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1.
Effect of mating on survival at low temperature in females of the Japanese common grass yellow,Eurema mandarina
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1. In some insects that overwinter as adults, mating occurs both before and after overwintering. Two hypotheses have been proposed to explain the adaptive significance of pre‐overwintering copulation of females. One is the bet‐hedging hypothesis, which explains pre‐overwintering copulation as a preparation for less chance of mating in the following spring. The other is the nuptial gift hypothesis, which states that secretions derived from males increase overwintering success of females. 2. In Eurema mandarina, both diapause autumn‐ and non‐diapause summer‐form male adults emerge with autumn‐form female adults in the last generation in a year. Most autumn‐form females mate with summer‐form males before winter, and re‐mate with autumn‐form males in the following spring. Because autumn‐form females have sufficient chances for mating after overwintering, the nuptial gift hypothesis has been regarded as the more probable hypothesis. 3. To test the nuptial gift hypothesis, the survival period was compared under short‐day conditions at 10 °C between mated and unmated females that had been reared on sucrose solution at 25 °C for 15–21 days. The mated females had significantly greater longevity than the unmated females, supporting the nuptial gift hypothesis. Body size also affected the survival period. 4. The results suggest that the nuptial gift is an important factor for the evolution of pre‐overwintering copulation in species in which females mate both before and after overwintering. 相似文献
2.
Solana Abraham Andrea Moyano Viviana Díaz M. Gabriela Murúa Juan Rull 《Insect Science》2023,30(4):1183-1190
Promiscuous mating systems provide the opportunity for females to bias fertilization toward particular males. However, distinguishing between male sperm competition and active female sperm choice is difficult for species with internal fertilization. Nevertheless, species that store and use sperm of different males in different storing structures and species where females are able to expel all or part of the ejaculates after copulation may be able to bias fertilization. We report a series of experiments aimed at providing evidence of female sperm choice in Euxesta eluta (Hendel), a species of ulidiid fly that expels and consumes ejaculates after copulation. We found no evidence of greater reproductive success for females mated singly, multiply with the same male, or mated multiply with different males. Female E. eluta possesses two spherical spermathecae and a bursa copulatrix for sperm storage, with a ventral receptacle. There was no significant difference in storing more sperm in spermathecae 24 h after copulation than immediately after copulation. Females mated with protein-fed males had greater reproductive success than similar females mated to protein-deprived males. Protein-fed females prevented to consume the ejaculate, retained more sperm when mated to protein-fed males than when mated to protein-deprived males. Our results suggest that female E. eluta can exert control of sperm retention of higher quality males through ejaculate ejection. 相似文献
3.
Jesus Wong‐Muñoz Chris N. Anderson Roberto Munguía‐Steyer Alex Córdoba‐Aguilar 《Ethology : formerly Zeitschrift fur Tierpsychologie》2013,119(5):407-416
Copulation duration is often highly variable within and among species. Here, we explore the roles of body size, male morph, morph frequency, and alternative reproductive tactics to explain copulation duration in the damselfly Paraphlebia zoe. P. zoe has two male morphs (pigmented or hyaline wings) which differ in reproductive tactics (territorial or non‐territorial behaviors). We also analyze the effects of season as the frequencies of both morphs tend to vary along the reproductive season. In the first non‐experimental year, we found that the relationship between body size and copulation duration depended on the time of year. Early in the season, body size positively correlated with copulation duration, while late in the year, body size negatively correlated with copulation duration. In the second experimental year (when we reversed the frequency of male morphs in the middle of the season: making pigmented males less frequent than hyaline males), size influenced copulation duration as well as morph – body size positively correlated with copulation duration, and hyaline males mated for longer than pigmented males. Contrary to our prediction, changes to the relative abundances of morphs did not influence copulation duration. Hyaline males may be under selection for longer copulation durations to compensate for their reduced access to females, as long copulations potentially lead to more rival sperm to be removed from the female sperm storage organs and/or increased mate guarding. We do not discard, however, other explanations that drive variation in copulation duration such as cryptic female choice and/or predation. 相似文献
4.
Tatsuro Konagaya Tomoyuki Yokoi Mamoru Watanabe Hideharu Numata 《Entomological Science》2018,21(2):216-224
The evolution of reproductive diapause is controversial in males as compared to females that must overwinter to leave offspring, because late‐autumn males can obtain offspring by pre‐overwintering copulation. The Japanese common grass yellow Eurema mandarina is suitable to examine the evolution of male reproductive diapause, because direct comparisons are possible between males that do and do not exhibit reproductive diapause. Approximately one‐half of males are insensitive to diapause‐inducing conditions, and emerge as non‐diapause summer‐form. Most autumn‐form females mate with summer‐form males in late autumn. Females that have overwintered re‐mate with autumn‐form males before the onset of oviposition. Because last‐male‐precedence is general in sperm competition in Lepidoptera, it is unclear why half of males emerge as summer‐form in late autumn. A potential adaptive benefit for emerging as summer‐form is increased sperm overwintering success, if autumn‐form females have a higher overwintering success than autumn‐form males. In the present study, overwintering success was estimated for both sexes of autumn‐form adults by rearing under seminatural conditions and a mark–release–recapture technique. Both approaches estimated an overwintering success of approximately 5% for both sexes. The absence of difference in overwintering success between the sexes suggests that pre‐overwintering copulation does not increase sperm overwintering success. However, a considerably low overwintering success may explain, at least partly, the presence of summer‐form males in late autumn. The degree of overwintering success might be more important than the sexual differences of overwintering success in the evolution of male reproductive diapause. 相似文献
5.
Seasonal variations in feeding range and flock structure of the Rook Corvus frugilegus in eastern Ireland 总被引:1,自引:1,他引:0
The feeding range and flock structure of Rooks showed temporal variations caused mainly by the dispersion of food and reproductive behaviour.
Feeding range was restricted in spring, autumn and early winter when food availability was high and Rooks were reproductively active. A large feeding range occurred in late summer and late winter, when food availability was either generally low or locally distributed and when Rooks were reproductively inactive. The occurrence of flocks common to several rookeries mirrored variations in feeding range; mixed rookery flocks were more common in late summer and late winter. Similarly, the size of the rookery (as measured by the number of nests) was related to feeding range only when Rooks were reproductively inactive and at such times larger rookeries had greater feeding ranges.
Flock structure showed similar seasonal variations; small widely spaced flocks predominated in summer, autumn, early winter and spring, whereas large dense flocks occurred in late winter. Diurnal variations in flock structure occurred within any one season. Both seasonal and diurnal variations in flock structure may be determined by the dispersion of the prey and the feeding strategy used to obtain it, reproductive behaviour and the risk of predation. 相似文献
Feeding range was restricted in spring, autumn and early winter when food availability was high and Rooks were reproductively active. A large feeding range occurred in late summer and late winter, when food availability was either generally low or locally distributed and when Rooks were reproductively inactive. The occurrence of flocks common to several rookeries mirrored variations in feeding range; mixed rookery flocks were more common in late summer and late winter. Similarly, the size of the rookery (as measured by the number of nests) was related to feeding range only when Rooks were reproductively inactive and at such times larger rookeries had greater feeding ranges.
Flock structure showed similar seasonal variations; small widely spaced flocks predominated in summer, autumn, early winter and spring, whereas large dense flocks occurred in late winter. Diurnal variations in flock structure occurred within any one season. Both seasonal and diurnal variations in flock structure may be determined by the dispersion of the prey and the feeding strategy used to obtain it, reproductive behaviour and the risk of predation. 相似文献
6.
Aurore D. C. Panel Ido Pen Bart A. Pannebakker Herman H. M. Helsen Bregje Wertheim 《Ecology and evolution》2020,10(17):9085-9099
Seasonal polyphenism in Drosophila suzukii manifests itself in two discrete adult morphotypes, the “winter morph” (WM) and the “summer morph” (SM). These morphotypes are known to differ in thermal stress tolerance, and they co‐occur during parts of the year. In this study, we aimed to estimate morph‐specific survival and fecundity in laboratory settings simulating field conditions. We specifically analyzed how WM and SM D. suzukii differed in mortality and reproduction during and after a period of cold exposure resembling winter and spring conditions in temperate climates. The median lifespan of D. suzukii varied around 5 months for the WM flies and around 7 months for the SM flies. WM flies showed higher survival during the cold‐exposure period compared with SM flies, and especially SM males suffered high mortality under these conditions. In contrast, SM flies had lower mortality rates than WM flies under spring‐like conditions. Intriguingly, reproductive status (virgin or mated) did not impact the fly survival, either during the cold exposure or during spring‐like conditions. Even though the reproductive potential of WM flies was greatly reduced compared with SM flies, both WM and SM females that had mated before the cold exposure were able to continuously produce viable offspring for 5 months under spring‐like conditions. Finally, the fertility of the overwintered WM males was almost zero, while the surviving SM males did not suffer reduced fertility. Combined with other studies on D. suzukii monitoring and overwintering behavior, these results suggest that overwintered flies of both morphotypes could live long enough to infest the first commercial crops of the season. The high mortality of SM males and the low fertility of WM males after prolonged cold exposure also highlight the necessity for females to store sperm over winter to be able to start reproducing early in the following spring. 相似文献
7.
JØRGEN BUNDGAARD J. S. F. BARKER 《Biological journal of the Linnean Society. Linnean Society of London》2000,71(1):145-164
The mating system of Drosophila buzzatii is characterized by short copulation duration, frequent remating in both males and females, and male ejaculate partitioning. Additional features of the system are strong sperm displacement and a high frequency of sterile matings. Remating frequencies and the effects of remating on various mating parameters were studied. In order to characterize variation, five isofemale lines from geographically distant localities in Australia (three localities), Brazil and the Canary Islands were used. Mating parameters studied were: premating time, copulation duration, interval between successive matings, and progeny number as a measure of sperm transfer. Variation for sperm displacement was studied in crosses between laboratory stocks and a number of isofemale lines from Australia. There were significant between‐line differences in female remating frequencies, premating time, copulation duration, interval between successive matings, and progeny numbers, indicating genetic variation for these traits. Females from the five lines mated on average 1.6 to 3.1 times in 4 h, with a maximum of eight matings for one female. The males were given a maximum of ten virgin females in sequence and more than one‐third of the males mated all ten females in the 2 h observation period. Copulation duration decreased and interval between matings increased with copulation number in multiply mated males. Mean copulation duration was c. 2 min. Sperm transfer, measured as the average number of progeny from a single mating, was low (c. 25) and multiply mated females gave more progeny than single mated females, although with much lower progeny numbers than observed in wild‐caught non‐virgin females. A surprisingly high proportion of observed matings gave no progeny, i.e. they were sterile matings. Sperm displacement was strong in most crosses and remained strong in multiply mated females. The results are discussed in relation to the evolution of mating patterns in Drosophila. 相似文献
8.
Melvin M. Bonilla David W. Zeh Angela M. White Jeanne A. Zeh 《Ethology : formerly Zeitschrift fur Tierpsychologie》2011,117(8):740-748
When both sexes mate with multiple partners, theory predicts that males should adjust their investment in ejaculates in response to the risk and/or intensity of sperm competition. Here, we demonstrate that, in the harlequin beetle riding pseudoscorpion, Cordylochernes scorpioides, males use cues deposited on females by previous males to distinguish between virgin, once‐mated, and multiply‐mated females and adjust sperm allocation accordingly. Sperm number declined in direct proportion to the number of previous males, with virgin females receiving nearly three times more sperm than females exposed to three previous males. Given the lack of first‐male sperm precedence in C. scorpioides, this pattern is not consistent with current sperm competition models and appears best explained by a significant risk of wasting ejaculates on deceitful, mated females. In C. scorpioides, males transfer sperm indirectly to females via a stalked spermatophore deposited on the substrate. Mated females often feign sexual receptivity and cooperate throughout mating, only to reject the sperm packet produced by the male. While indirect sperm transfer facilitates a high level of female deceit and control, females of many species are able to influence the number and fate of sperm transferred during copulation and are likely to conceal their sexual unreceptivity to minimize male retaliation. If males cannot accurately assess female receptivity, increased risk of sperm rejection by mated females could outweigh the risk of sperm competition and favor greater sperm allocation to virgin females. 相似文献
9.
The population dynamics of the Tatra vole Microtus tatricus (Kratochvíl, 1952) (Arvicolinae, Rodentia) was monitored as part of a long-term study (1996–2008) of demography of small
mammals conducted in Western Tatra Mountains—Roháče, Slovakia. We observed low abundance and population densities and a balanced
sex ratio but slightly more frequent captures of females. Reproductively active Tatra voles were significantly larger and
heavier than reproductively inactive voles. Reproduction in both sexes tended to begin in early spring, and females moved
less than males. Individuals start to reproduce after overwintering. Spatial characteristics differed between sexes, with
home range size, distance travelled, and observed range length being non-significantly greater in males than in females, suggesting
greater male mobility. Females remained longer on the site than did males. Mature individuals of both sexes exhibited territoriality
during the peak of breeding season in spring. Home range overlap occurred more often within females, and mainly in summer
and autumn. 相似文献
10.
Males of the sorghum plant bug, Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae), transfer a spermatophore to females during copulation. After a 1‐day interval between the first and second copulation, males transferred both sperm and a spermatophore to females during the second copulation. However, when male mating interval was <1 h, they transferred sperm but no spermatophores to females during the second copulation. Therefore, the male mating interval probably produces two types of mated females, those with and those without a spermatophore. Mated females of S. rubrovittatus do not remate for at least 3 days after mating, even when courted, and lay more eggs than virgin females at the beginning of the oviposition period. The effects of spermatophores on female sexual receptivity and fecundity were examined using mated females with or without a spermatophore. Only one of the 40 (2.5%) mated females with a spermatophore remated, whereas 10 of the 26 (38.5%) without a spermatophore remated. Furthermore, mated females with a spermatophore laid more eggs than those without a spermatophore. These results suggest that spermatophores participate in reducing female sexual receptivity and enhancing female fecundity in S. rubrovittatus. 相似文献
11.
Naoki Matsuda Takashi Kanbe Jun Endo Shin-Ichi Akimoto Hideharu Numata 《Physiological Entomology》2020,45(2-3):103-109
Photoperiod is the major seasonal cue for phenotypic plasticity in the regulation of development and reproduction. Aphids have a peculiar mechanism in which sensitivity to the photoperiod is lost for a few months through successive generations after hatching from diapause eggs, and therefore, the mechanism responsible for the photorefractory period is termed “a seasonal timer”. However, whether the seasonal timer has adaptive significance has never been investigated. Here, we show that the photorefractory generation avoids an unseasonal sexual morph production under short days in spring in the pea aphid, Acyrthosiphon pisum (Harris). When the seasonal timer operated, the overwintered generation, stem mothers, produced only parthenogenetic progenies under natural photoperiods and temperatures in both warm and cold springs. After repeated parthenogenesis following diapause, however, aphids with an expired seasonal timer produced sexual females and males typical of autumn under natural photoperiods and temperatures in a warm spring. These sexual morphs are thought to have a reproductive disadvantage compared to parthenogenetic morphs in the following summer. We thus conclude that the seasonal timer is adaptive for avoiding sexual morph production in spring. The present study shows, for the first time, that a photorefractory period lasting over generations is a trait of ecological importance. 相似文献
12.
The Indian pygmy field mouse, Mus terricolor, is a tiny, yet economically and ecologically important crop pest found throughout South-East Asia. There are no systematic reports exploring its reproductive physiology. We report the presence of distinct periods of annual reproductive activity and quiescence in M. terricolor. Body weight in males and females, relative weights of testis, epididymis and seminal vesicle in males, ovarian and uterine weight in females, gonadal histomorphic changes, testicular and ovarian cholesterol, sialic acid in epididymis, fructose in seminal vesicle, uterine protein content, melatonin in males and females, testosterone in males, estradiol, and progesterone in females were studied over a period of three years in both wild-caught and lab-acclimated mice. The number of Graafian follicles and corpora lutea, and plasma estradiol and progesterone, along with relative weights of ovary and uterus in females exhibited a peak in the months of October–January, compared to June. Based on histomorphic and hormonal status, the major reproductively active season is the winter (short-day breeding). There is a brief period of sub-maximal reproductive activity in April. M. terricolor is reproductively inactive in the summer, monsoons, and autumn. The results establish M. terricolor as a seasonal breeder in the field, with interesting implications for pest management. 相似文献
13.
Maria J. Albo Trine Bilde Gabriele Uhl 《Proceedings. Biological sciences / The Royal Society》2013,280(1772)
Polyandrous females are expected to discriminate among males through postcopulatory cryptic mate choice. Yet, there is surprisingly little unequivocal evidence for female-mediated cryptic sperm choice. In species in which nuptial gifts facilitate mating, females may gain indirect benefits through preferential storage of sperm from gift-giving males if the gift signals male quality. We tested this hypothesis in the spider Pisaura mirabilis by quantifying the number of sperm stored in response to copulation with males with or without a nuptial gift, while experimentally controlling copulation duration. We further assessed the effect of gift presence and copulation duration on egg-hatching success in matings with uninterrupted copulations with gift-giving males. We show that females mated to gift-giving males stored more sperm and experienced 17% higher egg-hatching success, compared with those mated to no-gift males, despite matched copulation durations. Uninterrupted copulations resulted in both increased sperm storage and egg-hatching success. Our study confirms the prediction that the nuptial gift as a male signal is under positive sexual selection by females through cryptic sperm storage. In addition, the gift facilitates longer copulations and increased sperm transfer providing two different types of advantage to gift-giving in males. 相似文献
14.
We examined the influence of female mating history on copulation behavior and sperm release in the haplogyne spider Tetragnatha versicolor. Despite significant behavioral differences during mating, males released equivalent amounts of sperm to virgin and non-virgin females. When mating with non-virgin females, males showed twice as many pedipalp insertions and half the copulation duration as compared to virgin females; however, males were as likely to mate with non-virgin as virgin females. Even with these overt behavioral differences, males released half of the sperm contained within their pedipalps during mating, regardless of female mating history. With respect to male mating order, first or second, we suggest the numbers of sperm released would lead to an expectation of unbiased paternity. In this species, sperm release is not directly proportional to total copulationduration. 相似文献
15.
Leif Engqvist Gabriele Dekomien Tanja Lippmann Jörg T. Epplen Klaus P. Sauer 《Evolutionary ecology》2007,21(6):801-816
Post-copulatory episodes of sexual selection can be a powerful selective force influencing the reproductive success of males.
In order to understand variation in male fertilisation success, we first need to consider the pattern of sperm utilisation
by females following matings with more than one male. Second, we need to study those traits responsible for male success in
sperm competition. Here we study both male sperm transfer characteristics as well as offspring paternity of females mated
to two males in the scorpionfly Panorpa cognata. By repeatedly mating males to virgin females and interrupting copulation at defined time points, we found for all males
that sperm transfer set off after approximately 40 min. During the remaining copulation, sperm transfer of individual males
was continuous and with constant rate. Yet the rate of sperm transfer differed between individual males from about one sperm
per minute to more than eight sperm per minute for the most successful males. In addition, we measured the fertilisation success
in sperm competition of males with known sperm transfer capability. The relative number of sperm transferred by males during
copulation, estimated from copulation duration and the males’ individual sperm transfer rate, explained a large proportion
of variation in offspring paternity. The mode of sperm competition in this species, thus, conforms largely to a fair raffle
following complete mixing of sperm prior to fertilisation. Hence, male differences in both the ability to copulate for long
and of rapid sperm transfer will translate directly into differences in reproductive success. 相似文献
16.
Scott P. Carroll 《Journal of Insect Behavior》1991,4(4):509-530
Male soapberry bugs (Jadera haematoloma)face severe mating competition at the northern edge of their range due to male-biased adult sex ratios. Copulations lasting up to 11 days may serve a mate guarding function (encompassing four or more ovipositions), but copulation duration is highly variable, with some pairings lasting as little as 10 min. Data were gathered to describe factors that influence the reproductive costs and benefits of prolonged copulation. Estimated copulation durations (mean ± SD) were 20 ± 23 h in the lab and 50 ± 8 h in the field and were only weakly affected by sex ratio. Females mated for 5 min produced as many fertile eggs as those mated for 600 min laid; they became depleted of fertile sperm after about 25 days. In twicemated females, the first male's paternity was reduced by about 60%, and all females (N =
13) whose mates were removed experimentally mated again within an average of 6 min. The outcome of sperm competition on a perclutch basis was not highly predictable. The possibility of increased sperm displacement in longer copulations was not tested. Males often guarded females during oviposition and successfully defended them from intruding single males by recopulating. Such intrusions occurred in the majority of oviposition attempts observed in nature. Even though most females mated promiscuously, in a focal aggregation with a mean sex ratio of 2.2 ± 0.4 males/female, the interval between matings by males was commonly several days. Males appeared to respond facultatively to several aspects of the distribution and availability of females. The intensities of mating competition and sperm competition indicate that monogamous mate guarding should be favored over nonguarding in nature. Unpredicted brief. pairings may result from assessment by males of female reproductive value or of their own physical condition, or from female resistance. 相似文献
17.
W.R.M. Sandanayaka A. Chhagan N.E.M. Page-Weir H.N. de Silva J.G. Charles 《Biocontrol Science and Technology》2011,21(4):485-496
Mastrus ridens (Horstmann) (Hymenoptera: Ichneumonidae) was imported into quarantine as a potential biocontrol agent for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Mating behaviour of the parasitoid and its effect on progeny sex ratio (as a proportion of males) were studied to help sustain the laboratory culture. Both females and males were reproductively active soon after emergence. Unmated females produced only male progeny, confirming males developed from unfertilized eggs. The proportion of males in a progeny was independent of the copulation period (24–40 s) of the parents. The progeny sex ratios from three parent ratios (f:m 2:1, 1:1 and 1:2) were not significantly different. Females effectively mated only once but males mated frequently in their lifetime. The progeny sex ratios from single females with a known single mating and possible multiple matings (through exposure to two males for 18 days) were not significantly different. However, when males copulated with five virgin females in sequence over a 2 h period, the fifth female produced more males than the preceding four, presumably due to sperm depletion. Results of this study provide data on progeny sex allocation of M. ridens that help to prevent the development of a male-biased sex ratio that could threaten the maintenance of the culture over time. 相似文献
18.
ANNE LIZÉ ANNE MARIE CORTESERO DENIS POINSOT GUY BOIVIN 《Physiological Entomology》2009,34(2):129-135
Abstract By contrast to females that can maximize reproductive success with only one or a few copulations, males generally increase their fitness with frequency of mating. Sperm storage and allocation is therefore crucial for both male and female fitness. Sperm storage in Aleochara bilineata (Coleoptera; Staphylinidae) is investigated by measuring the number of spermatozoa stored in the female spermatheca after single, double or triple successive copulations with different males. The potential advantages of polyandry are studied in terms of the number of sperm stored by females mated twice with the same male (i.e. repeated copulation), compared with females mated twice with two different virgin males (i.e. polyandry). Level of polygyny is also estimated by measuring sperm allocation when ten successive mates are offered to a virgin male. Aleochara bilineata females store the sperm of the same or different males additively, suggesting no advantage for polyandry in terms of the number of sperm stored. A virgin male is able to inseminate ten different females but the number of sperm transferred decreases linearly. Finally, the latencies and durations of copulations are measured in all experiments to estimate changes according to the male or female status (i.e. virgin or mated). The latency before mating is higher when females are virgin than when females have already mated. 相似文献
19.
Giselle Muschett Kate D. L. Umbers Marie E. Herberstein 《Ethology : formerly Zeitschrift fur Tierpsychologie》2018,124(10):751-759
In many species, males can increase their fitness by mating with the highest quality females. Female quality can be indicated by cues, such as body size, age and mating status. In the alpine grasshopper Kosciuscola tristis, males can be found riding on subadult females early in the season, and as the season progresses, males engage in fights over ovipositing females. These observations suggest that males may be competing for females that are either unmated (early season) or sperm‐depleted (late season). We thus hypothesised that male K. tristis may be choosy in relation to female mating status, and specifically, we predicted that males prefer females that are unmated. We conducted behavioural experiments in which males were given the choice of two females, one mated and one unmated. Contrary to our prediction, males did not mate preferentially with unmated females. However, copulation duration with unmated females was, on average, 24 times the length of copulation with mated females. While female K. tristis can reject mates, we did not observe any evidence of overt female choice during our trials. Females may gain additional benefits from mating multiply and may therefore not readily reject males. While our experiment cannot definitively disentangle female from male control over copulation duration, we suggest that males choose to invest more time in copula with unmated females, perhaps for paternity assurance, and that male mate assessment occurs during copulation rather than beforehand. 相似文献
20.
Kuhan Perampaladas J. A. Stoltz & M. C. B. Andrade 《Ethology : formerly Zeitschrift fur Tierpsychologie》2008,114(6):589-598
In many species, selection acts on males to recognize female reproductive status at a distance using pheromones. Unmated females may actively seek to attract males; however, mated females may become cryptic to avoid attracting additional males if multiple matings are costly. Although females of many species cease pheromone production after mating, it is often unclear whether this is a strategic part of a female reproductive strategy, or whether this is because of chemical manipulation by males. If variation in pheromone production is part of the female’s strategy, then we predicted mated females should eventually re‐advertise receptivity if the benefits of multiple mating increase with time since copulation (e.g. because of sperm depletion). Here, we tested this prediction in Australian redback spiders (Latrodectus hasselti). First, we replicated earlier results by showing that virgin males discriminate female maturity and mating status based exclusively on web‐borne chemicals. Our results show this difference must arise from a change in chemical deposition in the web as we controlled for web volume differences between mated and virgin females. Male activity on extracts from webs of virgin females exceeded activity on a solvent control and on extracts of webs of just‐mated females—confirming that female redbacks cease pheromone production immediately after mating. Second, we tested a new prediction that mated females might re‐advertise receptivity near the end of their normal breeding season to replenish diminished sperm stores prior to overwintering. Consistent with the prediction of strategic advertisement, we show that male activity on extracts from females’ webs increased significantly 3 mo after the female first mated (typical length of the breeding season). Thus, these females had begun to add pheromone to their web again. At this time, 26% of these females re‐mated with a second male. If females re‐advertise receptivity to ensure adequate sperm stores, then we predicted a positive relationship between female reproductive output during the 3‐mo interval after copulation and the subsequent intensity of male response to web extracts. However, differences in male activity time were not related to the total number of spiderlings or the number of egg sacs a female had produced during the 3‐mo interval after the first copulation. This result could arise if male chemical manipulation of female receptivity decreases with time after copulation, or if the testing interval used in our study was too long to reveal variation in sperm depletion in females. Thus, although our results are consistent with the idea that females strategically alter pheromonal advertisement, we cannot distinguish this from the hypothesis that female receptivity arises from chemical manipulation by males. 相似文献