Male mate choice favors more colorful females in the gift-giving cabbage butterfly

While the phenomenon of male mate choice has attracted considerable attention in the last two decades, whether this sexual selection mechanism could drive the evolution of female ornaments remains poorly understood. Here, we used experimental manipulation of female wing coloration to investigate male mate choice in Pieris rapae, a gift-giving butterfly. Further, we tested whether males’ nutritional status influenced their mating preferences by subjecting larvae to short periods of starvation. We found that males showed significantly more mating approaches toward control females with more colorful wings (higher pteridine content), and that this preference was strongest in low-nutrition males. Additionally, a study of field-collected females revealed that pteridine-based wing coloration was positively correlated with female egg load, which suggests such ornaments may signal female quality. Pteridine-based ornaments are widespread in nature, however their potential as honest signals in male mate choice remains largely unexplored. This work furthers our understanding of how male mate choice and female ornamentation may evolve in species whose mating systems include nutritional nuptial gifts.     

Sperm economy and limitation in spiny lobsters

Sperm limitation, when female fertilisation success is constrained by the supply of sperm, is generally perceived to be an uncommon feature of reproduction in species which directly transfer gametes during copulation. Male size, previous copulations, and the balance of expected reproductive return and future mating opportunity may, however, limit the amount of sperm males transfer to females. We used laboratory experiments where mate size could be manipulated and its consequences on spermatophore size and clutch size determined, to show that in two genera of spiny lobsters (Crustacea: Palinuridae) male reproductive output limits the size of clutches brooded by females. In Panulirus argus from the Florida Keys, we show that while male size affects spermatophore area, males also vary the amount of ejaculate positively with female size. Furthermore, the area of the spermatophore has a greater influence than female size on subsequent clutch weight. In Jasus edwardsii from New Zealand, female size, male size and mate order all affect clutch weight. In both species, clutches fertilised by small males in the laboratory are significantly smaller than clutches fertilised by large males. These results suggest that to ensure they receive sufficient sperm, females should either mate several times prior to oviposition, mate as early as possible in the reproductive season, or choose large, preferably unmated males as partners and thus compete with other females for preferred males. Sperm-limited female fecundity has the potential to limit the egg production of fished populations where large males are typically rare. Received: 18 May 1998 / Received in revised form: 20 November 1998 / Accepted: 30 November 1998     

Male genital length and mating status differentially affect mating behaviour in an earwig

Phenotypic variation in male genitalia may affect copulation behaviour, which can have important fitness consequences for males. Male genitalia commonly possess traits that increase male control over copulation, but in species where females control mating, a poor functional understanding often prevents insight into the processes responsible for such effects. Here, I investigate the effect of male genital length on copulation behaviour in the earwig Euborellia brunneri, where both sexes exhibit extremely elongated genitalia that correspond in shape. This model system is particularly suitable because pairs mate repeatedly and females can limit both the number and duration of copulations. I used both virgin and mated males and females in a double-mating design because longer male genitalia confer benefits in sperm competition. Consistent with a greater predicted male mating effort in mated females, the duration of individual copulations increased, but this traded off against mating frequency as cumulative mating duration remained unchanged. In contrast, male genital length increased both individual and cumulative mating duration, regardless of mating status. This difference suggests that, while males may modify copulation duration in response to mating status, females facultatively adjust mating frequency to prevent mating excessively or express preferences for increased male genital length. Notably, this study demonstrates that male genital phenotypes that are successful in sperm competition also enjoy female-mediated mating benefits.     

Sex-specific reproductive behaviours and paternity in free-ranging Barbary macaques (Macaca sylvanus)

In a wide variety of species, male reproductive success is determined by contest for access to females. Among multi-male primate groups, however, factors in addition to male competitive ability may also influence paternity outcome, although their exact nature and force is still largely unclear. Here, we have investigated in a group of free-ranging Barbary macaques whether paternity is determined on the pre- or postcopulatory level and how male competitive ability and female direct mate choice during the female fertile phase are related to male reproductive success. Behavioural observations were combined with faecal hormone analysis for timing of the fertile phase (13 cycles, 8 females) and genetic paternity analysis (n = 12). During the fertile phase, complete monopolisation of females did not occur. Females were consorted for only 49% of observation time, and all females had ejaculatory copulations with several males. Thus, in all cases, paternity was determined on the postcopulatory level. More than 80% of infants were sired by high-ranking males, and this reproductive skew was related to both, male competitive ability and female direct mate choice as high-ranking males spent more time in consort with females than low-ranking males, and females solicited copulations mainly from dominant males. As most ejaculatory copulations were female-initiated, female direct mate choice appeared to have the highest impact on male reproductive success. However, female preference was not directly translated into paternity, as fathers were not preferred over non-fathers in terms of solicitation, consortship and mating behaviour. Collectively, our data show that in the Barbary macaque, both sexes significantly influence male mating success, but that sperm of several males generally compete within the female reproductive tract and that therefore paternity is determined by mechanisms operating at the postcopulatory level.     

Polyandrous female butterflies forage for matings

Butterfly mating systems exhibit great variation and range from strict monandry to strong polyandry. During mating males transfer ejaculates containing both sperm and accessory substances to females. In the polyandrous green-veined white butterfly, Pieris napi (Lepidoptera, Pieridae) these ejaculates average 15% of male body mass, but can represent up to 23% of body mass for individual males. Hence, mating is costly to males, and recently mated males increase copula duration but decrease ejaculate mass transferred to females. Substances transferred to females during mating are later incorporated into female soma and reproductive tissues, and multiply mated female butterflies have higher lifetime fecundity, lay proportionately larger eggs, and live longer compared to once mated females. Here we report that females of P. napi allowed to mate at liberty with recently mated males only (i.e. males that delivered a small ejaculate) increased their lifetime number of matings compared to females allowed to mate with virgin males only (i.e. males that delivered large ejaculates), the former group mating on average 5.1 times (range 2–10) and the latter group mating on average 2.8 times (range 1–4). The lifetime fecundity of the two groups of females did not differ significantly. Because nutrient donation from males is essential for females to realize their potential fecundity, we conclude that females of the polyandrous green-veined white actively forage for matings.     

Female seed beetles, <Emphasis Type="Italic">Callosobruchus maculatus,</Emphasis> remate for male-supplied water rather than ejaculate nutrition

Female seed beetles, Callosobruchus maculatus, mate multiply even though association with males and copulations carry costs, such as injury to the genital tract. Multiple mating (polyandry) may, however, offset these costs through the acquisition of food and water, two material benefits hypothesized to be obtained from the large ejaculates produced by males. The material benefits hypothesis can be tested by increasing female access to nutrients and water, with the prediction that female mating frequency will decrease as copulation is no longer required to derive these materials. Females were given water, 5% sugar–water or baker’s yeast, and were compared with females deprived of these. We presented females with virgin males daily for 8 days and recorded female mating frequency, survivorship, and fecundity. Females provided with water and sugar–water decreased mating frequency. Thus, water, rather than nutrients in the ejaculate, appears to be important to females of this species. In addition, both life span and fecundity were extended for females in the sugar–water and water treatments. Since water is scarce in the arid environment in which this species is found, we conclude that polyandry provides material benefits to females that may offset some of the costs of associating with males.     

Different ejaculate delivery strategies in first versus subsequent matings in the swallowtail butterfly Papilio machaon L.

Summary Evidence suggests that males incur costs in producing ejaculates. Therefore some discrimination should be expected with respect to their pattern of allocating ejaculates. In a laboratory study, males of the European swallowtail butterfly Papilio machaon were mated with conspecific virgin females up to six times. The weight of the spermatophore and of the accessory substances delivered by males, the duration of mating, and the number of sperm in ejaculates were measured. The weight of the first spermatophore was related to male weight but that of accessory substances was not. The weight of the spermatophore delivered by males upon remating was always less than that of the first spermatophore. Second spermatophores Produced by males were smallest when delivered on the day after the first mating and increased asymptotically to about half the initial size with time elapsed since the first mating. Copula duration was highest for males remating on the day after the first mating but decreased to the duration of the first mating for males that were remated on the third day after the first mating or later. The weight of accessory substances delivered by males and the number of sperm in ejaculates were also higher in first matings compared to all subsequent matings. Both of two males that were handpaired on three consecutive days after the first mating produced a cumulative ejaculate mass equalling that transferred at the first mating. Thus the fact that males delivered smaller ejaculates upon remating on the third day after the first mating or later requires explanation, especially in view of the fact that copulations were not prolonged. We argue that the male ejaculate delivery strategy in mildly polyandrous species should be to mate for the first time with virgin females, when a maximum size ejaculate should be delivered, and then to maximize the number of matings. The rationale behind the male shift towards smaller ejaculate sizes delivered at subsequent matings is that: (1) the size of the ejaculate that can be produced is dependent on the time elapsed since the last mating; (2) the abundance of virgin females decreases as the flight season proceeds; and (3) there is an inverse relationship between the size and number of ejaculates that a male can produce in his life-time.     

Effects of mating history on ejaculate size, fecundity, longevity, and copulation duration in the ant-tended lycaenid butterfly, Jalmenus evagoras

The mating system of the Australian lycaenid butterfly, Jalmenus evagoras, is highly unusual compared to most other Lepidoptera. Characteristics of this system, which has been termed an ’explosive mating strategy,’ include the formation of an intensely competitive mating aggregation of males, a highly male biased operational sex ratio, a lack of discrimination and mate choice by both sexes, a high variance in male mating success, and female monogamy. In this study, we tested the hypothesis that multiple mating by males imposes physiological costs resulting in smaller spermatophores, and that this results in a fitness cost to females. We found that male J. evagoras transferred only 2.2% of their eclosion weight during their first mating, consistent with the hypothesis that males of monandrous species produce a relatively small investment. The wet weight of the ejaculate declined by an average of 27% at the second mating and the dry weight by 29%, and an intermating interval of 5–9 days was needed for the ejaculate to return to the size at the first mating, regardless of male size or age. Wet ejaculate mass increased proportionally with male size, though dry mass was proportionally larger in smaller males. Ejaculate mass tended to increase with male age at both first and second matings. Female characteristics, in general, did not affect ejaculate mass, although the wet weight of the ejaculate was positively associated with female weight at the second mating. Copulation duration increased from 2.4 h to approximately 3 h at the second mating, and to over 4 h at the third and fourth matings. Fecundity was positively correlated with female size but not with mating history, copulation duration, or any other characteristics measured for either males or females. Female longevity declined significantly as the number of times the male partner had previously mated increased. We conclude that despite the small male investment in ejaculate, the costs of multiple mating may nonetheless be significant, as indicated by the reduction in ejaculate mass, an increase in copulation duration, and reduction in female lifespan with increasing mating number. Received: 22 January 1999 / Received in revised form: 28 July 1999 / Accepted: 18 September 1999     

Polyandrous mating in treetops: how male competition and female choice interact to determine an unusual carnivore mating system

The diversity of mammalian mating systems is primarily shaped by sex-specific reproductive strategies. In the present study, we explored determinants and consequences of a unique mating system exhibited by fossas (Cryptoprocta ferox), the largest Malagasy carnivore, where females mate polyandrously on traditional mating trees, and males exhibit intrasexual size dimorphism. Males face both contest and scramble competition, and inter-sexual size dimorphism can be pronounced, but its magnitude depends on the male morph. Using a continuous behavioral observation of six estrous females over 4 years, we investigated correlates of male contest competition and female choice based on 316 copulations. Furthermore, we assessed correlates of male scramble competition based on testes size and movement data obtained from GPS tracking. We found that females dominated males regardless of their smaller size and that females actively solicited copulations. Heavy males had highest mating success during the female’s peak mating activity, but were discriminated against afterwards. Female choice and male–male competition thus converged to generate a mating advantage for heavier males. Our results suggest that females actively seek polyandrous matings, presumably for indirect genetic benefits. Since body mass is the major determinant of male mating success and is at the same time dependent on the degree of sociality and associated hunting mode of the respective male morph, a male’s feeding ecology is likely to influence its reproductive tactic. A combination of benefits from female polyandry and the consequences of different subsistence strategies may thus ultimately explain this unusual mating system.     

No cost of male mating experience on female reproductive success in the almond moth, <Emphasis Type="BoldItalic">Cadra cautella</Emphasis> (Lepidoptera; Pyralidae)

Male copulation experience may have a profound impact on female reproductive success if male reproductive investment declines over consecutive copulations and if females are unlikely to re-mate. Male reproductive investment is particularly interesting in lepidopterans because males produce dimorphic sperm: a fertilizing (eupyrene) and a non-fertilising (apyrene) sperm. In two experiments, we explored the lifetime reproductive investment of male almond moths, Cadra cautella (also known as Ephestia cautella) and examined its influence on female reproductive success. In the almond moth, females re-mate infrequently and males transfer sperm in a spermatophore. Attached to the spermatophore is a large chitinous process, the function of which is unknown. One group of males were permitted consecutive copulations with virgin females and the amount of sperm and size of the spermatophore transferred were compared for all females. We found that the number of both eupyrene and apyrene sperm per ejaculate decreased with his increased mating frequency, while the size of the spermatophore process decreased dramatically after the male’s first copulation. In a second experiment, we allowed males to mate with females throughout their lives and then compared female fecundity and fertilisation success. We found no obvious decrease in female fecundity and fertilisation success with increased male copulation experience, despite the likely reduction in male gametic investment. We discuss potential explanations for the development of this enlarged and elaborate first spermatophore of male almond moths given that it confers no clear fitness advantage to females.     

Indirect fitness benefits are not related to male dominance in a killifish

Recent theoretical and empirical studies have shown that male dominance is often at odds with female mate preference and that indirect (genetic) benefits of mate choice may not be related to male dominance. We tested whether female preference corresponded to male dominance and whether mating with dominant males conveyed benefits to offspring fitness in a small freshwater fish, the African annual killifish Nothobranchius korthausae (Cyprinodontiformes), a species without parental care. The experimental design used controlled for the effect of male age, possibility of sperm and egg depletion, and accounted for a potential that females express their preference through maternal effects by manipulation of egg mass during ovulation. By sequentially mating females with males of known dominance, we found that female N. korthausae showed no mate preference in terms of egg numbers deposited with respect to male dominance or body size and no congruent mate preference to specific males was detected. However, males sired offspring with consistently higher hatching success and the effect was repeatable across individual females. Thus, some males provided females with indirect benefits related to additive genetic quality (“good genes”) and expressed via increased hatching rate, but this benefit was not related to male dominance status or body size.     

Copulation duration and sperm competition in white-faced dragonflies (Leucorrhinia intacta; Odonata: Libellulidae)

Summary In many odonates, females mate with more than one male while laying a single clutch of eggs. We studied paternity of eggs laid by remated females of Leucorrhinia intacta, a small libellulid dragonfly, at a pond near Syracuse, NY, USA. The probability of a female remating is a function of male density on the pond. The length of copulations differs considerably among males active on the study pond at the same time. Much of this variation was correlated with differences in mating tactics of the males; copulations by males that stayed on their territories during copulation were shorter than those by other males (Fig. 2). Eggs collected from females mated to irradiated, sterile males and to free-living, fertile males indicated that the average paternity expectation was higher for long than for short copulations, and that the variance in paternity expectation was lower for long than for short copulations. Some possible causes of the high variation in paternity at low copulation durations and possible reasons for differences in copulation duration between male mating tactics are discussed.     

Coalitionary mate guarding by male chimpanzees at Ngogo, Kibale National Park, Uganda

Cooperative mate guarding by males is unusual in mammals and birds, largely because fertilizations are non-shareable. Chimpanzees live in fission-fusion communities that have cores of philopatric males who cooperate in inter-group aggression and in defending access to the females in their community. Male contest mating competition is restrained within communities, but single high-ranking males sometimes try to mate guard estrous females. Data from an unusually large chimpanzee commmunity at Ngogo, Kibale National Park, Uganda, that contains more males than any previously studied community show new variation in chimpanzee mate-guarding behavior. Contrary to expectation given the large number of males, mate guarding was as common as, or more common than, at other sites, and males other than the alpha male guarded more often. More strikingly, pairs or trios of top-ranking males sometimes engaged in cooperative aggression to prevent estrous females from mating with other males, but tolerated each other's mating activities. Both single males and coalitions mostly guarded periovulatory females. Mate-guarding coalitions were previously unknown in chimpanzees. Coalitions occurred in large mating parties, seemingly because these often contained too many males for single males to maintain exclusive access to estrous females. Coalition members gained higher shares of copulations than they could have expected from solo mate guarding, and suffered lower per capita costs of guarding (as inferred from aggression rates). Two males who most often participated in coalitions formed two-male coalitions at about the point where the number of males present made it unlikely that either could get 50% or more of total copulations on his own, and formed trios when this value dropped below 33%. Kin selection could be a factor in cooperation among male chimpanzees, but coalition members were not necessarily close relatives and the apparent structure of payoffs fit that of mutualism. Furthermore, reliance of male chimpanzees on support from allies to maintain high rank could have led to trading of mating exclusivity for support against mating competitors. Received: 28 May 1997 / Accepted after revision: 16 May 1998     

Sexual coercion by male chimpanzees shows that female choice may be more apparent than real

The extent to which active female mating preferences influence male reproductive success in mammals is unclear, particularly for promiscuously breeding species like chimpanzees (Pan troglodytes). Previous studies from multiple long-term study sites have shown that female chimpanzees mate more restrictively around ovulation, and this has been taken as evidence for female choice. However, none of these studies rigorously evaluated the alternative hypothesis that restrictive mating results not from unconstrained choice, but in response to coercive mate guarding, in which males use punishment and intimidation to reduce female promiscuity and promote their own mating interests. Nor did they consider evidence for the potential genetic or phenotypic benefits that females might be choosing. Using 11 years of data from the Kanyawara community in Kibale National Park, Uganda, we previously demonstrated that males achieve elevated mating success with those females toward whom they direct high levels of aggression. Here we extend those findings to show that even female copulatory approaches, which have previously been attributed to female choice, are correlated with male aggression. Specifically, individual females at our site initiated periovulatory copulations most frequently with the males who were most aggressive toward them throughout their cycles. Those males showed high rates of aggression toward females throughout estrus, despite achieving high copulation rates, demonstrating a continuing conflict of interest over the exclusivity of mating access. Because sexual coercion is potentially widespread in primates and other mammals, our results stress the importance of considering the influence of male aggression in studies of female choice.     

A female preference for experienced males in the almond moth, Cadra cautella

Male mating status can affect female reproductive output if male ejaculate investment declines over consecutive matings. Accordingly, females are predicted to mate preferentially with virgin males. In mildly polyandrous lepidopterans, female fitness is less affected by reduced male investment than in more polyandrous species, and so the predictions for female mating preferences are less clear. We examined female mating preferences in the mildly polyandrous almond moth, Cadra cautella, in which ejaculate size does not affect female reproductive output. First, we allowed females to mate with virgin or once-mated males, in which the males were presented individually or simultaneously. We recorded the latency to mating and, in the case of the simultaneously presented trials, the identity of the successful, copulating male. We found that females mated more frequently with mated males (when simultaneously presented with both males), yet females did not differ in the time taken to initiate copulation with any male. We further examined if this mated male advantage was due to differential mate detection or locomotory behaviour of the male treatments. We tested the ability of virgin and mated males to locate a receptive female within a wind tunnel using long-distance pheromone cues and recorded their activity budget. We found no difference in the ability of mated or virgin males to locate or approach a receptive female, or in their activity levels. These data suggest a female preference for mated males in this species, a preference that may minimise other potential costs of mating.     

Costs of courtship and mating in a sexually cannibalistic orb-web spider: female mating strategies and their consequences for males

The costs of courtship and mating may include increased risks of predation, the transmission of pathogens, and a loss of foraging opportunities. Thus, a female's decision to tolerate a courting male will depend upon how these costs offset the benefits of mating, which will depend on her reproductive and nutritional status. While these costs may be similar for mated and unmated females, the benefits of mating will be less for mated than virgin females. However, the cost of lost foraging opportunities may be higher for females with fewer nutritional reserves necessary for forming eggs. We examined how these costs and benefits influence the courtship and mating behaviour of male and female orb-web spiders, Argiope keyserlingi. In the field, females on webs that also contained a courting male intercepted fewer prey items per hour than females on webs without a male. In the laboratory, the presence of a courting male at the hub also attracted mantid predators to the web, increasing the risk of predation for both male and female. Staged mating experiments in the laboratory revealed that the frequency of female attacks and pre-copulatory cannibalism was greater among mated than virgin females. Feeding history did not affect aggression in virgin females but, among mated females, food-deprived spiders attacked and cannibalized males more frequently than sated females and only the latter ever remated. These differences in female behaviour influenced male mating strategies. Choice experiments demonstrated that males preferred to venture onto the silk threads of virgin rather than those of mated females. Similar patterns of mate selectivity were observed in the field; females with narrow abdomens attracted more males to the webs than females with broad abdomens, and copulations were observed more frequently among females with narrow abdomens. These smaller females are likely to be virgins that have recently molted. Males that preferentially mate with virgin females will not only avoid potentially fatal attacks but also obtain, on average, a higher fertilization success.     

Mate preferences by male guppies (Poecilia reticulata) in relation to the risk of sperm competition

We investigated male mate preferences in relation to the perceived risk of sperm competition in the guppy (Poecilia reticulata), a freshwater fish with a promiscuous mating system. Our laboratory experiments revealed that male mate choice behaviour is not influenced by the presence of rival males that are merely in close proximity to a potential mate, as there was no significant difference in the amount of time that males spent with females that were recently either alone or in close proximity to four rival males. Male mate choice behaviour was, however, strongly influenced by the presence of rival males in a second experiment, where those rivals were permitted to copulate with one of the females. In that situation, males spent significantly more time with, and directed significantly more sigmoid courtship displays toward, females that they had recently seen alone compared to females they had seen receiving forced copulations from up to four rival males. Our results therefore indicate that male guppies are sensitive to the risk of sperm competition and alter their mate choice behaviour in an adaptive fashion.Communicated by K. Lindström     

Does female plumage coloration signal parental quality? A male removal experiment with the bluethroat (Luscinia s. svecica)

Females in several sexually dimorphic species with conventional sex roles possess ornamental traits that resemble those found in males. The evolution of such traits, however, is still poorly understood. Bluethroats (Luscinia s. svecica) are socially monogamous, sexually dichromatic passerine birds, in which female throat patch coloration varies from near absence to near full expression of male-like coloration. A recent study, demonstrating that male bluethroats prefer colourful females, suggests that female coloration is subject to sexual selection through male choice. However, the benefits males may gain from mating with colourful females have not yet been identified. In this study we tested the hypothesis that female coloration signals parental quality (the good-parent hypothesis). During the course of the same day, we recorded female care both in the presence and the absence of the male mate. The latter was done to eliminate the confounding effect of variable male care by removing the male temporarily. Female coloration did not correlate with female feeding rates either in the presence or in the absence of the male. Female feeding rates in the absence and the presence of the male were positively, although weakly, correlated. Female coloration did not correlate with female ability to compensate for the loss of male care, or with the change in brood mass during male removal. Therefore, there is no evidence for the good-parent hypothesis to explain female plumage coloration in bluethroats. Received: 4 March 1999 / Received in revised form: 14 October 1999 / Accepted: 23 October 1999     

Mating behavior of <Emphasis Type="Italic">Abdopus aculeatus</Emphasis> (d’Orbigny 1834) (Cephalopoda: Octopodidae) in the wild

The mating system of Abdopus aculeatus incorporates sneaker matings, mate guarding, sex-specific body patterns, frequent copulations, and male–male competition for mates, making it more similar to that of aggregating decapod cephalopods than any previously known octopus social system. Large male–female A. aculeatus occupy ‘Adjacent’ (G_A) dens and copulate frequently in mate-guarding situations over successive days. Nearby individuals copulate in ‘Temporary guarding’ (G_T) and ‘Transient’ (T; non-guarding) situations, the latter of which can involve ‘Sneaker’ (S) mating. In a focal animal study of these octopuses in the wild (Sulawesi, Indonesia) we addressed the hypotheses that they demonstrate: (1) precopulatory mate choice, (2) differential copulation rates by individuals employing different mating tactics, and (3) distant sex identification. We quantified daily copulation rates of A. aculeatus of reproductive size as well as aspects of copulation duration, display, mate-competition, and mate rejection. Mating tactic correlated with daily copulation rates. ♂G_A spent significantly more time copulating than did ♂T, while ♀G_A spent more than twice as much time per day in copula than did other females. Sneaker copulations lasted longer than those by males adopting other tactics. Mate-guarding was an effective and important tactic used by males to temporarily monopolize mating with apparently non-selective females. Males demonstrated clear pre-copulatory mate choice by guarding and mating repeatedly with large females (typically ♀G_A). While foraging alone away from the den, ♂G procured ‘Transient’ copulations with unguarded females. However, mate-guarding reduced the amount of time ♂G were alone and may impede their ability to seek out new mates. Low-copulation rates by ♀T, the smallest female tactic on average, may reflect this trade-off between mate preference and mate-searching by males, or non-receptivity of some females. A male-typical body pattern (black and white stripes) appeared to facilitate distant sex identification. Although mating and aggression were often initiated before contact between individuals, same-sex copulations and intense male–female aggression were rare. By contrast frequent male–female copulations and intense male–male aggression were consistent behavioral components of mating in A. aculeatus at these sites. Because the behavioral and ecological characters conducive to this complex system are not exclusive to A. aculeatus, it is possible that other octopuses exhibit some or all of these behaviors. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Bushcricket song as a clue for spermatophore size?

Bushcricket males of Poecilimon zimmeri transfer large and protein-rich spermatophores during mating, which females directly ingest. There is correlational evidence that heavier males transfer larger nuptial gifts. In no-choice mating trials, females mated randomly with respect to male’s body weight. In contrast, in two-choice mating trials, female bushcrickets exhibit clear choice for the heavier male. This heavier male advantage was also found in pre-mating choice during phonotaxis. With manipulated mute males, females mated at random with regard to body weight of the competitors. The number of physical encounters between a female and males was low in all tests with a single male (no choice) and greater in choice-tests with two competing males. The latencies to mate also differed significantly between treatments. The time mating pairs spent in precopula was short in experiments where the males could hear rivals and significantly longer in all other tests using either a single male or mute males. Thus, acoustic signalling in male bushcrickets seems to signal male body weight. A preference for heavier males may reflect a female’s preference for a larger spermatophore and therefore a greater direct benefit.