Nectar dehydration by male carpenter bees as preparation for mating flights

Summary Females of all social and many solitary bees dehydrate nectar before storing it or adding it to larval provisions. Nectar dehydration by males has rarely been documented. We report on the neotropical facultatively social carpenter bee Xylocopa nigrocincta, in which the nest constant males are fed nectar by their female nestmates. Males dehydrate the nectar at the nest entrance before leaving the nest for mating territories. We show that males thereby minimize their water load, resulting in an improvement of their energy budget during hovering flights in their territories. Males can prolong the duration of territorial flights if they cany highly concentrated nectar. We assume that nectar dehydration as a pre-mating behavior is not correlated with the social organization in Xylocopa species. However, the behavior is particularly weil-developed in X. nigrocincta, where during the mating period males remain integrated in the nest society and are fed by their mothers and sisters.     

Male coalitions and female behaviour affect male mating success independent of dominance rank and female receptive synchrony in wild Barbary macaques

Dominant mammalian males should gain a reproductive advantage due to their greater fighting abilities. However, the extent to which they can monopolise access to females varies across species. In primates and recently other mammalian species, the Priority of Access (PoA) model is commonly used to measure the degree to which male rank and female receptive synchrony affect mating skew. Few studies have examined the factors which lead to deviations from the expectations of the model. Here, we investigate male mating skew in wild Barbary macaques (Macaca sylvanus). We examined four of the main factors which affect male mating success: the roles of male rank, female receptive synchrony, coalitionary activity and female behaviour. We found that male mating was skewed up the hierarchy, but there was a large deviation from the PoA model's expectations with high-ranked males not gaining as big a share as expected. Females frequently initiated sexual encounters, predominantly with mid-ranked males, increasing their mating success. Male coalitionary activity independently increased mating success. Frequent associations with females were costly to males as they were the targets of bridging coalitions, decreasing future mating opportunities for the targets. High-ranking males did not increase their mating success directly through bridging coalitions but acted to dilute the effects of female behaviour. By examining different factors affecting mating skew, we are able to show that alternative male and female mating strategies are effective in reducing the monopolisation potential of the dominant male.     

The invasive gastropod Crepidula fornicata: reproduction and recruitment in the intertidal at its northernmost range in Wales, UK, and implications for its secondary spread

The establishment and spread of a non-native species in an introduced range depends to a large extent on the performance of the species under the prevailing environmental conditions. The spawning, larval and spatfall periods of the invasive gastropod Crepidula fornicata were monitored in the intertidal zone at its northernmost range in Wales, UK, between February 2010 and January 2011. The duration of the reproductive season was similar to that recorded from more southerly European populations. Spawning and larval release occurred throughout most of the year even at low seawater temperatures of <7 °C, but benthic recruitment was observed over a much shorter period at seawater temperatures >16 °C. Recruitment was low and likely controlled by post-settlement mortality. These observations suggest that C. fornicata’s northwards spread in Welsh waters will not be limited by seawater temperature negatively affecting reproduction, but by processes acting after larval release. These data show the importance of incorporating settlement and post-settlement processes into studies on recruitment success when aiming to predict the potential spread of a potentially harmful invader such as C. fornicata.     

Variation in signal timing behavior: implications for male attractiveness and sexual selection

Mate choice often takes place in group settings, such as leks or choruses, in which numerous individuals display and compete for mates simultaneously. In addition to well-known preferences for male traits like size and signaling rate, females of group-displaying species often show preferences that are based on the relative timing of male signals, generally preferring the leading signal. Variation in male signal timing behavior may therefore affect male attractiveness and, ultimately, reproductive success. I used acoustic communication in green treefrogs (Hyla cinerea) to assess the amount of signal timing variation found in natural choruses and to test hypotheses about the sources of variation in signal timing behavior. I recorded dyads of vocally interacting males in the field to describe patterns of variation in signal timing behavior. Incorporating information about female signal timing preferences, I also assessed the amount of variation in signal timing that is likely to be selectively neutral, as well as the amount that is likely under selection by female choice because it involves attractive or unattractive signal placement. I show that there is considerable variation in signal timing behavior, particularly involving neutral signal timing placement. I also show that between-male variation in other traits (size, signal period) is partly linked to variation in signal timing behavior and discuss these findings in terms of male attractiveness and sexual selection in group-displaying organisms.     

Condition-dependent control of paternity by female purple martins: implications for coloniality

Proposed causal links between extra-pair copulation (EPC) and colony formation in socially monogamous birds hinge on the question of which sex controls fertilizations. We examined in colonial purple martins Progne subis (1) whether EPCs were forced or accepted by females, and (2) the degree to which apparently receptive females were able to obtain EPCs against their mates’ paternity defenses. Paternity analyses of multilocus DNA fingerprinting confirmed previous findings of a marked relationship between age class and extra-pair fertilizations (EPFs), with young males losing paternity of 43% (n = 53) of their putative offspring compared to 4% (n = 85) by old males. All assignable extra-pair offspring were sired by old males, with one male obtaining most EPFs each year. Contrary to the hypothesis that EPCs are forced, EPF frequency within age class did not increase with seasonal increases in the number of males per fertile female. Whereas the male control hypothesis predicted that the male age class that mate-guarded more would be cuckolded less, the reverse was true: young males guarded significantly more intensely. The male age class difference in cuckoldry could not be explained by the possibility that young and inexperienced females (which are usually paired to young males) were more vulnerable to forced copulation because EPFs were unrelated to female age. These findings suggest that females (1) pair with old males and avoid EPCs, or (2) pursue a mixed mating strategy of pairing with young males and accepting EPCs from old males. The receptivity to EPCs by females paired to young males put them in conflict with their mates. Two factors determined the paternity achieved by young males: (1) the relative size of the male to the female, with young males achieving much higher paternity when they were larger than their mates, and (2) the intensity of mate-guarding. Both variables together explained 77% of the variance in paternity and are each aspects of male-female conflict. Given female receptivity to EPCs, mate-guarding can be viewed as male interference with female mating strategies. We conclude that EPCs are rarely or never forced, but the opportunity for females paired to young males to obtain EPCs is relative to the ability of their mates to prevent them from encountering other males. Evidence of mixed mating strategies by females, combined with other features of the martin mating system, is consistent with the female-driven “hidden lek hypothesis” of colony formation which predicts that males are drawn to colonies when females seek extra-pair copulations. Received: 23 March 1995/Accepted after revision: 14 January 1996     

Chemical transformations of lead compounds under humid conditions: implications for bioaccessibility

This short communication documents chemical transformations caused by weathering of two Pb compounds that commonly occur in house dust. Chamber experiments were designed to simulate humid indoor environment conditions to determine whether Pb compounds undergo chemical transformations influencing bioaccessibility. Reference compounds of Pb metal (12 % bioaccessibility) and Pb sulfate (14 % bioaccessibility) were subjected to an oxygenated, humidified atmosphere in closed chambers for 4 months. X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES) spectroscopy were used to characterize the main Pb species, and the change in Pb bioaccessibility was determined using a simulated gastric acid digestion. At the end of the weathering period a small amount of Pb carbonate (9 % of total Pb) appeared in the Pb sulfate sample. Weathering of the Pb metal sample resulted in the formation of two compounds, hydrocerussite (Pb hydroxyl carbonate) and Pb oxide, in significant amounts (each accounted for 26 % of total Pb). The formation of highly bioaccessible Pb carbonate (73 % bioaccessibility), hydrocerussite (76 % bioaccessibility), and Pb oxide (67 % bioaccessibility) during weathering resulted in a measurable increase in the overall Pb bioaccessibility of both samples, which was significant (p = .002) in the case of the Pb metal sample. This study demonstrates that Pb compounds commonly found in indoor dust can ‘age’ into more bioaccessible forms under humid indoor conditions.     

Prior encounters with the opposite sex affect male and female mating behavior in a wolf spider (Araneae,Lycosidae)

Mate availability can vary widely in nature depending upon population density and sex ratio and can affect the ability of individuals to be selective in mate choice. We tested the effects of prior encounters with the opposite sex (i.e., exposure to the opposite sex either with or without mating) on subsequent mating behavior in two experiments that manipulated mate availability for both males and females in the wolf spider, Hogna helluo. The probability of mating in the experimental trial depended upon whether the prior encounter involved mating or not, and males and females responded in opposite directions. Exposure without mating resulted in a higher subsequent frequency of mating for females and a lower subsequent frequency of mating for males, while prior mating experience resulted in a lower frequency of female remating and a higher frequency of male remating. Prior exposure without mating did not affect female aggression. However, mated females engaged in precopulatory cannibalism more frequently than virgins. Mated males escaped postcopulatory cannibalism more frequently than virgins. Our results show that males respond to exposure without mating in the expected manner. However, prior mating (1 week earlier) had unexpected effects on males, which may be due to mated males being of higher quality. There were little or no effects of the size of the prior exposure individual or mate on subsequent mating behaviors. Further research is needed to determine why different species use different degrees of prior information in mate choice.     

Independent effects of male and female density on sexual harassment, female fitness, and male competition for mates in the western mosquitofish Gambusia affinis

Operational sex ratio (the ratio of sexually active males to fertilizable females) has a major influence on male competition for mates and male–female interactions. The contributions of male and female density per se to mating system dynamics, however, are rarely examined, and the fitness consequences are often inferred rather than quantified. Male mosquitofish (Gambusia affinis) compete aggressively and frequently harass females for copulations, a behavior thought to reduce female fitness. Female fitness can also be reduced by increases in female density, which may affect food availability, cannibalism rates, and chemical interactions between females. I manipulated male and female densities of G. affinis to measure their effects on male–male aggression, male harassment toward females, and female fitness. I found that males chased rivals more often and attempted fewer copulations when female density decreased, but surprisingly male density had no significant effect on the frequency of these male behaviors. In contrast, males’ agonistic displays toward other males increased with male density, but display behavior was unaffected by female density. These results suggest that male and female density do not always contribute equally or at all to the patterns of behavior we observe. Female fitness declined as female density increased, the opposite pattern expected if male harassment is costly to females. This suggests that a strong, negative effect of female density overwhelmed any potential costs of male harassment. Sources of female density dependence and the consequences of changes in male and female density to patterns of male behavior are discussed.     

Altered responses to female odors in parasitized male mice: neuromodulatory mechanisms and relations to female choice

There is accumulating evidence that females may preferentially select parasite-free or -resistant males. Minimal attention has, however, been paid to the mate preferences and responses of the parasitized male hosts themselves. Here, we considered the effects of parasitic infection on male host mate responses, the neuromodulatory correlates of these responses, and the relations of these responses to female mate choice. Using an odor “preference” test, we examined the effects of different stages of an acute, sub-clinical infection with the naturally occurring, enteric, single host, protozoan parasite, Eimeria vermiformis, on the responses of male mice, Mus musculus domesticus, to the odors of estrous females along with the responses of uninfected females to the parasitized males. At 4 days post-infection (non-infective, pre-patent stage) E. vermiformis-infected male mice showed a significantly decreased preference for the odors of estrous females, whereas at 10 days post-infection (infective, patent stage) infected males showed a significantly increased preference for the odors of estrous females. Parasitized males displayed no significant changes in their responses to the odors of non-estrous females, supporting effects on the reproductively related responses of the host. In parallel, estrous females displayed a reduced interest in the odors of infected males. Least interest was expressed in the odors of the patent, infective males, consistent with the avoidance of contagion. Using selective opioid peptide receptor agonists and antagonists we found evidence that enhanced kappa opioid peptide (e.g., dynorphin) activity was related to the decreased sexual interest of the pre-infective males, while augmented delta opioid peptide (e.g., enkephalin) activity was associated with the enhanced responses of the infective males to females. We further showed that acute kappa opiate administration reduced the responses of uninfected males to females and that uninfected females displayed modified responses to the odors of uninfected males subject to acute modifications of opioid activity. We suggest that these differential shifts in endogenous opioid activity in the parasitized males are associated with and, or related to alterations in neuro-immune and endocrine functions. These findings show that parasitic infection can have, depending on the stage of infection and associated neuromodulatory changes, either significant facilitatory or inhibitory effects on male host preferences for and responses to females. Received: 22 April 1996 / Accepted after revision: 15 March 1997     

Vocalizations by Alaskan moose: female incitation of male aggression

Evidence of female fomentation of male–male aggression as a mechanism of mate choice is rare, especially in mammals. Female choice of mates in polygynous species may be masked by intense male competition or by males attempting to restrict female choice. We studied protest moans of female Alaskan moose Alces alces gigas in interior Alaska, USA, from 1987 to 1990, to determine if moans incited male–male aggression. Alaskan moose exhibit a mating system in which one dominant male (the harem master) herds, defends, courts, and attempts to mate with females in his harem. Protest moans were given by females only in response to courtship. We hypothesized that if protest moans were related to females reducing harassment and exercising mate choice, females should give protest moans more frequently when courted by small males and less often when courted by large males, and that rates of male–male aggression would be elevated following protest moans. Harems were composed of one large male, with a mean of 4.4 females (median = 3 females); 10% of 132 harems included ≥10 females. The temporal pattern of protest moans from late August through November was associated with, but tended to lag behind, mating behavior. The rate of protest moans given by females decreased with increasing size of males courting them. Male–male aggression was significantly less during periods without protest moans than during periods in which protest moans occurred. These results indicate that female moose gave protest moans to reduce harassment by smaller males, and assure a mating opportunity with the most dominant male. Such a subtle mechanism of indirect mate choice by females may occur in other vertebrates in which choice is limited by a mating system in which male–male combat and male dominance over females reduces opportunities for female choice. The importance of female choice may be undervalued in studies of sexual selection in mammals.     

Lifetime and intergenerational fitness consequences of harmful male interactions for female lizards

Male mating behaviors harmful to females have been described in a wide range of species. However, the direct and indirect fitness consequences of harmful male behaviors have been rarely quantified for females and their offspring, especially for long-lived organisms under natural conditions. Here, lifetime and intergenerational consequences of harmful male interactions were investigated in female common lizards (Lacerta vivipara) using field experiments. We exposed females to male harm by changing the population sex ratio from a normal female-biased to an experimental male-biased sex ratio during the first experimental year. Thereafter, females and their first generation of offspring were monitored during two additional years in a common garden with a female-biased sex ratio. We found strong immediate fitness costs and lower lifetime reproductive success in females subjected to increased male exposure. The immediate fitness costs were partly mitigated by direct compensatory responses after exposure to male excess, but not by indirect benefits through offspring growth, offspring survival, or mating success of offspring. These results support recent empirical findings showing that the direct costs of mating are not outweighed by indirect benefits.     

Racketed tail of the male and female turquoise-browed motmot: male but not female tail length correlates with pairing success,performance, and reproductive success

Both males and females of many avian species maintain elaborate plumage traits, and elaborate monomorphic plumage may convey adaptive benefits to one or both sexes as inter- or intraspecific signals. Both sexes of the turquoise-browed motmot (Eumomota superciliosa) are elaborately plumed with long racket-tipped tail. I investigated whether the racketed tail functions as a sexually selected signal in one or both sexes by testing the predictions that males and/or females with the largest tails have: (1) greater pairing success, (2) greater reproductive performance (clutch-initiation date, clutch size, and hatching success), and (3) greater reproductive success. Yearling males with longer denuded rachises (wires) on the central tail feathers had greater pairing success. In addition, adult males with longer wires paired with females who laid larger clutches, had greater hatching success independent of clutch size, and fledged more young. There was no relationship between female tail plumage and pairing success, reproductive performance, or fledgling success. These results are consistent with the hypothesis that male tail plumage functions as a mate choice or status signal, but that the tail of the female does not function in a sexually selected context. I discuss alternative hypotheses for the evolutionary maintenance of the elaborate female tail plumage.     

Mating patterns of woolly spider monkeys,Brachyteles arachnoides: implications for female choice

Summary Woolly spider monkeys show a promiscuous, polygynous mating system in which a receptive female mates with several males, often in rapid succession. Copulation is prolonged with an average duration of 4.1±1.5 (SD) min. Coitus consists of a stationary phase with the male in intromission, followed by stercotypic behaviours of the female which appear to cue and/or accompany male climax and ejaculation. Subadult and adult males show different association patterns with individual females. Subadult males form long-term consortships with particular females while adult males appear strongly attracted to a particular female only when the is receptive. These different behavior patterns of males are viewed as age-specific mating tactics. Males in a mating aggregation show little intermale aggression for sexual access to a receptive female. Large testis size in this species suggests that much intermale competition for reproductive success may be carried out at a postcopulatory level, perhaps by sperm competition. The copulatory pattern of woolly spider monkeys may function primarily as a mechanism of female choice, aiding a female in assessing the quality of males in hei mating aggregation while helping to ensure that maximal high quality spermatozoa will be available at the proper time for fertilization.     

Competition and cooperation: bumblebee spatial organization and division of labor may affect worker reproduction late in life

Within-group conflict may influence the degree to which individuals within a group cooperate. For example, the most dominant individuals within a group often gain access to the best resources and may be less inclined to perform risky tasks. We monitored space use and division of labor among all workers in three colonies of bumblebees, Bombus impatiens, during the ergonomic and queenless phases of their colony cycle. We then measured the two largest oocytes in each worker to estimate each individual's reproductive potential at the end of the colony cycle. We show that workers that remained farther from the queen while inside the nest and avoided risky or more energy-expensive tasks during the ergonomic phase developed larger oocytes by the end of the colony cycle. These individuals also tended to be the largest, oldest workers. After the queen died, these workers were more likely than their nestmates to increase brood incubation. Our results suggest that inactive bumblebees may be storing fat reserves to later develop reproductive organs and that the spatial organization of workers inside the nest, particularly the distance workers maintain from the queen, may predict which individuals will later have the greatest reproductive potential in the colony.     

Tests of the mate-guarding hypothesis for social monogamy: does population density, sex ratio, or female synchrony affect behavior of male snapping shrimp (Alpheus angulatus)?

There are at least two mechanisms by which social monogamy in the absence of biparental care may evolve: as a form of territorial cooperation, in which one or both sexes benefits by sharing a territory with a partner, and as a form of extended mate guarding, in which males guard females through entire, and perhaps multiple, reproductive cycles. I examined the effects of population variables (density, sex ratio, female synchrony) on male pairing behavior in the snapping shrimp, Alpheus angulatus, to test the hypothesis that social monogamy in this genus has evolved as a result of selection on males for long-term mate guarding of females. There was no evidence that pairing behavior changes with differences in population density; in a natural population, there was a 1:1 relationship between the number in pairs and local population density. In a laboratory experiment, males altered their pairing behavior in response to manipulated differences in sex ratio. Males in female-biased sex ratios were significantly more likely to abandon recently mated females than males in equivalent sex ratios, though there was no significant difference in the duration of pairing or the number of times males switched females. Observations of shrimp maintained for an extended period in the laboratory revealed no evidence that females molt and become sexually receptive synchronously, which would reduce the likelihood that a searching male would encounter additional receptive females. These data suggest that sex ratio may have contributed to the evolution of social monogamy in snapping shrimp, but provide no evidence that population density or female synchronous receptivity have contributed to the evolution of social monogamy.     

Sexual conflict over fertilizations: female bluethroats escape male paternity guards

Extra-pair copulations create a potential for sexual conflict in pair-bonding birds. Here we report an experimental study of the bluethroat, Luscinia s. svecica, in which the throat ornament of males was blackened with Nyanzol D in order to reduce their sexual attractiveness and thus increase the sexual conflict over fertilizations. In an earlier study, we showed that males blackened before pairing had a lower success in attracting social mates than controls, whereas males blackened after pairing guarded their mates more intensely and sang less than controls. Here we add behavioural data from one more year on males blackened after pairing and corroborate our previous finding that the manipulation caused males to guard their mates more intensely and advertise less for additional mates. Blackened males did not suffer more intrusions from neighbouring males than did controls. Paternity analyses of the combined data set, using multilocus DNA fingerprinting and microsatellite typing, revealed that blackened males lost significantly more paternity than controls. There was also a tendency for blackened males to show a lower success in achieving extra-pair fertilizations. These results indicate that females have the upper hand in the sexual conflict over fertilizations, as females paired with unattractive males can achieve more extra-pair paternity despite the greater constraint posed by the intensified mate guarding. Still, within the blackened group, there were some indications that males guarding more intensely and singing less had higher paternity than males guarding less and singing more, suggesting a marginal positive effect of guarding for unattractive males. Male mate guarding must nevertheless be considered a best-of-a-bad-job strategy in this species. Received: 4 December 1997 / Accepted after revision: 14 June 1998     

Polygyny and male parental care in Savannah sparrows: effects on female fitness

Summary To determine the effects of male mating status on female fitness, we compared the reproductive success, survival, and future fecundity of female Savannah sparrows (Passerculus sandwichensis) mated to monogamous vs. polygynous males in a 5-year study on Kent Island, New Brunswick, Canada. The proportion of males with more than one mate varied from 15 to 43% between years and sites. Polygynous and monogamous males fledged young of equal size in every year of the study. Females who shared paternal care with other females laid as many eggs per clutch and clutches per season as monogamously mated females. In most years polygynously mated females showed no delay in laying a second clutch, and they suffered no reduction in fecundity the following year. Recruitment of a female's offspring into the breeding population was generally independent of her mating status. Fitness costs of being mated to a polygynous male were only apparent in one year of the study, during which females mated to polygynous males had higher over-winter mortality than those mated to monogamous males. That same year, young raised by polygynous males were only one-third as likely to survive to reproductive maturity (as inferred by returns) as those raised by monogamous males. A male's mating status had no effect on his own survivorship. A male's mating status did not necessarily reflect his contributions to raising nestlings, which may partially explain why monogamously and polygynously mated females had equal fitness. At 35 nests the proportion of food deliveries brought by individual males varied from 0 to 75%; on average, males brought fewer than 30% of all food deliveries. Yet parental care by polygynous males was no less than that of monogamous males, at least at the nests of their primary females. Secondary females tended to receive less male assistance during the nestling stage, but their reproductive success was indistinguishable from that of primary females. Females feeding young without male assistance made as many food deliveries/h as did pairs in which males brought at least 30% of all food deliveries. Unassisted females did not suffer diminished fledging success or produce smaller fledglings. The benefits of polygyny for male Savannah sparrows are clear: polygynous males recruit more surviving offspring into the breeding population than monogamous males. The fitness of females, on the other hand, appears to be unaffected by whether their mate was monogamous or polygynous except in occasional years. Polygyny may be maintained in this population by the constraints of a female-biased sex ratio, the inability of females to predict a male's paternal care based on his morphology or behavior, the poor correlation between a male's mating status and his assistance at the nest, and inconsistent natural selection against mating with a polygynous male. Correspondence to: N.T. Wheelwright     

Singing onstage: female and male common nightingales eavesdrop on song type matching

In bird communication, listening individuals may obtain information on the quality and motivation of a male not only from solo-singing, but also from song interactions and listeners base their future decisions in territorial and mating contexts on such public information. Eavesdropping on male interactions may thus have a strong influence on sexual selection. In singing interactions, temporal coordination (e.g. overlapping vs. alternating) of two singers as well as structural interaction patterns (e.g. song type matching or repertoire matching) have been described, but the latter is far less studied. By conducting dual-speaker playback experiments with common nightingales Luscinia megarhynchos, we simulated an interaction where one singer was repeatedly song–type matching his counterpart. Playbacks were broadcast to male and female nightingales, and their approach behaviour and singing responses (in the case of male focals) were analysed. We found that both, males and females, spent more time with the matched bird, whereas males additionally sang more songs towards the matching bird. This can be taken as strong hint that eavesdropping occurs in nightingale communication and that listening to male vocal contests might be an important strategy for both sexes to adjust their behavioural output. With regard to the function of song matching, we assume that song-matching is not an aggressive signal per se in nightingales. We rather conclude that vocal leaders within an interaction, here the matched bird, may elicit stronger responses in conspecifics than vocal followers, here the matching bird.     

Food abundance affects energy intake and reproduction in frugivorous female Assamese macaques

In most mammals, female fertility and reproduction are strongly influenced by nutritional status and, therefore, by foraging conditions. Here, we investigate the relationship between food resources, feeding competition, energy intake and reproduction in a group of wild female Assamese macaques (Macaca assamensis) in northeastern Thailand. Over 2,100 h of data on feeding behaviour, energy intake and activity budgets were combined with data on resource characteristics, female reproduction and physical condition. We found that an increase in food availability had a positive effect on female energy intake and conception rates. In addition, it appeared that females incurred energetic costs during lactation and that females with a better physical condition during the mating season were more likely to conceive. The annual birth season occurred a few months before the annual peak in food availability, causing peak lactation to coincide with a period of high food availability. This suggests that females use the increased food abundance to compensate for the energetic costs of lactation. Neither energy intake rates nor activity budgets were influenced by female dominance rank, even during periods when the levels of contest competition were predicted to be high. In line with this, we found no evidence for rank-related differences in reproduction. The apparently limited influence of feeding competition in female Assamese macaques adds to the debate on the extent to which patterns in feeding competition and fitness can reliably be predicted based on ecological conditions. We suggest that this may partially be resolved by including potential competition-reducing mechanisms into the predictive framework.     

Sequestration of plant secondary compounds by butterflies and moths

Summary A number of aposematic butterfly and moth species sequester toxic substances from their host plants. Some of these insects can detect the toxic compounds during food assessment. Some pipevine swallowtails use aristolochic acids among the host finding cues during oviposition and larval feeding and accumulate the toxins in the body tissues throughout all life stages. Likewise, a danaine butterfly,Idea leuconoe, which sequesters high concentrations of pyrrolizidine alkaloids in the body, lays eggs in response to the specific alkaloid components contained in the apocynad host. Insect species sharing the same poisonous host plants may differ in the degree of sequestration of toxins. Two closely ralated aposematic geometrid moth species,Arichanna gaschkevitchii andA. melanaria, sequester a series of highly toxic diterpenoids (grayanotoxins) in different degrees, while a cryptic geometrid species,Biston robstus, does not sequester the toxins, illustrating the diversity in adaptation mechanisms even within the same subfamily. By contrast, a number of lepidopteran species store the same compounds though feeding upon taxonomically diverse plant species. A bitter cyanoglycoside, sarmentosin, was characterised from several moth species in the Geometridae, Zygaenidae and Yponomeutidae, and from the apollo butterflies,Parnassius spp. (Papilionidae), although each species feeds on different groups of plants.Interspecific similarities and differences in life history and ecology are discussed in relation to variable characteristics of sequestration of plant compounds among these lepidopteran insects.