Exaggerated sexual traits, such as ornaments and courtship displays, are crucial for mate acquisition in many species and are often subject to directional runaway selection. However, in the face of ...high predation risk, natural selection can result in a reduction of conspicuous precopulatory displays to avoid detection by potential predators. Sexual selection may then favour increased investment in inconspicuous postcopulatory traits. Here, we investigated the transgenerational effects of predation on precopulatory male courtship and postcopulatory sexual traits (testes size, sperm length) in a dung fly, Sepsis punctum (Sepsidae). Behavioural assays prior to selection document a marked decrease in male courtship displays in the presence of a predator, the Asian Ant Mantis (Odontomantis planiceps). However, after ten generations of experimental evolution, flies exhibited a marked increase in courtship, both in the absence and presence of a predator. Additionally, under sustained predation pressure, male and female body size decreased but male postcopulatory traits were not significantly affected. These results suggest that precopulatory courtship can be under strong sexual selection even in the face of predation pressure. Larger flies were more susceptible to predation, and there could be canalisation of postcopulatory traits that are crucial for fertilisation.
•Male courtship activity increased over generations regardless of predation risk•Adult body size decreased over generations of sustained predation pressure•Male postcopulatory traits (testes volume, sperm length) were not significantly affected•Crucial postcopulatory traits may be under strong stabilising selection due to their role in fertilisation
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.
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.
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The structure of the contact network between individuals has a profound effect on the transmission of infectious disease. Using a novel technology - proximity sensing radio collars - we described the ...contact network in a population of Tasmanian devils. This largest surviving marsupial carnivore is threatened by a novel infectious cancer. All devils were connected in a single giant component, which would permit disease to spread throughout the network from any single infected individual. Unlike the contact networks for many human diseases, the degree distribution was not highly aggregated. Nevertheless, the empirically derived networks differed from random networks. Contact networks differed between the mating and non-mating seasons, with more extended male-female associations in the mating season and a greater frequency of female-female associations outside the mating season. Our results suggest that there is limited potential to control the disease by targeting highly connected age or sex classes.
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.
Mating behaviours were compared between the polygamy‐ and monogamy‐lines of Callosobruchus chinensis experimental evolution. Though sexual selection would primarily act on male in this system, female traits responded to the evolutionary treatment, whereas male ones did not. This result and previous studies collectively indicate intricate short‐term responses to sexual selection.
Lateralisation (i.e. functional and/or structural specialisations of left and right sides of the brain) of aggressive traits has been studied in a number of vertebrates, while evidence for ...invertebrates is scarce. Mosquito females display aggressive responses against undesired males, performing rejection kicks with the hind legs. In this research, we examined lateralisation of kicking behaviour in females of the Asian tiger mosquito, Aedes albopictus. We found a right-biased population-level lateralisation of kicking behaviour. Four repeated testing phases on mosquito females confirmed the preferential use of right legs. However, when left legs were used, the mean number of kicks per rejection event was not different to that performed with right legs. Both left and right kicking behaviour lead to successful displacement of undesired partners. This is the first report about behavioural lateralisation in mosquitoes.
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.
Behavioural assays in which animals recognize, localize or discriminate among signals are broadly useful for answering an array of biological questions, but results can be sensitive to the ...characteristics of individuals, including age and mating status. Researchers may prefer to use young, unmated individuals in experiments both to control for the effects of mating and because younger and unmated individuals may respond more often or more quickly. In natural contexts, virgin females are likely to behave differently than mated females, especially in animals that store sperm for future use, because the costs and benefits of mating are different for these two groups. In species in which multiple mating is common, individuals are much more likely to have mated at least once at the time of any given mating event than they are to be virgins, suggesting the use of virgin subjects in experiments is not reflective of most natural mating decisions. We conducted a literature review to sample the methods employed in empirical studies that use crickets in phonotaxis assays. Many studies draw conclusions based only on virgins, and methods vary widely with respect to the age of individual subjects. We then conducted an empirical study of the effect of mating status and age on female phonotaxis behaviour in Teleogryllus oceanicus, the Pacific field cricket. Our results show that both age and mating status affect some commonly used measures of female responsiveness in phonotaxis assays: older females begin moving more quickly in phonotaxis tests, while virgins have shorter response latencies. These findings are consistent with the idea that the cost of remaining unmated increases with age, and that virgin females benefit from an initial mating more than mated females benefit from additional matings.
•Virgin female crickets responded faster to playback than mated females.•Older females began moving towards playback faster than younger females.•Neither age nor mating status affected the probability of responding to standard song.•Phonotaxis assays with mated females may more accurately reflect mate choice.
Hybridization events have long interested biologists because of their implications for species concepts and taxonomy. Documenting hybridization events is important because hybridization rates are ...commonly used as support for accepted taxonomic divisions. In July 2017, we observed a nest where a male Cerulean Warbler (Setophaga cerulea) and a female Black-throated Blue Warbler (Setophaga caerulescens) were feeding nestlings. The Cerulean Warbler and Black-throated Blue Warbler communicated with each other using song (male) and calls (female), similar to a non-hybrid pair of either parent species, and the pair was not observed to engage in aggressive behaviors toward each other. Interestingly, the Black-throated Blue Warbler is not known to breed in Indiana, although it is a regular migrant in the spring and fall. We describe the behaviors of the hybrid pair at the nest, provide photographs and audio recordings for documentation, and hypothesize that this instance of hybrid pairing may have occurred due to mate scarcity. Received 1 November 2017. Accepted 8 August 2018. Key words: Black-throated Blue Warbler, Cerulean Warbler, hybrid, Parulidae, Setophaga caerulescens, Setophaga cerulea. wood-warbler. (Spanish)--Los eventos de hibridacion han interesado a los biologos por mucho tiempo debido a sus implicacioncs con los conceptos de especie y la taxonomia. La documentacion de estos eventos es importante porque las tasas de hibridacion son comunmente usadas en apoyo de divisiones taxonomicas aceptadas. En julio de 2017. observamos un nido en el que un macho del chipe Setophaga cerulea y una hembra de S. caerulescens alimentaban polluelos. Ambos chipes se comunicaban entre si utilizando su canto (macho) y llamado (hembra), de modo similar a una pareja no-hibrida de cualquiera de las especies parentales. y la pareja no fuc observada teniendo comportamientos agresivos hacia el otro. Es interesante senalar que no se sabe que S. caerulescens anide en Indiana, aunque es una migratoria regular en primavera y otoiio. Describimos los comportamientos de la pareja hibrida en el nido, proporcionamos fotografias y grabaciones de audio como documentacion e hipotctizamos que csta instancia de una pareja que se hibridizo pudiese haber ocurrido por la escasez de parcjas. Palabras clave: Chipes, hibrido, Parulidae, Setophaga caerulescens, Setophaga cerulea.
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).
