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Socially plastic behaviours are widespread among animals and can have a significant impact on fitness. Here, we investigated whether the socially plastic responses of female Drosophila melanogaster can evolve in predictable ways following long-term manipulation of adult sex ratio and adult nutrient availability. Previous reports show that female D. melanogaster respond plastically to their same-sex social environment and lay significantly fewer eggs after mating when previously exposed to other females. In this study, we tested 2 hypotheses, using females drawn from lines with an evolutionary history of exposure to variation in adult sex ratio (male-biased, female-biased or equal sex ratio) and adult nutritional environment (high or low quality). The first was that a history of elevated competition in female-biased regimes would select for increased plastic fecundity responses in comparison to females from other lines. The second was that these responses would also be magnified under poor nutritional resource regimes. Neither hypothesis was supported. Instead, we found that plastic fecundity responses were retained in females from all lines and did not differ significantly across any of them. The lack of differences does not appear to be due to insufficient selection, as we did observe significant evolutionary responses in virgin egg-laying patterns according to sex ratio and nutritional regime. The lack of variation in the magnitude of predicted plasticity is consistent with the idea that the costs of maintaining plasticity are low, benefits high, and that plasticity itself can be relatively hard wired. Graphical Abstract [ABSTRACT FROM AUTHOR]

Social interactions influence disease spread, information flow and resource allocation across species, yet heterogeneity in social interaction frequency and its fitness consequences are still poorly understood. Additionally, the role of exogenous chemicals, such as non‐nutritive plant metabolites that are utilised by several animal species, in shaping social networks remains unclear. Here, we investigated how non‐nutritive plant metabolites impact social interactions and the lifespan of the turnip sawfly, Athalia rosae. Adult sawflies acquire neo‐clerodane diterpenoids (‘clerodanoids’) from non‐food plants and this can serve as a defence against predation and increase mating success. We found intraspecific variation in clerodanoids in natural populations and laboratory‐reared individuals. Clerodanoids could also be acquired from conspecifics that had prior access to the plant metabolites, which led to increased agonistic social interactions. Network analysis indicated increased social interactions in sawfly groups where some or all individuals had prior access to clerodanoids, while groups with no prior access had fewer interactions. The frequency of social interactions was influenced by the clerodanoid status of the focal individual and that of other conspecifics. Finally, we observed a shorter lifespan in adults with prior clerodanoid access when grouped with individuals without prior access, suggesting that social interactions to obtain clerodanoids have fitness costs. Our findings highlight the role of intraspecific variation in the acquisition of non‐nutritional plant metabolites in shaping social networks. This variation influences individual fitness and social interactions, thereby shaping the individualised social niche. [ABSTRACT FROM AUTHOR]

Abstract Sexual conflict arises from differences in reproductive interests between the sexes. We allowed the female harvestman Phalangium opilio to sequentially mate with two different males to examine female sexual receptivity in this species. Virgin females were more sexually receptive than non-virgins. Males exhibited a high interest in repeated copulations with the same female, often engaging in aggressive behaviours such as biting and reversed sexual cannibalism. Fellatio, a behaviour in which females lick the male’s penis, was observed in 44% of trials and was associated with female unwillingness to mate and shorter copulation duration. Fellatio was repeatable, suggesting that it is influenced by individual characteristics or underlying physiological factors. Female lifespan was negatively correlated with the total number of eggs produced, suggesting a trade-off between reproduction and longevity. These findings provide evidence of the appearance of fellatio, a female mating strategy that evolved as compensation of avoiding unwanted sexual intercourse.

Speciation is a fundamental evolutionary process but the genetic changes accompanying speciation are difficult to determine since true species do not produce viable and fertile offspring. Partially reproductively isolated incipient species are useful for assessing genetic changes that occur prior to speciation. Drosophila melanogaster from Zimbabwe, Africa are partially sexually isolated from other D. melanogaster populations whose males have poor mating success with Zimbabwe females. We used the North American D. melanogaster Genetic Reference Panel (DGRP) to show that there is significant genetic variation in mating success of DGRP males with Zimbabwe females, to map genetic variants and genes associated with variation in mating success and to determine whether mating success to Zimbabwe females is associated with other quantitative traits previously measured in the DGRP. Incipient sexual isolation is highly polygenic and associated with the common African inversion In(3R)K and the amount of the sex pheromone 5,9-heptacosadiene in DGRP females. We functionally validated the effect of eight candidate genes using RNA interference to provide testable hypotheses for future studies investigating the molecular genetic basis of incipient sexual isolation in D. melanogaster. [ABSTRACT FROM AUTHOR]

Temperature influences nearly all aspects of fitness. However, reproduction is often more thermally sensitive than survival. Thermoregulation must maintain performance in both components of fitness to buffer populations from environmental change.We assessed the fitness benefits of thermoregulation in Enchenopa binotata treehoppers. Under realistic mesocosm conditions, we quantified fine‐scale microclimates using 3D‐printed operative temperature models. We then compared operative temperatures to treehopper body temperatures and translated patterns of thermoregulation into variation in survival and reproduction. We also assessed two thermoregulatory mechanisms: precise microclimate choice and heat‐escape behaviours. Finally, we applied our results to evaluate if arthropod thermoregulation is accurately characterized by two theoretical models commonly used to simulate responses to environmental change.We found substantial thermal variation at fine spatial scales relevant to insects: at a single point in time, temperatures within 30‐cm‐tall plants spanned ranges up to 19°C (23–42°C).Lethal operative temperatures were common when air temperatures were high. However, heat escapes allowed treehoppers to almost entirely avoid lethal temperatures.By contrast, individuals thermoconformed in the absence of lethal operative temperatures. This finding suggests that precise microclimate choice imposes high costs due to thermal uncertainty at fine spatial scales. Furthermore, given the narrow range of temperatures in which reproduction occurs, thermoregulation is unlikely to maintain reproduction.Thermoregulation was most effective in the lowest‐quality and most spatially variable thermal habitats. Treehopper thermoregulation therefore more closely follows cost–benefit models of thermoregulation compared to models that account for inhibited movement at extreme temperatures.Overall, even if thermoregulation can prevent lethal heat stress, it may have limited capacity to buffer arthropods and other small ectotherms from environmental change if it cannot maintain reproductive performance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Abstract Background Anopheles gambiae continues to be widespread and an important malaria vector species complex in Uganda. New approaches to malaria vector control are being explored including population suppression through swarm reductions and genetic modification involving gene drives. Designing and evaluating these new interventions require good understanding of the biology of the target vectors. Anopheles mosquito swarms have historically been hard to locate in Uganda and therefore have remained poorly characterized. In this study we sought to identify and characterize An. gambiae s.l mosquito swarms in three study sites of high An. gambiae s.l prevalence within Central Uganda. Methods Nine sampling visits were made to three villages over a 2-year period. Sampling targeted both wet and dry seasons and was done for 2 days per village during each trip, using sweep nets. All swarm data were analysed using the JMP 14 software (SAS Institute, Inc., Cary, NC, USA), parametrically or non-parametrically as appropriate. Results Most of the An. gambiae s.s. swarms sampled during this study were single-species swarms. However, some mixed An. gambiae s.s. and Culex spp. mosquito swarms were also observed. Swarms were larger in the wet season than in the dry season. Mean swarm height ranged from 2.16 m to 3.13 m off the ground and only varied between villages but not by season. Anopheles gambiae mosquitoes were present in all three villages, preferred to swarm over bare ground markers, and could be effectively sampled by field samplers. Conclusions This study demonstrated that An. gambiae s.l swarms could be effectively located and sampled in South Central Uganda and provided in-depth descriptions of hitherto poorly understood aspects of An. gambiae local swarm characteristics. Swarms were found close to inhabited households and were greater in size and number during the rainy season. Anopheles gambiae s.s swarms were significantly associated with bare ground markers and were sometimes at heights over 4 m above the ground, showing a necessity to develop tools suitable for swarm sampling at these heights. While mixed species swarms have been reported before elsewhere, this is the first documented instance of mixed genus swarms found in Uganda and should be studied further as it could have implications for swarm sampling explorations where multiple species of mosquitoes exist. Graphical Abstract

The bewildering courtship phenotypes of male birds of paradise (Paradisaedae) represent a classic example of sexual selection through mate choice. While the majority of sexual selection studies have focused on either mate choice or intrasexual competition, males across a variety of taxa adopt alternative mating tactics as additional means of obtaining fertilization when they are otherwise unable to. For example, across various polygynous birds, subordinate males engage in sneak copulations, which may offset the fitness costs of prolonged subordinate periods. Despite exhibiting strong mating skews and male delayed plumage maturation, reports of sneak copulation in the birds of paradise are exceedingly rare. After reviewing an extensive video collection of courtship interactions, we found examples of mountings by female‐plumaged birds in three birds of paradise species: the Western parotia Parotia sefilata, Carola's parotia Parotia carolae, and the magnificent bird of paradise Cicinnurus magnificus. While homosexual mountings by females have been documented previously in Lawes' parotia P. lawesii, adult males in the magnificent bird of paradise violently attacked intruding female‐plumaged birds attempting to mount receivers, suggesting that they may be immature males engaging in alternative mating tactics. Overall, the rare video footage described here is suggestive of two fascinating, yet unexplored phenomena in polygynous birds: alternative mating tactics and female homosexual behaviour. [ABSTRACT FROM AUTHOR]

Fossilized mating insects are irreplaceable material for comprehending the evolution of the mating behaviours and life-history traits in the deep-time record of insects as well as the potential sexual conflict. However, cases of mating pairs are particularly rare in fossil insects, especially aquatic or semi-aquatic species. Here, we report the first fossil record of a group of water striders in copulation (including three pairs and a single adult male) based on fossils from the mid-Cretaceous of northern Myanmar. The new taxon, Burmogerris gen. nov., likely represents one of the oldest cases of insects related to the marine environment, such as billabongs formed by the tides. It exhibits conspicuous dimorphism associated with sexual conflict: the male is equipped with a specialized protibial comb as a grasping apparatus, likely representing an adaptation to overcome female resistance during struggles. The paired Burmogerris show smaller males riding on the backs of the females, seemingly recording a scene of copulatory struggles between the sexes. Our discovery reveals a mating system dominated by males and sheds light on the potential sexual conflicts of Burmogerris in the Cretaceous. It indicates the mating behaviour remained stable over long-term geological time in these water-walking insects. [ABSTRACT FROM AUTHOR]

Heterospecific interactions are an important phenomenon of animal epigamic behaviour; however, they remain understudied within important groups, such as insects. Dragonflies are an ideal group for research on interspecific mating and possible hybridisation as they are easily identifiable, large insects, with a conspicuous mating process, often striking territorial behaviour and several mating systems.Using the genus Sympetrum as the model group, we examined heterospecific mating at three different levels. In the field, we identified whether species identity, time and weather affected heterospecific mating frequency. One important part of heterospecific mating is whether the process is completed. For dragonflies, this means that flying in tandem is followed by successful copulation, gamete fusion and oviposition (which comprise mating completeness). In a mesocosm experiment, we determined mating completeness (tandems, copulation, oviposition) of hetero‐ and homospecific pairs and the possible role of species density in heterospecific mating. In the laboratory, we compared the viability of the offspring from heterospecific pairs with different epigamous behaviour.We found heterospecific mating to be a relatively common phenomenon unaffected by environmental variables, that was primarily influenced by species identity, temporal distribution and abundance of dragonfly species. Consequently, the presence of counterparts of other species is the main predictor of the frequency of heterospecific mating.The probability of completed epigamic behaviour (copulation and subsequent oviposition) connected with gamete fusion is lower in heterospecific mating. Generally, based on our results we can assume that successful heterospecific mating (leading to gamete fusion) occurs in closely related species (e.g., Sympetrum striolatum and Sympetrum vulgatum). However, as pre‐copulatory barriers are not strongly developed in some dragonfly groups, less closely related species (e.g., Sympetrum sanguineum and S. striolatum) also may mate. This phenomenon requires further study as it may present a threat to the survival of some species in the context of changing environmental conditions, including climate change. [ABSTRACT FROM AUTHOR]

Background: Anopheles gambiae continues to be widespread and an important malaria vector species complex in Uganda. New approaches to malaria vector control are being explored including population suppression through swarm reductions and genetic modification involving gene drives. Designing and evaluating these new interventions require good understanding of the biology of the target vectors. Anopheles mosquito swarms have historically been hard to locate in Uganda and therefore have remained poorly characterized. In this study we sought to identify and characterize An. gambiae s.l mosquito swarms in three study sites of high An. gambiae s.l prevalence within Central Uganda. Methods: Nine sampling visits were made to three villages over a 2-year period. Sampling targeted both wet and dry seasons and was done for 2 days per village during each trip, using sweep nets. All swarm data were analysed using the JMP 14 software (SAS Institute, Inc., Cary, NC, USA), parametrically or non-parametrically as appropriate. Results: Most of the An. gambiae s.s. swarms sampled during this study were single-species swarms. However, some mixed An. gambiae s.s. and Culex spp. mosquito swarms were also observed. Swarms were larger in the wet season than in the dry season. Mean swarm height ranged from 2.16 m to 3.13 m off the ground and only varied between villages but not by season. Anopheles gambiae mosquitoes were present in all three villages, preferred to swarm over bare ground markers, and could be effectively sampled by field samplers. Conclusions: This study demonstrated that An. gambiae s.l swarms could be effectively located and sampled in South Central Uganda and provided in-depth descriptions of hitherto poorly understood aspects of An. gambiae local swarm characteristics. Swarms were found close to inhabited households and were greater in size and number during the rainy season. Anopheles gambiae s.s swarms were significantly associated with bare ground markers and were sometimes at heights over 4 m above the ground, showing a necessity to develop tools suitable for swarm sampling at these heights. While mixed species swarms have been reported before elsewhere, this is the first documented instance of mixed genus swarms found in Uganda and should be studied further as it could have implications for swarm sampling explorations where multiple species of mosquitoes exist. [ABSTRACT FROM AUTHOR]

Understanding how heatwaves impact on different aspects of mating behaviour and fertility is getting increasingly important. In this context, laboratory fertility and mating experiments involving manipulation and exposure of insects to different thermal conditions are common procedures. To conduct such experiments practical methods such as dyes are needed for an easy, non-invasive discrimination of individuals. We report here a study measuring the effect of an extended heat stress applied to males on several parameters of mating behaviour and fertility of laboratory populations of Drosophila subobscura derived from two distinct European locations. We found highly detrimental effects of heatwave on mating behaviour—with longer (courtship and copulation) latencies and lower mating occurrence but no changes in mating duration—and fertility, with reduced fecundity and reproductive success. Furthermore, we also tested the efficacy of food dye as a marker for individual discrimination and mating occurrence. While food dye did not allow to infer the occurrence of a mating based on a transfer of coloration from male to female, it did not affect mating and fertility, attesting its utility has a method for discriminating individuals within mating experiments in the context of thermal studies. Importantly, despite the fact that the heatwave was only applied in males, we observed an impact on behaviour of females that mated with stressed males, by often refusing their nuptial feeding. This opens possibilities for further integrated research on the changes of female and male mating behaviour and fertility under different thermal scenarios. [ABSTRACT FROM AUTHOR]

Sexual selection and the evolution of costly mating strategies can negatively impact population viability and adaptive potential. While laboratory studies have documented outcomes stemming from these processes, recent observations suggest that the demographic impact of sexual selection is contingent on the environment and therefore may have been overestimated in simple laboratory settings. Here we find support for this claim. We exposed copies of beetle populations, previously evolved with or without sexual selection, to a 10‐generation heatwave while maintaining half of them in a simple environment and the other half in a complex environment. Populations with an evolutionary history of sexual selection maintained larger sizes and more stable growth rates in complex (relative to simple) environments, an effect not seen in populations evolved without sexual selection. These results have implications for evolutionary forecasting and suggest that the negative demographic impact of sexually selected mating strategies might be low in natural populations. [ABSTRACT FROM AUTHOR]

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Baya Weaver Ploceus philippinus is a highly social and gregarious bird of the family Ploceidae that has been recently listed as 'Least Concern' by the IUCN Red List of Threatened Species. In India, four species of genus Ploceus are reported to date. This study focused on the appearance, distribution, diet specificity, nesting ecology, mating behaviour, and physiological responses to seasonal changes of P. philippinus. Populations have declined due to poor cultivation practices by farmers, rapid urbanization, and industrialization that have resulted in habitat loss. Weaver birds also face threats due to natural predators such as birds, and from insect damage to chicks, eggs, and nests. [ABSTRACT FROM AUTHOR]

Males of some species of the firefly Photinus produce nutritious spermatophores (nuptial gifts) the production of which is associated with a specific reproductive morphology. In fireflies and other insects, the production of nuptial gifts favours the evolution of polyandry. On the other hand, in fireflies, wing reduction (brachyptery) in females is associated with the lack of nuptial gifts. P. palaciosi is a synchronous firefly with brachypterous females, which would indicate an absence of nuptial gifts and a monandrous mating system. However, the reproductive morphology of P. palaciosi is like that of species producing nuptial gifts, which indicates this species should be polyandrous. Here, the results of an experimental study designed to test if females of the synchronous firefly Photinus palaciosi are polyandrous or monandrous are reported. The duration of copula was determined because this trait is associated with absence/presence of nuptial gifts in fireflies: it is very short (few minutes) in species lacking nuptial gifts and long (hours) in gift-giving species. More than sixty percent of the females mated with several males and the duration of each copulation was long. Thus, these results, together with those of previous studies on the morphology of the reproductive system, strongly indicate that males produce spermatophores (which usually contain nutrients and are, thus, considered nuptial gifts), which provides a possible explanation of both polyandry and prolonged copulations in P. palaciosi.

The exposure to sublethally high temperature reduces reproductive performance in diverse organisms. Although this effect has been particularly emphasized for males or male reproductive functioning, it remains largely unknown whether the effect of heat on fertility is sex-specific. Here we examined the impact of sublethally high temperature on male and female functions in a simultaneously hermaphroditic snail species, Lymnaea stagnalis. Examining hermaphrodites is useful to evaluate the sex-specific impacts of heat exposure, since they possess male and female functions within a single individual, sharing genetic and environmental factors. Moreover, previously developed sex allocation theory allows us to compare the differential performance of sex functions. In this study, we exposed snails to 20°C (control), 24°C and 28°C for 14 days and assessed their egg and sperm production, sperm transfer, mating behaviour and growth. Both types of gamete production were significantly reduced by higher temperature, leading to an overall reduction of reproductive investment. By quantifying sex allocation, we furthermore revealed that the heat-stressed snails reduced the relative investment in their male function. This study illustrates that examining simultaneous hermaphrodites can provide significant insights for the impact of heat, and the proximate mechanism, on reproduction in diverse organisms.

Cerambyx welensii Küster (Coleoptera: Cerambycidae) is a wood‐borer responsible for the decline of Mediterranean oaks in open woodlands.To establish that contact pheromones are involved in mate recognition of C. welensii, we extracted the cuticular hydrocarbons by solid phase microextraction at pre‐reproductive, beginning and ending of the reproductive period, and by solvent extraction of prothorax and elytra. The extracts were analysed by GC–MS under electron impact and chemical ionization conditions. Cuticular hydrocarbon profiles varied according to the reproductive period, although differences between sexes were not significant. Two compounds, 11/13‐methylheptacosane and 11‐methylnonacosane were more abundant in females at the beginning and ending of the reproductive periods. Compound 11/13‐methylheptacosane was also more representative in female prothorax than in males, and 2‐methyloctacosane was richer in male elytra than in females.We also studied the role of cuticular hydrocarbons in mate recognition in arena bioassays. Treatment of solvent‐washed dead females and glass dummies with one female equivalent (FE) of cuticular extract elicited mating responses in males, especially at the beginning of the reproductive period, with copulation attempts reaching 61.9% on solvent‐washed dead females and 23.8% on dummies. The successive treatment with synthetic compounds approaching a male cuticular profile inhibited male response.Our results confirm that contact pheromones mediate mate recognition in C. welensii. Knowledge of the precise role played by the major compounds 11/13‐methylheptacosane and 11‐methylnonacosane and other minor compounds representative in female prothorax may contribute to the development of novel management strategies against C. welensii. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that the Hainan's squat shrimp Thor hainanensis Xu & Li, 2014 undergoes a sex change and displays protandric hermaphroditism, a well-known feature from other congeners (T. dicaprio Anker & Baeza, 2021 and T. amboinensis (De Man, 1888)). We used morphological traits indicative of male function to categorize shrimp as prehensile males, non-prehensile males, and females. The linear relationship among the different morphological characters and the sexual morphs revealed that T. hainanensis has a sexual system of partial protandric hermaphroditism, where 50% of the population stays as active males and the rest of the population changes to female. Observations on the social and mating behaviour suggest that T. hainanensis exhibits a 'search and defend' mating system unlike other tropical caridean shrimps featuring protandrous hermaphroditism. [ABSTRACT FROM AUTHOR]

Males of some species of the firefly Photinus produce nutritious spermatophores (nuptial gifts) the production of which is associated with a specific reproductive morphology. In fireflies and other insects, the production of nuptial gifts favours the evolution of polyandry. On the other hand, in fireflies, wing reduction (brachyptery) in females is associated with the lack of nuptial gifts. P. palaciosi is a synchronous firefly with brachypterous females, which would indicate an absence of nuptial gifts and a monandrous mating system. However, the reproductive morphology of P. palaciosi is like that of species producing nuptial gifts, which indicates this species should be polyandrous. Here, the results of an experimental study designed to test if females of the synchronous firefly Photinus palaciosi are polyandrous or monandrous are reported. The duration of copula was determined because this trait is associated with absence/presence of nuptial gifts in fireflies: it is very short (few minutes) in species lacking nuptial gifts and long (hours) in gift-giving species. More than sixty percent of the females mated with several males and the duration of each copulation was long. Thus, these results, together with those of previous studies on the morphology of the reproductive system, strongly indicate that males produce spermatophores (which usually contain nutrients and are, thus, considered nuptial gifts), which provides a possible explanation of both polyandry and prolonged copulations in P. palaciosi. [ABSTRACT FROM AUTHOR]

Investigations of mate choice continue to address fundamental questions about the mechanisms and evolution of animal behaviour. A common behavioural assay used to study acoustically guided mate choice with playback experiments is phonotaxis, a typically robust response in which a chooser approaches acoustic signals, such as courtship songs or mating calls. Robust empirical studies of phonotaxis often require substantial laboratory facilities, such as a dedicated and sound-treated room or enclosure, in which the acoustic environment is controlled and in which animals are freely able to move about. The financial and space resources required to outfit a research laboratory to investigate phonotaxis may be sufficiently prohibitive such that some researchers are excluded from undertaking bioacoustic behavioural research. Here, we validate a new device designed to measure animal movements related to phonotaxis using an inertial measurement unit (IMU). The device is small and portable; it can be constructed for less than $300 USD (£ 238 GBP); and the build instructions and code for operation are freely available. In a series of four experiments with treefrogs, we demonstrate using the device that an IMU-based approach to measuring animal movement can replicate a broad range of findings from traditional phonotaxis experiments on species recognition and sexual selection. We conclude by discussing several possible uses for IMU-based measurements of phonotaxis. • Phonotaxis is a key assay in many behavioural studies. • Inertial measurement units (IMUs) provide new tools to measure phonotaxis. • An IMU is validated to study acoustically mediated mate choice in frogs. • The IMU produced results similar to those obtained in traditional phonotaxis tests. • IMUs are inexpensive alternatives to study species recognition and mate choice. [ABSTRACT FROM AUTHOR]

Sperm production is physiologically costly; therefore, males that mate multiple times are expected to allocate sperm prudently to maximize their fitness. Sperm allocation theory has been widely tested in internally fertilizing animals; however, few studies have investigated whether males adjust the number of sperm released according to their premating experience and cues from rival males. Here, we investigated sperm allocation strategies in an externally fertilizing fish, the medaka, Oryzias latipes , in controlled conditions. We used three treatments: direct interaction with a rival (two males were allowed to interact directly with each other), visual cue only (presenting a male in a separate compartment) and no rivals (control). In the direct interaction treatment, two types of alternative male mating behaviour, simultaneous sperm release and postspawn sperm release, were observed. Premating experiences affected subsequent mating behaviour: males that were more aggressive and exhibited more prominent courtship behaviour mated females without any disturbance from the other males, whereas simultaneous sperm release frequently occurred when both males exhibited similar levels of aggression and courtship behaviours. We also counted the sperm released per mating from the water tank. There was no change in the number of sperm released in the presence of visual cues of competition or direct interaction with the other males before mating. However, males (focal and/or rival) released more sperm only when sperm competition was high, that is, when a rival male successfully disrupted mating before simultaneous sperm release. Our results indicate that medaka males may adjust the number of sperm released per mating in different mating environments. • Detailed observations and an experimental control reveal sperm allocation in medaka. • Male competition and courtship affect mating behaviour and sperm allocation. • The visual cues of rivals do not increase the number of sperm released per mating. • Failure of disruption by rival males does not change the number of sperm released. • Males increase sperm number when disruption by rival males is successful. [ABSTRACT FROM AUTHOR]

The first representative of the genus Cerapus in the Gulf of Thailand, Cerapus rivulus sp. nov., is described from specimens sampled from Mae Klong Estuary, the inner Gulf of Thailand. The main identifying characteristics of this new amphipod species are pereonites 1 and 2 without constriction; male gnathopod propodus palm transverse with long posterior defining tooth and well-developed anterodistal recurved tooth adjacent to propodus articulation; pereopod 6 coxa without fine fringe setae ventrally, basis with setae on posterior margin; and telson with deep cleft. An updated identification key for the 25 known species in the genus is also presented. A discussion on their nesting and types of mating behaviour is provided. [ABSTRACT FROM AUTHOR]

Sexual conflict over mating may induce male mate-guarding prolonged in time in the absence of males, via devices such as mating plugs, widespread in insects. In most Lepidoptera, internal plugs are common, while in some butterfly families large external devices, called sphragides, evolved independently. Lack of, or incomplete sphragis in a few individuals were reported in sphragis-bearing species. Previous studies focused on typifying species-specific devices in a few specimens of many species. In contrast, we investigated alternative mate-guarding devices in detail of a sphragis-bearing butterfly. We conducted a six-year observational field study in a Clouded Apollo Parnassius mnemosyne population. Inspecting 492 females, we identified 3 different devices, filament, stopple and shield (i.e., sphragis) increasing in size and structure complexity, implying differential male investment and effectiveness in securing paternity. Shield dimensions, colour and all devices' shapes varied considerably. Shields were far more frequent than other devices. Some devices were lost, and a few were video-recorded when removed by males, showing the role of different parts of male external genitalia. We discuss potential causes of device variation and the role of removal attempts, and assess potential costs and benefits for both sexes. [ABSTRACT FROM AUTHOR]

Australian lizards are a diverse group distributed across the continent and inhabiting a wide range of environments. Together, they exhibit a remarkable diversity of reproductive morphologies, physiologies, and behaviours that is broadly representative of vertebrates in general. Many reproductive traits exhibited by Australian lizards have evolved independently in multiple lizard lineages, including sociality, complex signalling and mating systems, viviparity, and temperature-dependent sex determination. Australian lizards are thus outstanding model organisms for testing hypotheses about how reproductive traits function and evolve, and they provide an important basis of comparison with other animals that exhibit similar traits. We review how research on Australian lizard reproduction has contributed to answering broader evolutionary and ecological questions that apply to animals in general. We focus on reproductive traits, processes, and strategies that are important areas of current research, including behaviours and signalling involved in courtship; mechanisms involved in mating, egg production, and sperm competition; nesting and gestation; sex determination; and finally, birth in viviparous species. We use our review to identify important questions that emerge from an understanding of this body of research when considered holistically. Finally, we identify additional research questions within each topic that Australian lizards are well suited for reproductive biologists to address.

Animals adapt to their environments in the course of evolution. One effective approach to elucidate mechanisms of adaptive evolution is to compare closely related species with model organisms in which knowledge of the molecular and physiological bases of various traits has been accumulated. Drosophila elegans and its close relatives, belonging to the same species group as the model organism D. melanogaster, exhibit various unique characteristics such as flower-breeding habit, courtship display, territoriality, sexual dimorphism, and colour polymorphism. Their ease of culturing and availability of genomic information makes them a useful model for understanding mechanisms of adaptive evolution. Here, we review the morphology, distribution, and phylogenetic relationships of D. elegans and related species, as well as their characteristic flower-dependent biology, food habits, and life-history traits. We also describe their unique mating and territorial behaviours and note their distinctive karyotype and the genetic mechanisms of morphological diversity that have recently been revealed.

Reproduction is generally more sensitive to high temperatures than survival and arguably a better predictor of the response of populations to climate change than survival estimates. Still, how temperature simultaneously impacts male and female reproductive success, the mating system and the operational sex ratio remains an open question.Here, we addressed how a sublethal high temperature affects the reproductive system of the haplodiploid spider mite Tetranychus urticae. Males and females maintained at 25 or 36°C during development were paired and the fertility of both sexes, their mating and remating eagerness, and the paternity of the offspring of females with different mating histories were measured.Female and male fertility decreased at 36°C compared to 25°C, resulting in lower offspring production and a more male‐biased sex ratio, respectively, because of haplodiploidy. However, when either heat‐stressed females or females that mated with heat‐stressed males remated, there was a shift in paternity share, with more than one male contributing to the offspring. This was accompanied by reduced mating eagerness in pairs with partially sterile males and increased remating eagerness in pairs in which at least one sex was partially sterile in the first mating.The observed temperature‐induced changes in female remating eagerness and sperm use allowed restoring the offspring sex ratio, by increasing the proportion of fertilized offspring, but did not lead to the recovery of offspring number.The temperature‐induced changes in the mating behaviour and mating system should alter the interactions within and between the sexes, and with it the strength of sexual selection and sexual conflict in this species. Whether such changes are sufficient to prevent population extinction, despite the inability to recover offspring number, remains an open question. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Simple Summary: The mason bee Osmia cornuta is largely used for orchard crop pollination worldwide, both enhancing the maintenance of health ecosystems and providing economic benefits for human society. A deepening of the reproductive biology of O. cornuta could refine the management techniques of these pollinators. In the present study, the behavioural sequence of O. cornuta mating is described by using Marcov analysis, which revealed the occurrence of repeated, stereotyped, and regular sequences of behavioural units, including two types of copulations, i.e., short and long. The results reported in this paper support the hypothesis that ageing could negatively influence the success of reproduction in mason bees. Osmia cornuta Latr. is largely managed worldwide for the pollination of orchard crops, playing a key role in the maintenance of healthy ecosystems and ensuring economic and social benefits for human society. The management techniques of this pollinator include the possibility of delaying emergence from cocoons after diapause, allowing for the pollination of later-blooming fruit crops. In this study, the mating behaviour of bees emerging at the natural time (Right Emergence Insects) and of late-emerged bees (Aged Emergence Insects) was described in order to test if a delay in emergence could affect the mating sequence of O. cornuta. Markov analysis of the mating behaviour revealed the occurrence of antenna motion episodes that were repeated in a stereotyped manner at regular intervals during the mating sequence of both Right Emergence Insects and in Aged Emergence Insects. Pouncing, rhythmic and continuous emission of sound, motion of antennae, stretching of the abdomen, short and long copulations, scratching, inactivity, and self-grooming were identified as the stereotyped behavioural units of a behavioural sequence. The occurrence of short copulations, the frequency of which increased with the age of bees, could lead to a failure in the reproduction of the mason bee. [ABSTRACT FROM AUTHOR]

Accessory gland proteins contained within male ejaculates influence female reproduction and survival in insects. Nuptial food gifts offered by male crickets and katydids, the consumption of which may also alter female behaviour and physiology after mating, also contain accessory gland proteins. However, because nuptial feeding promotes the transfer of sperm and ejaculatory substances, it is unclear whether it is accessory gland proteins in the ejaculate, nuptial gifts or both that mediate these effects. Here we evaluate the effects of mating, nuptial gifts and accessory gland proteins on female reproduction in a gift-giving cricket (Gryllodes sigillatus) using a crossed experimental design. We injected females of varying mating experience with male accessory gland extract, permitting some females to consume the nuptial food gift, while experimentally preventing others from doing so. Mating resulted in a significant decrease in female sexual receptivity, an effect likely mediated by accessory gland proteins contained in the male's ejaculate. Consumption of the nuptial food gift resulted in the premature cessation of nuptial feeding following the female's next mating, leading to a concomitant decrease in sperm transfer by a rival male. This is a novel finding, demonstrating that fitness benefits to males of nuptial gift provisioning can also accrue over later copulations by their mates. Neither injection of accessory gland extract nor nuptial feeding influenced female oviposition; the absence of any effect of the injection of accessory gland proteins on female reproduction suggests that their efficacy may depend on their direct introduction into the female reproductive tract. More research is required to identify the specific accessory gland proteins in ejaculates and nuptial gifts that modulate female behaviour and physiology, potentially illuminating the evolution of these mechanistic tactics underlying sexual conflict. • How do accessory gland proteins affect female reproduction in crickets? • Mating resulted in a decrease in female sexual receptivity. • Nuptial feeding in one mating influenced time spent feeding in the next. • Thus, food gifts influence sperm transfer in both current and future copulations. • Neither injection of accessory gland extract nor nuptial gifts affected egg laying. [ABSTRACT FROM AUTHOR]

Compared to many types of phenotypic plasticity, developmental plasticity of mating behaviour in response to the social environment has received less attention. Understanding this type of plasticity is a challenge because when individuals adjust their trait expression in response to the trait distributions of other individuals, they change the social cue that those trait distributions represent. This feedback may limit when behavioural plasticity in response to social cues will prove adaptive. We used a livebearing fish (sailfin molly, Poecilia latipinna) to test two models for social plasticity: (1) socially cued anticipatory plasticity, which hypothesizes that developing juveniles use social environment directly to predict their optimum phenotype, and (2) condition dependence, which hypothesizes that developing juveniles use social environment indirectly to assess their competitive standing relative to other members of the social environment. Using a full-sibling split-brood design, we reared juvenile fish from birth until maturity in one of four social treatments: (1) three unrelated juveniles, (2) three females, (3) one small male and two females or (4) one large male and two females. Assessing mating behaviours at maturity and 1 month postmaturity, we found that a male's primary reproductive tactic (odds of using a courtship display over sneaking behaviour) was directly affected by the social environment during development as predicted by socially cued anticipatory plasticity (males were more likely to court when reared only with females and more likely to sneak when reared only with juveniles). However, rates of each type of mating behaviour (courtship or sneaking) were affected by interactions between social environment and heritable factors (sire size class and male body size), contrary to predictions from either socially cued anticipatory plasticity or condition dependence. These results suggest that socially cued anticipatory plasticity may be an important driver in the evolution of alternative mating behaviours and more likely to affect behavioural repertoires than current models of developmental plasticity suggest. • The social environment can affect development and fitness of phenotypes. • It is unclear how early life social environments affect adult mating behaviour. • Male primary mating tactics were directly affected by early life social environments. • Social environment by heritable factors interactions affected behavioural rates. • Early social environment may cue adult competition that males use to adjust behaviour. [ABSTRACT FROM AUTHOR]

Polygamous species vary in alternative reproductive tactics (ARTs) in relation to individual or environmental factors. Individuals may adopt fixed ARTs consistently across years, or may show flexible behaviour, changing tactic in different years. Different cost–benefit trade-offs should occur in relation to the adoption of each ART, possibly also influencing spatial behaviour and thus leading to alternative spatial tactics. Fixed ARTs are rare in mammals, whereas environmental variability is expected to favour flexibility in ARTs. We evaluated the potential for fixed versus flexible ARTs, and their correspondence with different spatial tactics, in a polygynous herbivore, the Alpine chamois, Rupicapra rupicapra rupicapra. We collected data on mating behaviour of 31 individually recognizable adult males during five rutting seasons and on their spatial behaviour throughout the same years. Fifteen males were classified as territorial and 16 as nonterritorial. No individual changed ART during our research. Moreover, we report a previously undocumented occurrence of different patterns of spatial behaviour across territorial males. Half of these individuals had overlapping or continuous winter and summer ranges, whereas the others moved between different areas (in winter, immediately after the rut, or between summer and autumn). No differences between males adopting diverse ARTs were found in age or body mass, or in their respective frequencies of intrasexual aggressive interactions. On the other hand, territorial males, dominant over nonterritorial individuals in aggressive interactions, had more mating opportunities than nonterritorial ones. Further work should test for the consistency of our results across broader spatial and temporal scales, as well as species. Differences in key aspects of behaviour (e.g. space use) and life history (e.g. reproductive success) would help explain ART evolution and coexistence in a population. If ARTs were fixed in male chamois, neither ART should have been selected against long enough to determine its extinction, over evolutionary times. • Alternative reproductive tactics (ARTs) have been described in male Alpine chamois. • Almost 50% of adult males were territorial and the others were nonterritorial. • No individual changed ART during our study, suggesting fixed ARTs in mature males. • Age and body size are not determinants of the adoption of ARTs in adult chamois. • We report two spatial behaviours in territorial males: residents versus migrants. [ABSTRACT FROM AUTHOR]

Mating rate optima often differ between the sexes: males may increase their fitness by multiple mating, but for females multiple mating confers little benefit and can often be costly (especially in taxa without nuptial gifts or mala parental care). Sexually antagonistic evolution is thus expected in traits related to mating rates under sexual selection. This prediction has been tested by multiple studies that applied experimental evolution technique, which is a powerful tool to directly examine the evolutionary consequences of selection. Yet, the results so far only partly support the prediction. Here, we provide another example of experimental evolution of sexual selection, by applying it for the first time to the mating behaviour of a seed beetle Callsorobruchus chinensis. We found a lower remating rate in polygamy‐line females than in monogamy‐line (i.e. no sexual selection) females after 21 generations of selection. Polygamy‐line females also showed a longer duration of first mating than monogamy‐line females. We found no effect of male evolutionary lines on the remating rate or first mating duration. Though not consistent with the original prediction, the current and previous studies collectively suggest that the observed female‐limited responses may be a norm, which is also consistent with the conceptual advances in the last two decades of the advantages and limitations of experimental evolution technique. [ABSTRACT FROM AUTHOR]

In explosive breeding frogs, high intrasexual competition between males leads to a sexual coercion ruled mating system, where males presumably evolved preferences for specific female traits. We tested these preferences in the European Common Frog by excluding intrasexual competition. We hypothesized that all males show preferences towards larger female body size, due to higher fecundity. Our results did not show any preference considering female body size, neither in the attempt to amplex a female nor during the formation of pairs. Additionally, we witnessed a high failure rate of male mating attempts, which hints at high mating costs and offers an explanation for the lack of preferences in males. Nonetheless, we observed a non-random mating pattern in successfully formed pairs, where in the absence of size dimorphism females were on average larger than males. This indicates a different mechanism for selection which is independent from male mating preference or scramble competition. [ABSTRACT FROM AUTHOR]

• Encarsia sophia is a heteronomous hyperparasitoid, reducing competition and maximizing biocontrol by producing fertilized female offspring. • Multiple matings extend the oviposition period of females and significantly increase parasitism on whiteflies. • In mass rearing, male provisioning time can be shortened to within 2 h, with each male capable of engaging in 2–3 mating sessions. • For field releases, maintain a balanced male–female ratio on pupae cards and supplement parasitoids 15 days after the initial release. Encarsia sophia is the dominant parasitoid of invasive whitefly pest such as Bemisia tabaci. This heteronomous hyperparasitoid species lays fertilised diploid eggs in whitefly nymphs, which serve as primary hosts. Larvae develop as female progeny by consuming whitefly hosts, providing direct biocontrol benefits. However, male progeny originate from unfertilised eggs laid on secondary hosts (primary parasitoids within whitefly nymphs) and develop by consuming primary parasitoid larvae rather than whitefly hosts. Therefore, it is crucial for indoor rearing and field release of the hyperparasitoid to determine whether a female with single-mating experience can parasitise primary hosts and produce female progeny for a whole lifetime and, if not, whether it is remating events and prolong the period of female production, thereby increasing the amount of parasitism on whiteflies. Our fecundity experiments of females with single-mating experience, equally provided with primary and secondary hosts, showed that single mating was insufficient for E. sophia females to lay fertilised eggs in whitefly nymphs for their whole lifetime. In multiple mating experiments, 76.7 % of male adults completed their second mating 2 h after the first, whereas female adults accepted the second mating only if primary hosts were available thereafter. Remating was beneficial for female adults as it prolonged the ovipositional period of fertilised eggs (from 13.3 ± 0.6 days for single to 17.1 ± 0.7 days for twice mating) and increased parasitism on B. tabaci primary host (from 53.1 ± 3.8 for single to 76.4 ± 5.9 for twice mating respectively). The mating experience of males increased their copulation success, whereas that of females decreased it. In conclusion, recommendations are provided for large-scale indoor rearing and field release of E. sophia. Firstly, sufficient time for providing males can be shortened to within 2 h, and a single male can engage in 2–3 mating sessions. Following the 15-day peak oviposition period, the addition of newly emerged males is advised. Secondly, for field release of adult parasitoids, it is recommended to concentrate on releasing females after completing mating indoors. For the release of pupae cards, ensure a balanced ratio of males and females on each card to facilitate mating upon emergence. Additionally, release extra males and females 2 weeks after the initial batch of releases. [ABSTRACT FROM AUTHOR]

In several butterflies, the posterior end of the hindwings resembles a butterfly head when the butterfly is perched with its wings closed. There is evidence that this "false head" (FH) deflects predator attacks towards non-vital parts of the body. If the FH protects from visually oriented predators, its condition in an individual butterfly could provide information about its quality to prospective mates. We tested two hypotheses based on this idea by comparing the probability of mating, duration of copulation and size of the ejaculate received by females of Callophrys xami (Lycaenidae) with an intact FH and those with an ablated FH in a paired experiment. The absence of a FH had no effect on the probability of mating, but females with an ablated FH copulated for longer and received larger ejaculates, which supports the hypothesis that males prefer females with damaged FHs because this reveals the female's ability to deflect attacks. Male or female (or both) cryptic choice could also account for our results, but more studies are needed to test this.

The paper contains information about 21 cases of abnormal amplexus among anurans (Amphibia) detected on the territory of the Chernivtsi Region, Ukraine. Multiple amplexus, consisting of one female and two or more males, was registered in three species: Bombina variegata, Bufo bufo, Rana temporaria. The author described interspecific amplexus in six cases. Five of them were among anurans (Bufo bufo male × Pelophylax lessonae male, Rana dalmatina males × Rana temporaria female or males, Rana temporaria male × Pelophylax ridibundus female) and one case — among Anura and Caudata (Bombina variegata male × Lissotriton montandoni female).

The paper contains information about 21 cases of abnormal amplexus among anurans (Amphibia) detected on the territory of the Chernivtsi Region, Ukraine. Multiple amplexus, consisting of one female and two or more males, was registered in three species: Bombina variegata, Bufo bufo, Rana temporaria. The author described interspecific amplexus in six cases. Five of them were among anurans (Bufo bufo male × Pelophylax lessonae male, Rana dalmatina males × Rana temporaria female or males, Rana temporaria male × Pelophylax ridibundus female) and one case -- among Anura and Caudata (Bombina variegata male × Lissotriton montandoni female). [ABSTRACT FROM AUTHOR]

Sexual dichromatism in animals is usually associated with mating displays and is linked to strong sexual selection. Among amphibians, it has mostly been reported in anurans and only in a few caudates. Here, we investigated sexual dichromatism in the only two extant species of the genus Salamandrina, testing for its possible role in intraspecific communication during the mating rituals of these terrestrially mating salamanders. In both S. terdigitata and S. perspicillata, we highlighted that males have more conspicuous ventral colourations, yet this is limited to the throat region, namely featuring rounder, larger and brighter gular white patches than females. We also described a new mating ritual behaviour performed by male S. perspicillata, that is, a stereotyped throat hyperextension, that enhances the visibility of the dimorphic colouration of the gular region of males, presumably representing a visual cue directed to females. We thereby discuss the potential role of sexual dichromatism in sexual selection and the evolutionary history of the genus Salamandrina. [ABSTRACT FROM AUTHOR]

Although morphological variation may have an effect on behaviour, there are only a few studies on julid millipedes in which the influence of the variability of some morphological traits on mating success has been explored. Hence, objectives of this study were to investigate mating behaviour in laboratory conditions and identify traits that could possibly be the target of pre-copulatory selection in the julid species Megaphyllum unilineatum. Behavioural sequences were quantified in three types of tests: a mating arena test, a female choice test, and a male choice test. Although the number of contacts with the first chosen partner (from the mating arena test) was greater than with newly offered individuals in choice tests, values of the sexual selection coefficient did not statistically confirm this preference. In addition, analyses of linear measurements (trunk height and width, length of the whole body, antennae, walking legs, and gonopod flagella) in individuals of different mating status were also conducted, as well as geometric morphometric analyses of size and shape of the antennae, heads, walking legs, and gonopod promeres and opisthomeres in such individuals. Antennal length and shape, head shape, and the walking legs shape, differed significantly, depending on the mating status of females. In males of different mating status, statistical significance was established only in the promere centroid size. The differences in certain behavioural sequences in M. unilineatum are similar to those previously reported in M. bosniense, while such similarity is not detected with respect to morphological variation in the mentioned species. [ABSTRACT FROM AUTHOR]

The success of autodissemination of entomopathogenic fungi depends to some degree on the transmission of infective conidia or spores from contaminated hosts to conspecifics. In the present study, we examined the potential for direct transmission of a lethal dose of Metarhizium brunneum (Petch) conidia between opposite sex pairs of Agriotes obscurus L in the laboratory. Male and female beetles were exposed to M. brunneum conidia prior to pairing with an uncontaminated opposite sex partner ('indirectly exposed' to M. brunnneum), 2, 21 and 45 h after M. brunneum exposure. Ninety-six percent of the female beetles that had been exposed to M. brunneum granules died by day 15, as compared to 59% and 53% of the indirectly exposed and control females. From 15 days after the beginning of the experiment, females indirectly exposed to M. brunneum had higher odds of dying at any point in time than unexposed females across all post-exposure time periods. There was no significant difference in the odds of dying between indirectly exposed males and their unexposed counterparts at any point during the experiment. When the female beetle was exposed to M. brunneum forty-five hours prior to pairing, the pairs engaged in fewer courtship interactions relative to the other treatment groups, however less than 50% of all the pairs engaged in courtship interactions. The low incidence of courtship interactions and limited transfer of conidia between A. obscurus beetle pairs suggests that negligible horizontal transmission of M. brunneum conidia may occur between conspecifics. [ABSTRACT FROM AUTHOR]

Sexual conflict arises from differences in reproductive interests between the sexes. We allowed the female harvestman Phalangium opilio to sequentially mate with two different males to examine female sexual receptivity in this species. Virgin females were more sexually receptive than non-virgins. Males exhibited a high interest in repeated copulations with the same female, often engaging in aggressive behaviours such as biting and reversed sexual cannibalism. Fellatio, a behaviour in which females lick the male's penis, was observed in 44% of trials and was associated with female unwillingness to mate and shorter copulation duration. Fellatio was repeatable, suggesting that it is influenced by individual characteristics or underlying physiological factors. Female lifespan was negatively correlated with the total number of eggs produced, suggesting a trade-off between reproduction and longevity. These findings provide evidence of the appearance of fellatio, a female mating strategy that evolved as compensation of avoiding unwanted sexual intercourse., (© 2024. The Author(s).)

Many arthropods carry maternally inherited endosymbionts that cause cytoplasmic incompatibility (CI), manifested as embryonic mortality in matings of infected males with uninfected females. Infected females, however, do not suffer this cost. Therefore, in populations with mixed endosymbiont infections, selection is expected to favour mechanisms that enable hosts to avoid or mitigate CI. This may include changes in mating behaviour, such as reduced female receptivity to mating and/or remating when approached by incompatible males. Here, we investigated mating behavioural traits in haplodiploid thrips naturally associated with two CI-inducing endosymbionts, Cardinium and Wolbachia . Compared with females with both endosymbionts, those with only Cardinium showed reduced receptivity to males carrying both. However, surprisingly, females without endosymbionts were not less receptive to incompatible males. Furthermore, in contrast to females without endosymbionts, females with Cardinium were far less likely to remate with incompatible than compatible males irrespective of the compatibility type of the first mating. Our results suggest that endosymbiont-specific sexual selection processes occur, whereby females carrying only Cardinium recognize Wolbachia in coinfected males to avoid CI. This may hinder a CI-driven Wolbachia spread. Endosymbiont-mediated mating behaviours may be crucial for the dynamics of CI-inducing endosymbionts and their application in pest management strategies.

In the natural mating system, the reproductive behaviour of birds plays an important role in fertility success. The aim of the research was to: (1) characterize the mating behaviour of the Zatorska goose in the harem and competitive social structure; (2) determine the relationship between parameters of mating activity (MA), fertility (F) and plasma testosterone (T) concentration. The Zatorska goose is a breed kept in accordance with the roles of the biodiversity conservation program, which makes it a unique research model. Observations were carried out in the Zatorska goose flock. The birds were kept on litter in pens with harem or competitive mating structure (sex ratio 1 ganders: 4 geese). The recordings were made using a digital recorder connected to the cameras. The MA was described by frequency of courtship displays (Cou), copulation attempts (CopA), successful copulation (SCop) and total mating activity (TMA). In addition, the levels of fertility (artificial incubation) and T concentrations (radioimmunoassay; RIA) were assessed. In a harem mating system the SCop was 0.65 times/6 h as an average and was higher in the first half of breeding season compared with second half. TMA ranged from 0.66 to 2.36 times/6 h and was higher in the morning than in the afternoon. There was a moderate positive correlation (r = 0.37) for SCop and F. The effect of the position of the ganders in the social hierarchy on the frequency of MA was observed. In dominant ganders, SCop frequency (1.5 times/3 h) was higher than in subordinate ones. The TMA for dominant ganders was 3.6 times/3 h. Plasma T concentration was higher in dominant ganders than in the subordinates. In both MA structures, goose-goose interaction seems to play an important role in mating activation. Conclusions: It can be assumed that the SCop can be used to identify ganders with poor reproductive potential at the onset of the breeding season. Furthermore, the dynamics of antagonistic gander-gander interactions should be taken into account when creating an optimal sex ratio in small flocks with a competitive social structure. [ABSTRACT FROM AUTHOR]

New records of Celonites tauricus Kostylev, 1935 are reported from Chios, Rhodes, Samos (Greece), Dagestan (Russia), Georgia, and the main portion of Azerbaijan (previous records were made from the Nakhchivan Autonomous Republic only). Flower visits of imagines were observed at six species of Lamiaceae, four of them being recorded for the first time as forage plants of C. tauricus. The newly recorded Teucrium canum Fisch. & C.A. Mey. and Ziziphora taurica M. Bieb. (both Lamiaceae) are principal forage plants in Dagestan and the Crimea, correspondingly. The behaviour of females at flowers of Z. taurica differs from that previously described at flowers of Teucrium chamaedrys L. and Satureja thymbra L. (also Lamiaceae) in that pollen removal from the anthers and nectar uptake take place separately from each other in temporal succession. This difference is obviously caused by the flower structure of the genus Ziziphora, specifically its much longer corolla tube. Females also try to collect pollen from flowers of Salvia nemorosa subsp. tesquicola (Klokov & Pobed.) Soó but usually without success, while nectar uptake from this species is successful. The specialized morphological structures of the females for pollen-uptake from the nototribic anthers and pollen-transfer from the exoskeleton to the mouthparts are described. They are similar to those of the closely related Celonites abbreviatus (Villers, 1789), and consist of specialized stiff “knobbed” pollen-collecting setae covering the anterior surface of the head, particularly the frons and the clypeus, as well as comb-like rows of specialized, particularly strong pollen-brushing setae along the anterior margins of the inner surface of the first and the second segments of the fore tarsi. Males of C. tauricus patrol in flight along the forage plants of the females. Successful copulations occur either on flowers or on the ground. [ABSTRACT FROM AUTHOR]

In facultatively parthenogenetic populations, the prevalence of sexual reproduction depends on whether females mate and therefore produce sons and daughters or avoid mating and produce daughters only.The relative advantage of mating in such species may depend on a female's own reproductive origin (i.e. development from a fertilised or unfertilised egg) if parthenogenesis reduces heterozygosity similar to sexual inbreeding, or if it inhibits mating, sperm storage or fertilisation. But effects of reproductive origin on development and performance are poorly understood.Using the facultatively parthenogenetic stick insect, Extatosoma tiaratum, we quantified morphology, mating probability, and reproductive success in mated versus unmated females of sexual versus automictic (parthenogenetic) origin.We found strong evidence that increased homozygosity negatively impacted some traits in parthenogenetically produced females: compared to sexually produced females, parthenogenetically produced females were smaller and more prone to deformities in vestigial wings, but not more prone to fluctuating asymmetry in their legs.Parthenogenetically produced females received fewer mating attempts and avoided mating more often than sexually produced females. Yet, contrary to the expectation that sex should rescue parthenogenetic lineages from the detrimental effects of increased homozygosity, parthenogenetically produced females gained no net reproductive benefit from mating, suggesting that physiological constraints limit fitness returns of sexual reproduction for these females.Our findings indicate that advantages of mating in this species depend on female reproductive origin. These results could help to explain spatial distributions of sex in facultatively parthenogenetic animals and evolutionary transitions to obligate asexuality. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The need to respond quickly to the presence of an ephemeral resource required for breeding is often a feature of scramble competition mating systems. Scramble competition mating systems can feature extreme levels of sexual conflict and coercive mating by males. As a result, sexual selection can act on various traits used by males to overcome female resistance behaviours. Selection on these traits may result in significant intra and intersexual size variation and sexual dimorphism. Additionally, traits that influence mating success in males often show positive static allometry. Kelp flies (Coelopidae) are a small family of Diptera which specialise on wrack (beach cast marine macroalgae), a highly ephemeral resource. The mating system of these flies involves high levels of sexual conflict, with females rejecting all male mating attempts. In this study we describe intra and intersexual size variation and static allometry of traits in two of Aotearoa|New Zealand's species, Coelopella curvipes and Chaetocoelopa littoralis. In addition, we investigate the mating behaviour of C. littoralis under ecologically relevant mating conditions. We found high levels of variation in both species with significant evidence of sexual dimorphism across all traits measured in C. littoralis, and in mid tibia length in C. curvipes. Furthermore, mid tibia length in both species exhibits positive static allometry and is disproportionally larger in larger males, suggesting that this trait in particular may be under strong sexual selection. We found that larger male C. littoralis which attempt to mate are significantly more likely to mate successfully demonstrating a large-size advantage in this species similar to findings across the Coelopidae. However, we only found a non-significant trend towards a mating advantage for males with longer mid-tibiae. We discuss these findings with reference to the population dynamics and ecology of these species. [ABSTRACT FROM AUTHOR]

In many avian species, age, body size, and song could signal quality or individual breeding experience and these traits are often correlated with reproductive success. The relationship between sexually selected signals and avian mating systems is a topic of active research, but still remains poorly investigated in species from southern latitudes. Here, we explored the relationships between body size, condition, age, song and social and genetic reproductive success in Sicalis flaveola pelzelni, a Neotropical thraupid. This socially monogamous species has both age-related changes in song and plumage colouration and extra-pair paternity. When measuring male song we found that a lower peak frequency may be associated with patterns of extra-pair paternity gain by males. We also found that male age may not have a marked effect on paternity assurance. In addition, we found that female body condition appears to influence on the proportion of extra-pair nestlings in females' nests. We contribute novel data to help bridge the geographic and taxonomic gap in this research field. [ABSTRACT FROM AUTHOR]

We present nine observations of abnormal amplexus in anurans, reported for the first time from Latvia. In total, nine types of abnormal amplexi are documented for four anuran species: Bombina bombina (Bombinatoridae), Bufo bufo (Bufonidae), Pelophylax lessonae and Rana temporaria (Ranidae). According to the one of our observations, abnormal amplexus resulted in the extirpation of a competing anuran species from a breeding pond for two seasons. [ABSTRACT FROM AUTHOR]