Morphological and physiological correlates of the colony foundation mode and reproductive role differentiation in <Emphasis Type="Italic">Belonogaster juncea juncea</Emphasis> (Vespidae,Polistinae)

A study on the reproductive status of Belonogaster juncea juncea individuals was conducted in Cameroon on 21 pre- and 15 post-emergence colonies. We compared the females’ size and ovarian development, and verified if they were inseminated or not. Dominant females were inseminated, had well developed ovaries, and were the largest individuals in pre-emergence colonies; in post-emergence colonies their size did not differ significantly from that of non-dominant females. Most subordinate females of both pre- and post-emergence colonies had thread-like ovaries, but a few had well developed ovaries. In pre-emergence colonies 13 subordinates had thread-like ovaries and several yellow bodies indicating that they had already laid eggs. We deduced that subordinates with well developed ovaries joined the foundations shortly before our study, while those with several yellow bodies had arrived some time before and their ovaries had regressed. At the end of the post-emergence phase appear non-dominant females with well developed ovaries. They are the future foundresses. Some females can disperse just after emergence and join a new foundation without mating. Nevertheless, most co-foundresses were inseminated when they joined the foundations, and so had the potential to reproduce, negating the hypothesis of swarm founding in B. j. juncea. Received 8 November 2006; revised 14 February 2007; accepted 16 February 2007.     

Male labial gland secretions and mitochondrial DNA markers support species status of Bombus cryptarum and B. magnus (Hymenoptera, Apidae)

Summary. Spring queens of Bombus cryptarum and B. magnus from 2 localities in Brandenburg/Germany and Scotland/United Kingdom respectively were determined by morphological characteristics. The lateral border of the collare at the border of the pronotallobus or at the episternum proved to be an especially useful character. Artificial colonies were reared from safely determined spring queens and the cephalic part of the labial glands of males from these colonies were investigated by GC/MS. The investigation identified approximately 50 compounds, as a mixture of straight chain fatty acid derivatives (alcohols, esters and hydrocarbons). The labial secretions of B. cryptarum and B. magnus are significantly different. Mitochondrial cytochrome oxidase 1 (CO1) of two queens from each locality and species were sequenced. Each species from the different localities formed a cluster. Sequence divergence between B. cryptarum and B. magnus was about 30 base substitutions and approximately 0.04 in Tamura-Nei genetic distance. Bombus cryptarum and B. magnus were closer to each other than to B. lucorum and made the sister group in the topology of the tree. Both the CO1 sequences and the labial gland secretions of males of B. cryptarum from Brandenburg and of males from artificial colonies reared from safely determined spring queens from Scotland are identical. B. cryptarum has thus, for the first time, been identified as part of the British bumble bee fauna. The differences of both the labial gland secretions, used as species recognition signals, and the genetic differences established by sequencing CO1 confirm the morphological findings that B. cryptarum and B. magnus are distinct taxa which should be treated as distinct species.Received 25 March 2004; revised 13 June 2004; accepted 15 June 2004.     

Nest-area marking with faeces: a chemical signature that allows colony-level recognition in seed harvesting ants (Hymenoptera, Formicidae)

Summary. Nestmate recognition systems in ants are largely based on chemical signals. The hydrocarbon fraction of the lipid layer which covers the insect cuticle plays a determinant role in this context. Here we report a novel extension of nestmate and alien recognition – nest area marking with faeces containing the same hydrocarbons as the cuticle of workers – in a harvesting ant, Messor capitatus. Workers of M. capitatus deposit large quantities of brown-yellow material from the hindgut (termed spots) in the vicinity of the nest. Behavioural investigation showed that such spotting behaviour has a communicative value in the context of nest area identification. Anal fluids deposited in the nest surroundings contain colony-specific cues which the ants use to recognize their own nest areas, and distinguish them from foreign areas even in the absence of nestmate or alien ants. Chemical analyses by gas chromatography-mass spectrometry (GC-MS) of the contents of anal spots, rectal sacs, and cuticular extracts revealed that all contain the same long-chained linear and branched hydrocarbons in varying proportions. Importantly, multivariate analyses showed that the relative proportions of these compounds on the cuticle and in spots are colony-specific. This provides a mechanism by which spot marking could be used by workers to define and recognize their colony area, and would represent a simple extension of the existing nestmate recognition template based on colonial cuticular signatures. The ecological and sociobiological implications of these findings are discussed.Received 3 February 2004; revised 10 June 2004; accepted 14 June 2004.     

Establishment of a free-ranging colony of stumptail macaques (Macaca arctoides): Social relations I

Data on the social behaviour of a free-ranging troop of Stumptail macaques are reported for a period starting of August 15th to November 7th of 1974. Positive interactions take a greater part in the daily life of the troop than negative interactions. Individuals order themselves in an essentially linear dominance hierarchy and offspring rank immediately below their mother. Agonism and displacement are good predictors of dominance rank. Dominant individuals are a strong source of attraction for subordinates and the alpha male is a powerful social magnet for immatures. Grooming was found to be correlated with dominance rank and individuals holding adjacent ranks tend to interact positively with one another. To gain access to dominant females, subordinates direct a great deal of positive behaviour to the female’s youngest offspring. As social distance decreases the selection of a social partner becomes more strict and tends toward adjacency. However, factors such as motherhood, genealogical ties, and special relationships with non adjacent individuals, can override the tendency. The direction and quantity of male-care displayed by the adult male and by juvenile males toward younger individuals was found to be influenced by the troop’s dominance patterns. Sex differences were found to exist in male-care received and a negative association was found with the age of the receiver. Adult females are the main regulators of social relations and their rank and friendships provide their offspring with the social format, before puberty, in which they develop socially. The alpha male is the group protector, the performer of policing, an important element in the immatures’ social development, and a powerful source of attraction for all troop members.     

Merging social hierarchies: Effects on dominance rank in male green swordtail fish (Xiphophorus helleri)

When the same set of individuals are placed in different social contexts, some groups members often experience a change in dominance status. We examined the context-dependence of social status using a group fusion protocol in male green swordtail fish (Xiphophorus helleri). Six individuals were matched for size and separated into two groups of three fish. Each triad established a stable hierarchy after which time the two subgroups were merged into one larger assemblage. The maintenance of within- and between-group rank relationships was examined. Relative rank was preserved within each subgroup across social contexts but we found no evidence that familiarity with dominant animals assists individuals of one subgroup in achieving higher rank (coat-tail effects). Dominant individuals from the pre-fusion groups were significantly likely to obtain high status in the merged group and vice versa for subordinate pre-fusion animals. These results demonstrate that social rank in swordtails is relatively impervious to changes in social context, but we address some deviations from this trend. Small differences in standard length were a significant predictor of the most dominant rank in the post-fusion hierarchy, with the largest animals tending to occupy the alpha position. We discuss our results in terms of the potential factors involved in within- and between-group rank maintenance, including individual recognition, winner and loser effects, or asymmetries in dominance-related characteristics.     

Social status in female bighorn sheep (Ovis canadensis): expression, development and reproductive correlates

Female bighorn sheep were studied over a 27-month period to quantify linearity and stability of social rank; expression of behaviour as a function of rank; development of rank relationships; and reproductive correlates of rank. Females exhibited a stable, non-linear hierarchy that correlated strongly with age. Dominant females used proportionally more threats, whereas subordinates used more subordinance patterns. Females integrated into the hierarchy at1–2 years of age and then fought their way to high social status. Dominant and subordinate females did not differ in pre-natal maternal investment, but dominant females nursed lambs at higher rates, and were more likely than subordinates to nurse alien lambs after their own lamb died.     

Morpho-physiological variability and differentiation of reproductive roles among foundresses of the primitively eusocial wasp, Belonogaster petiolata (Degeer) (Hymenoptera, Vespidae)

Summary: Pre-nesting foundresses of Belonogaster petiolata (Degeer) displayed a continuous variation in body size and ovarian development, wherein the majority (96%) of females possessed well-developed or developing ovaries. The latter indicates that most foundresses, including those that ultimately become subordinates in multiple-foundress colonies, have the potential to lay eggs when they first initiate or join nests. Relatively small differences in ovarian development between associated females at the start of the nesting season became pronounced over the course of the pre-emergence and early pre-matrifilial period concurrently with the differentiation of their roles as queens or subordinates. In pre-matrifilial colonies, ovarian development of queens was significantly greater than that of subordinates. Dominance rank and ovarian development among subordinates in pre-matrifilial colonies were not correlated, probably due to advanced ovarian regression in these females. The majority (96.5%) of foundresses from three successive nesting seasons were inseminated and would therefore have been capable of laying female-producing (i.e. worker- and queen-destined) eggs. Although queens of B. petiolata were not significantly larger than subordinates, they were the largest females in 41% of colonies. Similarly, #-foundresses were larger on average than %-foundresses. This indicates that body size may contribute to social and reproductive dominance, but is probably of secondary importance compared with hormonal and nutritional factors. These and previously published findings from B. petiolata suggest that the fitness benefits of associating with other foundresses during colony foundation may be largely mutualistic, and favoured by individual selection in addition to kin selection.     

Alpha male chimpanzee grooming patterns: implications for dominance “style”

In social primates, individuals use various tactics to compete for dominance rank. Grooming, displays and contact aggression are common components of a male chimpanzee's dominance repertoire. The optimal combination of these behaviors is likely to differ among males with individuals exhibiting a dominance “style” that reflects their tendency to use cooperative and/or agonistic dominance tactics. Here, we examine the grooming behavior of three alpha male chimpanzees at Gombe National Park, Tanzania. We found that (1) these males differed significantly in their tendency to groom with other males; (2) each male's grooming patterns remained consistent before, during and after his tenure as alpha, and (3) the three males tended to groom with high‐ middle‐ and low‐ranking partners equally. We suggest that body mass may be one possible determinant of differences in grooming behavior. The largest male exhibited the lowest overall grooming rates, whereas the smallest male spent the most time grooming others. This is probably because large males are more effective at physically intimidating subordinates. To achieve alpha status, a small male may need to compensate for reduced size by investing more time and energy in grooming, thereby ensuring coalitionary support from others. Rates of contact aggression and charging displays conformed to this prediction, suggesting that each male exhibited a different dominance “style.” Am. J. Primatol. 71:136–144, 2009. © 2008 Wiley‐Liss, Inc.     

Record of Eldana saccharina Walker (Lep,Pyralidae) in inland South Africa and its genetic relationship with the coastal population

Surveys to investigate the distribution and abundance of stem borers in natural habitats were conducted in February 2006 and January–February 2007. The surveys included eastern, northern and central parts of South Africa as well as three localities in Lesotho. During the surveys, Eldana saccharina Walker was recovered from three new localities in inland South Africa and two new indigenous hosts, Phragmites australis Cav. and Panicum maximum Jacq. from Boskop in the North‐West Province and Oribi Gorge in KwaZulu‐Natal respectively. Populations of E. saccharina in different parts of Africa are known for their differences in larval feeding behaviours, host plant choice and natural enemies. It is important to understand the origin of the newly recovered population for prevention of incursion and efficient management in case it invades crops. Molecular analysis indicated that the populations recovered in these new locations and from the new host plants are part of the southern African population of E. saccharina. With change in climate, and disturbance in wetlands the insect is expected in the future to be more abundant and problematic in inland areas of southern Africa.     

The role of cuticular hydrocarbons as chemical cues for nestmate recognition in the invasive Argentine ant (<Emphasis Type="Italic">Linepithema humile</Emphasis>)

Argentine ants (Linepithema humile) in their native South American range, like most other ant species, form spatially restricted colonies that display high levels of aggression toward other such colonies. In their introduced range, Argentine ants are unicolonial and form massive supercolonies composed of numerous nests among which territorial boundaries are absent. Here we examine the role of cuticular hydrocarbons (CHCs) in nestmate recognition of this highly damaging invasive ant using three supercolonies from its introduced range. We conducted behavioral assays to test the response of Argentine ants to workers treated with colonymate or non-colonymate CHCs. Additionally, we quantified the amount of hydrocarbons transferred to individual ants and performed gas chromatography-mass spectrometry (GC/MS) to qualitatively characterize our manipulation of CHC profiles. The GC/MS data revealed marked differences in the hydrocarbon profiles across supercolonies and indicated that our treatment effectively masked the original chemical profile of the treated ants with the profile belonging to the foreign individuals. We found that individual workers treated with foreign CHCs were aggressively rejected by their colonymates and this behavior appears to be concentration-dependent: larger quantities of foreign CHCs triggered higher levels of aggression. Moreover, this response was not simply due to an increase in the amount of CHCs applied to the cuticle since treatment with high concentrations of nestmate CHCs did not trigger aggression.The results of this study bolster the findings of previous studies on social insects that have implicated CHCs as nestmate recognition cues and provide insight into the mechanisms of nestmate recognition in the invasive Argentine ant. Received 6 February 2007; revised 31 May and 27 July 2007; accepted 16 August 2007.     

Epidermal structures and composition of epicuticular waxes of Sedum album sensu lato (Crassulaceae) in Balkan Peninsula

Sedum album is a succulent plant, with phenotypic variability resulting in delimitation of a number of taxa with diverse taxonomic recognition. We analyzed the taxa from Sedum album in broad sense (S. album, S. micranthum, S. athoum and S. serpentini) from Balkan Peninsula, to check whether the variability of their epidermal structures and epicuticular wax composition corresponds to their taxonomic reliability. Epidermal structures and epicuticular waxes were analyzed using light and scanning electron microscopy, gas chromatography-mass spectrometry and gas chromatography-flame ionization detector chromatography and multivariate statistical techniques. Analyses of studied taxa have shown that significant systematic characters include adaxial epidermal and guard cell length, stomatal frequency and subsidiary cells area on abaxial epidermis. The content of n-alkanes C₂₉, C₃₀, C₂₇, C₃₂ and C₃₃ was shown to be valuable criterion for their phytochemical delimitation. The comparison of epicuticular wax microstructures has shown no significant differences. Results indicate presence of two (micromorphology) or three (phytochemistry) well-defined groups of populations, with S. serpentini manifesting a considerable level of separation toward the others. Sedum athoum have shown weak to moderate degree of differentiation, while S. micranthum has shown general resemblance to S. album.     

Endochironomus tendens (F.) (Chironomidae,Diptera) an example of stasipatric speciation

Endochironomus tendens has been studied from different localities and geographically isolated populations. On the basis of the detailed karyotaxonomic analysis the investigated material can be divided into two forms. These forms are distinguished by their karyotype and phenotype. The results of the karologica and hybridization analysis showed that the differences between these forms lie only on the basis of microevolution differentiation of species, without being reproductively isolated. This is an example of stasipatric speciation-chromosomal aberrations having an adaptive value in a homozygous state are fixed in definitive localities of species range.     

Longitudinal stability in adult status hierarchies among vervet monkeys (Cercopithecus aethiops)

Status hierarchies were examined in a captive group over a 12-year period (1968–1979) to establish the stability and structure of vervet monkey dominance relationships. Dyadic records of spontaneous avoid, bite, chase, and supplant behaviors are summarized into a win/lose matrix to produce a rank order of status at the end of each calendar year. The 13,717 agonistic acts tabulated are drawn from both focal and ad lib data. Relative rank is computed by dividing the rank position of each individual by the number of individuals ranked for that year. Relative rank was found to be quite stable for adults of both sexes, although males were more variable than females. There was a strong matinrline effect on all captive born animals' rank position. No gender difference in rank was demonstrable. Infants were very subordinate at the end of their first year, but rose to positions near those of their mothers by the end of the fourth year. Presence or absence of canine teeth had no demonstrable effect on status. The results emphasize the relative importance of social learning in the establishment and maintenance of dominance relationships. The apparent gender difference in rank among wild living vervets is hypothesized to be a consequence of the male intergroup mobility. If a male is restrained from emigration, he is strongly affected by his mother's rank as he establishes his own dominance position in the troop.     

Juvenile hormone and the ontogeny of cockroach aggression

Our previous study [Kou et al., 2008. Juvenile hormone levels are increased in winners of cockroach fights. Horm. Behav. 52, 252–260] showed that the basic principle of the challenge hypothesis (hormone levels can respond to social stimuli to modulate aggression in vertebrates] could be applied to juvenile hormone (JH) levels and aggression in the lobster cockroach Nauphoeta cinerea. In that study, 80- to 85-day-old socially naïve males were used, as fighting is much more easily initiated in these older animals than in younger males, and JH III levels in the dominant were found to be significantly increased after an encounter compared to before the encounter and were significantly higher than those in the subordinates. In N. cinerea, newly emerged males usually show no aggressiveness towards each other and aggression is only initiated after several days of close contact. To investigate the development of aggression from an early age, in the present study, newly emerged males were paired to investigate the relationship between JH levels and aggression. The results showed that injection of JH III significantly increased the probability of the young males being fight winners. In each age group in which aggression was initiated, the dominants had significantly higher JH levels than either the subordinates or the same aged non-fighters. JH injection of subordinates on the day of rank establishment had no effect on the probability of rank switch. These results indicate that, (i) in newly emerged male pairs, JH plays a decisive role in rank establishment and the fact that dominant status is significantly associated with a higher JH titer and subordinate status with a lower JH titer is consistent with the basic principle of the challenge hypothesis, and (ii) after rank establishment, the lack of effect of JH treatment on rank change is consistent with the idea of “social inertia” in vertebrates.     

Dominance, aggression and physiological stress in wild male Assamese macaques (Macaca assamensis)

In group-living animals relative rank positions are often associated with differences in glucocorticoid output. During phases of social stability, when dominance positions are clear and unchallenged, subordinates often face higher costs in terms of social stress than dominant individuals. In this study we test this prediction and examine additional potential correlates of stress, such as reproductive season, age and amount of aggression received in wild, seasonally breeding Assamese macaques (Macaca assamensis). During a mating and a non-mating season we collected 394 h of focal observational data and 440 fecal samples of six adult and six large subadult males living in a multimale–multifemale group in their natural habitat in northeastern Thailand. The mating season was characterized by a general increase in aggressive behavior and glucocorticoid excretion across all males compared to the non-mating season. Among adult males, mating season glucocorticoid levels were significantly negatively related with dominance rank and positively with the amount of aggression received. Both relationships were non-significant among large subadult males. Thus, our results suggest that in adult Assamese macaques a high dominance position is not associated with high costs. Low costs of dominance might be induced by strong social bonds among top-ranking males, which exchange frequent affiliative interactions and serve as allies in coalitionary aggression against potentially rank-challenging subordinate males.     

Comparative analysis of micromorphological characters in two distantly related Mexican oaks, Quercus conzattii and Q. eduardii (Fagaceae), and their hybrids

Interspecific hybridization occurs with high frequency in the genusQuercus, but few studies have analyzed and compared micromorphological characters in putative parental species and their hybrids.Quercus eduardii andQ. conzattii are two Mexican black oak species that, although distantly related, have formed at least one population of hybrid origin, where individuals with intermediate macromorphology are present. The purpose of this investigation was to analyze the degree of differentiation in micromorphological characters between the two species and to assess the expression of these characters in individuals with intermediate macromorphology. Foliar trichomes, epicuticular waxes, stomata, and pollen grains, were examined using scanning electron microscopy (SEM) in the three types of individuals (Q. conzatti, Q. eduardii, and intermediates). Trichome density was quantified with light microscopy. Types of trichomes present, length of trichome arms, types of epicuticular wax on the leaf surfaces, and the position of stomata with respect to the foliar surface were characters useful to differentiate betweenQ. conzattii andQ. eduardii. Plants with intermediate macromorphology displayed a pattern of micromorphological characters that were identical to one parental species (Q. conzattii), or extreme or novel relative to both species.     

Juvenile hormone levels are increased in winners of cockroach fights

In lobster cockroach (Nauphoeta cinerea) adult males, concomitant expression of attack behavior and an increase in juvenile hormone (JH) III titer can be induced by contact with an isolated antenna [Chou et al., 2007. Antenna contact and agonism in the male lobster cockroach, Nauphoeta cinerea. Horm. Behav. 52, 252–260]. In the present study, socially naïve N. cinerea males that were either aggressive posture-adopting (i.e., “ready-for-fight”) or not (i.e., “non-ready-for-fight”) were paired to ask if status was determined by JH III levels before the encounter and if JH III levels were altered in dominants and subordinates after the encounter. The results showed that, although in the non-aggressive posture-adopting male pairs, the one with higher JH titers before the encounter was more likely to become the dominant, this was not the case in pairs formed between aggressive posture-adopting males or between non-aggressive posture-adopting and aggressive posture-adopting males. In all types of male pairs combined, JH III levels in the dominant were significantly increased after the encounter compared with before the encounter and were significantly higher than those in the subordinates, suggesting that the JH III increase in the dominants may serve to sustain aggression. JH III application before rank formation had a significant effect on establishment of dominant status in non-aggressive posture-adopting, but not aggressive posture-adopting, males. After rank formation, JH III application to subordinates had no effect on rank switch. These results indicate that the relationship between JH and aggression in this cockroach species is broadly consistent with the vertebrate challenge hypothesis, which predicts that testosterone levels increase in response to social stimuli to modulate aggression.     

Winter survival and breeding success of dominant and subordinate Willow Tits Parus montanus

We studied the effect of winter rank on survival rate and reproductive success in Willow Tits Parus montanus, a resident passerine living in dominance-structured flocks during the nonbreeding season, in 6 years. Winter survival was dependent on both the birds' age and rank. Adults survived better than first-year birds, and within first-year males, dominants survived better than subordinates. In other sex and age classes, rank did not contribute to survival. Although first-year males were in excess among nonbreeders, no connection existed between breeding status and rank. Female rank did not explain the variation in the start of laying, clutch size, number of fledglings or recruit production. We conclude that social status in Willow Tits affects individual fitness mainly through rank-dependent survival. Acquiring a high rank position seems to be most important for first-year birds, especially first-year males.     

Alarm communication in <Emphasis Type="Italic">Ropalidia</Emphasis> social wasps

Summary Alarm pheromones, chemical substances produced by social insects to alert the colony to threat, are the principal means by which colony defence is co-ordinated. We present the results of a study on alarm behaviour in 5 swarming species of wasps belonging to the genus Ropalidia. These species show a remarkably efficient strategy of alarm communication, including visual display and attack synchronization. We show that pheromones released from the venom gland play an important role in alarm recruitment in species belonging to the Ropalidia flavopicta group, but not in Ropalidia sumatrae. We analysed the contents of the venom reservoirs content of four of the studied species by gas chromatography-mass spectrometry. Glands were found to contain a complex mixture of volatile compounds as well as spiroacetals of higher molecular weight. Interestingly, despite all species producing similar chemical compounds from the venom gland, these were found to elicit alarm behaviour in only those species that build nest envelopes, suggesting a link between chemical release of alarm behaviour and the evolution of nest architecture in Ropalidia wasps.Received 19 August 2003; revised 29 February 2004; accepted 10 March 2004