Intersexuality

BACKGROUND: Sexual dimorphism in size and shape is widespread among squamate reptiles. Sex differences in snake skull size and shape are often accompanied by intersexual feeding niche separation. However, allometric trajectories underlying these differences remain largely unstudied in several lineages. The sea krait Laticauda colubrina (Serpentes: Elapidae) exhibits very clear sexual dimorphism in body size, with previous studies having reported females to be larger and to have a relatively longer and wider head...

Aggressive behaviour is thought to have significant consequences for fitness, sexual selection and the evolution of social interactions, but studies measuring its expression across successive encounters-both intra- and intersexual-are limited. We used the field cricket Teleogryllus oceanicus to evaluate factors affecting repeatability of male aggression and its association with mating success. We quantified focal male aggression expressed towards partners and received from partners in three successive, paired trials, each involving a different male partner...

Mating interactions are rife with conflict because the evolutionary interests of males and females seldom coincide. Intersexual conflict affects sexual selection, yet the proximate factors underlying male coercive ability and female resistance are poorly understood. Male combat outcomes are often influenced by bite force, with superior biters being more likely to achieve victory over poorer biters in a range of species, including crickets. If good performers also achieve mating success through sexual coercion, then bite force might play a role in intersexual conflict as well...

Sexual dimorphism is often considered to be the result of differences in the intensity of sexual selection between sexes. From this point of view, the sexual dimorphism of the limb bones of the Bufo gargarizans in southwest China was studied. Results showed that the fore- and hindlimb skeletons of this species were sexually dimorphic in anatomy. The humerus, radioulna, and total lengths of the forelimb skeleton of males were substantially longer than those of females, but the hand length of males was smaller than that of females...

Little is known about how sex differences in root zone characteristics, such as contents of allelochemicals and soil microbial composition, mediate intra- and intersexual interactions in dioecious plants. We examined the processes and mechanisms of sex-specific belowground interactions mediated by allelochemicals and soil microorganisms in Populus cathayana females and males in replicated 30-yr-old experimental stands in situ and in a series of controlled experiments. Female roots released a greater amount and more diverse phenolic allelochemicals into the soil environment, resulting in growth inhibition of the same sex neighbors and deterioration of the community of soil microorganisms...

Consumers always delay their choices, which can cause companies to suffer tremendous losses. One reason for such delay is a lack of confidence. Confidence in consumer decision-making can stem from many sources, including social power. In this research, we find that selection power with regard to choosing a romantic mate increases consumers' decision confidence and, in turn, decreases choice deferral. We define the concept of intersexual selection power (ISP), and propose certain factors that can induce individuals' asymmetric ISP...

The evolution of secondary sex-specific traits of dioecious species under abiotic stress conditions has received limited research, especially in the case of Amaranthus palmeri, a fast adapting and highly competing plant. Here, we have examined the interactive effects of abiotic stress on mineral accumulation, chlorophyll a and b content, and the operating capacity of Photosystem II (PSII) in both male and female A. palmeri plants grown under three different intensities of white light, and under N, K or P deficiency...

Sex differences in mating strategies and partner preferences are well established. However, most research solely focused on heterosexual women and men. We examined the mate selection, marriage, and age preferences of a sample of lesbian women, gay men, and bisexual women and men (LGB) who took part in an online dating survey. Additionally, we analyzed inter- and intrasexual differences in these preferences. A total of 710 participants rated the importance of 82 mate selection criteria and 10 marriage criteria, and they also indicated their age preferences and short-term and long-term relationship orientation...

The wandering spider, Phoneutria depilata , is one of Colombia's most active nocturnal arthropod predators of vertebrates and invertebrates. Its venom has been a relevant subject of study in the last two decades. However, the scarcity of transcriptomic data for the species limits our knowledge of the distinct components present in its venom for linking the mainly neurotoxic effects of the spider venom to a particular molecular target. The transcriptome of the P. depilata venom gland was analyzed to understand the effect of different diets or sex and the impact of these variables on the composition of the venom...

Sexual selection often shapes social behavioural activities, such as movement in the environment to find possible partners, performance of displays to signal dominance and courtship behaviours. Such activities may be negatively influenced by increasing temperatures, especially in ectotherms, because individuals either have to withstand the unfavourable condition or are forced to allocate more time to thermoregulation by increasing shelter seeking behaviour. Thus, they "miss" opportunities for social and reproductive interactions...

Human appearance enhancement effort has recently been considered from an evolutionary perspective as an adaptive and sexually dimorphic strategy for effective female intrasexual and intersexual competition. Most writing and research on the topic to date has focused on appearance enhancement as a means of mate attraction, with relatively less research examining its role in mate retention. The present study considered whether romantic jealousy, as a negative emotion experienced in response to perceived threat to a desired relationship, predicts costly and/or risky appearance enhancement independent of the closely related emotion of envy...

Quantifying effects of individual attributes and population demographic characteristics that affect inter- and intrasexual interactions and adult reproductive success, and the spatial and temporal contexts in which they are expressed is important to effective species management. Multi-year individual-based analyses using genetically determined parentage allowed the examination of variables associated with the reproductive success of male and female lake sturgeon ( Acipenser fulvescens ) in the well-studied population in Black Lake, Michigan, USA...

Population structure determines individuals' interactions and trade-offs with evolutionary consequences. Male-biased populations increase intrasexual competition and intersexual harassment, reducing female resource acquisition, and thus, resources availability for the following generation. We analyzed direct and cross-generational effects of male harassment in two generations of damselflies (Odonata). We exposed adult females to treatments with different sex-ratio and density (balanced and male-biased) to modify the male harassment level...

PREMISE: In flowering plants, intersexual mating facilitation has been left largely underexplored. Duodichogamy is a rare flowering system designating plants that flower in the sequence male-female-male. We study the adaptive advantages of this flowering system using chestnuts (Castanea spp., Fagaceae) as models. These insect-pollinated trees produce many unisexual male catkins responsible for a first staminate phase and a few bisexual catkins responsible for a second staminate phase...

In dioecious populations, the sexes employ divergent reproductive strategies to maximize fitness and, as a result, genetic variants can affect fitness differently in males and females. Moreover, recent studies have highlighted an important role of the mating environment in shaping the strength and direction of sex-specific selection. Here, we measure adult fitness for each sex of 357 lines from the Drosophila Synthetic Population Resource (DSPR) in two different mating environments. We analyze the data using three different approaches to gain insight into the sex-specific genetic architecture for fitness: classical quantitative genetics, genomic associations, and a mutational burden approach...

BACKGROUND: The ricefield eel is a freshwater protogynous hermaphrodite fish and has become an important aquaculture species in China. The sex change of ricefield eel is impeding its aquaculture practice, particularly the large-scale artificial breeding. Many studies including transcriptomes of mixed gonadal samples from different individuals have been aimed to elucidate mechanisms underlying the sex change. However, the key physiological factors involved in the initiation of sex change remain to be identified...

Interlocus sexual conflict (IRSC) occurs because of shared interactions that have opposite effects on male and female fitness. Typically, it is assumed that loci involved in IRSC have sex-limited expression and are thus not directly affected by selective pressures acting on the other sex. However, if loci involved in IRSC have pleiotropic effects in the other sex, intersexual selection can shape the evolutionary dynamics of conflict escalation and resolution, as well as the evolution of reproductive traits linked to IRSC loci, and vice versa...

Phenotypic sexual dimorphism can be mediated by sex differences in gene expression. We examine two forms of sexual dimorphism in gene expression in Drosophila melanogaster: (i) sex-biased gene expression (SBGE) in which the sexes differ in the amount a gene is expressed and (ii) sexual dimorphism in isoform usage, i.e., sex-specific splicing (SSS). In whole body (but not head) expression, we find a negative association between SBGE and SSS, possibly suggesting these are alternate routes to resolving sexual antagonistic selection...

Sexual dimorphism has often been recorded in apple snails (Caenogastropoda Ampullariidae), but reports are concentrated in a few species, either invasive or with biocontrol potential, which sugests some taxonomic bias. To find out evolutionary and ecological correlates of sexual dimorphism it is necessary to detect and quantify it but also is important to detect its absence. Our aims were to confirm or not the existence of sexual dimorphism in shell shape of Felipponea neritiniformis and Asolene platae, using Pomacea canaliculata as reference and applying the same methodology (landmark-based geometric morphometrics) and statistical power...

Previously there were only three cases of mayfly gynandromorphism reported from Asia, occurring in the families Baetidae and Heptageniidae. Here, we report two intersex individuals of Choroterpes facialis (Gillies, 1951) (Ephemeroptera: Leptophlebiidae) from southeastern China. They have similar external morphologies (each having two different eyes, two shortened penes, and female sternum IX) but with one being predominately male and the other being predominately female (one with eggs in the abdomen, but the other apparently with sperm)...