Male Courtship Behavior Research Articles

Mating plugs and sexual cannibalism in the Colombian orb‐web spiderLeucauge mariana

AbstractInLeucaugeorb‐web spiders, females form mating plugs, which play a part in cryptic female choice after they evaluate male performance during courtship and mating. Our aim was to assess sexual behavior and mating plug formation ofLeucauge marianafrom Colombia (CO). We carried out mating trials to describe in detail courtship and mating behavior of sexual pairs from theCOpopulation, and then compared the results to previously collected data from a Costa Rican population (CR). In addition, we assessed the amount of sperm transferred during mating predict plug formation inCOpairs. AllCOvirgin females mated (n = 23), and mating plug formation occurred in only 11 cases (48%). In contrast, allCRvirgin females mated (n = 43) and 74% formed mating plugs. None of the male courtship or mating behaviors that we measured inCOpairs predicted mating plug formation, in contrast to previous reports fromCR. Mating plugs ofCOconsisted of a matrix of unknown composition (77.2%) and encapsulated and decapsulated sperm (22.8%). InCR, plug composition varied in color and consistency, but also comprised a matrix with encapsulated and decapsulated sperm. We observed female cannibalism of males inCOpairs, which had never been reported inCRpairs. Some female displays during courtship and mating were unique to each population. Different female preferences could explain the observed geographic differences betweenL. marianain male traits and behaviors that could, in turn, promote reproductive isolation. More studies are needed to test this hypothesis.

The mushroom body D1 dopamine receptor controls innate courtship drive.

Mating is critical for species survival and is profoundly regulated by neuromodulators and neurohormones to accommodate internal states and external factors. To identify the underlying neuromodulatory mechanisms, we investigated the roles of dopamine receptors in various aspects of courtship behavior in Drosophila. Here, we report that the D1 dopamine receptor dDA1 regulates courtship drive in naïve males. The wild‐type naïve males actively courted females regardless their appearance or mating status. On the contrary, the dDA1 mutant (dumb) males exhibited substantially reduced courtship toward less appealing females including decapitated, leg‐less and mated females. The dumb male's reduced courtship activity was due to delay in courtship initiation and prolonged intervals between courtship bouts. The dampened courtship drive of dumb males was rescued by reinstated dDA1 expression in the mushroom body α/β and γ neurons but not α/β or γ neurons alone, which is distinct from the previously characterized dDA1 functions in experience‐dependent courtship or other learning and memory processes. We also found that the dopamine receptors dDA1, DAMB and dD2R are dispensable for associative memory formation and short‐term memory of conditioned courtship, thus courtship motivation and associative courtship learning and memory are regulated by distinct neuromodulatory mechanisms. Taken together, our study narrows the gap in the knowledge of the mechanism that dopamine regulates male courtship behavior.

Doublesex alters aggressiveness as a function of social context and sex in the polyphenic beetle Onthophagus taurus

Despite sharing nearly the same genome, individuals within the same species can vary drastically in both morphology and behaviour as a function of developmental stage, sex or developmental plasticity. Thus, regulatory processes must exist that enable the stage-, sex- or environment-specific expression of traits and their integration during ontogeny, yet exactly how trait complexes are co-regulated and integrated is poorly understood. In this study, we explore the developmental genetic basis of the regulation and integration of environment-dependent sexual dimorphism in behaviour and morphology in the horn-polyphenic dung beetle Onthophagus taurus through the experimental manipulation of the transcription factor doublesex (dsx). The gene dsx plays a profound role in the developmental regulation of morphological differences between sexes as well as alternative male morphs by inhibiting horn formation in females but enabling nutrition-responsive horn growth in males. Specifically, we investigated whether experimental downregulation of dsx expression affects male and female aggressive and courtship behaviours in two social contexts: interactions between individuals of the same sex and interactions between males and females. We find that dsx downregulation significantly alters aggressiveness in both males and females, yet does so differently for both sexes as a function of social context: dsxRNAi males exhibited elevated aggression towards males but showed reduced aggression towards females, whereas dsxRNAi females became more aggressive towards males, while their aggressiveness towards other females was unaffected. Moreover, we document unexpectedly high levels of female aggression independent of dsx treatment in both wild-type and control-injected individuals. Lastly, we found no effects of dsxRNAi on courtship and mating behaviours. We discuss the role of dsx in the regulation of sex-specific and plastic behaviours, the unexpectedly high levels of aggression of hornless dsxRNAi males in relation to the well-established description of the hornless sneaker phenotype and the potential ecological function of high female aggression.

Refinement of ectopic protein expression through the GAL4/UAS system in Bombyx mori: application to behavioral and developmental studies

Silkmoth, Bombyx mori, is one of the important model insects in which transgenic techniques and the GAL4/UAS system are applicable. However, due to cytotoxicity and low transactivation activity of GAL4, effectiveness of the GAL4/UAS system and its application in B. mori are still limited. In the present study, we refined the previously reported UAS vector by exploiting transcriptional and translational enhancers, and achieved 200-fold enhancement of reporter GFP fluorescence in the GAL4/UAS system. Enhanced protein expression of membrane-targeted GFP and calcium indicator protein (GCaMP5G) drastically improved visualization of fine neurite structures and neural activity, respectively. Also, with the refined system, we generated a transgenic strain that expresses tetanus toxin light chain (TeTxLC), which blocks synaptic transmission, under the control of GAL4. Ectopic TeTxLC expression in the sex pheromone receptor neurons inhibited male courtship behavior, proving effectiveness of TeTxLC on loss-of-function analyses of neural circuits. In addition, suppression of prothoracicotropic hormone (PTTH) or insulin-like peptide (bombyxin) secretion impaired developmental timing and growth rate, respectively. Furthermore, we revealed that larval growth is sex-differentially regulated by these peptide hormones. The present study provides important technical underpinnings of transgenic approaches in silkmoths and insights into mechanisms of postembryonic development in insects.

Inbreeding produces trade-offs between maternal fecundity and offspring survival in a monandrous spider

Offspring born to related parents often have lower fitness than those born to unrelated parents, a phenomenon termed inbreeding depression. While many species have been shown to rely on pre- and/or postcopulatory mate choice to avoid inbreeding, such research has focused largely on polyandrous rather than monandrous species. The absence of postcopulatory mate choice in monandrous species suggests that precopulatory mate choice should play a more important role in inbreeding avoidance. We used a monandrous wolf spider, Pardosa astrigera , as a model system to investigate whether (1) male spiders respond differently to sibling and nonsibling females; (2) female spiders respond differently to sibling versus nonsibling males; and (3) inbreeding affects females and their offspring. Male courtship behaviour was similar for sibling and nonsibling females; although females were less likely to mate with siblings, over half did mate successfully with them. Sibling-mated females produced fewer offspring from the first egg sac and fewer total offspring, but inbred offspring survived longer in a range of environments than their outbred counterparts. This suggests that the fitness costs of reduced fecundity in sibling-mated females may be offset by higher offspring survivorship. Our results highlight the importance of considering both parent and offspring fitness when addressing the costs of inbreeding, and are the first to document the impact of inbreeding on sexual behaviour and reproductive fitness in a monandrous spider.

Exploring the influence of individual courtship behaviors on male mating success in a blow fly

Male courtship behavior and displays influence female mating decisions, and therefore affect mating success in a diverse range of organisms. While there is substantial evidence confirming that females prefer males who invest more in courtship, less attention has been paid to the relative importance of individual behaviors, and the discrete sequences of courtship that result in mating success. The small hairy maggot blow fly, Chrysomya varipes, performs stereotyped courtship behaviors, involving orienting, tapping, waving, arching, wing vibration and mounting. This study aimed to quantify male investment in specific courtship behaviors, and compare courtship investment and behavioral transitions between males who gained mating success (successful males) and those that did not (unsuccessful males). Our results show that mating success was influenced by the behaviors orienting, tapping, arching and mounting. Behavioral transitions revealed a distinct pattern of behaviors leading to a mating attempt, and some differences were observed between successful and unsuccessful males. Overall, our findings suggest that female mating decisions were based on differences in specific male courtship behaviors. This detailed observational study has quantified multiple courtship behaviors for the first time in C. varipes, and highlights the importance of considering multiple behavioral traits when exploring the influence of male courtship on mating success.

Neural Mechanisms Underlying the Disruption of Male Courtship Behavior by Adult Exposure to Di(2-ethylhexyl) Phthalate in Mice.

Background:Courtship behavior plays a critical role in attracting females and reproduction success. However, the effects of exposure to a ubiquitous contaminant di(2-ethylhexyl) phthalate (DEHP) on these behaviors and, in particular, on courtship vocalizations have not been examined.Objective:The effects of adult exposure to DEHP on courtship and mating behaviors and gonadotropic axis and neural mechanisms involved in DEHP-induced effects were analyzed in male mice.Methods:Adult C57BL/6J males were orally exposed to DEHP (0, 0.5, 5, and ) for 4 wk. Olfactory preference, ultrasonic vocalizations (USVs), partner preference and mating, as well as locomotor activity and motor coordination, were measured. The kisspeptin system and testosterone levels were analyzed. Proteomic and molecular studies were conducted on the hypothalamic preoptic nucleus, the key region involved in sexual motivation to vocalize and mate.Results:DEHP at reduced the emission of USVs, whereas lower doses changed the ratio of syllable categories. This was associated with diminished sexual interest of female partners toward males exposed to 5 or and increased latency to mate, despite normal olfactory preference. The kisspeptin system and circulating testosterone levels were unaffected. In DEHP-exposed males, proteomic analysis of the preoptic nucleus identified differentially expressed proteins connected to the androgen receptor (AR). Indeed, exposure to 5 or of DEHP induced selective AR downregulation in this nucleus and upstream chemosensory regions. The involvement of AR changes in the observed alterations was further supported by the reduced emission of courtship vocalizations in males with disrupted neural AR expression.Conclusions:These data demonstrate the critical role of neural AR in courtship vocalizations and raises the possibility that the vulnerability of this signaling pathway to exposure to endocrine disrupters may be detrimental for courtship communication and mating in several species. https://doi.org/10.1289/EHP1443

Androgens Support Male Acrobatic Courtship Behavior by Enhancing Muscle Speed and Easing the Severity of Its Tradeoff With Force.

Steroid hormone action in the brain regulates many animals' elaborate social displays used for courtship and competition, but it is increasingly recognized that the periphery may also be a site for potent steroidal modulation of complex behavior. However, the mechanisms of such "bottom-up" regulation of behavioral outflow are largely unclear. To study this problem, we examined how androgenic sex hormones act through the skeletal muscular system to mediate elaborate courtship acrobatics in a tropical bird called the golden-collared manakin. As part of their display, males snap their wings together above their backs at rates that are at least 2× faster than the normal wing-beat frequency used for flight. This behavior, called the roll-snap, is actuated by repeatedly activating a humeral retractor muscle-the scapulohumeralis caudalis (SH)-which produces contraction-relaxation cycling speeds similar to the "superfast" muscles of other taxa. We report that endogenous androgenic activation of androgen receptor (AR) sustains this muscle's exceptionally rapid contractile kinetics, allowing the tissue to generate distinct wing movements at oscillation frequencies >100 Hz. We also show that these effects are rooted in an AR-dependent increase to contractile velocity, which incurs no detectable cost to force generation. Thus, AR enhances SH speed necessary for courtship display performance while avoiding the expected tradeoff with strength that could otherwise negatively influence aspects of flight. Peripheral AR therefore not only sets up the muscular system to perform a complex wing display, but does so in a way that balances the functional requirements of this muscle for other life-sustaining behavior.

The white gene controls copulation success in Drosophila melanogaster

Characteristics of male courtship behavior in Drosophila melanogaster have been well-described, but the genetic basis of male-female copulation is largely unknown. Here we show that the white (w) gene, a classical gene for eye color, is associated with copulation success. 82.5% of wild-type Canton-S flies copulated within 60 minutes in circular arenas, whereas few white-eyed mutants mated successfully. The w+ allele exchanged to the X chromosome or duplicated to the Y chromosome in the white-eyed genetic background rescued the defect of copulation success. The w+-associated copulation success was independent of eye color phenotype. Addition of the mini-white (mw+) gene to the white-eyed mutant rescued the defect of copulation success in a manner that was mw+ copy number-dependent. Lastly, male-female sexual experience mimicked the effects of w+/mw+ in improving successful copulation. These data suggest that the w+ gene controls copulation success in Drosophila melanogaster.

A Circuit Node that Integrates Convergent Input from Neuromodulatory and Social Behavior-Promoting Neurons to Control Aggression in Drosophila

Diffuse neuromodulatory systems such as norepinephrine (NE) control brain-wide states such as arousal, but whether they control complex social behaviors more specifically is not clear. Octopamine (OA), the insect homolog of NE, is known to promote both arousal and aggression. We have performed asystematic, unbiased screen to identify OA receptor-expressing neurons (OARNs) that control aggression in Drosophila. Our results uncover a tiny population of male-specific aSP2 neurons that mediate a specific influence of OA on aggression, independent of any effect on arousal. Unexpectedly, these neurons receive convergent input from OA neurons and P1 neurons, a population of FruM+ neurons that promotes male courtship behavior. Behavioral epistasis experiments suggest that aSP2 neurons may constitute an integration node at which OAergic neuromodulation can bias the output of P1 neurons to favor aggression over inter-male courtship. These results have potential implications for thinking aboutthe role of related neuromodulatory systems in mammals.

Using whole-group metabolic rate and behaviour to assess the energetics of courtship in red-sided garter snakes

Reproductive effort is an important aspect of life history as reproductive success is arguably the most important component of fitness. Males tend to compete for access to females and, in the process, expend their energetic capital on mate searching, male–male competition and courtship rather than directly on offspring. Red-sided garter snakes, Thamnophis sirtalis parietalis , are an exceptional model for studying energetic costs of courtship and mating as they fast during the spring mating season, which segregates the cost of energy acquisition from the cost of courtship and mating. However, measuring an individual male's metabolic rate during courtship is complicated by the fact that male courtship behaviour in red-sided garter snakes is dependent on both the detection of a female sexual attractiveness pheromone and on facilitated courtship (i.e. vigorous courtship is only exhibited in the presence of other males). Thus, traditional techniques of placing a mask over the head of individuals would prevent male courtship behaviour, and single animals placed in a flow-through chamber would not yield ecologically realistic levels of courtship, which are only seen in the context of a mating aggregation in this species. Because of these difficulties, we placed groups of males in a flow-through metabolic chamber together with a single female whose respiratory gases were vented outside the chamber to yield a whole-group metabolic rate during competitive courtship. We also measured the standard metabolic rates (SMR) of the males individually for comparison with active metabolic rates. Conservative estimates of peak group metabolic rates during courtship are 10–20 times higher than resting group metabolic rate, which was 1.88 times higher than SMR. These measurements, coupled with the fact that these males are aphagous during the breeding, indicates that costs of courtship may be high for males and has implications for the male mating tactics in this system.

Condition- and context-dependent factors are related to courtship behavior of paired and unpaired males in a socially monogamous songbird

ABSTRACT Males of many animal species display to attract and stimulate potential mates. In socially monogamous species, males will court females both to establish a pair bond and to solicit extrapair copulations. We investigated whether paired and unpaired male Dark-eyed Juncos (Junco hyemalis) differ in their courtship of a novel female and whether their courtship behavior is related to their morphology or circulating hormones. We conducted simulated courtship interactions (SCI) by presenting free-living paired and unpaired males with a live, caged conspecific female accompanied by playback of a precopulatory trill, a signal of female receptivity, and tested predictions of multiple hypotheses. We quantified courtship behaviors for 20 min and then captured the males, measured them, and collected blood samples to quantify circulating post-SCI testosterone and corticosterone levels as well as restraint-induced corticosterone. Paired males approached the female more rapidly and spent more time in close proxi...

Identifying individual male reproductive consistency in Drosophila melanogaster: The importance of controlling female behaviour

Work on the repeatability of reproductive behaviour has mainly focused on the consistency of female preferences. We characterised the consistency of individual male Drosophila melanogaster reproductive behaviour in two experiments. In the first experiment, we allowed males to interact with a pair of live females that differed in body size. We then controlled female behaviour in a second experiment by examining the courtship behaviour of individual males interacting with a pair of decapitated females that varied in body size. In both experiments, we examined the consistency of individual male reproductive behaviour across two repeated trials on the same day. Males did not exhibit a courtship preference for the larger female in either experiment, but, in experiment 1, males did exhibit post-copulatory choice by copulating for longer durations with the large female, and males that mated with the same type of female in both trials exhibited repeatable behaviour. In general, we found weak evidence of consistent male courtship behaviour in the presence of behaving females. However, when female behaviour was controlled in experiment 2, we found that male courtship behaviour was highly repeatable. These results indicate that individual male D. melanogaster exhibit consistent reproductive behaviour and demonstrate the importance of controlling female behaviour when attempting to characterise the repeatability of male reproductive behaviour.

Sex differences in neuromuscular androgen receptor expression and sociosexual behavior in a sex changing fish.

Androgen signaling, via receptor binding, is critical for regulating the physiological and morphological foundations of male-typical reproductive behavior in vertebrates. Muscles essential for male courtship behavior and copulation are highly sensitive to androgens. Differences in the distribution and density of the androgen receptor (AR) are important for maintaining dimorphic musculature and thus may provide for anatomical identification of sexually selected traits. In Lythrypnus dalli, a bi-directional hermaphroditic teleost fish, both sexes produce agonistic approach displays, but reproductive behavior is sexually dimorphic. The male-specific courtship behavior is characterized by rapid jerky movements (involving dorsal fin erection) towards a female or around their nest. Activation of the supracarinalis muscle is involved in dorsal fin contributions to both agonistic and sociosexual behavior in other fishes, suggesting that differences in goby sexual behavior may be reflected in sexual dimorphism in AR signaling in this muscle. We examined sex differences in the local distribution of AR in supracarinalis muscle and spinal cord. Our results demonstrate that males do express more AR in the supracarinalis muscle relative to females, but there was no sex difference in the number of spinal motoneurons expressing AR. Interestingly, AR expression in the supracarinalis muscle was also related to rates of sociosexual behavior in males, providing evidence that sexual selection may influence muscle androgenic sensitivity to enhance display vigor. Sex differences in the distribution and number of cells expressing AR in the supracarinalis muscle may underlie the expression of dimorphic behaviors in L. dalli.

The bachelorette: Female Siamese fighting fish avoid males exposed to an estrogen mimic

Due to improper disposal and a lack of removal during the wastewater treatment process, endocrine disrupting chemicals enter aquatic ecosystems where they exert detrimental effects on fish behavior and physiology. Perhaps the most well-studied and prevalent EDC is 17α-ethinylestradiol (EE2), an active ingredient in oral contraceptives, which is known to cause dramatic reductions in male-typical behaviors. While it is likely that alterations in male courtship behavior decrease reproductive fitness, this is rarely explicitly examined. To this end, whether EE2 exposure reduces male attractiveness to female Siamese fighting fish, Betta splendens, was investigated by showing females video images of exposed and unexposed males. Females were randomly assigned to one of two exposure conditions (exposed to EE2, control) and each subject then viewed four different video combinations of male conspecifics (courting exposed+exposed; courting unexposed+unexposed; courting unexposed+exposed; swimming unexposed+exposed). Females, regardless of whether or not they were exposed to EE2, directed markedly less behavior towards exposed males, especially when they viewed an exposed male and an unexposed male simultaneously. These findings demonstrate that EE2 can have significant individual- and population-level consequences on fitness by disrupting sexual selection and, ultimately, the success of exposed males.

Highly variable male courtship behavioral sequences in a crambid moth

Research on male courtship behavior of moths has focused on documenting stereotyped sequences for successful copulation. We characterized successful male courtship behavior among 126 virgin mating pairs of Ostrinia nubilalis. Using Markov analysis, stereotypy indices, and a novel application of ecological network analysis, we found high variability in these sequences. Fifteen courtship behaviors were described and 96 behavioral transitions were observed, 39 of which occurred only once. The number of courtship bouts ranged from one to ten, the number of behavioral transitions ranged from four to 41, and the number of copulation attempts ranged from one to 29. Only 23% of males used a common, simple behavioral sequence. Females exhibited acceptance or rejection behaviors in 40% of the sequences, but these did not explain the high variability in male courtship sequences. About half of the transitions occurred non-randomly, and stereotypy was low. Network analysis revealed that the courtship sequences started and ended with stereotyped behaviors and the high variability occurred in the middle of the sequences. Whole system analysis showed that the courtship sequences were more variable than for optimal transfer of information. Overall, these results suggest that the sequence of behaviors may be less important than the occurrence of certain behavioral elements for successful mating.

Male–male courtship behaviour, not relatedness, affects the intensity of contest competition in the field cricket

Males often compete intensely against rival males because access to females is a major factor contributing to their reproductive success. However, there is controversy over whether male–male competition is weakened when rival males are related, with reduced aggressiveness leading to inclusive fitness benefits. Furthermore, same-sex sexual behaviour is also expected to mitigate male–male contests. Here, I examined how relatedness, developmental familiarity (i.e. males reared in the same container or not) and same sex sexual behaviour affect the intensity of male–male competition in wild-caught field crickets, Teleogryllus occipitalis. Relatedness and familiarity had no significant effect on the intensity of male–male contest behaviour. However, same-sex sexual behaviour did weaken male–male competition. In conclusion, my results indicate that same-sex sexual behaviour in this cricket has adaptive significance by mitigating risky male–male contest behaviour.

Quantitative analysis of visually induced courtship elements in Drosophila subobscura

We developed a new paradigm for quantitative analysis of courtship behavior in flies, Fly Motion-detector with an Actuator-Coupled Stimulator (FlyMacs), in which the stimulation of a fly with a moving visual target and recording of induced behaviors are automated under computer control. We employ FlyMacs for the identification of motion features that trigger specific courtship elements in Drosophila subobscura, whose mating is suggested to be strongly vision dependent. A female abdomen attached to the actuator, when moved in an appropriate pattern, evokes in the test male tapping-like foreleg motions, midleg swing and proboscis extension, which are considered to be elementary actions in male courtship behavior. Tapping is primarily induced when the target is moving, whereas midleg swing and proboscis extension are most frequently observed after the target stops moving. In contrast to midleg swing, which tends to occur immediately after target cessation (∼3000 ms), the incidence of proboscis extension gradually increases with time after target cessation, reaching a plateau at 3000 ms. The results suggest that tapping, midleg swing and proboscis extension are each induced by different movement features of the visual target. These findings do not support the view that a single key stimulus induces the entire courtship ritual. Rather, courtship behaviors in D. subobscura are correlated with movement and position of the target, which suggests that D. subobscura uses sensory information to pattern its courtship.

Genetic editing of the androgen receptor contributes to impaired male courtship behavior in zebrafish.

Elucidating the genes that contribute to behavioral variation has become an important endeavor in behavioral studies. While advances in genomics have narrowed down the list of candidate genes, functional validation of them has lagged behind, partly because of challenges associated with rapid gene manipulations. Consequently, few studies have demonstrated causal genetic changes linked to behaviors. The 'gene editing revolution' has offered unprecedented opportunities to investigate candidate genes responsible for critical behaviors. Here, we edited the androgen receptor gene (AR), which is associated with male reproductive behavior in zebrafish, using TAL effector nucleases (TALENs), and tested whether modifications at the AR impacted courtship during mating trials. We reveal that males lacking AR courted females significantly less, showing reduced levels of stereotypic behaviors. Consistent with previous studies, disrupting androgen mechanisms can lead to behavioral changes with potential fitness consequences. Our study highlights the possibility of genetically altering a reproductive behavior, further solidifying the link between genotype and behavior.

Functional insights into the testis transcriptome of the edible sea urchin Loxechinus albus.

The edible sea urchin Loxechinus albus (Molina, 1782) is a keystone species in the littoral benthic systems of the Pacific coast of South America. The international demand for high-quality gonads of this echinoderm has led to an extensive exploitation and decline of its natural populations. Consequently, a more thorough understanding of L. albus gonad development and gametogenesis could provide valuable resources for aquaculture applications, management, conservation and studies about the evolution of functional and structural pathways that underlie the reproductive toolkit of marine invertebrates. Using a high-throughput sequencing technology, we explored the male gonad transcriptome of this highly fecund sea urchin. Through a de novo assembly approach we obtained 42,530 transcripts of which 15,544 (36.6%) had significant alignments to known proteins in public databases. From these transcripts, approximately 73% were functionally annotated allowing the identification of several candidate genes that are likely to play a central role in developmental processes, nutrient reservoir activity, sexual reproduction, gamete generation, meiosis, sex differentiation, sperm motility, male courtship behavior and fertilization. Additionally, comparisons with the male gonad transcriptomes of other echinoderms revealed several conserved orthologous genes, suggesting that similar functional and structural pathways underlie the reproductive development in this group and other marine invertebrates.