Body Colors Indicate the Reproductive Status of Female Common Chameleons: Experimental Evidence for the Intersex Communication Function

Female common chameleons, Chamaeleo chamaeleon , show temporary body color changes during the reproductive season, probably in synchrony with their reproductive status. In a field study, the color changes of 21 radio-tagged females were monitored for the apparent effects that three selected colorations (green body with yellow lines, green body with yellow spots and black body with yellow spots, abbreviated to GYL, GYS and BYS, respectively) had on the reproductive behavior of both sexes. In a field experiment, females naturally displaying GYL were artificially painted to resemble GYL (or control), GYS and BYS. They were released in the wild and the response of males was recorded. The frequency of male-female behaviors, the pairing time and the outcome of male copulation attempts were consistent with the respective neutral (GYL), receptive (GYS) and gravid (BYS) functions of female color phases since a high percentage of copulations occurred during the short-term GYS phase, whereas all copulation attempts by males were violently rejected during the BYS phase. In addition, BYS females also displayed specific behavioral postures to prevent matings. In the field experiment, the number of approaching males and the strength of the response by males were significantly higher for painted GYS females. The data show strong evidence that temporary body color changes in female common chameleons are associated with changes in their reproductive status and hence, function as signals used in inter-sex communication.     

Visual Cues in Mate Recognition by Males of the Damselfly, Coenagrion puella (L.) (Odonata: Coenagrionidae)

Coenagrion puella males search actively for mates and are not aggressive to other males. To study the role of visual cues in male–female discrimination, four types of models were used: (1) bodies of intact insects, (2) models of painted males, (3) models of male–female chimerae, and (4) models of female body parts. Abdomen coloration pattern and presence of wings were the most important cues for sexual recognition by males. Step-by-step elimination of male coloration pattern leads to an increase in the tandem response rate. A female model painted as a male repelled males like the intact male model. The absence of either the head or the thorax slightly decreased the number of tandem responses, but models without both the head and the thorax were not recognized as a mate. Abdomen thickness larger than that of a normal female decreased the attractiveness of the model. Models of the gynochrome female were significantly more attractive than models of the androchrome one. Female models containing male parts were less attractive than models without any structure at this place. Using principal-components analysis, it is shown that models repelling males usually were those containing an intact male abdomen or a female abdomen painted with blue. The results indicate that C. puella males can distinguish males from females visually by morphological structures and coloration pattern.     

The role of receptivity in the courtship behavior of Podocnemis erythrocephala in captivity

The courtship behavior of Podocnemis erythrocephala (Red-headed Amazon River Turtle) in captivity was studied to examine female receptivity and male response to female rejection. We observed 20 females and 39 males in 150 sessions (3–6 h/day for a total of 450 h). In 36% of the trials, there was no interaction between males and females, and 20% of the trials resulted in copulations. All males introduced into tanks approached females, and eventually there was aggression among the males. In 48% of the experiments, females also searched for or approached males. When males initially approached females, they either accepted the male’s advances (14%), rejected the male passively (38%), or rejected the male aggressively (48%). In 86% of the cases where males were rejected, 4% attempted to approach females again, and in 51% they were ultimately successful.     

The courtship tracking of Drosophila melanogaster

The courtship of male Drosophila melanogaster, which occurs so far as is known exclusively on the ground, may be regarded as a tracking process upon which are superimposed specific elements of courtship behaviour. Two methods were utilised to study this process, both of which involved the use of a fixed female courtship stimulus. The male courted this female whilst 1. running on the moving floor of a revolving chamber (female stationary) and 2. tracking her as she was rotated on a radius in a stationary chamber. Behaviour in the first apparatus was recorded via an electronic eye watching the flies and a keyboard operated by the experimenter. Behaviour in the second apparatus was filmed and subsequently analysed frame by frame. The patterning of courtship around the female was shown to be limited by the velocity at which the male had to run in order to court the female. At lower velocities more excursions (circling) to the side of the female were made. The mean distance of the male behind the female increased with velocity. The slope of this effect provides an estimate of the reciprocal feedback gain of the control system for tracking. Strain and velocity dependent differences in courtship variables were revealed. The proportion of wing extension emitted in tracking varied widely, the lowest value being shown by the strain which tracked the fastest (WT Kapelle). It is proposed that the relation between these two variables is of fundamental importance in determining the outcome of courtship. Using females moving sideways it was demonstrated that males orientate to the abdomen in close range of the female (<4 mm centre to centre), and more centrally at greater distance, where visual stimuli probably dominate as cues to orientation. Sinusoidal modulation of the female's velocity enabled a preliminary stimulus-response analysis of the linear aspects of courtship tracking. For males tracking females whose speed was modulated at a mean of 1.2 Hz a phase lag of 148±30ms was determined for the translatory component and 21±55ms for the rotatory component of the male's response. A strain difference between wild type Kapelle and Canton-S strains in tracking efficiency permits the conclusion that courtship tracking ability may provide a basis for selective mating in Drosophila.     

White Flank Spots Signal Feeding Dominance in Female Diamond Firetails,Stagonopleura guttata

Plumage colour can be used as an honest signal to convey health and status, which has traditionally been examined in the sexual selection context of choosy females and elaborate males. We use a model avian system to study the role of plumage coloration in a social context such as inter‐ and intrasexual competition over food resources. The diamond firetail (Stagonopleura guttata) is an endemic Australian finch: females have more white flank spots than males, and white spot number was correlated with cell‐mediated immune response in females. We use two experimental designs to test the role of white flank spots for feeding dominance and dominance discrimination in a group‐living bird. The results from two‐choice trials and from single‐arena trials showed that female ornamentation was consistently important in social food contests, and males consistently responded to female spot number. Females with higher spot number fed first, in trials with males and/or females. Also, females preferred to feed next to test birds with low spot number, but males showed no preference for feeding next to birds with few or many spots. Finally, latency to feed was predicted by spot number: both males and females had longer latency to feed if test birds had more spots than the focal birds. We conclude that female, but not male, ornamentation was important for inter‐ and intrasexual food competition. This is one of the very few studies to show that the same plumage ornament can have a different function between the sexes as a signal of social status. Moreover, this study shows that white plumage can be a signal of dominance.     

INTRASEXUAL COMPETITION ALONE FAVORS A SEXUALLY DIMORPHIC ORNAMENT IN THE RUBYSPOT DAMSELFLY HETAERINA AMERICANA

I studied the sex-limited red spots on the wings of male rubyspot damselflies (Hetaerina americana) in relation to territoriality and fitness in the wild. Both observational and experimental (wing spot manipulation) studies indicated that wing spots were selected through competition among males for mating territories, not through female choice or direct competition for females. Males with naturally or artificially large wing spots were more successful at holding territories and consequently mated at higher rates than males with relatively small wing spots. In contrast, sexual selection on male body size appeared to operate among nonterritorial males at the clasping stage of the mating sequence, perhaps because larger males were better at clasping females forcibly. Of four models proposed to explain the evolution of ornaments through territory competition, only the agonistic handicap model makes predictions consistent with the results of this study.     

Plasticity of the mate choice mind: courtship evokes choice‐like brain responses in females from a coercive mating system

Female mate choice is fundamental to sexual selection, and determining molecular underpinnings of female preference variation is important for understanding mating character evolution. Previously it was shown that whole‐brain expression of a synaptic plasticity marker, neuroserpin, positively correlates with mating bias in the female choice poeciliid, Xiphophorus nigrensis, when exposed to conspecific courting males, whereas this relationship is reversed in Gambusia affinis, a mate coercive poeciliid with no courting males. Here we explore whether species‐level differences in female behavioral and brain molecular responses represent ‘canalized’ or ‘plastic’ traits. We expose female G. affinis to conspecific males and females, as well as coercive and courting male Poecilia latipinna, for preference assays followed by whole‐brain gene expression analyses of neuroserpin, egr‐1 and early B. We find positive correlations between gene expression and female preference strength during exposure to courting heterospecific males, but a reversed pattern following exposure to coercive heterospecific males. This suggests that the neuromolecular processes associated with female preference behavior are plastic and responsive to different male phenotypes (courting or coercive) rather than a canalized response linked to mating system. Further, we propose that female behavioral plasticity may involve learning because female association patterns shifted with experience. Compared to younger females, we found larger, more experienced females spend less time near coercive males but associate more with males in the presence of courters. We thus suggest a conserved learning‐based neuromolecular process underlying the diversity of female mate preference across the mate choice and coercion‐driven mating systems.     

The Role of Wing Coloration in Sex Recognition and Competitor Recognition in Rubyspot Damselflies (Hetaerina spp.)

The decision rules that animals use for distinguishing between conspecifics of different age and sex classes are relevant for understanding how closely related species interact in sympatry. In rubyspot damselflies (Hetaerina spp.), the red wing coloration of mature males is hypothesized to be a key trait for sex recognition and competitor recognition within species and the proximate trigger for interspecific male–male aggression. We tested this hypothesis by manipulating the wing coloration of tethered conspecific intruders and measuring the responses of territory holders of three species in the field. As predicted, covering the red spots of mature males with black ink nearly eliminated territorial responses, and in some cases, territorial holders clasped the blackened males as if they were females. Adding red spots to female wings triggered territorial responses and nearly eliminated sexual responses. Immature males with artificial red spots were attacked at the same rate as mature male intruders, and much more frequently than were immature male controls. The results varied somewhat by species. In H. titia, the only species of Hetaerina with substantial black wing pigmentation, the effects of blackening the red spots of intruders varied both geographically and seasonally. But even when blackening the red spots of male intruders did not reduce the aggressive response of H. titia territory holders, adding artificial red spots to female wings elicited aggressive responses and nearly eliminated sexual responses. The results of this study further strengthen the evidence that interspecific aggression in Hetaerina results from overlap in territorial signals and that the derived black wing pigmentation of H. titia reduces interspecific aggression.     

The female sex pheromone of the staphylinid beetle, Aleochara curtula

The grasping reaction with the parameres towards the female was used as the criterion of male sexual behaviour in Aleochara curtula. Visual, gustatory, and mechanical stimuli were excluded as triggers in releasing the reaction. Extracting the females with acetone, or covering the females with wax resin eliminated the male response. The grasping reaction was shown towards models contaminated with hexane extracts of females, whereas extracts of males were ineffective, as was the pure solvent. 0.5 female equivalents appears to give the optimal response. This is the first record of female sex pheromones acting as an aphrodisiac in the Staphylinidae.The pheromone is spread over the entire surface of the body, and the trapping of the pheromone by the epicuticular waxes is discussed. The evaporation of the pheromone from freshly-killed females is slow by comparison with that from extracts. A reduction of the free surface area of pheromone-bearing models causes a reduction in the response by the males.     

Male courtship signals and female signal assessment in Photinus greeni fireflies

The evolutionary dynamic of courtship signaling systems is drivenby the interaction between male trait distributions and femalepreferences. This interaction is complex because females maychoose mates based on multiple components of male signals, andfemale preference functions may vary depending on mate availability,female reproductive state, and environmental conditions. InPhotinus fireflies (Coleoptera: Lampyridae), flying males emitbioluminescent flash signals to locate sedentary females, whichreply selectively to attractive male flash signals with theirown response flash. In this study, we first examined temporalvariation in the paired-pulse flash patterns produced by Photinusgreeni males in the field and found significant among-male variation(70% of total variation) in interpulse intervals (IPIs). Therewas no significant relationship between male IPI and spermatophoresize, suggesting that P. greeni male courtship signals do notprovide females with reliable indicators of male material resources.In laboratory playback experiments, we presented P. greeni femaleswith simulated flash signals to assess how IPI and pulse durationindependently affected the likelihood of female flash response.We also examined the effects of female body mass and time duringthe mating season on female preference functions, hypothesizingthat females would be less discriminating when they were heavier(more fecund) and when mate availability declined. We foundthat P. greeni females discriminated among signals within theirspecies' range based primarily on flash pattern IPI. Neitherthe time during the mating season nor female weight alteredfemale preference functions for IPI, although season did influencefemale response to pulse duration. These results reveal thatP. greeni females discriminate among conspecific males basedprimarily on male IPIs, the same signal character previouslyshown to be important for firefly species recognition. Fieldplayback experiments indicated that female responsiveness peakednear the average IPI given by males at different ambient temperatures,suggesting that fireflies exhibit temperature coupling similarto that seen in many acoustically signaling animals.     

Information transmission during intra- and interspecific courtship inEphestia elutella andCadra figulilella

Using information theory, courtship posturing in the moths Ephestia elutella(Hübner) and Cadra figulilella(Gregson) was analyzed for information transmission, which was partitioned into autocovariability (intraindividual transmission) and cross-covariability (interindividual transmission). This two-factor analysis was sufficient to account for more than 60% of the behavioral variance in males of E. elutellaand in both sexes of C. figulilelladuring intraspecific courtships; however, there were large residual variances in the behavior of male and female C. figulilelladuring interspecific courtships and in E. elutellafemales during both inter- and intraspecific courtships. In E. elutella,significant levels of transmission were attributable to both inter- and intraindividual effects, whereas in C. figulilella,only autocovariability was high and no interindividual communication could be assigned to courtship postures. Although courtship in these two species was qualitatively very similar and males readily courted nonconspecific females, high levels of reproductive isolation resulted from courtship. Male C. figulilellahad 94% fewer copulations with E. elutellafemales than with conspecific females and E. elutellamales had 78% fewer copulations with C. figulilellafemales than with conspecifics. These reductions were due to a differential response in both females and males, causing inter-specific courtships to be terminated much earlier than intraspecific courtships. This discrimination indicates that interindividual communication was indeed occurring during courtship and was only partially measured by analysis of postures. Thus, communication took place largely in some other modality, most likely the chemical modality, where species specificity is suggested for both male and female pheromones.     

Evolutionary trends in the male pheromone systems of arctiid moths: evidence from studies of courtship in Phragmatobia fuliginosa and Pyrrharctia isabella (Lepidoptera: Arctiidae)

Male Phragmatobia fuliginosa and Pyrrharctia Isabella evert tubular abdominal scent-organs (coremata: during courtship. The coremata secrete a pheromone that is derived from pyrrolizidine alkaloids (PAs) obtained during larval feeding. Field-collected males vary widely in the amount of pheromone they possess. The courtship behaviour of these species was studied to determine whether this variation among males serves as a basis for mate choice by females, in a wind-tunnel a male approaches a pheromone-releasing female from downwind with his coremata everted in flight. A female perceiving the pheromone responds by fluttering her wings and emitting a clicking sound. This response did not occur in all courtships, and successful copulation was not dependent on its occurrence. Males denied access as larvae to the PA-precursors of the corematal pheromone (PA-denicd males' mated as rapidly as males allowed access to pheromone precursor (PA-supplied males). Moreover, antennectomized females mated as rapidly as normal females. Comparative analyses of transitional probabilities indicated no differences among courtships involving ! I': PA-denicd males and normal females, (II) PA-supplied males and normal females, or antennectomized females and normal males of unspecified feeding history. Field observations of courtship interactions between laboratory-reared females and wild males indicated that males having little or no pheromone succeed in mating in a natural setting as do males having a relativelv large amount of pheromone. It is hypothesized that the failure of female Ph. fuliginosa and Py, Isabella to enforce the display of PA-derived pheromone is related to an cvolutionarv trend away from an ancestral larval host-range restricted to PA-containing plants toward the polyphagv shown by manv temperate and arctic arctiids in the lineage (subfamily Arctiinae: tribe Arctiini) to which Ph. fuliginosa and Py. Isabella belong. Parallels in other moth groups are cited to support the notion that a plesiomorphic courtship pheromone system could persist in a vestigial state, despite the loss of its adaptive raison dêtre.     

Role of host fruit color in the behavior of the walnut fly Rhagoletis juglandis

Observations and sticky-trap tests were used to assess the effect of fruit color on the behavior of adult male and female Rhagoletis juglandis Cresson (Diptera: Tephritidae), a tephritid that infests husks of Arizona walnut in southeastern Arizona. In the first experiment, during which flies were observed foraging among walnut models suspended from small walnut trees, models were painted green to appear ripe and uninfested or yellow with brown patches to appear ripe and infested. Flies used for this first experiment were also of two types: prior to observations, one group of flies had access to real walnuts for 1.5 days (prior experience) while the other group of flies was held without real walnut fruits (no prior experience). Regardless of prior experience with real walnut fruits, female flies landed on green models more than yellow/brown models. Experienced males also were more likely to land on green models than on yellow/brown models. More interactions also occurred on green models, because there were more landings.In the field behavioral assay, flies from a natural population given a choice of green, yellow, and yellow/brown models landed most often on green models, and all interactions and oviposition attempts occurred on green models. Flies also distinguished models by color in field sticky trap assays.These results suggest that female response to ripeness cues is innate, while males develop a preference for green based on their encounter rate with females.     

Androgen influence on male mouse ultrasounds during courtship

Ultrasonic vocalizations are emitted by adult male mice (Mus musculus) shortly after an adult female or her odor are encountered, possibly as an early part of courtship behavior. Consistent with this hypothesis, it was found that castration of adult male mice increased the latency to first ultrasonic vocalization in response to an adult female. In addition, castrated males, subsequently injected once with 200 μg of testosterone propionate, reduced their latency, whereas oil-injected castrates did not.     

Preliminary experiments on the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact plants

1 In two successive years, the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact cabbage and white clover plants were studied, using a four‐arm olfactometer. 2 The first set of experiments tested the response to the odours of cabbage, white clover and the two plants grown together against potting compost; in the second and third sets of experiments, white clover and cabbage were tested, respectively. 3 The results indicate that female P. melanarius individuals are arrested by the combined odours of cabbage and white clover, spending significantly more time in the cabbage with white clover odour field than in either the cabbage, white clover or control odour fields. 4 Similar results were not found for males. 5 Cabbage plants alone did not elicit significant responses in either sex. 6 White clover alone did not elicit significant responses by females and the responses of males were not uniform in the two successive years.     

同种雄性竞争对手的存在对星豹蛛雄蛛求偶和交配行为的影响

越来越多的研究发现,雄性产生精子(精液)也需付出代价。雄性除了依据配偶质量和竞争对手的竞争强度适应性调整生殖投入外,雄性在求偶和交配行为上也相应产生适应性反应,求偶和交配行为具有可塑性。目前雄性求偶和交配行为可塑性研究主要集中于雌性多次交配的类群中,在雌性单次交配的类群中研究甚少。以雌蛛一生只交配一次而雄蛛可多次交配的星豹蛛为研究对象,比较:(1)前一雄性拖丝上信息物质对后续雄蛛求偶和交配行为的影响,(2)雌雄不同性比对雄蛛求偶和交配行为的影响。研究结果表明,星豹蛛前一雄蛛拖丝上的信息物质对后续雄蛛求偶潜伏期、求偶持续时间和交配持续时间都没有显著影响,但前一雄蛛拖丝上的信息物质对后续雄蛛求偶强度有显著抑制作用。同时,性比对星豹蛛雄蛛求偶和交配行为都没有显著影响。可见,星豹蛛雄蛛对同种雄性拖丝上的化学信息可产生求偶行为的适应性调整,而对性比不产生适应性反应。     

The significance of sound interception to males of the bicolor damselfish,Pomacentrus partitus,during courtship

Synopsis Playback experiments conducted in the field and the laboratory demonstrated the use of sound interception in bicolor damselfish,Pomacentrus partitus. Two courtship sounds produced by male bicolors: the ‘chirp’ which occurs at the initiation of courting and the ‘grunt’ which occurs near the termination, just prior to spawning, were found to hold different meanings to intercepting male competitors. Males responded to grunt playback with directional swimming towards the sound source and increased courtship behavior. No directional response was observed during chirp playback. The grunt sound appears to indicate that a spawn-ready female is present near the sound source. Males therefore move towards it, likely to interfere with the imminent spawning or to gain a possible spawning partner. Such is not observed in response to chirps, as little advantage would be gained by moving to the source of a sound which is known to serve as an ‘advertisement’ or ‘territorial keep-out’ signal. Thus, upon intercepting a neighbor's chirps, males exhibit courting within their own territory, or directly court a nearby female.     

Flash behavior of femalePhoturis versicolor fireflies (Coleoptera: Lampyridae) in simulated courtship and predatory dialogues

FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.