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Floral characteristics of 27 mango varieties were studied during February-May, 2024. Distinct variations were found among the studied varieties. Significant variation were observed in term of number of male flower per inflorescence, number of hermaphrodite flower per inflorescence, length of inflorescence and width of inflorescence ranging from 57 to 1737, 7 to 461, 19 cm to 40.6 cm, 6.4 cm to 25.7 cm respectively. The result disclosed that in all varieties flowers were of pentamerous type and inflorescence position were found terminal. The number of male flower per inflorescence were highest in Bombay (1737). In term of number of hermaphrodite flowers per inflorescence, chausa has highest number (461). In overall, male flower per inflorescence were more than hermaphrodite flower per inflorescence across all varieties except Amrapali, Jarda and Chausa. Ratna has the longest inflorescence (40.6 cm) and widest inflorescence (25.7 cm). From the study, it can be inferred that chausa will have more fruit set as it has more hermaphrodite flowers but seeing the overall floral character Ratna is more superior as it has longest and widest inflorescence and second highest in term of number of hermaphrodite flower among the studied varieties. The findings of the study will be beneficial for breeding purposes while developing new varieties of superior quality. [ABSTRACT FROM AUTHOR]

Copyright of Acta Veterinaria Brasilica is the property of Acta Veterinaria Brasilica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The common snook (Centropomus undecimalis) is a protandric hermaphrodite fish that undergoes a sex change during its life cycle. In nature, common snook females develop directly from males shortly after spawning. However, the factors triggering this process remain unknown. This knowledge gap poses challenges for managing the species in captivity. To address this, we conducted a study on sex change induction in three-year-old males using estradiol and evaluated the potential effects of photoperiod manipulation on early maturation. Four treatment groups were employed: (1) fish with estradiol + natural photoperiod; (2) fish without estradiol + natural photoperiod; (3) fish without estradiol + controlled photoperiod; and (4) fish with estradiol + controlled photoperiod. The effectiveness of these treatments was assessed through histological procedures, which allowed for the examination of the fishes' gonads. Furthermore, the concentration of alkali labile phosphorus in fish plasma was measured and correlated with the histological results. Our findings revealed that administering 2 mg/kg estradiol implants resulted in a remarkable 100% female population within the estradiol-treated groups. No significant effect on fish maturation was observed due to the manipulated photoperiod conditions. This protocol offers improved management strategies for captive broodstock. Firstly, the concentration of estradiol used in this study proved sufficient to induce sex change in this hermaphroditic species, enabling the production of viable females at an early age and smaller size and facilitating easier broodstock manipulation. Secondly, the implementation of the alkali labile phosphorus technique allows for sex identification without the need to sacrifice the fish. In conclusion, our study provides valuable insights into sex change induction and photoperiod manipulation in common snook. The findings contribute to enhanced management practices for captive broodstock. However, further research is needed to explore the underlying mechanisms triggering sex change and to optimize protocols for long-term maintenance and successful reproduction in captivity. [ABSTRACT FROM AUTHOR]

Understanding the life-history traits of invasive species can increase the effectiveness of eradication efforts and decrease costs. In the giant African snail Lissachatina fulica , one of the 100 worst invasive species on the planet, age structure can be an important indicator of invasiveness. Here, we associated variation in snail size with variation in weight and shell shape, in an effort to better understand the growth pattern in this species. Our study involved two components: we estimated the allometric relationship between weight and length in a natural population and monitored developmental variation in snail shape, weight, length and nutritional condition (condition factor) in a lab population. The weight and length growth patterns of the lab population were estimated independently using exponential regressions based on weekly measurements; shell shape was quantified using geometric morphometrics. In both populations, we found negative allometry between weight and length, suggesting that snail shells tend to elongate during growth. Geometric morphometrics confirmed this pattern and revealed that the change from a rounded to an elongated shell shape does not occur at a constant pace but during a specific growth interval (i.e. at a shell length of 55–65 mm), which is described in the literature as the size when the animal becomes hermaphroditic. Future studies should test whether the shape change reported here corresponds to the transition to the hermaphrodite age class, and with this in mind, we provide two simple morphological indexes that allow us to characterize shell shape as rounded or elongated. If shell size and shape are indicative of the transition to the hermaphroditism, then our findings can help to place individuals of L. fulica into appropriate age classes, and this will represent a useful baseline for development of eradication policies. [ABSTRACT FROM AUTHOR]

Xenoturbella is a marine invertebrate with a simple body plan, with recent phylogenomic studies suggesting that it forms the phylum Xenacoelomorpha together with the acoelomorphs. The phylogenetic position of the phylum is still under debate, whether it is an early branching bilaterian or a sister group to the Ambulacraria. Phylogenetic traits often appear during development, and larva resembling the cnidarian planula has been reported for Xenoturbella. However, subsequent developmental studies on Xenoturbella have been scarce. This is mainly due to the difficulties in collecting and keeping adult animals, resulting in the lack of data on the reproduction of the animal, such as the breeding season and the spawning pattern. Here we report on the reproduction of X. bocki and confirm that its breeding season is winter. Spawning induction resulted in gametes being released from body ruptures and not the mouth. No evidence supported the animal as a simultaneous hermaphrodite. The marine invertebrate Xenoturbella bocki breeds in the winter and the induction of spawning leads to gamete release through body ruptures, not the mouth. [ABSTRACT FROM AUTHOR]

Most plants and many animals are hermaphroditic; whether the same forces are responsible for hermaphroditism in both groups is unclear. The well‐established drivers of hermaphroditism in plants (e.g., seed dispersal potential, pollination mode) have analogues in animals (e.g., larval dispersal potential, fertilization mode), allowing us to test the generality of the proposed drivers of hermaphroditism across both groups. Here, we test these theories for 1153 species of marine invertebrates, from three phyla. Species with either internal fertilization, restricted offspring dispersal, or small body sizes are more likely to be hermaphroditic than species that are external fertilizers, planktonic developers, or larger. Plants and animals show different biogeographical patterns, however: animals are less likely to be hermaphroditic at higher latitudes—the opposite to the trend in plants. Overall, our results suggest that similar forces, namely, competition among offspring or gametes, shape the evolution of hermaphroditism across plants and three invertebrate phyla. [ABSTRACT FROM AUTHOR]

Females and males can exhibit striking differences in body size, relative trait size, physiology, and behavior. As a consequence, the sexes can have very different rates of whole-body energy use, or converge on similar rates through different physiological mechanisms. Yet many studies that measure the relationship between metabolic rate and body size only pay attention to a single sex (more often males), or do not distinguish between sexes. We present four reasons why explicit attention to energy-use between the sexes can yield insight into the physiological mechanisms that shape broader patterns of metabolic scaling in nature. First, the sexes often differ considerably in their relative investment in reproduction, which shapes much of life-history and rates of energy use. Second, males and females share a majority of their genome but may experience different selective pressures. Sex-specific energy profiles can reveal how the energetic needs of individuals are met despite the challenge of within-species genetic constraints. Third, sexual selection often pushes growth and behavior to physiological extremes. Exaggerated sexually selected traits are often most prominent in one sex, can comprise up to 50% of body mass, and thus provide opportunities to uncover energetic constraints of trait growth and maintenance. Finally, sex-differences in behavior such as mating-displays, long-distance dispersal, and courtship can lead to drastically different energy allocation among the sexes; the physiology to support this behavior can shape patterns of metabolic scaling. The mechanisms underlying metabolic scaling in females, males, and hermaphroditic animals can provide opportunities to develop testable predictions that enhance our understanding of energetic scaling patterns in nature. [ABSTRACT FROM AUTHOR]

Two bisexual lures have been developed using iso‐amyl alcohol plus acetic acid combined with red wine extract (semisynthetic bisexual lure, SBL), or synthetic floral compounds (FLO) for trapping of noctuid moths with early spring activity of adults. Orthosia species were attracted by the tested semi‐synthetic and synthetic lures indicating the possible role of the fermenting liquids and floral compounds in the feeding of these species. Bisexual lures attracted generally a lower number of individuals than the synthetic sex attractants of the given species, except for O. cerasi where FLO lures were more attractive than the sex attractant. Bisexual lures caught both sexes and females composed a sizable percentage of the catch. Since traps baited with different types of bisexual lures provided similar data on sex ratios, thus these presumably reflected the actual sex ratio of the given population. The use of these bisexual lures, especially of FLO in case of Orthosia spp., can be useful in surveys in which the capture of females and data on sex ratios are indispensable, for example in population dynamic and polyandry surveys. In contrast, in case of low population densities, the use of sex attractant lures seem to be still more efficient. [ABSTRACT FROM AUTHOR]

The current article describes an interesting case of geographic parthenogenesis among European mites from the Labidostommidae family (Acari: Prostigmata). In earlier publications on Labidostomma luteum Kramer, 1879, the authors pointed out that most of the populations of this species in Europe consisted of parthenogenetic females. Until now, populations of both sexes were known only in southwestern France. In the north–west areas, the number of males in the populations has gradually decreased, and in the populations found west of Paris there are no males at all. During the research project carried out in 2018, Błoszyk found the presence of populations which consisted of both sexes of the species in question near the town of Bény (60 km NE of Lion). This is the easternmost site of L. luteum in France where males have been found. All other known sites located east and north of the Bény–Paris line have only parthenogenetic females. Thus, this line can be considered as the boundary of L. luteum populations reproducing sexually. However, establishing the exact course of this range requires further research. [ABSTRACT FROM AUTHOR]

Argopecten scallops are hermaphroditic bivalves and commercially important in aquaculture. Up to now, the molecular mechanism of sex differentiation and gonad growth/maturation in hermaphroditic animals is still largely unknown. In this study, we analyzed the transcriptome of the gonads at different stages of the QN Orange scallop, a new scallop strain selected from the hybrids between the bay scallop and the Peruvian scallop. Among sex differentiation‐related genes, 5 transcription factors (TFs) (1 SOX, 2 FOXL and 2 GATA) and 2 TGF‐βs (2 BMP) were mainly expressed in the male part and 2 TFs (1 FOXL and 1GATA) and 2 TGF‐βs (2 BMP) were mainly expressed in the female part of the gonads. Among gonad growth/maturation related genes, 1 TF (GATA) might be only involved in male gonad growth/maturation, 8 TFs (1 SOX, 1 WNT, 2 FOXL and 4 GATA) and 3 TGF‐βs (1 GDF and 2 BMP) only participated in ovarian growth/maturation, 3TFs (1 SOX, 1 DMRT and 1 FOXL) and 2 TGF‐βs (1 GDF and 1 BMP) might be involved in both male and female gonad growth/maturation. Based on the results of transcriptome and qRT‐PCR, 11 genes were screened to be involved in sex differentiation and 16 genes might be involved in gonad growth/maturation. The results of this study may provide new insights into the understanding of the mechanisms of sex differentiation and gonad growth/maturation in hermaphroditic scallops. [ABSTRACT FROM AUTHOR]

Copyright of Bio-grafía. Escritos Sobre la Biología y su Enseñanza is the property of Universidad Pedaggica Nacional and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Birds perform some of the most elaborate intersexual displays in the animal kingdom, but while these are typically associated with the pre‐copulation stage of sexual interactions, the males of some species also display following copulation. Here we report that immediately after dismounting from females, male Superb Lyrebirds Menura novaehollandiae perform a striking multimodal display comprising a repetitive clicking vocalization and a stereotyped tail posture, while walking backwards away from the female. This ubiquitous postcopulatory display constitutes the fourth, structurally distinct multimodal display performed by male Superb Lyrebirds during intersexual interactions and points to a role for sexual selection after copulation in the lyrebird's lek‐like mating system. As such, this study highlights an additional and largely overlooked functional context for complex courtship choreography in birds. [ABSTRACT FROM AUTHOR]

In Australia, destruction of overwintering pupae of Helicoverpa armigera (Hübner) and H elicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) has been a key component of mandatory resistance management schemes to constrain development of resistance to Bt toxins in transgenic cotton. This has been accomplished by tillage ('pupae busting'), but it is expensive and can interfere with farming operations. Bisexual attract-and-kill technology based on plant volatile formulations offers a potential alternative in some circumstances. We discuss strategies for using such products and describe two trials in which three applications of an attract-and-kill formulation substantially reduced the numbers of Helicoverpa spp. moths and the numbers of potentially overwintering eggs they laid. One trial tested a curative strategy in which the last generation of moths emerging from transgenic cotton was targeted. The other tested a preventive strategy which aimed to reduce the numbers of eggs in the last generation. The preventive strategy reduced egg numbers by about 90% and is now included as an optional alternative to pupae busting in resistance management strategies for Australian cotton. It is limited to fields which have not been defoliated prior to 31 March and was developed to be used primarily in southern New South Wales. In the 2020–2021 cotton season, it was adopted on approximately 60% of the eligible cotton area. We describe the process whereby the strategy was developed in collaboration with the transgenic technology provider, supported by the cotton industry, and approved by the regulatory authority. [ABSTRACT FROM AUTHOR]

Increased demands of the seafood market have led to the rapid growth in crustacean aquaculture production in various parts of the world. Therefore, an expansion in the knowledge of the reproductive biology of crustaceans has become more important. Hormones released from the androgenic gland (AG) in crustaceans are liable for both the separation of primary and secondary sexual features and reproductive behavior. AG removal in male crustaceans causes a transformation of the intersex animals towards the females and a degeneration of spermatids and reproductive organs. AG implantation and injection of AG extracts are common approaches for crustacean masculinization. In this review, the importance of AG and its implication in crustacean aquaculture are reiterated, while the discovery, identification, chemical nature, and isolation of insulin-like androgenic gland hormone are also overviewed. [ABSTRACT FROM AUTHOR]

In field trapping tests the addition of 4‐oxoisophorone (2,6,6‐trimethylcyclohex‐2‐ene‐1,4‐dione) to the known ternary bisexual lure (consisting of phenylacetaldehyde + benzyl acetate + eugenol) significantly increased catches of the silver Y moth Autographa gamma, an important migratory noctuid pest. Both female and male moths were attracted, supposedly in the natural sex ratio of the local population. Traps baited with the quaternary lure caught 27.9% of the number of moths in traps baited with synthetic sex pheromone (all males), and the two types of lures showed similar seasonal trends when following the quantitative changes in moth flight throughout the whole season. This suggests that the improved quaternary bisexual lure could be efficient enough to yield a new tool for detection and monitoring of A. gamma, resulting in more reliable plant protection decisions based on female catches, and can provide data for studies where the catch of females and data on sex ratio are indispensable. [ABSTRACT FROM AUTHOR]

Many species in the family Serranidae are hermaphrodites and of commercial importance. Paranthias colonus belongs to this family, and its reproductive traits are unknown. The present research was carried out with specimens taken from the commercial fishery on the southern coast of Jalisco, Mexico. A total of 1,541 specimens were processed, with an average length of 30.30 ± 0.10 cm and a length interval of 19.80 to 38.00 cm. Specimen gonads were analyzed macro- and microscopically. The sex ratio was 1.00:0.97 (F:M). According to the maximum monthly values of the gonadosomatic index, gonad maturity stages, and oocyte diameters, P. colonus has 2 broad reproductive periods, from March to June and from November to December. A significant correlation was found between the monthly mean values of the gonadosomatic index and the relative condition factor. Gonads in the mature stage had oocytes in 6 different development phases, with diameters that ranged from 14.30 to 417.40 μm, which means that oocyte development is asynchronous. In the testicle, the development of the germ line is of the unrestricted lobular type. This organ did not present the typical arrangement found in teleost fish, since lobes seem to be delimited by lamellae. The information developed in this study indicates that P. colonus is a gonochoric species. Average length at sexual maturity was 26.80 cm for females and 26.90 cm for males. Average catch lengths indicated that 79.70% of females and 83.30% of males had already reproduced at least once before being caught. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of Wolbachia on fitness of their hosts, the biological characteristics of a primarily parthenogenetic line and a bisexual restored line (obtained by antibiotic treatment) of Trichogramma pretiosum were compared in the laboratory. Results indicated that both the mean longevity and fecundity of parthenogenetic line (14.2 d and 165 eggs/female) were significantly higher than those in bisexual restored line (8.4 d and 124.2 eggs/female). Both lines of T. pretiosum had the highest daily fecundity (23.3 eggs/female for parthenogenetic line and 19.8 eggs/female for bisexual restored line) on the first day during their reproduction period, and their survival rate and daily fecundity decreased gradually with age; however, the survival rate and daily fecundity of the parthenogenetic line were always higher than those of bisexual restored line, during the entire experimental period. There was no significant difference in emergence rate and deformity rate between the two T. pretiosum lines. The life-table parameter results indicated that net reproduction rate (R 0) and mean generation time (T) in parthenogenetic line (133 and 16.8) were significantly higher than those in bisexual restored line (61.7 and 15.5); intrinsic rate of natural increase (r m) and finite rate of increase (λ) in parthenogenetic line (0.29 and 1.34) were higher than those in bisexual restored line (0.26 and 1.3). Based on these results, it can be confirmed that the removal of Wolbachia in the parthenogenetic line had an adverse effect on fitness of T. pretiosum. [ABSTRACT FROM AUTHOR]

Life in extreme environments is typically studied as a physiological problem, although the existence of extremophilic animals suggests that developmental and behavioral traits might also be adaptive in such environments. Here, we describe a new species of nematode, Tokorhabditistufae, n. gen., n. sp., which was discovered from the alkaline, hypersaline, and arsenic-rich locale of Mono Lake, California. The new species, which offers a tractable model for studying animal-specific adaptations to extremophilic life, shows a combination of unusual reproductive and developmental traits. Like the recently described sister group Auanema, the species has a trioecious mating system comprising males, females, and self-fertilizing hermaphrodites. Our description of the new genus thus reveals that the origin of this uncommon reproductive mode is even more ancient than previously assumed, and it presents a new comparator for the study of mating-system transitions. However, unlike Auanema and almost all other known rhabditid nematodes, the new species is obligately live-bearing, with embryos that grow in utero, suggesting maternal provisioning during development. Finally, our isolation of two additional, molecularly distinct strains of the new genus—specifically from non-extreme locales—establishes a comparative system for the study of extremophilic traits in this model. [ABSTRACT FROM AUTHOR]

The experiment was conducted at Instructional Research Farm, School of Agricultural Sciences and Rural Development, Nagaland University, Nagaland during November 2017-August 2018 in a randomized block design with three replications and seven treatments of different boron sources, viz., Agricol 5 g, Agricol 10 g, Chemibor- P 5 g, Chemibor-P 10 g, Disodium Octaborate Tetrahydrate 5 g, Disodium Octaborate Tetrahydrate 10 g and the control (distilled water). The aqueous solution of boron was applied on the soil at two stages, i.e. before flowering and at pea-sized stage. Data were collected from N-E and S-W aspects of the tree canopy. The earliest panicle emergence, minimum number of days for 50% flowering (22.51 and 22.07), days to fruit set time (57.27 and 56.82) and days to harvesting from panicle initiation (168.26 and 168.00) were obtained with Agricol (5 g) on N-E and SW aspects of the canopy respectively. Maximum fruit yield (46.2 and 45.92 kg/tree) significantly increased with Agricol (5 g) application. The number of hermaphrodite flower/panicle (208.55 and 207.71), sex ratio/panicle (0.66 and 0.61) and least fruit drop (51.23 and 50.50) were found maximum with application of DOT (5g). The pulp weight (153.23 and 152.04) and fruit quality parameters significantly increased with Agricol (5 g) application. The maximum fruit length (9.38 and 9.17 cm) and width were recorded with application of Chemibor-P and fruit bioactive compounds like vitamin C (65.31 mg/100g pulp and 65.64 mg/100g pulp) and beta-carotene (3330.55 μg/100g and 3315.18 μg/100g) were recorded maximum with application of DOT (10g) on north-east and southwest canopy of the plant. The lower concentrations of boron from various sources performed better in the present study. [ABSTRACT FROM AUTHOR]

In organisms with discrete generations such as most insects, life-history traits including dispersal abilities often vary between generations. In particular, density-dependent differences in dispersal of bi- and multivoltine species may be expected because subsequent generations are usually characterized by a drastic increase in individual abundance. We investigated the inter-sexual and inter-generation differences in dispersal of a bivoltine butterfly, Lycaena helle, testing the following hypotheses: (1) male emigration is higher in spring generation, as males are prone to leave their natal habitat patches when the density of mating partners is low; (2) female emigration is higher in summer generation, when it helps to reduce intraspecific competition between offspring. The outcome of our analyses of dispersal parameters showed that females of the summer generation emigrated from their natal patches considerably more often than those of the spring generation, whereas an opposite trend was detected in males. These findings offer a novel perspective for our understanding of the advantages of voltinism for metapopulation functioning. The spring generation dispersal mainly improves the random mating opportunities favoured by the increase in male emigration. In turn, the dispersal of females of the summer generation appears the key to long-term metapopulation persistence. [ABSTRACT FROM AUTHOR]

Sexual selection often leads to evolution of conspicuous signals, raising the chances of attracting not only potential mates, but also predators. In lacertid lizards, ultraviolet (UV)–blue spots on flanks and shoulders represent such a trait. Some level of correlation between male and female ornamentation is also known to exist. Therefore, the phenotype of females may change in the absence of sexual selection. We tested this hypothesis on a complex of parthenogenetic and bisexual lizards of the genus Darevskia. We evaluated area, counts, and chromatic properties (UV opponency, saturation) of UV–blue spots and compared the values between the clones and their bisexual progenitor species. We found a fair heterogeneity between the parthenogenetic species, but no general tendency toward higher crypsis or conspicuousness. Values of the parthenogens were not significantly different from the values of sexual females. A possible explanation is that the changes in selective forces associated with parthenogenetic reproduction are too small to affect the resulting pattern of selective pressures on the studied traits, or that the phenotypes of the parthenogens result from the unique combination of parental genomes and are conserved by clonal reproduction. [ABSTRACT FROM AUTHOR]

The relationship between growth and sexual maturation is central to understanding the dynamics of animal populations which exhibit indeterminate growth. In sequential hermaphrodites, which undergo post-maturation sex change, the size and age at which sex change occurs directly affects reproductive output and hence population productivity. However, these traits are often labile, and may be strongly influenced by heterogenous growth and mortality rates. We analysed otolith microstructure of a protandrous (i.e., male-to-female) fish (barramundi Lates calcarifer) to examine growth in relation to individual variation in the timing of sex change. Growth trajectories of individuals with contrasting life histories were examined to elucidate the direction and extent to which growth rate influences the size and age individuals change sex. Then, the relationships between growth rate, maturation schedules and asymptotic maximum size were explored to identify potential trade-offs between age at female maturity and growth potential. Rapid growth was strongly associated with decreased age at sex change, but this was not accompanied by a decrease in size at sex change. Individuals that were caught as large females grew faster than those caught as males, suggesting that fast-growing individuals ultimately obtain higher fitness and therefore make a disproportionate contribution to population fecundity. These results indicate that individual-level variation in maturation schedules is not reflective of trade-offs between growth and reproduction. Rather, we suggest that conditions experienced during the juvenile phase are likely to be a key determinant of post-maturation fitness. These findings highlight the vulnerability of sex-changing species to future environmental change and harvest. [ABSTRACT FROM AUTHOR]

The invasion history and current distribution of the alien marine mussel, the bisexual mussel Semimytilus algosus, on rocky shores of South Africa is described in this study. The eastern edge of its distribution has been monitored since 2014, and the most-recent observations were made between January and March of 2020, at 16 sites between Hondeklipbaai on the west coast and Nature's Valley on the south coast. From these 2020 records, the species ranged across approximately 840 km along the coast, from Hondeklipbaai to Hermanus. The species' invasion history and distribution suggests that this mussel has persisted on the west coast over the past decade, and spread along the coast in both northward and south–southeastward directions. Since 2010, the species has spread predominantly in a southerly and then easterly direction, extending its range by ∼270 km into the Agulhas ecoregion. In contrast, its spread has been slower to the north, with a range extension of only ∼75 km. Long-term, routine monitoring of the coast to track the spread of S. algosus and other invasive marine species, and to identify new incursions, is recommended to support evidence-based management of biological invasions. [ABSTRACT FROM AUTHOR]

Small‐scale fisheries (SSFs) tend to target shallow waters, but the depth distributions of coastal fish can vary depending on species, size, and sex. This creates a scope for a form of fishing selectivity that has received limited attention but can have considerable implications for monitoring and management of these fisheries. We conducted a case study on the Norwegian wrasse fishery, a developing SSF in which multiple species are caught in shallow waters (mean depth = 4.5 m) to be used as cleaner fish in aquaculture. Several of these wrasses have life histories and behaviors that are sensitive to selective fishing mortality, such as sexual size dimorphism, paternal care, and sex change. An experimental fishery was undertaken over three sampling periods in 2018. Data on catch, length, and sex of wrasses across a depth gradient (0–18 m) were collected and analyzed. We found that depth distributions were species specific and the vertical overlap with the fishery was high for Corkwing Wrasse Symphodus melops and Ballan Wrasse Labrus bergylta, which were most abundant at depths less than 5 m. Three other wrasse species had invariant or increasing abundance with depth and were therefore less likely to be negatively impacted by this fishery. Body size was positively correlated with depth for these wrasses, and sex ratio became more male biased for the Corkwing Wrasse, the only species that could be visually sexed. This study demonstrates that depth can have strong effects on fishing selectivity at multiple scales and that such knowledge is necessary to develop management strategies that balance fishing mortality sustainably across species, sizes, and sexes. We recommend that management priorities be directed toward the Ballan and Corkwing wrasses—the species having the highest vertical overlap with the fishery. Furthermore, CPUE was strongly affected by seasonality and positively correlated with increasing wave exposure for one of the species. This underscores the general importance of standardizing catch data for several environmental covariates when monitoring species that are affected by SSFs. [ABSTRACT FROM AUTHOR]

Optimizing reproductive success is an essential part of evolution for both sexes. Females can optimize mating by avoiding superfluous mating advances and insemination, since both take time away from other activities and may incur costs related to sperm receipt. While many separate-sexed organisms are known to exhibit mate avoidance, much less is known about this for simultaneous hermaphrodites. We addressed this here, using a simultaneously hermaphroditic species that can choose to mate in either of the two sex roles during each mating interaction. Recently, avoidance behaviours in response to natural matings were observed in the hermaphroditic pond snail Lymnaea stagnalis , potentially deterring insemination. To disentangle whether such behaviours are mediated by the mechanical act of mating or the receipt of accessory gland proteins and/or sperm, we intravaginally injected individuals with control or test fluids. Our results show that the avoidance behaviours, crawl-out and biting, were more frequently expressed when individuals were inseminated with accessory gland proteins and/or sperm. These behavioural components of the recipient increased time in courtship prior to insemination, which is concordant with the hypothesis that the partner tries to discourage the potential sperm donor from inseminating. Understanding the mechanism underlying the effects that molluscan accessory gland proteins induce contributes to our understanding of the molecular basis of the recipient's (behavioural) responses as well as how such biochemical postcopulatory strategies evolve. • Reproduction can be optimized by avoiding surplus mating advances and inseminations. • Being inseminated takes time and can incur costs related to sperm receipt. • Simultaneous hermaphrodites cope with this while serving both reproductive interests. • Accessory gland proteins and/or sperm are found to induce crawl-out and biting. • Earlier reported avoidance behaviours seem to be used to discourage new sperm donors. [ABSTRACT FROM AUTHOR]

Doubly uniparental inheritance (DUI) of mitochondrial DNA is a rare phenomenon occurring in some freshwater and marine bivalves and is usually characterized by the mitochondrial heteroplasmy of male individuals. Previous research on freshwater Unionida mussels showed that hermaphroditic species do not have DUI even if their closest gonochoristic counterparts do. No records showing DUI in a hermaphrodite have ever been reported. Here we show for the first time that the hermaphroditic mussel Semimytilus algosus (Mytilida), very likely has DUI, based on the complete sequences of both mitochondrial DNAs and the distribution of mtDNA types between male and female gonads. The two mitogenomes show considerable divergence (34.7%). The presumably paternal M type mitogenome dominated the male gonads of most studied mussels, while remaining at very low or undetectable levels in the female gonads of the same individuals. If indeed DUI can function in the context of simultaneous hermaphroditism, a change of paradigm regarding its involvement in sex determination is needed. It is apparently associated with gonadal differentiation rather than with sex determination in bivalves. [ABSTRACT FROM AUTHOR]

Cases of true and pseudo-hermaphroditism, in which animals possess both ovaries and testes or have a single chromosomal and gonadal sex but secondary features of the other sex, have been documented in several cervids, including Odocoileus (deer) and Capreolus (roe deer) species. Another form of intersexuality that has been well documented in Domestic Cattle (Bos taurus) and induced in Red Deer (Cervus elaphus) is freemartinism, where blood is shared between heterosexual twins leading to XX/XY chimeras. We report the first case of pseudo-hermaphroditism in wild Elk (Cervus canadensis), observed in the central east slopes of the Rocky Mountains of Alberta, Canada, from September through December 2019. The Elk had no antlers, exhibited female external genitalia, and displayed male secondary sexual characteristics, including colouring and breeding behaviour. To determine whether this is a case of true hermaphroditism, pseudo-hermaphroditism, or freemartinism would require blood analysis and inspection of internal sex organs by necropsy. [ABSTRACT FROM AUTHOR]

The scorpion Tityus serrulatus Lutz & Mello, 1922 (Buthidae) is endemic to Brazil and is considered the most toxic South American scorpion species. The ample distribution of this species and its occurrence in urban areas has been attributed primarily to the parthenogenetic mode of reproduction. For a long time, only all-female T. serrulatus populations were known. Male specimens are very rare and have been recently discovered in natural environments within the Brazilian semi-arid zone. In the present study, we investigated cytogenetically bisexual populations of T. serrulatus, and compared the data with those available for parthenogenetic specimens. The diploid number (2n=12) and the general configuration of the chromosomes in male and female specimens were similar to those recorded for parthenogenetic populations. Male postpachytene cells contained chromosomes in a parallel arrangement with no differentiation of the bivalents, indicating the absence of heteromorphic sex chromosomes. However, the number of 28S rDNA sites varied between male and female specimens. Females invariably presented only one rDNA cistron, while all the males had two. This finding seems to indicate the existence of a sex-specific heteromorphism in T. serrulatus, in which the females are heterogametic and the males are the homogametic sex. [ABSTRACT FROM AUTHOR]

The present paper describes the pathological findings of the reproductive tracts of two 6-month-old Staffordshire bull terriers that were neutered at separate veterinary clinics in Wagga Wagga and a 7-month-old Shetland sheepdog that was neutered in Melbourne. Case 1 was recognised as abnormal by its owner at 2 months of age, as the dog had a phallus protruding from its vulva. The other two dogs were considered by their owners to be normal bitches. During ovariohysterectomy, all dogs presented with small uteri, and gonads that grossly appeared more like testes than ovaries. Histological examination of the gonads from Case 1 revealed well-developed seminiferous tubules with rare germ cells in lumina. There was a primitive, convoluted epididymis attached to one testis. In Cases 2 and 3, there were similar testicular gonadal tissues with pseudo-uterine horns consistent with retention of the paramesonephric ducts. The pathology in of all of these cases was consistent with a primary genetic intersex disorder, with Cases 2 and 3 also exhibiting persistent Müllerian ducts. Disorders of sexual development occur due to aberrations at the chromosomal, gonadal and/or phenotypic level. Differentiation between these can be assisted by genetic profiling, such as karyotyping, and histopathology. These disorders have a low incidence in clinical practice, however, due to the complex pathway of sexual development there can be many different presentations. Case descriptions such as these can be of great benefit to clinicians when they are performing routine surgery and are faced with an unexpected presentation. [ABSTRACT FROM AUTHOR]

The Sparids are an ideal group of fishes in which to study the evolution of sexual systems since they exhibit a great sexual diversity, from gonochorism (separate sexes) to protandrous (male-first) and protogynous (female-first) sequential hermaphroditism (sex change). According to the size-advantage model (SAM), selection should favour sex change when the second sex achieves greater reproductive success at a larger body size than the first sex. Using phylogenetic comparative methods and a sample of 68 sparid species, we show that protogyny and protandry evolve from gonochorism but evolutionary transitions between these two forms of sequential hermaphroditism are unlikely to happen. Using male gonadosomatic index (GSI) as a measure of investment in gametes and proxy for sperm competition, we find that, while gonochoristic and protogynous species support the predictions of SAM, protandrous species do not, as they exhibit higher GSI values than expected even after considering mating systems and spawning modes. We suggest that small males of protandrous species have to invest disproportionally more in sperm production than predicted not only when spawning in aggregations, with high levels of sperm competition, but also when spawning in pairs due to the need to fertilize highly fecund females, much larger than themselves. We propose that this compensatory mechanism, together with Bateman's principles in sequential hermaphrodites, should be formally incorporated in the SAM. [ABSTRACT FROM AUTHOR]

Sex allocation (SA) theory for simultaneous hermaphrodites predicts an influence of group size on SA. Since group size can vary within an individual's lifetime, this can favor the evolution of phenotypically plastic SA. In an emerging comparative context, we here report on SA plasticity in three closely related Macrostomum flatworm species, namely Macrostomum janickei, Macrostomum cliftonensis, and Macrostomum mirumnovem. For each species, we experimentally raised worms in three group sizes (isolated, pairs, and octets) and two enclosure sizes (small and large) in all factorial combinations and studied the effects of these factors on different estimates of SA. In addition, we also evaluated whether isolated worms engage in self‐fertilization. We found that all species have plastic SA, with M. cliftonensis being more plastic than the other two species, as assessed by comparing standardized effect sizes of (a) the presence/absence of mating partners and (b) the strength of sexual competition. Moreover, we found that sperm production rate—but not sperm morphology—is plastic in M. cliftonensis, and that only M. mirumnovem self‐fertilized during our observation period. Our study suggests that both SA and SA plasticity can diverge even between closely related species. [ABSTRACT FROM AUTHOR]

Callichirus major is a species of ghost shrimp that has burrowing habits, building underground galleries in the intertidal region of beaches. This study aimed to analyse some morphological parameters to verify its type of sexual pattern. A sample of 79 individuals, collected at the beach of Corujão, Espírito Santo, Brazil, was used. Data on the external morphology, presence of gonopores, carapace length (CL) and cheliped lengths (Lch) were obtained. In addition, the gonads were processed for histological analysis. The animals were divided into three categories: A, individuals with male characteristics; B, those presenting exclusively female characteristics; C, animals with characteristics of intersex, which presented supernumerary gonopores. Positive allometries were found for Lch versus CL only for category A, characterizing the group's marked heterochely. Histologically, it was possible to observe the presence of oocytes in category A and one case of male tissue in an intersex individual (category C). However, no genital ducts of both sexes were found in that individual. Callichirus major presents controversial sexual characters, which makes it difficult to understand the reproductive parameters and sexual pattern. However, maybe that species can develop a sexual system of hermaphroditism. [ABSTRACT FROM AUTHOR]

We characterized the Andrias davidianus T-box 1 (Tbx1) gene. Tbx1 expression was high in testis and low in other examined tissues. Immunohistochemistry detected tbx 1 expression in somatic and germ cells 62 days post-hatching (dph), prior to gonad differentiation. At 210 dph, after gonad differentiation, tbx1 was expressed in spermatogonia and testis somatic cells and in granulosa cells in ovary. Tbx1 expression was up-regulated in ovary after high temperature treatment. In the neomale, tbx 1 expression showed a similar profile to normal males, and vice-versa for genetic male. Over-expression of tbx1 in females after injection of TBX1 protein down-regulated the female-biased genes cyp19a and foxl2 and up-regulated the male-biased amh gene. When tbx 1 was knocked down by tbx 1/siRNA, cyp19a and foxl2 expression was up-regulated, and expression of amh , cyp26a , dmrt1 , and wt1 was down-regulated. Results suggest that tbx1 influenced sex-related gene expression and participates in regulation of A. davidianus testis development. • Characterization and expression profile of Tbx1 in Andrias davidianus • Tbx1 initially expressed in the somatic and germ cells at 62 days post-hatching, prior to gonad differentiation. • Tbx1 expression profiles were changed in the sex reversal individuals • Tbx1 identified by overexpression and knockdown test presented a testicular differentiation gene in Andrias davidianus [ABSTRACT FROM AUTHOR]

Due to its exceptionally small genome size and protogynous hermaphroditism, Monopterus albus has been proposed as a model for vertebrate sexual development. The Kiss/GPR54 system is a central regulator of sexual development in most vertebrates, but its role in sex reversal remains hypothetical. In contrast to mammals, fishes often possess more than one copy of the kiss and gpr54 genes. Our objectives were to identify all kiss/gpr54 genes in the genome of M. albus and to assess their involvement in sex reversal via their expression patterns (qPCR) in females, males, and intersex specimens. We identified only two genes: kiss2 and gpr54‐2. kiss2 expression was extremely high in the gonads of males, intermediate in females, and low in intersex; and reduced in all tissues of intersex. gpr54 expression was also extremely high in the gonads of males, high in intersex, but low in females. gpr54 expression in brain was high in all three sexes. In conclusion, (a) kiss1 has been functionally replaced in M. albus; (b) the functions of gpr54‐2 in brain are not sex‐specific; (c) kiss2 appears to undergo a 'reset' in the expression during the sex change; and (d) sex‐specific expression patterns in the gonads indicate that these two genes may play a role in sex reversal in fish. [ABSTRACT FROM AUTHOR]

Meta‐studies on hermaphrodites have found a negative relationship between primary selfing rates and levels of inbreeding depression (ID) and, thus, generally support purging in inbred systems. However, in plants, high among‐taxa variance in ID results in no difference in the mean ID between outcrossing and mixed‐mating taxa. Selective interference likely explains high ID among mixed‐mating taxa, whereas low levels of ID among mixed‐mating taxa are not as stressed. Among animal hermaphrodites, primarily molluscs, there are little data on mixed‐mating systems. To fill a taxonomic and mating system gap, we tested for ID in a mixed‐mating tapeworm, Oochoristica javaensis. We provide a direct estimate of ID across infection of an intermediate host by comparing selfing rates at two life history stages. We found little to no evidence for ID, and the level of ID falls in line with what is reported for highly selfing species even though O. javaensis has mixed mating. We discuss this result within the context of kin mating in O. javaensis. Our results emphasize that primary selfing rates alone may be insufficient to classify the inbreeding history in all species when testing for a relationship to ID. Mixed‐mating taxa, and possibly some outcrossing taxa, may exhibit low levels of ID if biparental inbreeding is also driving purging. We advocate that ID studies report estimates of inbreeding history (e.g. FIS or identity disequilibrium) from nature‐derived adult samples to provide context rather than relying on primary selfing rates alone. [ABSTRACT FROM AUTHOR]

The orange-spotted grouper Epinephelus coioides is one of the most important commercially exploited fish species in the Arabian Gulf. Studies to establish the basic biological knowledge necessary for sustainable exploitation are few and of limited spatial extent. We carry out a comparative analysis of life history traits of this sequential hermaphrodite and of trends of abundance in coral reefs, northern vs. southern Gulf. We found remarkable differences in sex proportion by length and age, rates of somatic growth, size at maturity and production of gonadic biomass, and no differences in the age composition, mode of growth, timing and duration of spawning, natural mortality rate, and trends of abundance. In the northern Gulf, the reproductive tactics could be diandric protogyny or protandric because males disappear at higher size and later age. In the southern Gulf, the strategy is protogyny, with full predominance of females in early life and full predominance of males in late life. In the northern Gulf, the orange-spotted grouper could exhibit bidirectional sex change. We suggest that fisheries policies should be versatile, consisting of regional-wide as well as local management measures, to account for local differences and regional-wide commonalities in life history traits and trends of abundance. [ABSTRACT FROM AUTHOR]

Parthenogenetic species are usually considered to be short‐lived due to the accumulation of adverse mutations, lack of genetic variability, and inability to adapt to changing environment. If so, one may expect that the phenotype of clonal organisms may reflect such genetic and/or environmental stress. To test this hypothesis, we compared the developmental stability of bisexual and parthenogenetic lizards of the genus Darevskia. We assessed asymmetries in three meristic traits: ventral, preanal, and supratemporal scales. Our results suggest that the amount of ventral and preanal asymmetries is significantly higher in clones compared with their maternal, but not paternal, progenitor species. However, it is questionable, whether this is a consequence of clonality, as it may be considered a mild form of outbreeding depression as well. Moreover, most ventral asymmetries were found in the bisexual species Darevskia valentini. We suggest that greater differences in asymmetry levels among bisexuals may be, for instance, a consequence of the population size: the smaller the population, the higher the inbreeding and the developmental instability. On the basis of the traits examined in this study, the parthenogens do not seem to be of significantly poorer quality. [ABSTRACT FROM AUTHOR]

Sexual reproduction is overwhelmingly the most common reproductive mode among Metazoans, although it has been secondarily lost in some organisms. Ephoron shigae is a geographically parthenogenetic mayfly. Here, we provide details of the frequency of bisexual and parthenogenetic strains of E. shigae together with data on their sex ratios in the Abukuma-gawa River and one of its downstream tributaries, the Surikami-gawa River, in Japan. In a previous study in the 1990s, bisexual populations were observed in both rivers. The present study clearly shows that sex ratios have since changed to be almost entirely unisexual within the downstream area of the Abukuma-gawa River and the Surikami-gawa River. Our genetic analyses also show that these females are of a parthenogenetic strain, and that the original bisexual strains were overwhelmed within a period of <20 years. However, it was recently observed that many males and females of the bisexual strains continue to inhabit upstream areas of the Abukuma-gawa River. Therefore, we suggest that the parthenogenetic strains have increased in abundance primarily downstream. We show that a drastic change has occurred over a short period, involving the replacement of one strain and a corresponding change in reproductive mode along a riverine environment. [ABSTRACT FROM AUTHOR]

The postembryonic development of the gonad in the hermaphroditic appendicularian O. gracilis was studied using transmission electron microscopy. The primordial germ cells were detected first in 10-h-old larvae and represent migrating primordial germ syncytium (mPGS) localized in the hemocoel of the tail/trunk junction and several haemocoel areas of the digestive compartment. The mPGS consisted of primordial germ nuclei (PGN) 2 μm in diameter, and elongate somatic-line nuclei 1.8 μm in diameter. In 12.5-h-old juveniles the gonad primordium 40 × 90 μm in size, was separated by a narrow space of haemocoel between the gut and the epidermis of the reproductive compartment. The gonad primordium consisted of the central syncytial part of primordial germ nuclei (PGN), enclosing a single layer of somatic epithelium. In 3-day-old juveniles, the gonad was differentiated into testis and ovary. The testis, 400 × 550 μm in size, is a syncytium of spermatogonial nuclei, covered by a single layer of somatic epithelium. The ovaries, 350 × 850 μm in size, consist of a syncytium with nurse nuclei and meiotic nuclei. The hermaphroditic gonad originates from extragonadal mPGS. Early gonadogenesis in appendicularians has ultrastructural features in common with early gonadogenesis in ascidians. [ABSTRACT FROM AUTHOR]

Protandrous black porgy (Acanthopagrus schlegelii) is a popular and valuable commercial marine fish in China and East Asian countries. Controlling and managing its breeding has been an imperative step towards obtaining a sustainable supply of this fish in aquaculture production systems. Therefore, study on the molecular mechanisms of sex change in black porgy has both scientific and commercial importance. Previously, we identified some candidate genes related to sex determination and differentiation from a high-quality genome assembly of the black porgy. In the present study, transcriptome sequencing of developmental gonads (including testis, ovotestis and ovary) of black porgy was performed to further investigate the sex-change mechanisms. Our results showed that the highly expressed male-related genes (dmrt1, piwi1, piwi2, sox9, sox30 and amh) at the male phase were significantly down-regulated to a substantial degree at the intersexual stage, and the female-related genes (jnk1, vasa, wnt4, figla and foxl2) were distinctly up-regulated when the fish grows into a female adult, suggesting the potential roles of these genes in sex change of the black porgy. These data also support a previous hypothesis that the femaleness will be switched on when the testis is entering the degenerated stage through the diminished dmrt1 expression. Our transcriptome data provide a very useful genomic resource for future studies on sex change and practical aquaculture in the black porgy. • Transcriptome sequencing of developmental gonads was performed in black porgy to investigate the sex-change mechanisms. • Our data support the hypothesis that the femaleness will be switched on when the testis is entering the degenerated stage. • The ovarian development is a passive process that is controlled by the testis through the brain - pituitary-gonad axis. [ABSTRACT FROM AUTHOR]

Sex differentiation in teleost fishes occurs in response to sex determination signals, which induce the gonad to develop as either an ovary or testis. However, sex differentiation mechanisms in fishes are diverse, and information on gonad differentiation in sex changing fishes remains limited. The orange-spotted grouper (Epinephelus coioides) is a protogynous hermaphroditic fish that provides an ideal model for investigating gonad differentiation in vertebrates. In this study, Transcriptome data showed that expression levels of amh and amhrII in gonads were increased during sex differentiation. Then we investigated the effect of overexpression anti-Müllerian hormone (Amh) on gonad development in juvenile orange-spotted groupers. Expression levels of female-related genes and serum 17β-estradiol levels were decreased, while expression of male-related genes and serum 11-ketotestosterone levels were increased in fish fed with amh -plasmid. Overexpression of Amh was also promoted the spermatogonia proliferation and induced the development of male gonads in undifferentiated orange-spotted groupers, but that this male tendency was preceded by female differentiation. In summary, these results illustrated that Amh overexpression by amh -plasmid feeding induced male gonad development in undifferentiated groupers. [ABSTRACT FROM AUTHOR]

Abstract The bay scallop Argopecten irradians , a warm-water and hermaphroditic bivalve species, is native of the Atlantic coast of North America and was introduced for aquaculture to the Chinese coast in 1982 and, in turn, to the Korean coast in 1996. The present study analyzed the gross biochemical composition and stable isotope ratios of separated organs (i.e., the adductor muscle, digestive gland, gonad, mantle, and gill tissues) of the scallop over a culturing cycle (September 2015 to May 2016), to understand its energy-storage allocation strategy in association with reproductive success for survival in the new habitat. The condition index (CI) of the bay scallop increased slowly but steadily from the beginning of deployment in the grow-out area in September and peaked in the following month of March. The gonadosomatic index (GSI) increased rapidly in April and peaked in May, when the CI decreased drastically. The seasonal somatic growth, as defined by dry tissue weight, of whole tissues and individual organ tissues differed from each other. Most of the energy reserves were stored in the adductor muscle in the summer–fall period. The subsequent sudden decreases in proteins and carbohydrates in the adductor muscle suggested that these reserves were used as catabolic substrates during winter maintenance in the December–January period, and during spring spawning in the April–May period. The δ13C values of all the lipid-free organ tissues displayed seasonal fluctuations in parallel with those of phytoplankton. Seasonal fluctuations in gross weights of biochemical constituents as well as δ13C and δ15N values of individual organ tissues confirmed a mobilization of proteins from the digestive gland to the gonad, suggesting that gonadal growth is catabolized by recently assimilated food (i.e., phytoplankton). Overall, our results clearly indicate that, although the bay scallop in a newly introduced coast of Korea possessed slightly different energy-gain-allocation processes vs the native US populations, they might adapt to new environments and keep an intrinsic trait of fast growth and reproductive success through a slight modification of adaptive strategy for survival. Highlights • Somatic growth and reproduction of Argopecten irradians cultured in suspension in Korean coastal water were investigated. • Seasonal gross biochemical and isotopic composition of separated organs highlight energy storage-allocation strategy. • Results emphasize the roles of adductor muscle reserves for maintenance and digestive gland nutrients for gonadal growth. • The bay scallop adapts to new environment and keeps an intrinsic trait of fast growth and reproductive success. [ABSTRACT FROM AUTHOR]

Highlights • Various strategies, observed in natural populations of hydras, are successful. • Low competition among polyps to fertilize eggs favors dioecy. • When mate competition increases, the coexistence of hermaphrodites is successful. • High mating competition may exist in populations of Hydra circumcincta. Abstract Clonal populations in which, after switching to sexual reproduction, simultaneous hermaphrodites may coexist with variable proportions of hermaphrodites functioning only as male or female provide an opportunity to test sex ratio bias and sex investment within a simultaneous hermaphrodite, which are collectively referred to as the modular reproductive effect in this study. An individual-based model (IBM) was used to determine how sex investment and sex ratio bias affect the cnidarian Hydra circumcincta's fitness. Its clone-mates represent a genet, and after switching to sexual reproduction, they can be simultaneous hermaphrodites, hermaphrodites functioning as females, or hermaphrodites functioning as males, depending on their body size. The results of the model indicated that under low competition among polyps to fertilize eggs, hermaphrodites functioning as females and those functioning as males coexist, with the numerical superiority of the latter being more successful than simultaneous hermaphroditism independently of male-biased allocation of sex functions. When mate competition increases, the coexistence of hermaphrodites functioning as females and those functioning as males with the fundamental sex ratio 1:1 and females able to change their investment in eggs is the most successful. When there is strong mate competition, simultaneous hermaphroditism with strongly female-biased allocation of sex functions is the optimal strategy, except in scenarios with constrained investment in eggs. In such scenarios, various strategies, observed in natural populations of hydras, become successful. [ABSTRACT FROM AUTHOR]

In outcrossing hermaphrodites with unilateral mating, where for each mating interaction one individual assumes the female role and the other the male role, each individual must take a sexual role opposite to that of its partner. In the polychaete worm Ophryotrocha diadema , the decision on sexual role is likely at stake during the day-long courtship. Here we describe, for the first time, courtship and pseudocopulation in this species, quantify their pre-copulatory behavior, and search for behavioral traits predicting the prospective sexual role (i.e., behavioral sexual dimorphism), by analyzing the courtship behavior of pairs of worms during the day preceding a mating event. We did not find any behavioral cue predicting the sexual role worms were to play; partners' pre-copulatory behaviors were qualitatively and quantitatively symmetrical. We interpret this as the outcome of a war of attrition where partners share the preference for the same sexual role, and both hide their 'willingness' to play the less preferred one, until one individual reaches its cost threshold and accepts the less preferred sexual role. [ABSTRACT FROM AUTHOR]

Abstract Endocrine active compounds (EACs) are pollutants that have been recognized as an emerging and widespread threat to aquatic ecosystems globally. Intersex, the presence of female germ cells within a predominantly male gonad, is considered a biomarker of endocrine disruption caused by EACs. We measured a suite of EACs and assessed their associated impacts on fish intersex occurrence and severity in a large, regulated river system in North Carolina and South Carolina, USA. Our specific objective was to determine the relationship of contaminants in water, sediment, and fish tissue with the occurrence and severity of the intersex condition in wild, adult black bass ( Micropterus ), sunfish ( Lepomis ), and catfish (Ictaluridae) species at 11 sites located on the Yadkin-Pee Dee River. Polycyclic aromatic hydrocarbons (PAHs), ethinylestradiol (EE2), and heavy metals were the most prevalent contaminants that exceeded effect levels for the protection of aquatic organisms. Fish intersex condition was most frequently observed and most severe in black basses and was less frequently detected and less severe in sunfishes and catfishes. The occurrence of the intersex condition in fish showed site-related effects, rather than increasing longitudinal trends from upstream to downstream. Mean black bass and catfish tissue contaminant concentrations were higher than that of sunfish, likely because of the latter's lower trophic position in the food web. Principal component analysis identified waterborne PAHs as the most correlated environmental contaminant with intersex occurrence and severity in black bass and sunfish. As indicated by the intersex condition, EACs have adverse but often variable effects on the health of wild sport fishes in this river, likely due to fluctuations in EAC inputs and the dynamic nature of the riverine system. These findings enhance the understanding of the relationship between contaminants and fish health and provide information to guide ecologically comprehensive conservation and management decisions. Graphical abstract Unlabelled Image Highlights • Fish intersex is a common condition related to endocrine disrupting contaminants. • Contaminant concentrations and fish intersex are rarely examined simultaneously. • Fish, water, and sediment were evaluated in a large southeastern USA regulated river. • Intersex occurrence was greatest in black bass and varied throughout the river. • PAHs, mercury, and pesticides correlated most with fish intersex. [ABSTRACT FROM AUTHOR]

Androdioecy (males and hermaphrodites) is a rare breeding system in multicellular organisms, found mostly in barnacles and branchiopod crustaceans. The most speciose and longest-lived androdioecious clade is the genus Eulimnadia Packard, 1874 (Branchiopoda, Spinicaudata), the clam shrimps, consisting of over 50 species that have maintained androdioecy for an estimated 24–180 million years. Many populations of Eulimnadia nevertheless comprise entirely "monogenic" hermaphrodites. Hypotheses proposed to explain the relative stability of androdioecy (sexual conflict, overdominance, and metapopulation model) differ in their predictions of the resistance of existing all-hermaphrodite populations to invasion of males and hermaphrodites. We tested whether all-hermaphroditic populations of Eulimnadia texana Packard, 1871 may be resistant to male invasion by adding males and "amphigenic" hermaphrodites to all-hermaphrodite, monogenic populations that have been inbred for eight generations. All-hermaphrodite populations of E. texana that have been selfing for multiple generations are easily invaded by males, both directly and indirectly. The addition of males also increased the productivity of these experimental treatments, suggesting a selective benefit to outcrossing and thus to males. These results do not align with the sexual conflict nor the overdominance models, but are consistent with the metapopulation model of the maintenance of androdioecy. [ABSTRACT FROM AUTHOR]