwa picha kwa kutumia filamu ya monochromatic (Fujifilm Neoprene SS) kupitia kichujio cha UV (Hoyama UV36) kulingana na taratibu zilizoelezwa na Obara na Hidaka (1968). Filter hii ni uwazi kwa mwanga na urefu wa wimbi kutoka 300 nm hadi 400 nm na kilele cha uwazi katika 360 nm. Kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano. Kwa ajili ya tathmini hii, sehemu ya 5mm x 5mm kutoka katikati, distal sehemu ya mabawa ya nyuma ilikuwa makini excised (tazama duru katika Fig. "Kufikia sasa, ""spectrophotometer"" ni kifaa cha kupima mwangaza wa urefu wa mawimbi ya 4nm, ambayo huonekana kwenye sampuli." Kwa mfano, sehemu ya nyuma ya mrengo wa nyuma ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege ya ndege. Uchunguzi wa kwanza ulikusudiwa kutoa maoni ya jumla juu ya tabia ya kujamiiana ya spishi ndogo za Uingereza. Uangalifu ulilazimishwa kwa kuamua ni jinsia gani inayoanzisha tabia ya kuoa, na kwa tabia za kina za wanaume na wanawake wakati wa uchumba. Takwimu kutoka kwa uchunguzi huu zililinganishwa na maelezo sawa, yaliyochapishwa hapo awali ya tabia ya uchumba na uchumba wa aina ndogo za Kijapani (Obara, 1970). Kwa sababu ya uchunguzi wa kwanza wa tabia, tulichunguza ni sehemu zipi za mwili wa mwanamke zinazovutia wanaume na kusababisha tabia ya kuoa ya kiume. Mabawa ya wanawake yalipunguzwa mbali na mwili, na mabawa ya mbele na ya nyuma ya kushoto na kulia yalifungwa pamoja, katika msimamo uliochukuliwa na kipepeo anayepumzika (mfano wa mrengo). Kichwa, kifua na tumbo kutoka ambayo mabawa yalikuwa kuondolewa, walikuwa kuhifadhiwa kama kitengo integral (naked dummy). Mfano wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege wa ndege. Uchunguzi ulifanywa kuhusu ikiwa wanaume walivutiwa na dummy mwenye mabawa au dummy aliye uchi, au zote mbili. Ili kuamua kama mwanaume angeweza kutofautisha kati ya mwanamke na mwanaume na kumtambua kama mwenzi, wanasesere wa kamba wa kike na wa kiume waliwasilishwa pamoja kwa wanaume wanaotafuta. Katika jaribio hili, dummies 6 za kiume na rangi ya mabawa ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi. "Mwanamke na mwanaume walijengwa kwa urefu wa sentimita 15 kutoka kwa kila mmoja, wakiwa wamepumzika na mabawa yao yamefungwa, juu ya majani ya kabichi (yaani ""specimens iliyofunuliwa.""" Vipimo vya manicure ya kiume na ya kike vilibadilishwa kila baada ya dakika 15 ili kuondoa athari za uwezekano wa nafasi ya ndani. Katika jaribio tofauti iliyoundwa kuchunguza kama chemosensory stimuli kuwa na jukumu katika utambuzi wa wanawake na wanaume wa Uingereza, single wanawake na wanaume mabawa dummies walikuwa kuwekwa 15cm mbali juu ya 20cm x 25cm uwazi vinyl chloride bodi, framed nyembamba na mbao. Kisha, viumbe hao walifungwa kwa filamu ya kufunika ya jikoni (Saran wrap: Asahi-Chemical Industry Co., Ltd.) (iliyoitwa sampuli zilizofungwa). Mfumo wa mbao ulifungwa ili kuzuia wrap ya filamu kutoka kwa kupotoshwa na sampuli, ili kusababisha kutafakari kuenea. "Kulingana na utafiti huo, ""bodi ya rangi nyeusi isiyo na rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi ya rangi.""" Bodi ya uwazi na dummies mrengo uliofungwa iliwekwa wima kati ya mimea ya kabichi. Majaribio hayo yalifanywa katika ngome ya 3m x 3m x 2m iliyojengwa nje ya kituo cha uwanja wa Idara ya Genetics ya Chuo Kikuu cha Cambridge huko Cambridge, Uingereza. Katika majaribio hayo idadi ya wanaume waliokaribia, kuwasiliana, na kujaribu kuunganisha, dummies ya aina mbalimbali zilirekodiwa. 1. Uwe na mtazamo wa kweli Mnyama wa kiume na wa kike wa Brisish wanaweza kutofautishwa kwa urahisi kutokana na alama zilizo kwenye sehemu ya nyuma ya mabawa ya mbele, kwa kuwa huku wanawake wakiwa na madoa mawili meusi kwenye sehemu hiyo, wanaume wana moja tu. 1A) Wanaume wana madoa mawili meusi kwenye sehemu ya mbele ya mabawa yao, na sehemu ya nyuma ya mabawa hayo, ambayo inalingana na madoa ya pili ya wanawake, inaweza kuonekana kwa macho ya kiume kwa uchunguzi wa karibu. Hii ni kinyume na aina ndogo ya Kijapani, ambayo jinsia zote mbili zina madoa mawili meusi (Fig. 1A) Kwa kuongezea, wanawake wa Uingereza kwa ujumla huwa na rangi nyeusi zaidi kwenye ukingo wa mbele na wa mbele wa mabawa ya mbele kuliko wanaume. Kwa upande mwingine, sehemu za ndani za mabawa ya wanaume na wanawake zilitofautiana kidogo tu kwa rangi, huku mabawa ya wanawake yakiwa na rangi ya manjano zaidi. Hii ni kweli kwa pande zote mbili za nyuma na mbele za mabawa ya mbele, ambazo zinaonekana na wanawake wakati wa kupumzika, na hivyo zina uwezo wa kuonekana na kutumika kama ishara za hisia na wanaume wanaotafuta washirika wa kuoa, ikiwa wanaume hutumia ishara za kuona kutambua wanawake. Kwa kuzingatia dimorphism ndogo ya kijinsia ya watu wa aina ya Uingereza katika wigo unaoonekana na binadamu, utambuzi wa macho wa jinsia, na wanaume, kwa msingi wa urefu wa mawimbi yanayoonekana na binadamu, unaonekana kuwa ngumu. Mkataa huohuo unaonekana kuwa unatumika kwa rangi ya UV. Mabawa ya wanawake wa Uingereza huonyesha mwangaza mdogo wa UV (Sura. 1b) ingawa uchunguzi wa karibu wa picha ya UV unaonyesha mwangaza mdogo sana wa UV na uso wa nyuma wa mrengo wa mbele. Vipimo vya spectrophotometric ni sawa na matokeo ya picha. Kwa upande wa nyuma, mabawa ya nyuma ya kiume na ya kike yana tofauti ndogo ya kutafakari katika safu ya urefu wa mawimbi ya 440 nm na 530 nm, na kutafakari kutoka kwa kiume ni nguvu zaidi, kama inavyoonyeshwa na picha katika picha. 1b (Fig. 2a) Ventral nyuso za nyuma ya mabawa ya jinsia mbili na sifa sawa sana reflection (Fig. 2 (b) Kwa muhtasari, spishi ndogo za Uingereza zinaonekana kuonyesha dimorphism ndogo tu ya kijinsia inayoonekana katika urefu wa mawimbi yanayoonekana na binadamu, lakini ni nadra katika urefu wa mawimbi ya UV. 2. Uwezekano wa kupata Tabia ya kujamiiana Tabia ya kujamiiana ya spishi ndogo za Uingereza ni sawa na ile ya spishi ndogo za Kijapani. Wanaume huanza tabia ya kujamiiana, wakiruka wakitafuta wanawake na kukaribia na kujaribu kuungana na wale wanaowapata. Wanawake wa bikira huitikia tabia ya kuoa ya kiume kwa kuchukua nafasi ya kupumzika na mabawa yamefungwa, wakati wanawake waliofanana hapo awali hukataa wanaume kwa kuchukua nafasi ya kukataa kuoa na mabawa yamefunguliwa na kushuka, na tumbo limeinuka. Wanawake huendelea na msimamo huu kwa muda mrefu kama ndege wa kiume wanabaki karibu (Obara, 1964). "Jibu la flutter", lililoelezwa hapo awali kwa spishi ndogo za Kijapani (Obara na Hidaka, 1964), lilionekana pia katika spishi ndogo za Uingereza. Jibu hilo huhusisha kuruka kwa haraka kwa mabawa ya wanaume wanaopumzika kwa kujibu mbinu za wanaume wanaoruka. Katika jumla ya 36 ya mbinu za wanawake kutafuta wanaume kwa wanaume kupumzika, wote walikuwa kufuatiwa na majibu flutter na mwisho. Wanaume wote wa kike wanaotafuta kisha walionekana kuruka mbali kufuatia mwingiliano mfupi wa tabia na wanaume wanaopumzika, bila jaribio la ngono. Katika majaribio ya dummies uchi na dummies mrengo, 37 wanaume walikuwa kuchunguzwa kukaribia dummies mrengo na 31 wao kuwasiliana na dummies mrengo. 22 kati ya hizo za mwisho zilionyesha majaribio ya kufanya ngono na wanasesere wa mabawa. Kwa upande mwingine, wanaume hawakutambuliwa wakikaribia wanasesere hao waliokuwa uchi. Katika jaribio la kutumia sampuli iliyofunuliwa, wanaume 42 walikaribia sampuli ya kike, wakati wanaume 28 walikaribia sampuli ya kiume. 3) Kati ya wanaume 42 waliomkaribia mwanamke huyo, wanaume 39 (93%) waliwasiliana naye. Kwa mfano, kati ya wanaume 28 (89%) waliomkaribia mnyama huyo, 25 walifanya hivyo. Tofauti kati ya jinsia mbili ni muhimu tu kwa njia ya kukaribia na kuwasiliana na p-thamani ya 0.12 na 0.10 (mtihani wa binomial wa mkia mbili). Wanaume 22 kati ya 42 (52%) waliojaribu kuwasiliana na wanawake waliendelea kujaribu kuwasiliana na wanawake, wakati wanaume 12 kati ya 28 (43%) waliojaribu kuwasiliana na wanaume walijaribu kuwasiliana na wanaume. Hapa tena tofauti katika uwiano kwa ajili ya jinsia mbili ni tu marginally muhimu (Two-mwisho binominal mtihani, p = 0.12). Baada ya kukaribia, ni uwezekano mkubwa kwa kiume kujaribu kuunganisha na mwanamke wing dummy kuliko na kiume wing dummy (mtihani wa p = 0.25). Tabia kama hizo zilionekana kwa sampuli iliyofungwa (Fig. 4) Wanaume 38 walimkaribia mwanamke na wanaume 26 walimkaribia mwanamume. Wanaume wengi waliendelea kuwasiliana na sampuli waliozungumza nao (kwa wanawake, 37 (97%); kwa wanaume, 25 (96%)). Tofauti kati ya jinsia mbili si muhimu na p-thamani ni 0.17 kwa ajili ya kukaribia na 0.16 kwa ajili ya kuwasiliana (tatu binomial). Wanaume 5 tu (13%) waliojaribu kuwasiliana na mwanamke walijaribu kufanya ngono naye, na hakuna hata mmoja kati ya wanaume waliojaribu kuwasiliana na mwanamume. Inaonekana kwamba baadhi ya wanaume walijaribu kushuka kwenye kifuniko cha filamu kilichokuwa kimefunika kiolezo hicho. Hata hivyo, hilo lilionekana kuwa jambo gumu kwa kuwa filamu hiyo laini, inapowekwa wima, haishikili sana makucha ya kifuani. 1. Uwe na mtazamo wa kweli Matokeo ya majaribio na mrengo wa kike na dummies uchi ilifunua kwamba katika British subspecies, kama katika Japanese subspecies, ni mrengo wa kike, si mwili wa kike yenyewe, kwamba huvutia wanaume na elicits tabia yao ya kuoa. Kwa kuongezea, matokeo ya majaribio ya kuigiza ya mabawa yaliyotolewa na kufungwa yalionyesha kwamba ishara za kuona, badala ya kugusa au chemosensory, kutoka kwa mabawa ya wanawake huchochea tabia ya kuunganisha ya kiume; yaani. kutambua awali mate ni mediated visually (Fig. 3 na 4). Matokeo ya majaribio na dummies mrengo alionyesha kwamba uso ventral ya mabawa ya wanawake ni ya kutosha katika kuchochea tabia ya kuoa kutoka kwa wanaume. Kama ilivyo katika spishi ndogo za Kijapani, mwanamke wa Uingereza hufunga mabawa yake katika hali ya kupumzika anapopatikana na mwanamume wa spishi hiyo. Katika hali hii, sehemu za mabawa ya mwanamke ni pembe ya mbele ya tumbo pamoja na kilele cha mabawa ya mbele (FWVA) na uso wote wa tumbo la mabawa ya nyuma (HWV). Kwa hiyo, hw-WV hufanyiza sehemu kubwa ya sehemu ya mabawa ambayo wanaume huona na labda hutimiza fungu muhimu katika kutambua mwenzi wao wa kwanza. Utafiti huu ulifunua dimorphism ndogo ya kijinsia kwa rangi ya mrengo katika FW-VA au HW-WV, katika spectra inayoonekana ya binadamu, lakini kidogo katika spectra ya UV. 1) Kuonekana sawa kati ya jinsia ilikuwa dhahiri wote wakati sampuli walikuwa viewed na jicho, na wakati wao walikuwa chini ya uchambuzi spectrophotometric (Fig. 2) Tofauti ndogo sana katika nyuso za ventral za mrengo wa kike ikilinganishwa na mrengo wa kiume katika UV (Fig. Hii ni tofauti na tofauti zilizopatikana katika aina za Japani, ambapo wanawake, lakini si wanaume, ventral wing surfaces huonyesha UV kwa nguvu. (Obara na Hidaka, 1968; Obara, 1970). Tofauti katika rangi ya mabawa ya jinsia kati ya spishi hizo mbili hueleza kwa nini wanaume wa spishi hizo mbili wana tabia tofauti za kujamiiana. Kwa wanaume wa Uingereza kutumia ishara za kuona kutambua wenzao, ubaguzi wa kijinsia lazima uwe mgumu kwa sababu ya dimorphism ya mrengo wa macho inayoonekana kidogo tu na idadi ya wanaume itatarajiwa kufanya njia za kukutana na wanaume wa aina moja. Hii ilionyeshwa kuwa ni kesi katika uchunguzi huu. Kwa upande mwingine, katika aina ndogo za Kijapani zenye dimorphism ya kijinsia tofauti katika rangi ya mrengo wa UV, hakuna wanaume (mmoja kati ya wanaume 107) waliokaribia dummies za mrengo wa kiume wakati dummies za kiume na za kike zikiwa zimejengwa 20 cm mbali (Obara, 1970). Basi, wanaume wa Uingereza hutambuaje mwenzi wao wa mwisho? Katika visa ambapo kiume alikaribia conspecific kupumzika wanaume, hakuna majaribio ya copulatory ilitokea kwa sababu kupumzika mwanaume alionyesha majibu flutter. Hii ilizuia kiume anayekaribia kutoka kwa kutua kando ya kiume anayepumzika, ambayo ni sharti la kwanza kwa kiume kujaribu ngono. Hii inaonyesha kwamba majibu ya kupumzika ya wanaume hucheza jukumu muhimu katika utambuzi wa mwenzi wakati wanaume wanaotafuta wanawake wanakaribia. majibu flutter kazi kama "mechanical kutengwa utaratibu" dhidi ya kuoa mwingiliano kati ya wanaume. 2. Uwezekano wa kupata Ohtani na Yamamoto (1980) walipendekeza kwamba majibu ya flutter na kiume katika copula kazi ya kuondoa wanaume ambao kukaribia na kujaribu copulate na mwanamke katika copula. Hata hivyo, hawakutoa ufafanuzi wowote kuhusu jinsi wanaume wasio katika ndoa wanavyopiga makofi. Obara na Hidaka (1964) waliripoti kwamba majibu ya flutter hutumikia kusudi la wazi kwa wanaume ambao huchochea au kwa wanaume ambao hufanya. Kwa hiyo, itikio la kupiga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga-piga. Mazungumzo haya huruhusu uvumi juu ya ambayo ya spishi mbili ni evolutionarily babu kwa mwingine. Ni uwezekano mdogo kwamba majibu ya flutter yamebadilika katika aina ndogo za Kijapani kwa kujitegemea, kwa sababu ya gharama kwa wanaume wa kutafuta wanawake na wanaume wa kupumzika, bila faida ya wazi inayotokana. Kwa upande mwingine, kwa ajili ya British subspecies na kidogo ya kijinsia dimorphism, majibu flutter inaweza kuwa muhimu sana kwa ajili ya kutambua mate na kiume. Huenda pia ilikuwa na manufaa kwa wanaume kwa kuongeza ufanisi wa muda na nishati ya kutafuta mwenzi wao. Hata hivyo, mara tu ishara ya rangi ya UV ilipopatikana kwa ajili ya kutambua mwenzi katika spishi ndogo za Kijapani, majibu ya kupapasa-papasa yangekuwa ya ziada katika kutambua mwenzi. Kwa kuzingatia mjadala huu, hatukufikiria sababu za tabia-ekolojia ambazo zingeweza kuendeleza mageuzi ya majibu ya flutter katika spishi ndogo za Kijapani, wakati majibu ya flutter yangepaswa kupendekezwa na uteuzi wa asili katika spishi ndogo za Uingereza. Kwa hiyo, huenda ikawa kwamba majibu ya flutter labda yalibadilika kwanza katika spishi ndogo za Uingereza kama utambuzi wa mwenzi au "mfumo wa kutengwa kwa mitambo" kati ya wanaume na kwamba imebaki katika spishi ndogo za Kijapani kama tabia ya msingi bila kazi ya wazi. Kwa hivyo, hii inaweza kuwa ushahidi kwa nadharia kwamba aina ya Uingereza, P. r. rapae, ni babu wa aina ya Kijapani, P. r. crucivora, na kwa hivyo kwamba kutokuwepo kwa rangi ya mrengo wa UV ya kike ni hali ya baba. Tunamshukuru Daktari Y. Katoh kwa tathmini ya mwangaza wa mabawa ya kipepeo. Utafiti huu ulifadhiliwa na Grant-in-Aid kwa Utafiti wa Sayansi kutoka Wizara ya Elimu, Michezo na Utamaduni ya Japani (09041151).