Mating Resets Male Cricket Aggression

An animal’s motivational state can significantly impact its behavior. We examined the effects of mating on the aggression of male Acheta domesticus crickets. Pairs of males were allowed to establish dominance and subordinance and were then physically separated. Subordinate males were then allowed to either copulate with a female or to have chemo-tactile contact with, but to not copulate with, a female. Less than 15 min after separation, all male pairs engaged in a second agonistic encounter. Subordinate males that copulated with females were significantly more aggressive toward their dominant partners than un-mated subordinate males. Many mated subordinates became dominant. Allowing a subordinate male to contact, but not copulate with, a female had a similar effect, suggesting that chemo-tactile cues from the female are sufficient to elicit this change in aggression.     

Status referents in long-tailed macaques (Macaca fascicularis): Precursors and effects of a female rebellion

The antecedents and consequences of a change in status in the female line have been documented in the course of an ongoing study of a captive colony ofMacaca fascicularis. A conjunction of two events appears to have been a cause of the timing. The first is the maturation of the eldest female offspring of the subordinate lineage, and the second the insertion of an intrauterine device into the mother of that lineage. These changes made these two females simultaneously sexual associates of the adult male, while the dominant female of the other lineage was still pregnant. In the course of these events the maturing sub-adult female of the subordinate lineage underwent the most dramatic change of status, eventually rising from the lowest position to that of alpha female. The complex changes which heralded this alternation in status are described in terms of the referent relations and alliances which were evolving in the group. The word “revolution” is reserved for a change in the type of social structure brough about by insurrection: rebellion occurs when insurrection changes the position of the individuals in a structure which is itself left unchanged -vide, Webster’s English Dictionary.     

A preliminary study on the social relationships in a semi-free ranging colony of sun-tailed monkeys (Cercopithecus solatus), a species recently discovered in Gabon

In 1984, a species of guenon endemic to Gabon was discovered: the sun-tailed monkey (Cercopithecus solatus). This species is difficult to locate and observe in the wild, and hence to date has been little studied. The Centre International de Recherches Médicales de Franceville (CIRMF), Gabon, houses the world’s only breeding colony ofC. solatus, on which eco-ethological investigations can be carried out in a semi-free ranging environment. The data reported here present the first results of observations on the social relationships of this colony and support the scant field observations available on this species, showing a basic social unit of one adult male and several females with their offspring. The resident male systematically repulses any second adult male in proximity to the group. A clear hierarchy exists among the females, with mature female offspring eventually acquiring a rank just below that of their mother.     

Female preference for dominant males in the Mexican mojarra cichlid fish,Cichlasoma istlanum

It is widely assumed that female preference and male competition operate simultaneously during sexual selection. Dominance is likely an honest indicator of male quality, and females can identify and choose the dominant male to reproduce with individuals with greater competitive abilities, thus improving the quality and competitiveness of their offspring. In this context, few studies have investigated female preference in relation to male fighting ability. The Mexican mojarra, Cichlasoma istlanum, is a cichlid species native to the Balsas River basin. It is territorial during reproduction and provides parental care. Males commonly engage in territorial defence, whereas females care directly for offspring. This study examined whether females prefer dominant males that exhibit more aggressive behaviour. The authors conducted experiments using groups of two males and one female to test competitive ability in males and female preference. They also quantified the time during which the female associated with the dominant male and the subordinate male after observing the outcome of a fight between the two males. They found that Mexican mojarra females preferred dominant males and that the time females spent associating with males was positively related with their aggressive behaviours during competition. These results indicate that dominant males were more attractive than subordinate males to female Mexican mojarra. The relationship between female preference and male dominance in the Mexican mojarra demonstrates the importance of male competitive ability for future parental care in reproduction.     

Reproductive suppression in female Alpine marmots, Marmota marmota

We studied mechanisms responsible for reproductive skew in female Alpine marmots. In each social group, only dominant females produced weaned young although subordinate females had similar body condition, were fertile as indicated by high levels of oestradiol during the mating season, and occasionally started pregnancies. During the period of gestation, dominant females initiated significantly more agonistic interactions against subordinate females, resulting in significantly increased levels of glucocorticoids and decreased levels of progesterone in subordinates. Results suggested that reproductive suppression in female Alpine marmots is mediated by the negative effects of stress (glucocorticoids) on the activity of the hypothalamic-pituitary-gonadal axis. The strength of competition between subordinate and dominant females was affected by their relatedness. Dominant females attacked unrelated subordinate females more, whereas amicable behaviour was observed mainly between dominant females and their daughters. These differences could be explained by differences in indirect fitness: related subordinate females benefited from warming the offspring of the dominant female during hibernation. Reproductive suppression was apparently costly for dominant females, because their reproductive success decreased as the number of adult subordinate females in a group increased. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Effect of mating frequency on fecundity and longevity of the predatory mite <Emphasis Type="Italic">Kampimodromus aberrans</Emphasis> (Acari: Phytoseiidae)

The effect of single versus multiple mating on longevity and fecundity as well as the number of matings required to maximize a female’s reproductive success of the predatory mite Kampimodromus aberrans Oudemans were studied under laboratory conditions. Newly emerged adult females of the stock colony of K. aberrans were placed individually on a bean leaf disc, and maintained at 25°C and 16:8 LD. A young male remained with a female for limited periods or continuously. Mating was a requisite for oocyte maturation and oviposition. Females which mated three to four times during their life and females in continuous presence of males, laid significantly and considerably more eggs than single-mated females. Virgin females lived the longest, and those in continuous presence of males the shortest. In all cases and irrespective of the number of matings, the sex ratio of the offspring was male-biased in the first three to four days of oviposition period, and female-biased in later days.     

The Effects of Clofentezine on Life-table Parameters in Two-spotted Spider Mite Tetranychus urticae

Sublethal effects of the growth inhibitor, clofentezine, on life-table parameters of Tetranychus urticae Koch females treated at different developmental stages with a concentration causing ≥90% mortality were investigated. Females which survived treatment as ‘early’ (0–24 h old) eggs produced 12% more offspring than the untreated females during the first five days of oviposition. This resulted in a significant rise in the intrinsic rate of increase (r _j ): 0.324, compared to 0.299 in the untreated females. This effect may be interpreted as hormoligosis. Clofentezine treatment at any other developmental stage of T. urticae significantly decreased both longevity and fertility of female survivors. Females which survived treatment either as ‘late’ (72–96 h old) eggs or larvae had 2.6 times lower net reproductive rate (R ₀) than the untreated females, and the r _j values were significantly lower: 0.242 and 0.215, respectively (0.285 in the untreated females). Females which survived treatment either as protonymphs or deutonymphs had 3.9 times and 6 times lower R ₀, respectively. Corresponding r _j values were 0.178 and 0.146, respectively (0.247 in the untreated females). The clofentezine treatment at all stages influenced the age distribution of survivors. The sublethal effects of clofentezine and their impact on T. urticae management are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spatial structure of chacma baboon groups

A method is presented for measuring the location of individuals with respect to the center or perimeter of a primate group. The method estimates an individual’s domain of danger: the area in which a hidden predator is closer to the individual than to other group members (cf. Hamilton, 1971). A domain is determined by the directions and distances of particular neighbors from a given individual. Animals at peripheral locations have relatively large domains, whereas animals at central locations have relatively small domains. Domains of danger were sampled for members of two groups of chacma baboons (Papio ursinus)in northern Botswana, to test for nonrandom spatial patterns throughout the day. Females with infants had significantly smaller domains than did females without infants. Domains also were correlated with social ranks of females;high-ranking females had smaller domains than did low-ranking females, possibly because high-ranking females were more likely to have infant offspring. For adult males, however,domain sizes were not significantly correlated with social ranks. Immigration status of adult males, rather than social rank, better accounted for spatial positioning.     

First occurrence of twins in provisioned free-ranging Tibetan macaques (Macaca thibetana) at Huangshan, China

A first case of newborn Tibetan macaque (Macaca thibetana) twins was observed in a free-ranging group at Huangshan, China. The female that gave birth to the twins was studied during their first 5 months post-partum, and her activity budget was compared to those of adult females with single or no offspring in order to assess her behavioral changes. Our report shows that female Tibetan macaques can produce twins, and that twins can successfully survive. The adult female with twins spent more time foraging and resting, but less time moving and engaged in other social behaviors than adult females with a single infant or no infant. Our report provides a case of successfully surviving twins in a wild environment and suggests that the mother modified her behavior patterns to adapt to the heavy burden. We conclude that both food provisioning and the mother’s behavioral strategies facilitated the survivorship of twins. This expands our understanding of the reproductive biology of Tibetan macaques.     

Female dominance rank and behavior during artificial menstrual cycles in social groups of rhesus monkeys (Macaca mulatta)

We recently reported (Michael & Zumpe: American Journal of Primatology 15:157–170, 1988) evidence for the hypothesis that copulations by pairs of rhesus monkeys are linked more closely to the ovulatory phase of the female's menstrual cycle when a male has access to several females in different cycle phases rather than access to females in the same cycle phase. We have now used data from this earlier study to assess the role of female dominance. Artificial menstrual cycles were induced with hormone injections in two of four ovariectomized females in eight social groups (each consisting of one male and four females). The artificial cycles were either synchronized or offset by 7-day increments. There were differences in the behavioral interactions of the higher-ranking (dominant) and lower-ranking (subordinate) hormone-treated females in each group. The amount of male sexual activity received by dominant and subordinate females differed little, but dominant females initiated significantly more sexual activity (P<.0001) than did subordinate females. Dominant females were significantly more aggressive (P<.0001) toward other females and received more direct and redirected aggression from males. Males generally initiated and maintained more social contacts with dominant than with subordinate females, and dominant females were less active than subordinates in initiating and maintaining social interactions with males. The findings provide new evidence for both female mate competition and mate choice by males for higher-ranking females.     

Social behavior of infant and mother Japanese Macaques (Macaca fuscata): Effects of kinship,partner sex,and infant sex

The behavioral interactions of 22 infant and mother Japanese macaques with other group members were studied. Focal-animal observations were made from the time of each infant’s birth until 1 year of age. Infants and mothers both displayed exceedingly strong preferences for associating with matrilineal kin and, specifically, for female kin. The degree of genetic relatedness was positively correlated with levels of spatial proximity, contact, grooming, aggression, and play. Overall frequencies of interactions with nonkin were very low, and partner sex was not an important factor in interactions with nonkin. There were no significant differences between male and female infants in interactions with kin versus nonkin. There was only one significant difference between male and female infants in interactions with males versus females: female infants showed stronger preferences for initiating proximity with females over males than did male infants. Because mothers provide the focal point for infant interactions during the first year of life, we compared the behavior of infants and mothers. Mothers were the recipients of more social interactions than were infants, mothers engaged in more grooming than did infants, and infants engaged in more social play than did mothers. These findings are only partially consistent with kin-selection theory, and the inadequacies of studying matrilineal kin discrimination to test kin selection are reviewed. The near-absence of infant sex differences in associations with social partners suggests that although maternal kin other than the mother are important to infant socialization, they probably do not contribute to the development of behavioral sex differences until after the first year of life.     

The Effects of Age and Previous Mating Experience on Pre- and Post-copulatory Mate Choice in Female House Crickets (<Emphasis Type="Italic">Acheta domesticus</Emphasis> L.)

Although females’ mating preferences are influenced by male characteristics, there are a number of factors intrinsic to females and unrelated to male phenotype that can modulate female choice. We assessed the effects of age and mating experience on mechanisms of pre- and post-copulatory mate choice in female house crickets, Acheta domesticus L., by randomly assigning males to females, but independently varying the age and number of previous matings of females at the time of experimental matings. Latency to mating, a measure of a female’s pre-copulatory preference, was influenced by female age at the time of mating, with older females mating sooner than younger females. The reduced selectivity of older females appears consistent with life-history theory, which predicts that the reproductive value of females should decline with age. The length of time that females retained the spermatophore after mating, a measure of a female’s post-copulatory mating preference, was not influenced by female age at the time of mating, the number of previous matings, or any interaction between the two main effects. Contrary to previous reports, male mass had no effect on either the latency to mating or female retention of the spermatophore in A. domesticus. We conclude that female age and mating experience can moderate female selectivity, but that their impact varies according to the mechanism by which females favor particular sires.     

Group composition affects male reproductive partitioning in a cooperatively breeding cichlid

Individuals within groups of cooperatively breeding species may partition reproduction, with the dominant pair often taking the largest share. The dominant's ability to reproductively control subordinates may depend on differences in competitive ability, due to, e.g. body size differences, but may also depend on the number of same‐sex competitors inside the group. We tested experimentally whether subordinates reproduce more when these subordinates are large or when a second subordinate of the same sex need to be controlled by the dominants, using the cooperatively breeding cichlid Neolamprologus pulcher. Dominant pairs were assisted by a large and a small unrelated subordinate; sexes of these fish were varied in a full‐factorial design (giving four treatments). Dominant males lost significantly more parentage to the large subordinate male when a small subordinate male was also present, compared to when a small subordinate female was present. However, subordinate paternity was generally low and did not significantly curb total dominant male reproductive output, which was more affected by the sizes and numbers of reproductive females present inside his group. Dominant female maternity, clutch sizes and total output did not depend on the treatments. Subordinate–subordinate reproduction was virtually absent (one out of 874 offspring). Female subordinates were more likely to provide care for their own broods. In contrast, male subordinates did not adjust their level of care to their parentage. Variability in female subordinate alloparental brood care was particularly high, with females showing more care than males in general. We also detected effects of growth rate and food ration on parentage independent of the treatments, most notably: (i) a trade‐off between dominant male growth rate and paternity; (ii) a decrease in dominant male paternity with increasing food ration; (iii) a positive effect of growth rate on paternity in small males. We conclude that dominant males should be sensitive to the number and sizes of subordinate males present in their group, particularly when these subordinates are not helpful or grow fast, and food is plentiful. Dominant females should be less sensitive, because female subordinates do not appear to impose reproductive costs and can be helpful through alloparental brood care.     

Host Selection by the Herbivorous Mite Polyphagotarsonemus latus (Acari: Tarsonemidae)

This study examined the host-selection ability of the broad mite Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae). To make long-distance-shifts from one host plant patch to another, broad mites largely depend on phoretic association with whiteflies. However, the host plants of whiteflies and broad mites are not necessarily the same. We determined the host-preference and acceptance of free-moving and phoretic broad mites using two behavioral bioassays. We used a choice test to monitor host selection by free-moving mites. In the case of phoretic mites, we compared their rate of detachment from the phoretic vector Bemisia tabaci placed on leaves taken from various host plants. The suitability of the plant was further determined by monitoring mite’s fecundity and its offspring development. We compared the mites’ responses to young and old cucumber (Cucumis sativus cv. ‘Kfir’) leaves (3rd and 8–9th leaf from the apex, respectively), and two tomato (Solanum lycopersicum cvs. ‘M82’ and ‘Moneymaker’). Free-moving mites of all stages and both sexes preferred young cucumber leaves to old cucumber leaves and preferred young cucumber rather than young tomato leaves, demonstrating for the first time that broad mites are able to choose their host actively. As for phoretic mated females, although eventually most of the mites abandoned the phoretic vector, the rate of detachment from the whitefly vector was host dependent and correlated with the mites’ fitness on the particular host. In general, host preference of phoretic female mites resembled that of the free-moving female. Cues used by mites for host selection remain to be explored.     

Longitudinal changes of dominance rank among the females of the Koshima group of Japanese monkeys

The changes of dominance rank among female Japanese monkeys of the Koshima group over a period of 29 years from 1957 were studied. The dominance rank order was relatively stable in the early population growing phase, while large scale-changes of dominance rank order occurred successively in the phase of population decrease brought about by the severe control of artificial feeding after 1972. Nevertheless, the rank order of several females of the highest status was stable. Furthermore, the reproductive success of these highest status females was high (Mori, 1979a;Watanabe et al., in prep.). Divergence of the dominance rank order fromKawamura's rules (Kawamura, 1958) was observed in the following respects: (1) Some females significantly elevated their rank depending on the leader males. (2) If mothers died when their daughters were still juveniles or nulliparous, the dominance rank of some of these offspring females was significantly lower than the mother's one. However 55% of daughters which lost their mothers at a young age inherited the mother's rank. (3) Dominance among sisters whose mother had died when at least one of the daughters was under 6 years old followed the rule of youngest ascendancy in 60% (Kawamura, 1958), and in 80% when both of the daughters were nulliparous at the mother's death. The mean rate of aggressive interactions for each female with subordinates to her was calculated by dividing the total aggressive interactions between the female in question and her subordinates by the number of subordinate females to the female in question. A female which showed a high rate of aggressive interactions with her subordinates was categorized as an “Attacker”, and a female showing a lower rate was categorized as a “Non-attacker”. Similarly, categories of “Attacked”, and “Non-attacked” were distinguished by using the rate of aggressive interactions with dominant females. Several females which were once categorized in one category in a year were repeatedly categorized in the same category over different years. The “Attacked” tended to be females of higher rank, and “Non-attackers” tended to be females of lower rank. “The second-higher-status females”, were “Attacked”, and their rank was unstable. In particular, females of lower rank within the lineage of the highest rank suffered this kind of severe status. Most of the daughters of these females showed a sharp drop of rank, and died when they were still at a young age, i.e. “the second-higher-status females” displayed low fitness. “Non-attackers” were significantly “Non-attacked”; i.e. they were females which showed a non-social attitude. Females which underwent a drop of rank tended to be “Non-attackers”. The most important factor which determined the females' rank was the memory of their dominance relations under the influence of their mother [dependent rank (Kawai, 1958)] in their early life during development. This finding corresponds well with the results in baboons obtained byWalter (1980); the target females of aggressive interactions by adolescent females were determined by the rank of the mothers when these adolescent females were born.     

First evidences of sexual selection by mate choice in marine zooplankton

Sexual selection is potentially important in marine zooplankton, presumably the most abundant metazoans on earth, but it has never been documented. We examine the conditions for sexual selection through mate choice and describe mating preferences in relation to size in a marine zooplankter, the pelagic copepod Acartia tonsa. Males produce spermatophores at a rate (~1 day⁻¹) much lower than known female encounter rates for most of the year and the decision to mate a particular female thus implies lost future opportunities. Female egg production increases with female size, and males mating larger females therefore sire more offspring per mating event. Similarly, females encounter males more frequently than they need to mate. Large males produce larger spermatophores than small males and the offspring production of female increases with the size of the spermatophore she receives. Additionally, large spermatophores allow females to fertilize eggs for a longer period. Thus, mating with large males reduces the female’s need for frequent matings and she may sire sons that produce more offspring because size is heritable in copepods. Finally, we show that both males and females mate preferentially with large partners. This is the first demonstration of sexual selection by mate choice in a planktonic organism.     

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.     

Decision making in grooming by Japanese macaques (Macaca fuscata)

I analyzed the temporal organization of individual Japanese macaques’ (Macaca fuscata) grooming sequences in 14 mothers and 13 offspring of different age/sex classes and 4 nonkin females. I hypothesized that preceding grooming affects subsequent grooming by the same individual. Grooming bouts were likely to be terminated as the bouts became longer when females groomed nonrelatives. Moreover, the duration of first bouts was longer than that of following bouts. These effects were also seen in grooming of mothers by their offspring > 1 year old and that of adult and adolescent female offspring by their mothers. In contrast, neither the duration of first bouts nor the number of preceding bouts had much effect on the occurrence or duration of subsequent bouts in any subject.     

Ranging Behavior and Possible Correlates of Pair-Living in Southeastern Avahis (Madagascar)

Researchers have proposed several hypotheses to explain pair-living in primates. In particular, when males are not involved in direct parental care, pair-living may be related to female dispersal, infanticide prevention, or male mate/resource defense. We aimed to evaluate, through a better understanding of the ranging patterns of avahis, which hypotheses may best account for pair-living in these nocturnal lemurs. We collected focal observations over 26 nights, June–September 2004, in a littoral forest (Sainte Luce, southeastern Madagascar) on 4 adult radiocollared avahis [Avahi laniger (Tattersall, I. (1982). The Primates of Madagascar. Columbia University Press, New York.) or Avahi meridionalis (Zaramody in Primate Reports 74:9–22, 2006)]. We followed 2 males and 2 females from 2 groups: B, a male-female couple, and A, comprising the parental pair and 1-yr-old female offspring. The adult females birthed in August. We recorded resting and feeding tree points (via global positioning system) for home range calculation through minimum convex polygon and kernel methods. We provide the first quantitative information on the ranging behavior of 2 male and 2 female avahis. Home range/daily path length values (means) are higher than the ones previously reported for the same and other folivorous pair-living lemur species. On average, the 2 females spent more time feeding and traveled shorter distances than the 2 males did. Male–female cohesion (mean values), possibly enhanced by offspring presence, was higher in A and after births than in B and before births, respectively. Although male avahis may be forced into pair-living owing to energy constraints related to size, locomotion, and diet, females might accept pair-living in exchange for indirect territory defense and mate guarding.     

A role of the Dufour's gland in the dominance interactions of the paper wasp,Polistes fuscatus (Hymenoptera: Vespidae)

The Dufour's gland of the paper wasp, Polistes fuscatus,is a source of the cues used by dominant females to recognize the eggs laid by subordinates or nonnestmates on pre (worker)-emergence nests. When dominant wasps were presented with an egg covered with either (1) the Dufour's gland extract of a subordinate cofoundress, (2) the extract of an egg from the same subordinate, or (3) the solvent alone, the dominant female destroyed and replaced the eggs covered with the Dufour's extract significantly more frequently than the other eggs. Eggs with the extract of a nonnestmate's Dufour's gland were also eaten significantly more frequently than those with the solvent. Given similar choices, subordinates did not destroy any eggs. The Dufour's gland appears to have little or no role in communicating dominance directly among aggressively interacting cofoundresses.