Heterospecific Females Research Articles

Modification of the activation of the hypothalamic-pituitary-gonadal axis in males of the house mouse (Mus musculus wagneri) exposed to the odor of receptive con- and heterospecific females: influence of early experience and maternal environment

Modification of the activation of the hypothalamic-pituitary-gonadal axis in males of the house mouse (Mus musculus wagneri) exposed to the odor of receptive con- and heterospecific females: influence of early experience and maternal environment

Male recognition of conspecific female chemical cues in a diverse clade of freshwater fishes.

Where orangethroat darters (Etheostoma: Ceasia) and rainbow darters (Etheostoma caeruleum) co-occur, males prefer conspecific over heterospecific females. The cues males use to identify conspecific females remain unclear. We conducted behavioral trials to ask whether chemical cues function in conspecific recognition. We found that males from three orangethroat darter species preferentially associate with female scent over a control. Our results support the use of olfaction in conspecific identification in the orangethroat clade and contribute to our understanding of signals that may facilitate species recognition and underlie the evolution of behavioral isolation.

Early Postnatal Experience Modifies Activation of the Pituitary Testicular Complex in Male House Mice (Mus Musculus) Exposed to the Odor of Receptive Con- and Heterospecific Females

For the first time, it was shown that activation of the pituitary–testicular complex in male house mice exposed to the odor of receptive females of their own and closely related species was modified under the influence of early postnatal experience and the maternal environment. We have confirmed associated formation of behavioral and physiological mechanisms of precopulatory isolation in early ontogenesis. The serum levels of free testosterone in males of closely related species M. spicilegus and M. m. wagneri differ, it is significantly lower in mound-building mice. In males fostered by a conspecific female, the level of free testosterone was significantly lower when exposed to a heterospecific female odor in comparison with a conspecific odor. The rearing of M. m. wagneri males by females of a closely related species led to a decrease in the testosterone response caused by exposure to female chemosignals (both con- and heterospecific) and to the absence of differences in the serum level of free testosterone when exposed to the odor of a female of their own or closely related species. These results indicate that the rearing conditions had a significant influence on the formation of hormonal mechanisms of reproductive isolation.

REARING RODENT PUPS IN FOSTER FAMILIES OF TNEIR OWN OR ANOTHER MAMMAL SPECIES: SURVIVAL AND THE CAUSES OF MORTALITY

Conditions of rearing pups at an early age render a significant impact on subsequent development, reproduction and certain features of the behavior of mammals including rodents. Parents, mostly lactating females, are the main component of the social environment of pups at the early period of postnatal ontogenesis in most mammal species. Therefore, rearing pups in foster families of their own (in-fostering) or another, even taxonomically distant species (cross-fostering) is one of the main methods of assessing the impact of early experience and maternal environment on the development of animal behavior. Cross-fostering or in-fostering is also used for the conservation of valuable animal species. Therefore, more effective fostering methods that provide the maximum survival of the young are necessary to be developed. According to this, we investigated the survival and possible causes of the mortality of rodent pups representing several species in foster families of their own or another mammal species. We conducted a series of experiments on the cross-fostering and in-fostering of house (Mus musculus) and mound-building (Mus spicilegus) mice, yellow steppe lemmings (Eolagurus luteus) and brown rats (Rattus norvegicus), and on rearing rat pups in foster families of the European polecat (Mustela putorius). The proportion of successfully cross-fostered pups (0–68.4) was lower compared to the in-fostered (93.3–100) ones. This result is presumably explained by more significant differences in the maternal environment when reared by a heterospecific female. According to the literature data, the age of foster and recipient female pups, species-specific differences of odor, the presence or absence of a male and the level of paternal care, the level of stress of the mother and offspring, the expression of maternal instinct, the previous female experience in rearing its own and foster pups, the duration of lactation and the nutritional value of maternal milk are the factors that seem to affect the survival and mortality of foster pups.

Male attention allocation depends on social context

Allocation of attention, typically a limited capacity, is a mechanism used to filter large amounts of information and determine what stimuli are most relevant at a particular moment. In dynamic social environments as found in almost all species, including humans, multiple individuals may play a pivotal role in any given interaction where a male’s attention may be divided between a rival, a current mate, and/or future potential mates. Although clearly important, the role of the social environment on attention in animals is not well understood. Here, we investigated impacts of the social environment on attention allocation using male sailfin mollies, Poecilia latipinna, which are a part of a sexual-unisexual mating system with the Amazon molly, Poecilia formosa. We asked: 1) Does the species of female influence the amount of attention a male allocates to her? And 2) Is a male’s attention towards his mate influenced by different social partners? We show that males perceive a larger male as a more relevant stimulus to pay attention to compared to a smaller male, and a conspecific female (either a partner or audience) as a more relevant stimulus compared to a heterospecific female. Our results show that differential allocation of attention is dependent upon multiple components of the social environment in which an individual interacts. Understanding what qualities of rival males or potential mates provide enough meaning to males to cause a shift in attention away from a mating opportunity is essential to understanding the influence of the social environment in sexual selection.

Footprints of the lady beetles Cryptolaemus montrouzieri and Tenuisvalvae notata affect their foraging behavior and predation rate

AbstractThe lady beetles Tenuisvalvae notata (Mulsant) and Cryptolaemus montrouzieri Mulsant (both Coleoptera: Coccinellidae), are used in biological control of mealybugs in many countries, including Brazil. As individuals of these species walk on plant surfaces, they leave chemical footprints that can affect their interactions with conspecifics, as well as other coccinellid species in the same environment. Therefore, this study aimed to evaluate the effects of T. notata and C. montrouzieri footprints on both their own and each other's foraging behavior and predatory potential. Arena bioassays were conducted to evaluate the effect of the footprints on conspecifics and heterospecifics. In addition, the chemical profiles of these footprints were analyzed by gas chromatography, flame ionization detection, and mass spectrometry (GC‐FID and GC–MS). For this, extracts of footprints were obtained from a glass Petri dish where 20 adults (males or females) were allowed to walk for 24 h. Behavioral bioassays showed that both species can recognize each other's footprints. Tenuisvalvae notata females avoided areas treated with footprints of heterospecific females, whereas C. montrouzieri females were arrested on areas with footprints of T. notata females. Tenuisvalvae notata adults did not change their predation rate when exposed to the footprints of heterospecifics, but second instars had a higher predation rate on areas treated with heterospecific footprints. Second instar C. montrouzieri also had an increase in predation when exposed to footprints of heterospecifics, and females captured significantly more prey when exposed to footprints of conspecifics, whereas males' predation rate decreased when exposed to footprints of both conspecifics and heterospecifics. The chemical analyses showed that the hexane extracts of footprints were composed mainly of linear hydrocarbons, saturated and non‐saturated, from C20 to C33. The composition (qualitative and quantitative) of footprint extracts is species‐ and sex‐specific. This is the first report on the effects of footprints on the behavior of these species.

Organization of the parallel antennal-lobe tracts in the moth.

The olfactory pathways of the insect brain have been studied comprehensively for more than 40years, yet the last decade has included a particularly large accumulation of new information relating to this system's structure. In moths, sharp intracellular recording and staining has been used to elucidate the anatomy and physiology of output neurons from the primary olfactory center, the antennal lobe. This review concentrates on the connection patterns characterizing these projection neurons, which follow six separate antennal-lobe tracts. In addition to highlighting the connections between functionally distinct glomerular clusters and higher-order olfactory neuropils, we discuss how parallel tracts in the male convey distinct features of the social signals released by conspecific and heterospecific females. Finally, we consider the current state of knowledge regarding olfactory processing in the moth's protocerebrum and make suggestions as to how the information concerning antennal-lobe output may be used to design future studies.

Mate choice errors may contribute to slow spread of an invasive Eurasian longhorn beetle in North America

Tetropium fuscum (Coleoptera: Cerambycidae) is a Eurasian longhorn beetle and forest pest that first became invasive to Nova Scotia, Canada around 1990. In the time since its introduction, T. fuscum has spread only about 150 km from its point of introduction. In its invasive range, T. fuscum co-exists with its congener Tetropium cinnamopterum. Although they are ecologically similar species, T. fuscum tends to infest healthier trees and has a smaller host range than T. cinnamopterum. If they successfully interbreed, this could lead to hybrid individuals that are more problematic than either parent species. On the other hand, if T. fuscum can make mating errors in the field, but is not producing hybrid offspring, then this waste of mating resources could help explain the slow spread of T. fuscum in North America. We conducted no-choice and choice mating experiments between T. fuscum and T. cinnamopterum males and females and determined that both T. fuscum and T. cinnamopterum males make mate-choice errors with heterospecific females in a laboratory setting. Our results suggest that mating errors may play a role in the slow spread of T. fuscum in North America.

Interaction between sexual communication functions leads to reproductive interference in two syntopic scorpion species

Sexual communication in mate choice scenarios involves nonmutually exclusive functions: species recognition, mate location and mate assessment. Most studies on sexual communication in mate choice have focused on female assessment of conspicuous male traits, such as visual and acoustic signals. Only a few studies have addressed male assessment of female traits, especially those that are inconspicuous to the human sensory system, such as chemical signals. Although chemical signals are important in sexual communication of many arachnids, there is a gap in our knowledge about how male scorpions use these signals to evaluate potential partners. Here we studied sexual communication functions in two scorpion species (Urophonius brachycentrus and Urophonius achalensis) with sympatric populations and synchronic reproduction, where males are under a scramble competition mating system. We addressed the volatile pheromones role in each of the sexual communication functions. We used Y-mazes to test volatile pheromones, exposing males to different female stimulus arrays in single-signal (conspecific only) and mixed-signal (conspecific and heterospecific) contexts. Males located conspecific females through volatile pheromones, and the time spent in proximity to the female was proportional to males' perception of the female's quality, reinforcing the pheromones' function in mate location and assessment in single-signal environments. However, these sexually selected functions were overridden in mixed-signal contexts, in which males could not differentiate conspecific from heterospecific females, suggesting that pheromones do not allow species recognition. This interaction between sexual communication functions can lead to reproductive interference in this sympatric zone. Male indiscriminateness mediated by scramble competition could attenuate pheromones' species recognition function during mate choice. We provide a comprehensive study of the pheromones' role for mate and species recognition in different social contexts in scorpions. We found support for nonindependent and interacting functions of sexual communication, indicating that mate choice is a complex process in scorpions.

Prioritizing Sex Recognition Over Learned Species Recognition: Hierarchical Mate Recognition in an Invasive Fish

Mate recognition is the process of identifying and assessing the appropriate species, sex or population of another individual for their suitability as a potential mate. Recognition may be innate or learned. Learning, the acquisition of knowledge or skills through experience, involves a relatively long-term change in behavioral responses. In this study we examined learned and innate mate recognition in invasive male mosquitofish, Gambusia holbrooki, interacting with female conspecifics and male and female native toothcarp, Aphanius iberus. Male mosquitofish directed no mating attempts at male toothcarp whereas numerous attempts were made toward female toothcarp. Male mosquitofish therefore differentiated between males and females, but initially did not distinguish between con- and heterospecific females. Neither the presence of a male toothcarp, nor the presence of a refugia affected the number of mating attempts received by females. However, by the second day males appeared to learn to more accurately direct their mating attempts, with larger female mosquitofish receiving the most attention, though smaller toothcarp females were still harassed. We propose that male mosquitofish, with a coercive mating system, are selected for persistence despite rejection by potential mates. In this scenario, the pool of potential mates may include heterospecifics whose avoidance of mating attempts may be ignored by male mosquitofish. It may thus be adaptive for male mosquitofish to prioritize sex recognition over species recognition: if one sex is recognized as a “non-mate” this will cut 50% from the pool of potential mates whereas recognition of a single species will remove many fewer potential mates from the pool. This innate sex recognition together with rapid learning of species identity may be a factor in the invasive success of mosquitofish.

Alternative reproductive tactics in male freshwater fish influence the accuracy of species recognition.

Sexual conflict can result in coercive mating. Because males bear low costs of heterospecific mating, coercive males may engage in misdirected mating attempts toward heterospecific females. In contrast, sexual selection through consensual mate choice can cause mate recognition cues among species to diverge, leading to more accurate species recognition. Some species show both coercive mating and mate choice‐associated courtship behaviors as male alternative reproductive tactics. We hypothesized that if the selection pressures on each tactic differ, then the accuracy of species recognition would also change depending on the mating tactic adopted. We tested this hypothesis in the guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis) by a series of choice experiments. Poecilia reticulata and G. affinis males both showed imperfect species recognition and directed all components of mating behavior toward heterospecific females. They tended to direct courtship displays more frequently toward conspecific than heterospecific females. With male P. reticulata, however, accurate species recognition disappeared when they attempted coercive copulation: they directed coercions more frequently toward heterospecific females. We also found that heterospecific sexual interaction had little effect on the fecundity of gravid females, which suggests that prepregnancy interactions likely underpin the exclusion of G. affinis by P. reticulata in our region.

Chemical Species Recognition in a Tetragnatha Spider (Araneae: Tetragnathidae).

Much of our knowledge regarding the role of chemicals in species recognition in arthropods is based on a few taxonomic groups, predominantly insect pest species. To investigate the chemical underpinnings of species recognition cues in other arthropods, we conducted mate choice experiments and analyzed the chemical profiles of two species in the long-jawed spider genus Tetragnatha from allopatric populations across two different continents. In two separate bioassays, in which male T. extensa spiders were presented with either web silk or extracts from the silk of conspecific and heterospecific females, males consistently chose the silk or silk extract of conspecific females over those of heterospecifics. We examined the chemistry affecting this response using gas chromatography/mass spectrometry to analyze silk and whole-body extracts of the spiders. The major compounds in the extracts were identified as long chain aliphatic methyl ethers. The chemical profiles of the two species differed: the T. extensa profile consisted of 12,20-dimethylnonacosyl methyl ether (A), 8,14,20-trimethylnonacosyl methyl ether (B), and 6,14,20-trimethylnonacosyl methyl ether (C), while the profile of T. versicolor consisted of B and 14,20-dimethylnonacosyl methyl ether (D). Within each species, chemical profiles of females and males did not differ. Our results suggest that these methyl ethers are involved in species recognition of Tetragnatha spiders. This is the first study to propose compounds involved in species recognition in spiders.

Mate attraction, chemical defense, and competition avoidance in the parasitoid wasp Leptopilina pacifica

A major hypothesis for the evolution of chemical signals is that pheromones arise from non-communicative precursor compounds. However, data supporting this hypothesis are rare, primarily because the original functions of the antecedent compounds often have been lost. A notable exception, however, is the parasitoid wasp species Leptopilina heterotoma, whose compound (−)-iridomyrmecin is used as a defensive secretion, a cue for females to avoid competition with con- and hetero-specific females, and as the primary component of the females’ sex pheromone. To better understand the evolution of sex pheromones from defensive compounds, we examined the chemical ecology of L. pacifica, the sister species of L. heterotoma. Here, we show that L. pacifica also produces a defensive secretion containing a species-specific mixture of mostly iridoid compounds. However, the composition of the secretion is more complex than in L. heterotoma, and iridomyrmecin is only a minor component. Moreover, in contrast to L. heterotoma, conspecific female competitors were not avoided by female subjects, and a role of the iridoids in the female sex pheromone of L. pacifica can be excluded, as only the females’ cuticular hydrocarbons (CHCs) resulted in the elicitation of courtship by males. Although closely related, the two sister species show substantial differences in the use of the defensive secretion for communicative purposes. Variation in pheromone usage in this genus still presents a conundrum, highlighting the need for additional studies to understand the selective forces shaping the evolution of pheromone composition.

Infestation of fruit by conspecific and heterospecific females deters oviposition in two Tephritidae fruit fly species

AbstractTephritidae fruit fly larvae develop entirely in the host chosen by the females. To improve the fitness of their progeny, females would benefit from rejecting previously exploited hosts. Anastrepha fraterculus and Ceratitis capitata are two species of fruit flies having similar nutritional requirements and overlapping in their distribution. Previous studies found that competition between the larvae of these species might reach high levels, suggesting that cross‐recognition would be an adaptive trait. In this work, we tested the ability of A. fraterculus and C. capitata females to recognize and avoid fruits previously infested by both conspecific and heterospecific females. In laboratory behavioural arenas, females were presented with fruits that had been previously exposed to either conspecific or heterospecific females. Then, we conducted choice and non‐choice assays to compare the response of A. fraterculus and C. capitata females to infested and non‐infested fruits. In non‐choice tests, the females from both species rejected fruits previously infested by conspecific and heterospecific individuals. However, the rejection occurred at different steps of the sequence leading to oviposition: A. fraterculus showed a lower rate of visits to infested fruits, whereas C. capitata visited both infested and non‐infested fruits, but the latency to visit a fruit and the rejection frequency were higher and the duration of the visit to infested fruit was lower. In choice assays, the rejection of heterospecific infested fruit was higher than that of conspecific infested fruits, for both species. Our results suggest that, regardless of the sensory mechanism used by females, the recognition of previous infestation is bidirectional and females of both species, belonging to different genera, recognize fruit infested by heterospecifics. These responses indicate that cross‐recognition, supposedly a highly beneficial trait, could be occurring in nature, thus reducing interspecific competition and contributing to the coexistence of these species.

Artificial selection on sexual aggression: Correlated traits and possible trade-offs.

Forced copulation is an extreme form of sexual aggression that can affect the evolution of sex-specific anatomy, morphology, and behavior. To characterize mechanistic and evolutionary aspects of forced copulation, we artificially selected male fruit flies based on their ability to succeed in the naturally prevalent behavior of forced matings with newly eclosed (teneral) females. The low and high forced copulation lineages showed rapid divergence, with the high lineages ultimately showing twice the rates of forced copulation as the low lineages. While males from the high lineages spent more time aggressively pursuing and mounting teneral females, their behavior toward non-teneral and heterospecific females was similar to that of males from the low lineages. Males from the low and high lineages also showed similar levels of male-male aggression. This suggests little or no genetic correlations between sexual aggression and non-aggressive pursuit of females, and between male aggression toward females and males. Surprisingly however, males from the high lineages had twice as high mating success than males from the low lineages when allowed to compete for consensual mating with mature females. In further experiments, we found no evidence for trade-offs associated with high forced mating rates: males from the high lineages did not have lower longevity than males from the low lineages when housed with females, and four generations of relaxed selection did not lead to convergence in forced mating rates. Our data indicate complex interactions among forced copulation success and consensual mating behavior, which we hope to clarify in future genomic work.

Are bolder individuals more likely to choose heterospecific mates? A test in cyprinid fishes

Mating between different species is ubiquitous in nature. While environmental conditions and population density have been shown to affect the occurrence of heterospecific matings, much less is known about the potential role of individual characteristics. Here, we examined the association between boldness and mate choice to con- and heterospecifics in a cyprinid fish (Pseudaspius sachalinensis) which naturally hybridizes with congeneric species. We found a positive correlation between risk-taking tendency in an emergence test and a preference for heterospecific females. This finding suggests that bolder males may prefer novel phenotypes or are likely to make a wrong choice for their mating partners.

Influence of female cuticular hydrocarbon (CHC) profile on male courtship behavior in two hybridizing field crickets Gryllus firmus and Gryllus pennsylvanicus

BackgroundThe hybridizing field crickets, Gryllus firmus and Gryllus pennsylvanicus have several barriers that prevent gene flow between species. The behavioral pre-zygotic mating barrier, where males court conspecifics more intensely than heterospecifics, is important because by acting earlier in the life cycle it has the potential to prevent a larger fraction of hybridization. The mechanism behind such male mate preference is unknown. Here we investigate if the female cuticular hydrocarbon (CHC) profile could be the signal behind male courtship.ResultsWhile males of the two species display nearly identical CHC profiles, females have different, albeit overlapping profiles and some females (between 15 and 45%) of both species display a male-like profile distinct from profiles of typical females. We classified CHC females profile into three categories: G. firmus-like (F; including mainly G. firmus females), G. pennsylvanicus-like (P; including mainly G. pennsylvanicus females), and male-like (ML; including females of both species). Gryllus firmus males courted ML and F females more often and faster than they courted P females (p < 0.05). Gryllus pennsylvanicus males were slower to court than G. firmus males, but courted ML females more often (p < 0.05) than their own conspecific P females (no difference between P and F). Both males courted heterospecific ML females more often than other heterospecific females (p < 0.05, significant only for G. firmus males).ConclusionsOur results suggest that male mate preference is at least partially informed by female CHC profile and that ML females elicit high courtship behavior in both species. Since ML females exist in both species and are preferred over other heterospecific females, it is likely that this female type is responsible for most hybrid offspring production.

Size, species and audience type influence heterospecific female–female competition

Female–female competition for mates can be as intense as male–male competition, but it has received little attention until recently. Typically, such competition is expressed as context-dependent aggressive encounters between individuals of the same species within a complex social environment. Unlike male competition, in cases of sexual parasitism, female competition includes important heterospecific interactions. We explore how competitor body size and species influence female–female aggression in a sexual–unisexual mating system where heterospecific females compete for males of the sexual species. Specifically, we examined whether (1) the size and species of female competitors and (2) the sex and species of an audience influence female–female aggression in sailfin mollies, Poecilia latipinna. We found that competitor body size had a secondary effect on the amount of aggression a female performed when compared to the species of her female competitor. Female sailfin mollies were more aggressive towards conspecifics than they were towards Amazon mollies, Poecilia formosa, especially in front of a sailfin molly male and female audience. These results demonstrate that the social environment greatly influences how females regulate their aggressive behaviours, and they highlight not only the role of female competition for males, but also the importance of understanding the impact of the social environment on female competition.

Male rainbow darters (Etheostoma caeruleum) prefer larger conspecific females

Female mate choice is a well studied mechanism of sexual selection that can affect the evolution of male secondary sexual traits. However, males also exhibit selective mate choice in some animals, which can affect the evolution of female phenotypes. We tested for evidence of intraspecific male mate choice in the Rainbow Darter (Percidae: Etheostoma caeruleum). Males of numerous darter species have been shown to prefer conspecific over heterospecific females; however, intraspecific preferences in males have not yet been demonstrated in this genus. This study investigated male preference for indicators of female fecundity, specifically female size. We found that male Rainbow Darters prefer larger females, both in dichotomous choice tests, when access between individuals was prevented, and in unrestricted behavioral tests with full access to females. Notably, however, the dichotomous trials were not repeatable; males only displayed a significant preference for larger females in the first dichotomous trial and in the unrestricted trial. We discuss our results in light of experimental methods and the role of male mate choice in sexual selection.

Male responses suggest both evolutionary conservation and rapid change in chemical cues of female widow spiders

Understanding patterns of diversity in sexual signals can give insight into processes initiating, mediating or following from species diversification. Here we focus on female sex pheromones, which are widespread among animals, where some taxa show phylogenetic patterns of variation, but for others, ecological factors better explain pheromone diversity. Causes of differences in these patterns are unclear, and general insights require studying a broader range of taxa. Here we examined variation in the responses of male redback spiders, Latrodectus hasselti, to sex pheromones produced by three allopatric female congeners with different degrees of phylogenetic relatedness (from the same clade: Latrodectus mirabilis, Latrodectus hesperus; and from a different clade: Latrodectus geometricus) to infer pheromone divergence. We examined variation in male responses to conspecific and heterospecific females’ airborne and contact pheromones, which attract males and elicit courtship behaviour, respectively. We measured male courtship responses to extracted contact pheromones in isolation and male preferences in response to airborne pheromones and combined cues (pheromones, silk) in a two-choice maze. Male responses to airborne chemicals, contact chemicals and combined cues suggested variation in species specificity, with L. hasselti males showing strong discrimination against airborne pheromones of L. hesperus females (same clade), moderate evidence for discrimination based on contact cues of L. geometricus, but only when multiple sources of information were available (different clade), and no discrimination of L. mirabilis females (same clade) relative to conspecifics, regardless of the types of information available. Thus, male responses were not consistent with a phylogenetic pattern. Moreover, airborne pheromones can apparently diverge relatively rapidly, but airborne and contact pheromones may remain similar across long evolutionary timescales. We propose that differential responses to L. hesperus may arise from selection for population-level pheromone divergence within that species and that, in general, pheromones and male responses may be evolutionarily conserved across Latrodectus.