Non‐Conceptive Sexual Behavior in Spiders: A Form of Play Associated with Body Condition,Personality Type,and Male Intrasexual Selection

In the socially polymorphic spider Anelosimus studiosus, males mature early in the reproductive season and recruit to the webs of juvenile females and guard them until they mature. During the period before females mature, males and females engage in repeated bouts of non‐conceptive (play) sexual behavior, where the pair courts and engages in mock copulation; both males and females gain performance‐enhancing experience via these encounters. In this study, we examined the factors that underlie individual variation in the tendency to engage in non‐conceptive mating and determine whether it impacts male–male competition for females. We found that docile females, being less resistant to mating in general, are more likely to accept male courtship and non‐conceptive copulation as juveniles. Personality type influenced the exhibition of non‐conceptive sexual behavior in males as well. High body condition males of the aggressive phenotype were more likely to engage in non‐conceptive sexual behavior than males with lower body condition. Body condition did not influence docile males’ propensity to engage in non‐conceptive sexual behavior, but female size did. Docile males engaged in more non‐conceptive sexual displays with larger females. Engaging in non‐conceptive sexual displays negatively impacted male performance in staged male–male contests for access to females. This cost was greatest for males of the aggressive phenotype, which are otherwise favored in male–male contests. Our findings indicate expression of non‐conceptive sexual displays is linked to personality and results in reproductive performance trade‐offs for male A. studiosus.     

Urine Marking and Territoriality in Galago alleni (Waterhouse, 1837 — Lorisoidea,Primates) — A Field Study by Radio-telemetry

Behavioral interactions among color-marked individual Vidua chalybeata that shared common song dialects were observed for 5 years in two populations at Lochinvar National Park, Zambia. Social interactions involved ♂♂ visiting and competing for mating sites and ♀♀ visiting ♂♂ in an apparent sampling of potential copulating partners. Differences in mating success among the polygynous ♂♂ were compared with male behavior and territory resources, and criteria were developed to test the importance of intrasexual male competition and female mate choice in explaining the mating system of the populations. Song behavior best explained differences in mating success of ♂♂ with lesser effects of neighboring ♂♂ and the defensible resources around the call-sites. The social organization of song populations resembles that of a dispersed lek with ♀♀ visiting many ♂♂ but mating with few ♂♂. We discuss the observations on indigobirds in relation to behavioral selection, sexual selection, and mating systems. Mating systems of certain populations and species are compared using statistics of individual mating success.     

Sex,Age, and Population Density Affect Aggressive Behaviors in Island Lizards Promoting Cannibalism

Island populations may evolve distinct behavioral repertoires as a response to the conditions of insular life. Strong intraspecific competition is typical in insular lizards and may include cannibalism. In this study, we investigated sexual and age patterns of aggression in two populations of the Skyros wall lizard (Podarcis gaigeae), one from the main island of Skyros (Aegean Sea, Greece) and another from the satellite islet Diavates. The latter is terrestrial predator‐free biotope, hosting a dense population of large‐bodied lizards that have been reported to exert cannibalism. In staged encounters, we examined the aggressive propensities of adult male and female lizards against their age‐peers and juveniles. Males from both populations were much more aggressive than females toward juveniles and other adults. Males from Diavates were more frequently aggressive to juveniles and other male lizards than males from Skyros. Diavates cannibals also captured their targets at shorter latency. We ascribe this distinct behavioral pattern to the high population density. Infanticide and intramale aggressiveness confer two great advantages to cannibals: food and elimination of future rivals.     

Testicular Size,Mating System,and Maturation Schedules in Wild Anubis and Hamadryas Baboons

We report body mass and testicular size in 258 anubis (Papio anubis or P. hamadryas anubis) and 59 hamadryas (P. hamadryas or P. h. hamadryas) baboons, live-trapped in Ethiopia. As predicted by theories of sexual selection by sperm competition, among hamadryas baboons, which are monandrous, fully adult males have absolutely and relatively smaller testes than those of comparable males among anubis baboons, which are polyandrous. Male hamadryas are also ca. 10% smaller in bodily mass as adults. The intertaxonal difference in adults is due entirely to the fact that in male anubis baboons, testicular and bodily mass continue to grow up to full adulthood–the age at which most males emigrate from their natal troop and initiate a confrontational breeding strategy among unrelated animals. By contrast, male hamadryas baboons, which are usually philopatric, attain adult body mass and testicular size as subadults. In both species, juveniles experience rapid testicular growth peaking in rate at ca. 12kg body mass, but testicular descent and growth starts earlier in hamadryas than in anubis baboons. Juvenile hamadryas baboons have relatively larger testes than their anubis equivalents, perhaps because male philopatry allows the mating strategy of male hamadryas baboons to be initiated during juvenile life and therefore permits some sperm competition between juveniles and adults.     

Agonistic Interactions of Juvenile Savanna Baboons

19 juvenile members of known genealogies in two wild baboon groups were studied over a 16-month period to compare the ontogeny of agonistic experience and dominance relations for males and females. Juveniles of all age-sex classes were disproportionately likely to receive aggression from and submit to adult males per unit of time spent in proximity. This pattern intensified with increasing juvenile age. With age, juvenile females more often submitted to unrelated adult females from higher-ranking families, whereas this was not true for juvenile males. All juveniles received aggression from older group members more often during feeding than was expected by chance. High rates of agonistic interaction with unrelated adult females accounted for old juvenile females (3–5.5 years-old) interacting agonistically more frequently than male age peers and young juveniles of either sex (1–2.5 years-old). Adult females were also more aggressive toward females among young juveniles, suggesting that adult females target females among juveniles for aggression and resistance to rank reversal. Within juvenile age groups, males dominated all females and all younger males, irrespective of maternal dominance status. Dominance relations among female age-peers were generally isomorphic with relations among their mothers. No juvenile targeted any older male for rank reversal. Males targeted all older females, whereas females typically targeted only older females from families lower-ranking than their own. The strong sexual dimorphism in adult body size in baboons may explain why juvenile males' dominance relations with peers and adult females are not structured along lines of family membership as is true for the less dimorphic macaques. Acquisition of higher agonistic status probably allows juveniles of both sexes to increase their success in within-group feeding competition during late stages of juvenility, which, in turn, could affect important life-history traits such as age at menarche and adult body size.     

Territorial Behavior and Ecology of the Anemonefish Amphiprion melanopus on Guam1)

Field observations and experiments on the Indo-Pacific anemonefish Amphiprion melanopus at Guam show that it colonizes the aggregating sea anemone Physobrachia douglasi extensively and nearly exclusively. There are an average of four fish per colony. The total standard length of anemonefish at each aggregation is highly correlated with the total area covered by resident anemones, suggesting both a carrying capacity and some form of social control of growth of anemonefish²). Inter-colony migration of juveniles, as well as larval recruitment, may contribute to maintenance of the optimum colony size. Adults do not migrate. Both juveniles and adults defend territory. Juvenile territories are mutually exclusive areas within the confines of the anemone aggregation, while adult territories are considerably larger than the area covered by the anemone aggregation. Though territories of mated ♀♀ and ♂♂ overlap completely, female emphasis is peripheral relative to the ♂. Adult conspecific intruders are attacked more heavily and at greater distances than are juveniles. Intraspecific territoriality in juveniles probably reflects the limited availability of critical habitat. In adults it may function to protect the pair bond. Interspecific aggression is less intense and appears to protect both the spawn and host anemones from various predators.     

Sexual Behaviour in the Slave-making Ant,Harpagoxenus canadensis M. R. Smith,and Sexual Pheromone Experiments with H. canadensis,H. americanus (Emery), and H. sublaevis (Nylander) (Hymenoptera; Formicidae)

The sexual behaviour of Harpagoxenus canadensis closely resembles that of European H. sublaevis. Young ♀♀ of both species exhibit a sexual-calling behaviour (Locksterzeln) during which they attract the ♂♂ by poison gland secretion. The sexual pheromones of both species seem to be identical, but interspecific mating is prevented by various behavioural mechanisms of the ♀♀. A third species, H. americanus, seems to be less closely related to H. canadensis and H. sublaevis: Its ♂♂ are not sensitive to the pheromones of these two species.     

The Effect of Social Environment on Male–Male Competition in Guppies (Poecilia reticulata)

We examined male–male competition in guppies (Poecilia reticulata) to test for evidence of hierarchy formation and any subsequent effects on male mating success by comparing the interactions of pairs of males that were siblings and life‐long tank mates with those of unrelated pairs that had never met. These pairs of males were first observed in the absence of a female; then a female was added to gauge the effects of the initial male–male interactions on male sexual behaviour. The unfamiliar/unrelated pairs engaged in significantly more aggressive interactions such as physical contacts, nipping and chasing than the familiar/related pairs. Based on several previous studies, we suggest that familiarity played a greater role than relatedness in the differences in behaviour that we observed. Our results suggest that, in some circumstances, more aggressive males may have more mating opportunities than less aggressive males. Our results also indicate that males adjust their aggressive and courtship behaviours to the perceived intensity of competition for mates, based on the number of mature males in their rearing tanks. We suggest that male–male competition for mating opportunities may play a more important role in the guppy mating system than previously thought.     

Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles,Graptemys oculifera and Graptemys flavimaculata

Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves.     

Zur Genetik und biologischen Bedeutung des Aggressionsverhaltens von Poecilia sphenops (Pisces,Poeciliidae)

The aggressive behaviour of hybrids between an epigeous and a cave-dwelling form of the toothcarp Poecilia sphenops was investigated in order to test whether a genetically determined reduction of aggressive behaviour exists in the cave population. The scores for five different elements of this behaviour as well as for the duration of fights support this hypothesis and suggest that aggressive behaviour in Poecilia spbenops is controlled by a closely linked polygenic system. On the basis of laboratory and field investigations, to aggressive behaviour is attributed the function of giving large ♂♂ a reproductive advantage within the framework of a body-size dependent rank order. Small ♀♀ appear to counteract this onesided selective advantage through a special strategy of sexual behaviour.     

Role of body size in dominance interactions between male water striders, Aquarius paludum

Water striders are a model system for the study of sexual size dimorphism, but the effect of body size on the dominance relationship between individuals has not been experimentally tested. In 34 staged contests between males of the water strider Aquarius paludum, we determined the effect of body size difference between contestants on the outcome of the aggressive interactions. In contests between a large and a small male, the larger individuals won the interactions significantly more often than expected by chance. This is the first experimental evidence for the importance of body size in pair-wise contests among water striders.     

Influence of male courtship intensity and male–male competition on paternity distribution in Hermann's tortoise,Testudo hermanni hermanni (Chelonia: Testudinidae)

Honest‐advertisement models of sexual selection suggest that condition‐dependent male secondary sexual characters could function as reliable signals of male quality, enabling females to discriminate among potential partners, both in the pre‐ and post‐copulatory phases. In this context, many studies have revealed the importance of promiscuous mating systems and female sperm storage in determining the occurrence of such a model of sexual selection. By contrast, few studies have investigated the presence and extent of post‐copulatory female choice in chelonian species. The present study aimed to investigate the effect of male size, male–male competition, and courtship intensity on paternity distribution in Testudo hermanni hermanni, combining behavioural and genetic data. We created experimental groups composed of two males of different sizes and three or four randomly selected females. Observations conducted during social interactions between males revealed that a hierarchy, unrelated to male size, was soon established: Alpha males were more aggressive towards competitors and courted females more intensively. Alpha males also achieved a higher mounting success than Beta males. Paternity analysis performed on hatchlings produced from experimental females revealed that male reproductive success was not correlated with male–female size ratio. Finally, despite the higher mounting success of Alpha males, paternity analysis revealed that male reproductive success did not differ between Alpha and Beta males. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 656–667.     

Juvenile dispersal in Calomys venustus (Muridae: Sigmodontinae)

Both spacing behaviour and dispersal movement are viewed as hierarchical processes in which the effects may be expressed at spatial scale. This research was carried out to examine the hypothesis that the presence of parents promotes the dispersal of juveniles from their natal nest and their father or mother home-range, in Calomys venustus.The study was carried out in four 0.25 ha fences (two controls and two experimentals), in a natural pasture. This study had two periods: Father Removal (FR) (August and December 1997; year one) and Mother Removal (MR) (August 1998 and January 1999; year two). For the FR treatment fathers were removed after juveniles were born, but in the MR treatment mothers were removed after the juveniles were weaned. The effect of parents on the dispersal distance of juveniles was analysed with respect to their natal nest and their mother and father home-range. Dispersal distance from the nest of C. venustus was independent of either male or female parent. Juveniles were more dispersing in relation to the centre of activity of their mothers than to that of their fathers, and females were more dispersing than males. Female juveniles overlap their home-range with their parents less than male juveniles do. The differences observed between female and male juveniles would be related to their different sexual maturation times, as well as to the female territoriality.     

Sexual selection and infection by ectoparasites in Wellington tree weta,Hemideina crassidens (Orthoptera: Anostostomatidae)

Abstract Sexual selection can affect the prevalence and intensity of infection of individuals by ectoparasitic mites. According to this theory, males should exhibit greater infection by parasites than females and juveniles should be less infected than adults. In the wild, I investigated whether prevalence and intensity of the chyzeriid mite, Nothotrombicula deinacridae (Dumbleton) differed between the sexes and between developmental stages in Wellington tree weta, Hemideina crassidens. Despite being under strong sexual selection, male tree weta did not exhibit greater parasitism and there was some evidence that adults and juveniles differed in prevalence. The sexual selection hypothesis was not supported in this study.     

Intraspecific correlations among morphology, performance and habitat use within a green anole lizard (Anolis carolinensis) population

We examined habitat use, morphology, jumping and clinging ability for 403 juvenile, female and male green anole lizards, Anolis carolinensis, in a population in south‐eastern Louisiana. We sought to answer three questions: (1) Do age/sex classes differ in habitat use, morphology and performance ability? (2) Do habitat use, morphology and performance correlate among all individuals across three age/sex classes (juveniles, females and males)? (3) Do juveniles compensate for their poor absolute performance capacities by being better performers on a relative scale? The three age/sex classes were found to differ significantly in size‐adjusted morphology, habitat use and size‐adjusted performance capacity. Juveniles tended to occupy perches which were closer together than those of adult males and females. The distal elements of the hindlimb (femur, tibia) were significantly longer in males than in females and juveniles, while females were more stocky than males and juveniles. The only significant overall ecomorphological relationship detected was between the lengths of the distal hindlimb elements and maximum jump acceleration. Our hypothesis that juveniles should be better performers (relative to size) compared to adults was disproved, as adult females were always the best performers relative to size. Our analysis of a mainland anole population presents a different view of population structure compared to similar studies involving Caribbean Anolis lizards, which show more ecological differentiation among age/sex classes, and also show that juveniles are relatively good performers. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 211–221.     

Density and Lek Displays in Drosophila grimshawi (Diptera: Drosophilidae)

Frequencies of stereotyped lek displays of male Drosophila grimshawi were measured in groups of different sizes (2, 4, 8, or 16 ♂♂ per container). In one experiment ♀♀ were absent, and in a second experiment two ♀♀ were present in each male group. In both experiments the frequency of courtship displays was linearly dependent upon density. Two agonistic displays and a communal display were density-dependent only when ♀♀ were present. The strategy ♂♂ adopted only in the presence of ♀♀ was: (1) to balance the relative frequencies of communal and aggressive behavior, and (2) to increase the ratio of contact to noncontact aggression with increasing density.     

Body size, male combat and the evolution of sexual dimorphism in eublepharid geckos (Squamata: Eublepharidae)

Lizards of the family Eublepharidae exhibit interspecific diversity in body size, sexual size dimorphism (SSD), head size dimorphism (HSD), occurrence of male combat, and presence of male precloacal pores. Hence, they offer an opportunity for testing hypotheses for the evolution and maintenance of sexual dimorphism. Historical analysis of male agonistic behaviour indicates that territoriality is ancestral in eublepharid geckos. Within Eublepharidae, male combat disappeared twice. In keeping with predictions from sexual selection theory, both events were associated with parallel loss of male-biased HSD and ventral scent glands. Eublepharids therefore provide new evidence that male-biased dimorphic heads are weapons used in aggressive encounters and that the ventral glands probably function in territory marking rather than in intersexual communication. Male-biased SSD is a plesiomorphic characteristic and was affected by at least three inversions. Shifts in SSD and male combat were not historically correlated. Therefore, other factors than male rivalry appear responsible for SSD inversions. Eublepharids demonstrate the full scope of Rensch's rule (small species tend to be female-larger, larger species male-larger). Most plausibly, SSD pattern hence seems to reflect body size variation. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76 , 303–314.     

Relationships among male sexually selected traits in the bean bug,Riptortus pedestris (Heteroptera: Alydidae)

Current concepts of sexual selection suggest that male reproductive success is determined by multiple sexual traits. As expression and production of multiple sexual traits are frequently associated with each other, positive or negative correlations among multiple sexual traits ensue. These relationships among traits associated with male reproductive success may be crucial in the evolution of male reproductive strategies. Here, we investigate phenotypic relationships among sexually selected traits in the armed bean bug Riptortus pedestris. In this insect, males with a larger body and weapon are more likely to win male–male competitions, and males with a larger weapon or higher courtship rate are more attractive to females. There was a significant positive correlation between body size and weapon size, whereas the courtship rate had significant negative correlations with body size and weapon size. Our results suggested that there was a phenotypic trade‐off between courtship rate and male morphology. In this insect, smaller males may make more effort in courtship behavior as an alternative mating tactic.     

Phenotypic quality and molt in the barn swallow, Hirundo rustica

Phenotypic quality may determine the development and expressionof secondary sexual characters. We studied the relationshipbetween molt and several measures of phenotypic quality in thesexually size-dimorphic barn swallow (Hirundo rustica) in itswinter quarters in Namibia. Males were in a more advanced stageof molt than females and juveniles, and the speed of molt asdetermined from the residual of the regression of the size ofthe gap in wings caused by missing and growing feathers on wingmolt score (residual wing raggedness) was also higher in malesthan in females and juveniles. Male barn swallows with longand symmetric tail feathers had a more advanced stage of moltand molted at a higher speed than males with short and asymmetrictails. Long-tailed females had a delayed molt, and females withasymmetric tails had less advanced molt and lower rates of feathergrowth than females with symmetric tails. Molt of secondariesin juveniles also appeared to be less advanced if they had longtails. Adult barn swallows molted their tail feathers in anirregular sequence with the longest, outermost tail featherusually replaced before the second or the third outermost feathers.Good body condition was positively associated with a high moltscore for some feather tracts and a rapid wing molt in adultfemales and tail molt in juveniles. Mallophaga were only weaklynegatively associated with primary and secondary molt scorein adult females and speed of wing molt in adult males. In conclusion,phenotypic quality of adult male barn swallows as reflectedby the expression of their secondary sexual character duringthe previous molt reliably reflected stage and speed of currentmolt.     

Aggression bei Drosophila melanogaster— Laboruntersuchungen

Experiments on the behaviour of Drosophila melanogaster of the breeds Berlin, Oregon-R, Abeele, vermilion and curled show that ♂♂ have pronounced aggressive behaviour under laboratory conditions. Victorious ♂♂ not only defend a certain area of food against intruding rivals, but are also much more successful in copulating.