大猿叶虫滞育进程中成虫内生殖系统的形态特征

大猿叶虫Colaphellus bowringi Baly是十字花科蔬菜的一种重要害虫,以成虫在土壤中滞育越冬和越夏。本研究通过解剖大猿叶虫非滞育成虫,观察描述了雌雄成虫内生殖系统的结构特点,并绘制了雌雄成虫内生殖系统模式图。对滞育初期、滞育期间、滞育解除后未取食和滞育解除后取食成虫解剖显示,滞育初期,雌雄成虫内生殖系统几乎与羽化初期成虫一致。滞育期间雄成虫的附腺和射精管亦不发达,滞育解除后未取食雄成虫的附腺膨大且粗于输精管,射精管略膨大,取食雄成虫的射精管呈不透明淡桔黄色。滞育期间雌成虫的卵巢小,略大于滞育初期卵巢,少数卵巢小管的基部可见具卵黄原沉淀的卵粒。滞育解除后未供食雌成虫卵巢明显膨大可见大量成形卵粒,部分卵粒可见卵黄原沉淀;取食雌成虫的卵巢膨大,可见大量成熟卵粒,侧输卵管和总输卵管中可见待产的卵。作者认为,大猿叶虫成虫在滞育期间能够缓慢发育,部分滞育前积累的代谢物质被用于滞育后发育,但只有经过取食,成虫才能正常交配和产卵。     

Energy versus risk: costs of reproduction in free‐ranging pythons in tropical Australia

Abstract Data from a 12‐year field study have allowed us to quantify ‘costs of reproduction’ in a natural population of water pythons (Liasis fuscus) in tropical Australia. Both sexes of pythons cease feeding during the reproductive season. For males, this involves fasting for a 6 week period. Adult males lose weight rapidly over this period (approximately 17% of their body mass) but regain condition in the following months, and do not experience reduced survival. In contrast, reproductive adult females cease feeding for 3 months, lose an average of 44% of their body mass over this period, and experience increased mortality. A causal link between reproductive output and reduced female survival is supported by (i) a decrease in survival rates at female maturation; (ii) a correlation between survival rates and frequency of reproduction, in a comparison among different size classes of adult pythons; and (iii) a lowered survival rate for females that allocated more energy to reproduction. Hence, both sexes experience substantial energy costs of reproduction, but a relatively higher energy cost translates into a survival cost only in females. Such non‐linearities in the relationship between energy costs and survival costs may be widespread, and challenge the value of simple energy‐based measures of 'reproductive effort’.     

Costly reproductive competition between females in a monogamous cooperatively breeding bird

In many cooperatively breeding societies, only a few socially dominant individuals in a group breed, reproductive skew is high, and reproductive conflict is common. Surprisingly, the effects of this conflict on dominant reproductive success in vertebrate societies have rarely been investigated, especially in high-skew societies. We examine how subordinate female competition for breeding opportunities affects the reproductive success of dominant females in a monogamous cooperatively breeding bird, the Southern pied babbler (Turdoides bicolor). In this species, successful subordinate reproduction is very rare, despite the fact that groups commonly contain sexually mature female subordinates that could mate with unrelated group males. However, we show that subordinate females compete with dominant females to breed, and do so far more often than expected, based on the infrequency of their success. Attempts by subordinates to obtain a share of breeding impose significant costs on dominant females: chicks fledge from fewer nests, more nests are abandoned before incubation begins, and more eggs are lost. Dominant females appear to attempt to reduce these costs by aggressively suppressing potentially competitive subordinate females. This empirical evidence provides rare insight into the nature of the conflicts between females and the resultant costs to reproductive success in cooperatively breeding societies.     

Cryptic reproductive isolation in the Drosophila simulans species complex

Forms of reproductive isolation that act after copulation but before fertilization are potentially important components of speciation, but are studied only infrequently. We examined postmating, prezygotic reproductive isolation in three hybridizations within the Drosophila simulans species complex. We allowed females to mate only once, observed and timed all copulations, dissected a subset of the females to track the storage and retention of sperm, examined the number and hatchability of eggs laid after insemination, counted all progeny produced, and measured the longevity of mated females. Each of the three hybridizations is characterized by a different set of cryptic barriers to heterospecific fertilization. When D. simulans females mate with D. sechellia males, few heterospecific sperm are transferred, even during long copulations. In contrast, copulations of D. simulans females with D. mauritiana males are often too short to allow sperm transfer. Those that are long enough to allow insemination, however, involve the transfer of many sperm, but only a fraction of these heterospecific sperm are stored by females, who also lay fewer eggs than do D. simulans females mated with conspecific males. Finally, when D. mauritiana females mate with D. simulans males, sperm are transferred and stored in abundance, but are lost rapidly from the reproductive tract and are therefore used inefficiently. These results add considerably to the list of reproductive isolating mechanisms in this well-studied clade and possibly to the list of evolutionary processes that could contribute to their reproductive isolation.     

Reproductive potential of field-collected overwintering boll weevils (Coleoptera: Curculionidae) fed on pollen in the laboratory

Abstract  The reproductive potential of overwintering boll weevil, Anthonomus grandis grandis (Boheman), females collected from pheromone traps in September, November and January, fed for 1, 3, and 5 weeks on plant pollens, and then provided cotton squares, was determined in the laboratory at 27 ± 1°C, 65% RH, and a photoperiod 13 : 11 (L : D) h. Duration of pollen feeding by overwintering boll weevils did not significantly influence egg and feeding punctures, or puncture ratios (egg to total punctures) for any of the three months of parent weevil collections when provided cotton squares on a daily basis. However, punctures and puncture ratios are significantly different when comparing mean data between months of boll weevil collections. When boll weevils were provided with cotton squares daily, the pre-ovipositional periods of female parents captured in September, November and January were 5, 9 and 14 days, respectively. The rate of eggs by females was significantly lower during November and January than September. Female parents collected in September produced a significantly higher percentage of eggs yielding adult progeny than those collected in November and January. Life table parameters indicated that net reproductive rate ( R _o) of boll weevil females collected in September was 1.2-fold higher than those collected in November and 10.7-fold higher than those collected in January. Except for testes size, no differences in male reproductive parameters were observed during the cotton-free period compared with males captured during mid-cotton (June). The number of oocytes in the ovarioles and the number of oocytes containing yolk were significantly lower during September, November and January compared with June. The reproductive potential of overwintering boll weevil females collected in different months is an important consideration in determining the success of any control strategy.     

Strategic female reproductive investment in response to male attractiveness in birds

Life-history theory predicts that individuals should adjust their reproductive effort according to the expected fitness returns on investment. Because sexually selected male traits should provide honest information about male genetic or phenotypic quality, females may invest more when paired with attractive males. However, there is substantial disagreement in the literature whether such differential allocation is a general pattern. Using a comparative meta-regression approach, we show that female birds generally invest more into reproduction when paired with attractive males, both in terms of egg size and number as well as food provisioning. However, whereas females of species with bi-parental care tend to primarily increase the number of eggs when paired with attractive males, females of species with female-only care produce larger, but not more, eggs. These patterns may reflect adaptive differences in female allocation strategies arising from variation in the signal content of sexually selected male traits between systems of parental care. In contrast to reproductive effort, female allocation of immune-stimulants, anti-oxidants and androgens to the egg yolk was not consistently increased when mated to attractive males, which probably reflects the context-dependent costs and benefits of those yolk compounds to females and offspring.     

Body mass variation in breeding Florida Scrub‐Jays

ABSTRACT Many birds lose mass when feeding dependent young and multiple hypotheses have been proposed to explain this loss. The reproductive‐stress hypothesis suggests that mass loss results from an energy deficit. The flight‐efficiency hypothesis suggests that breeders lose mass in advance of feeding young to save energy during flight. The reserve‐mobilization hypothesis suggests that female breeders accumulate energy reserves during egg production and incubation and mobilize those reserves to meet their own energy needs after eggs hatch. Finally, birds may lose mass due to gonadal regression. From 1999 to 2001, we attracted Florida Scrub‐Jays (Aphelocoma coerulescens), sedentary cooperative breeders, to a portable electronic balance. Our objective was to determine which hypotheses might best explain mass variation during breeding. Both male and female Florida Scrub‐Jays lost mass during the period of nestling care (males, 3.2%; females, 6.5%), but not when feeding fledglings, despite this being the period of peak effort. Such results are consistent with both the flight‐efficiency and reserve‐mobilization (females only) hypotheses. We also found a significant negative influence of brood size on mass change in males, providing support for the reproductive‐stress hypothesis, and we conclude that, for males, both the flight‐efficiency and reproductive‐stress hypotheses apply. For female scrub‐jays, our results were consistent with the flight‐efficiency and energy‐reserve mobilization hypotheses, both of which view mass loss as beneficial.     

Senescence and costs of reproduction in the life history of a small precocial species

Species following a fast life history are expected to express fitness costs mainly as increased mortality, while slow‐lived species should suffer fertility costs. Because observational studies have limited power to disentangle intrinsic and extrinsic factors influencing senescence, we manipulated reproductive effort experimentally in the cavy (Cavia aperea) which produces extremely precocial young. We created two experimental groups: One was allowed continuous reproduction (CR) and the other intermittent reproduction (IR) by removing males at regular intervals. We predicted that the CR females should senesce (and die) earlier and produce either fewer and/or smaller, slower growing offspring per litter than those of the IR group. CR females had 16% more litters during three years than IR females. CR females increased mass and body condition more steeply and both remained higher until the experiment ended. Female survival showed no group difference. Reproductive senescence in litter size, litter mass, and reproductive effort (litter mass/maternal mass) began after about 600 days and was slightly stronger in CR than IR females. Litter size, litter mass, and offspring survival declined with maternal age and were influenced by seasonality. IR females decreased reproductive effort less during cold seasons and only at higher age than CR females. Nevertheless, offspring winter mortality was higher in IR females. Our results show small costs of reproduction despite high reproductive effort, suggesting that under ad libitum food conditions costs depend largely on internal regulation of allocation decisions.     

Effects of larval diet on development rates and reproductive maturation of male and female Mediterranean fruit flies

Abstract Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) larvae are capable of developing in one of many hosts that may vary greatly in quality. We hypothesized that they will respond to the larval environment in a manner beneficial to their subsequent reproductive performance. Accordingly, we investigated the effects of various larval diets (varying in the amount of protein and sugar they contain) on the size, development time, nutritional status and reproductive maturation (ovarian development and onset of sexual behaviour) of females and males. We found that flies which undergo larval development in artificial host fruit that contain sugar and protein ('protein-fed') were larger, developed faster and emerged with more nutritional reserves than flies that were protein-deprived as larvae. Protein-fed males, regardless of their size, became sexually active before males that developed in hosts with no protein. Protein-fed females produced more mature eggs than protein-deprived ones. Moreover, protein-fed females tended to copulate sooner than females that developed in hosts with no protein. In addition, regardless of female larval diet, females with more mature eggs tended to copulate sooner than females with less mature eggs. In light of these results, the importance of the larval environment for adult reproductive success is discussed.     

Breeding success of male brook trout (Salvelinus fontinalis) in the wild

Competition for females generally results in some males adopting alternative reproductive tactics to acquire matings. For fish, the ecological and evolutionary consequences of these tactics are not well understood because of an inability to link directly the interactions of individuals on the breeding grounds with genetic data. This study combines behavioural observations with genetic estimates of male reproductive success within an intensively studied wild population of lacustrine brook trout (Salvelinus fontinalis). Male brook trout exhibit a conditional reproductive strategy with small males adopting a peripheral position to that of larger dominant males in their proximity to spawning females. Parentage analysis of eggs collected from wild redds confirmed the reproductive success of individual males. Males relegated to peripheral positions during spawning participated frequently in spawning events, but in most cases the first male to spawn was the sole contributor, and no more than two males contributed successfully to a single brood. While behavioural observations of salmonines suggests that reproduction is partitioned among males in a manner dependent upon body size and proximity to spawning females, the genetic evidence from this study suggests a more limited distribution of reproductive success in the field. The genetic contributions of male brook trout are highly skewed towards larger males for this population. A review of the salmonine literature suggests little difference in individual reproductive success for males exhibiting size-related tactics within a conditional mating strategy vs. precocial maturation. Collectively, these genetic studies provide new insights on the evolution of alternative life histories among salmonines.     

Mate desertion by male Great Reed Warblers Acrocephalus arundinaceus at the end of the breeding season

Male Great Reed Warblers usually take part in the care of offspring as nest defenders and by feeding young, but at the end of the breeding season they desert their mates with eggs or nestlings. Deserted females continue offspring care. Desertion does not depend on the male's mated status (polygynous or monogamous) nor on his past breeding success. Deserted females compensate for the loss of their partners by increasing the frequency of food-bringing, resulting in a reduction in the amount of time the nestlings are brooded. Although desertion may lead to increased rates of offspring mortality through predation, breeding success of deserted females was high, especially if the male assisted during the early stages. Deserters pay costs by giving up the chance of additional matings and by lowering the reproductive success of existing mates. Male warblers reduce the former cost by choosing the season of desertion and the latter is lowered by the female's high parental ability. A deserter was found to start moulting while his mate was still feeding his nestlings, and an earlier start to the moult may be the primary benefit that he gains. Male Great Reed Warblers usually take part in the care of offspring as nest defenders and by feeding young, but at the end of the breeding season they desert their mates with eggs or nestlings. Deserted females continue offspring care. Desertion does not depend on the male's mated status (polygynous or monogamous) nor on his past breeding success. Deserted females compensate for the loss of their partners by increasing the frequency of food-bringing, resulting in a reduction in the amount of time the nestlings are brooded. Although desertion may lead to increased rates of offspring mortality through predation, breeding success of deserted females was high, especially if the male assisted during the early stages. Deserters pay costs by giving up the chance of additional matings and by lowering the reproductive success of existing mates. Male warblers reduce the former cost by choosing the season of desertion and the latter is lowered by the female's high parental ability. A deserter was found to start moulting while his mate was still feeding his nestlings, and an earlier start to the moult may be the primary benefit that he gains. Male Great Reed Warblers usually take part in the care of offspring as nest defenders and by feeding young, but at the end of the breeding season they desert their mates with eggs or nestlings. Deserted females continue offspring care. Desertion does not depend on the male's mated status (polygynous or monogamous) nor on his past breeding success. Deserted females compensate for the loss of their partners by increasing the frequency of food-bringing, resulting in a reduction in the amount of time the nestlings are brooded. Although desertion may lead to increased rates of offspring mortality through predation, breeding success of deserted females was high, especially if the male assisted during the early stages. Deserters pay costs by giving up the chance of additional matings and by lowering the reproductive success of existing mates. Male warblers reduce the former cost by choosing the season of desertion and the latter is lowered by the female's high parental ability. A deserter was found to start moulting while his mate was still feeding his nestlings, and an earlier start to the moult may be the primary benefit that he gains. Male Great Reed Warblers usually take part in the care of offspring as nest defenders and by feeding young, but at the end of the breeding season they desert their mates with eggs or nestlings. Deserted females continue offspring care. Desertion does not depend on the male's mated status (polygynous or monogamous) nor on his past breeding success. Deserted females compensate for the loss of their partners by increasing the frequency of food-bringing, resulting in a reduction in the amount of time the nestlings are brooded. Although desertion may lead to increased rates of offspring mortality through predation, breeding success of deserted females was high, especially if the male assisted during the early stages. Deserters pay costs by giving up the chance of additional matings and by lowering the reproductive success of existing mates. Male warblers reduce the former cost by choosing the season of desertion and the latter is lowered by the female's high parental ability. A deserter was found to start moulting while his mate was still feeding his nestlings, and an earlier start to the moult may be the primary benefit that he gains. Male Great Reed Warblers usually take part in the care of offspring as nest defenders and by feeding young, but at the end of the breeding season they desert their mates with eggs or nestlings. Deserted females continue offspring care. Desertion does not depend on the male's mated status (polygynous or monogamous) nor on his past breeding success. Deserted females compensate for the loss of their partners by increasing the frequency of food-bringing, resulting in a reduction in the amount of time the nestlings are brooded. Although desertion may lead to increased rates of offspring mortality through predation, breeding success of deserted females was high, especially if the male assisted during the early stages. Deserters pay costs by giving up the chance of additional matings and by lowering the reproductive success of existing mates. Male warblers reduce the former cost by choosing the season of desertion and the latter is lowered by the female's high parental ability. A deserter was found to start moulting while his mate was still feeding his nestlings, and an earlier start to the moult may be the primary benefit that he gains.     

The fitness effects of delayed switching to sex in a facultatively asexual insect

Facultative reproductive strategies that incorporate both sexual and parthenogenetic reproduction should be optimal, yet are rarely observed in animals. Resolving this paradox requires an understanding of the economics of facultative asexuality. Recent work suggests that switching from parthenogenesis to sex can be costly and that females can resist mating to avoid switching. However, it remains unclear whether these costs and resistance behaviors are dependent on female age. We addressed these questions in the Cyclone Larry stick insect, Sipyloidea larryi, by pairing females with males (or with females as a control) in early life prior to the start of parthenogenetic reproduction, or in mid‐ or late life after a period of parthenogenetic oviposition. Young females were receptive to mating even though mating in early life caused reduced fecundity. Female resistance to mating increased with age, but reproductive switching in mid‐ or late life did not negatively affect female survival or offspring performance. Overall, mating enhanced female fitness because fertilized eggs had higher hatching success and resulted in more adult offspring than parthenogenetic eggs. However, female fecundity and offspring viability were also enhanced in females paired with other females, suggesting a socially mediated maternal effect. Our results provide little evidence that switching from parthenogenesis to sex at any age is costly for S. larryi females. However, age‐dependent effects of switching on some fitness components and female resistance behaviors suggest the possibility of context‐dependent effects that may only be apparent in natural populations.     

Relatively large males lower reproductive success in female zebrafish

Females can adjust their reproductive effort in relation to their partner’s perceived fitness value. In zebrafish (Danio rerio), large males are typically preferred mating partners. However, females have been observed to reduce their reproductive output with exceptionally large males but it remains unknown whether it is due to sexual harassment or aggressive behavior to establish and maintain dominance. Here, we study the association between relative male size, sexual harassment and dominance behavior, female stress status (stress behaviors and whole-body cortisol concentration), and reproductive success during a 4 day spawning trial. We found female cortisol to correlate negatively with female body size and positively with female dominance behavior. However, male and female behavior as well as female cortisol level were not related to relative male size. Females mating with relatively large males produced more and most of their eggs during the first spawning day, while females with smaller males produced few eggs during the first day but then increased egg production. Despite females produced more eggs when mating with relatively larger males, their eggs had substantially lower fertilization rates compared to females mating with relatively smaller males. Hence, overall, the reproductive fitness was lowest when females mated with a relatively large male. These findings could help to explain the maintenance of male size variation under natural conditions.     

Fluctuating asymmetries and reproductive success in the peacock blenny

In an investigation of the relationship between reproductive success and fluctuating asymmetry (FA) in the peacock blenny Salaria pavo , FA was measured in four bilaterally paired characters in successful and unsuccessful males during the breeding season. Reproductive success among successful males was assessed by calculating the number of eggs the males were defending. Absolute FA values relative to trait size were high for all characters and it is suggested that this could be a consequence of sub-optimal environmental conditions. Two of the traits presented higher absolute FA values suggesting a lower canalization during ontogeny. No difference in FA between successful and unsuccessful males was found and no relationship between FA and number of eggs among the successful males occurred for any of the measured traits. A composite index of FA, that should better reflect overall developmental competence, was also unrelated to reproductive success. These results indicate that FA is not associated with reproductive success among males of S. pavo . Successful males were larger than unsuccessful males and a strong positive correlation was detected between the body length of the parental males and the number of eggs they had in the nest, even when controlling for the internal nest area. Body size may give males a reproductive advantage by being preferred by females and by having an advantage in male-male competition for nests of higher quality.     

Mate-Guarding as a Male Reproductive Tactic in <Emphasis Type="Italic">Propithecus verreauxi</Emphasis>

Sexual selection theory predicts that in group-living mammals, male reproductive tactics can lead to high reproductive skew in favor of dominant individuals. In sifakas (Propithecus verreauxi), a group-living primate with extremely seasonal reproduction, male reproductive success is highly skewed because dominant males sire almost all offspring despite a tendency toward an even adult group sex ratio. To understand the underlying behavioral mechanism resulting in this rank-related reproductive skew in male sifakas, we studied mate-guarding as a potential reproductive tactic. Behavioral observations of dominant males and adult females in combination with hormonal determination of timing of female receptivity in 9 groups at Kirindy Forest revealed that dominant males spent more time in proximity to females when they were receptive and were responsible for the maintenance of this proximity. Results also indicated that monopolization of receptive females was facilitated by both estrous asynchrony within groups and by the ability of dominant males to obtain olfactory cues as to the timing of female receptivity. Although dominant males engaging in mate-guarding are expected to experience various costs, there was no evidence for decreased foraging behavior and only a trend toward increased aggression between dominant and subordinate non-natal males within groups. Our results are in accordance with the hypothesis that dominant males use mate-guarding to monopolize receptive females and that it is one proximate mechanism that contributes to the high reproductive skew observed within the population of male sifakas at Kirindy.     

Activity budgets and activity rhythms in red ruffed lemurs (Varecia rubra) on the Masoala Peninsula, Madagascar: seasonality and reproductive energetics

The activity budgets and daily activity rhythms of Varecia rubra were examined over an annual cycle according to season and reproductive stage. Given the relatively high reproductive costs and patchy food resources of this species, I predicted that V. rubra would 1) travel less and feed more during seasonal resource scarcity in an attempt to maintain energy balance, and 2) show sex differences in activity budgets due to differing reproductive investment. Contrary to the first prediction, V. rubra does not increase feeding time during seasonal food scarcity; rather, females feed for a consistent amount of time in every season, whereas males feed most during the resource-rich, hot dry season. The results are consistent with other predictions: V. rubra travels less in the resource-scarce cold rainy season, and there are some pronounced sex differences, with females feeding more and resting less than males in every season and in every reproductive stage except gestation. However, there are also some provocative similarities between the sexes when activity budgets are examined by reproductive stage. During gestation, female and male activity budgets do not differ and appear geared toward energy accumulation: both sexes feed and rest extensively and travel least during this stage. During lactation, activity budgets are geared toward high energy expenditure: both sexes travel most and in equal measure, and rest least, although it remains the case that females feed more and rest less than males. These similarities between female and male activity budgets appear related to cooperative infant care. The high energetic costs of reproduction in V. rubra females may require that they allot more time to feeding year round, and that their overall activity budget be more directly responsive to seasonal climate change, seasonal food distribution, and reproductive schedules.     

Do reproductive characteristics of the species explain differences in the investment in weapon size present in males?

Sexually selected traits, such as male weapons, are highly variable in shape and size across species. However, little is known about the mechanisms that may govern this variation. Because males with greater investment in weapon size tend to win more fights, but also pay higher costs related to weapon development and maintenance, larger weapons should be expected only in species in which victory in male–male fights generate reproductive benefits that outweigh investment costs. Here, we hypothesized that the reproductive characteristics that increase the chances of winners to access females or to fertilize eggs will favor the evolution of larger weapons. To evaluate this hypothesis, we conducted a meta-analysis using arthropods as model organisms. To measure investment in weapon size, we gathered both Pearson correlation coefficient and the standardized (but non centralized) slope values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing female eggs with a victory does not modulate the investment in male weapon size. Perhaps the cost–benefit ratio between weapon size investment and reproductive success is not the main factor driving the variation in weapon size.     

Influence of sex, body size, and reproduction on overwinter lipid depletion in brook trout

Expressed as percentages of total fresh body weight, lipids of brook trout Salvelinus fontinalis declined between October and April: reproductive males from 2·89 to 1·22%, reproductive females from 3·19 to 1·84%, and non-reproductive males and females from 2·75 to 2·08%. The absolute and proportional overwinter reduction in lipids among reproductive trout was more than twice that of non-reproductive trout, with reproductive males losing significantly more lipids than reproductive females. Larger reproductive individuals lost more lipids during winter, relative to body size, than smaller individuals, although such an effect was not evident among non-reproductive trout. The average overwinter reduction in lipids for reproductive males (58%), females (42%), and non-reproductive trout (24%) was negatively associated with mark-recapture estimates of overwinter survival probabilities of 0·27, 0·36, and 0·58, respectively, providing support for the hypothesis that energy is allocated to reproduction to the detriment of post-reproductive survival. Our emergent hypothesis that reproductive costs differ between sexes, and the life history consequences thereof, merit further study.     

Comparative evidence supports a role for reproductive allocation in the evolution of female ornament diversity

1. Sexually selected ornaments are highly variable, even among closely related species, and the ultimate causes of variation in ornament evolution are unclear, including in rare cases of female ornament expression. One hypothesis is that differences across species in female reproductive allocation may help to explain patterns of female ornament expression among insects with nuptial gifts. 2. Dance flies (Diptera: Empididae: Empidinae) vary considerably among species in the presence and extravagance of female ornaments, which probably evolved through female contests for mates. In most dance flies, adult females appear to acquire all their dietary protein from nuptial gifts provided by males during mating. The importance of nuptial feeding on egg development is not yet known. 3. To test the prediction that the presence of female ornaments reflects differences in the degree to which females rely on nuptial feeding for egg development, egg development was examined in wild females of two species, one ornamented and the other unornamented. An ageing technique based on cuticular bands was validated, which permitted a regression of egg size on adult age. 4. We found that egg development depended on mating status in the ornamented species alone, meaning the eggs of unmated females of the ornamented species did not develop. This contrast across species is consistent with expectations that females of different species vary in their dependence on nuptial gifts for egg development. 5. These findings provide preliminary support for the hypothesis that differences in reproductive allocation mediate the intensity of female contests for nuptial gifts.