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Spermatogenesis is a process of self-renewal and differentiation in spermatogonial stem cells. During this process, germ cells and somatic cells interact intricately to ensure long-term fertility and accurate genome propagation. Spermatogenesis has been intensely investigated in mammals but remains poorly understood with regard to teleosts. Here, we performed single-cell RNA sequencing of ~9500 testicular cells from the male, orange-spotted grouper. In the adult testis, we divided the cells into nine clusters and defined ten cell types, as compared with human testis data, including cell populations with characteristics of male germ cells and somatic cells, each of which expressed specific marker genes. We also identified and profiled the expression patterns of four marker genes ( calr , eef1a , s100a1 , vasa ) in both the ovary and adult testis. Our data provide a blueprint of male germ cells and supporting somatic cells. Moreover, the cell markers are candidates that could be used for further cell identification.

Background: The fragrant flower plant Osmanthus fragrans has an extremely rare androdioecious breeding system displaying the occurrence of males and hermaphrodites in a single population, which occupies a crucial intermediate stage in the evolutionary transition between hermaphroditism and dioecy. However, the molecular mechanism of androdioecy plant is very limited and still largely unknown., Results: Here, we used SWATH-MS-based quantitative approach to study the proteome changes between male and hermaphroditic O. fragrans pistils. A total of 428 proteins of diverse functions were determined to show significant abundance changes including 210 up-regulated and 218 down-regulated proteins in male compared to hermaphroditic pistils. Functional categorization revealed that the differentially expressed proteins (DEPs) primarily distributed in the carbohydrate metabolism, secondary metabolism as well as signaling cascades. Further experimental analysis showed the substantial carbohydrates accumulation associated with promoted net photosynthetic rate and water use efficiency were observed in purplish red pedicel of hermaphroditic flower compared with green pedicel of male flower, implicating glucose metabolism serves as nutritional modulator for the differentiation of male and hermaphroditic flower. Meanwhile, the entire upregulation of secondary metabolism including flavonoids, isoprenoids and lignins seem to protect and maintain the male function in male flowers, well explaining important feature of androdioecy that aborted pistil of a male flower still has a male function. Furthermore, nine selected DEPs were validated via gene expression analysis, suggesting an extra layer of post-transcriptional regulation occurs during O. fragrans floral development., Conclusion: Taken together, our findings represent the first SWATH-MS-based proteomic report in androdioecy plant O. fragrans, which reveal carbohydrate metabolism, secondary metabolism and post-transcriptional regulation contributing to the androdioecy breeding system and ultimately extend our understanding on genetic basis as well as the industrialization development of O. fragrans., (© 2021. The Author(s).)

Sexual systems are surprisingly diverse, considering the ubiquity of sexual reproduction. Sequential hermaphroditism, the ability of an individual to change sex, has emerged multiple times independently across the animal kingdom. In molluscs, repeated shifts between ancestrally separate sexes and hermaphroditism are generally found at the level of family and above, suggesting recruitment of deeply conserved mechanisms. Despite this, molecular mechanisms of sexual development are poorly known. In molluscs with separate sexes, endocrine disrupting toxins bind the retinoid X receptor (RXR), activating ectopic male development in females, suggesting the retinoid pathway as a candidate controlling sexual transitions in sequential hermaphrodites. We therefore tested the role of retinoic acid signaling in sequentially hermaphroditic Crepidula snails, which develop first into males, then change sex, maturing into females. We show that retinoid agonists induce precocious penis growth in juveniles and superimposition of male development in females. Combining RXR antagonists with retinoid agonists significantly reduces penis length in induced juveniles, while similar treatments using retinoic acid receptor (RAR) antagonists increase penis length. Transcripts of both receptors are expressed in the induced penis. Our findings therefore show that retinoid signaling can initiate molluscan male genital development, and regulate penis length. Further, we show that retinoids induce ectopic male development in multiple Crepidula species. Species-specific influence of conspecific induction of sexual transitions correlates with responsiveness to retinoids. We propose that retinoid signaling plays a conserved role in molluscan male development, and that shifts in the timing of retinoid signaling may have been important for the origins of sequential hermaphroditism within molluscs., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Posttranscriptional regulation of gene expression, typically effected by RNA-binding proteins, microRNAs (miRNAs), and translation initiation factors, is essential for normal germ cell function. Numerous miRNAs have been detected in the germline; however, the functions of specific miRNAs remain largely unknown. Functions of miRNAs have been difficult to determine as miRNAs often modestly repress target mRNAs and are suggested to sculpt or fine tune gene expression to allow for the robust expression of cell fates. In Caenorhabditis elegans hermaphrodites, cell fate decisions are made for germline sex determination during larval development when sperm are generated in a short window before the switch to oocyte production. Here, analysis of newly generated mir-44 family mutants has identified a family of miRNAs that modulate the germline sex determination pathway in C. elegans. Mutants with the loss of mir-44 and mir-45 produce fewer sperm, showing both a delay in the specification and formation of sperm as well as an early termination of sperm specification accompanied by a premature switch to oocyte production. mir-44 and mir-45 are necessary for the normal period of fog-1 expression in larval development. Through genetic analysis, we find that mir-44 and mir-45 may act upstream of fbf-1 and fem-3 to promote sperm specification. Our research indicates that the mir-44 family promotes sperm cell fate specification during larval development and identifies an additional posttranscriptional regulator of the germline sex determination pathway., (© The Author(s) 2020. Published by Oxford University Press on behalf of Genetics Society of America. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The impacts of human and natural disturbances on coral reefs are typically quantified through visible damage (e.g., reduced coral coverage as a result of bleaching events), but changes in environmental conditions may also cause damage in less visible ways. Despite the current paradigm, which suggests consistent, highly synchronized spawning events, corals that reproduce by broadcast spawning are particularly vulnerable because their reproductive phenology is governed by environmental cues. Here, we quantify coral spawning intensity during four annual reproductive seasons, alongside laboratory analyses at the polyp, colony, and population levels, and we demonstrate that, compared with historical data, several species from the Red Sea have lost their reproductive synchrony. Ultimately, such a synchrony breakdown reduces the probability of successful fertilization, leading to a dearth of new recruits, which may drive aging populations to extinction., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Heritable variation in, and genetic correlations among, traits determine the response of multivariate phenotypes to natural selection. However, as traits develop over ontogeny, patterns of genetic (co)variation and integration captured by the G matrix may also change. Despite this, few studies have investigated how genetic parameters underpinning multivariate phenotypes change as animals pass through major life history stages. Here, using a self-fertilizing hermaphroditic fish species, mangrove rivulus (Kryptolebias marmoratus), we test the hypothesis that G changes from hatching through reproductive maturation. We also test Cheverud's conjecture by asking whether phenotypic patterns provide an acceptable surrogate for patterns of genetic (co)variation within and across ontogenetic stages. For a set of morphological traits linked to locomotor (jumping) performance, we find that the overall level of genetic integration (as measured by the mean-squared correlation across all traits) does not change significantly over ontogeny. However, we also find evidence that some trait-specific genetic variances and pairwise genetic correlations do change. Ontogenetic changes in G indicate the presence of genetic variance for developmental processes themselves, while also suggesting that any genetic constraints on morphological evolution may be age-dependent. Phenotypic correlations closely resembled genetic correlations at each stage in ontogeny. Thus, our results are consistent with the premise that-at least under common environment conditions-phenotypic correlations can be a good substitute for genetic correlations in studies of multivariate developmental evolution.

This study documents changes in gonadal structure for the serial hermaphrodite (or bidirectional sex changer) divine dwarfgoby Eviota epiphanes (family Gobiidae) as individuals transition in both directions. To evaluate transitional gonad morphology, individuals actively producing the same gamete type (oocytes or sperm) were set up into pairs and euthanised over a period of 14 days to get a time series of morphological changes during gonad transformation. Results from this study show that rapid changes in the gonad take place at a structural level as individuals change their reproductive function and gamete production. Changing from oocyte production (o-phase) to sperm production (s-phase) starts with the breakdown of vitellogenic oocytes (i.e., atresia) followed by the appearance and proliferation of spermatogenic tissue which, in most cases, was not previously visible. Changing from sperm production to oocyte production included the cessation of sperm production, a reduction in size and number of seminiferous lobules and the maturation of previtellogenic oocytes already present in the gonads. Experimental fish changed from oocyte production to sperm production more readily than from sperm production to oocyte production. The hypothesis that shifts in sexual function among serially hermaphroditic fish species have a similar cost in either direction is not supported in E. epiphanes., (© 2018 The Fisheries Society of the British Isles.)

Sex determination and sexual development are highly diverse and controlled by mechanisms that are extremely labile. While dioecy (separate male and female functions) is the norm for most animals, hermaphroditism (both male and female functions within a single body) is phylogenetically widespread. Much of our current understanding of sexual development comes from a small number of model systems, limiting our ability to make broader conclusions about the evolution of sexual diversity. We present the calyptraeid gastropods as a model for the study of the evolution of sex determination in a sequentially hermaphroditic system. Calyptraeid gastropods, a group of sedentary, filter-feeding marine snails, are sequential hermaphrodites that change sex from male to female during their life span (protandry). This transition includes resorption of the penis and the elaboration of female genitalia, in addition to shifting from production of spermatocytes to oocytes. This transition is typically under environmental control and frequently mediated by social interactions. Males in contact with females delay sex change to transition at larger sizes, while isolated males transition more rapidly and at smaller sizes. This phenomenon has been known for over a century; however, the mechanisms that control the switch from male to female are poorly understood. We review here our current understanding of sexual development and sex determination in the calyptraeid gastropods and other molluscs, highlighting our current understanding of factors implicated in the timing of sex change and the potential mechanisms. We also consider the embryonic origins and earliest expression of the germ line and the effects of environmental contaminants on sexual development.

One of the most studied phosphoinositides is phosphatidylinositol 4,5-bisphosphate (PIP2), which localizes to the plasma membrane, nuclear speckles, small foci in the nucleoplasm, and to the nucleolus in mammalian cells. Here, we show that PIP2 also localizes to the nucleus in prophase I, during the gametogenesis of C. elegans hermaphrodite. The depletion of PIP2 by type I PIP kinase (PPK-1) kinase RNA interference results in an altered chromosome structure and leads to various defects during meiotic progression. We observed a decreased brood size and aneuploidy in progeny, defects in synapsis, and crossover formation. The altered chromosome structure is reflected in the increased transcription activity of a tightly regulated process in prophase I. To elucidate the involvement of PIP2 in the processes during the C. elegans development, we identified the PIP2-binding partners, leucine-rich repeat (LRR-1) protein and proteasome subunit beta 4 (PBS-4), pointing to its involvement in the ubiquitin⁻proteasome pathway.

Bivalve mollusks exhibit hermaphroditism and sex reversal/differentiation. Studies generally focus on transcriptional profiling and specific genes related to sex determination and differentiation. Few studies on sex reversal/differentiation have been reported. A combination analysis of gonad proteomics and transcriptomics was conducted on Chlamys nobilis to provide a systematic understanding of sex reversal/differentiation in bivalves. We obtained 4258 unique peptides and 93,731 unigenes with good correlation between messenger RNA and protein levels. Candidate genes in sex reversal/differentiation were found: 15 genes differentially expressed between sexes were identified and 12 had obvious sexual functions. Three novel genes (foxl2, β-catenin, and sry) were expressed highly in intersex individuals and were likely involved in the control of gonadal sex in C. nobilis. High expression of foxl2 or β-catenin may inhibit sry and activate 5-HT receptor and vitellogenin to maintain female development. High expression of sry may inhibit foxl2 and β-catenin and activate dmrt2, fem-1, sfp2, sa6, Amy-1, APCP4, and PLK to maintain male function. High expression of sry, foxl2, and β-catenin in C. nobilis may be involved in promoting and maintaining sex reversal/differentiation. The downstream regulator may not be dimorphic expressed genes, but genes expressed in intersex individuals, males and females. Different expression patterns of sex-related genes and gonadal histological characteristics suggested that C. nobilis may change its sex from male to female. These findings suggest highly conserved sex reversal/differentiation with diverged regulatory pathways during C. nobilis evolution. This study provides valuable genetic resources for understanding sex reversal/differentiation (intersex) mechanisms and pathways underlying bivalve reproductive regulation.

Gynodioecy is the coexistence of hermaphrodites and females in a population. It is supposed to be an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy in angiosperm. Hermaphrodites gain fitness through both seed and pollen production whereas females gain fitness only through seed production. As females spread in a gynodioecious population, sexual selection prompts hermaphrodites to invest in male function and male-biased hermaphrodites prevail. In the gynodioecious shrub Daphne jezoensis (Thymelaeaceae), female frequency is stably around 50% in most populations, and fruit-set rate of hermaphrodites is commonly low. Therefore, D. jezoensis is likely at a later stage in the evolutionary pathway. Female function of hermaphrodites (fruit-set rate, selfing rate, seed size, and germination rate) was assessed in three populations under natural conditions. In order to evaluate the potential seed fertility and inbreeding depression by selfing in hermaphrodites, hand pollination treatments were also performed. Over a 2-year period under natural conditions, 18-29% of hermaphrodites and 69-81% of females set fruit. Across all three populations, the mean fruit-set rate ranged 9.5-49.2% in females and only 3.9-10.2% in hermaphrodites. Even with artificial outcross-pollination, 59-91% of hermaphrodites failed to set any fruit. When self-pollination was performed in hermaphrodites, both of fruit-set and germination rates were decreased, indicating early-acting inbreeding depression. In addition, more than half of the hermaphrodite seeds were produced by selfing under natural pollination, but pollinator service was still required. Totally, hermaphrodites performed poorly as seed producers because of the intrinsically-low fruiting ability and a combination of autogamous selfing and strong inbreeding depression, indicating the absence of reproductive assurance. These results indicate that the mating system of D. jezoensis is functionally close to dioecy.

Sex differentiation is a puzzling problem in fish due to the variety of reproductive systems and the flexibility of their sex determination mechanisms. The Sparidae, a teleost family, reflects this remarkable diversity of sexual mechanisms found in fish. Our aim was to capture the transcriptomic signature of different sexes in two protogynous hermaphrodite sparids, the common pandora Pagellus erythrinus and the red porgy Pagrus pagrus in order to shed light on the molecular network contributing to either the female or the male phenotype in these organisms. Through RNA sequencing, we investigated sex-specific differences in gene expression in both species' brains and gonads. The analysis revealed common male and female specific genes/pathways between these protogynous fish. Whereas limited sex differences found in the brain indicate a sexually plastic tissue, in contrast, the great amount of sex-biased genes observed in gonads reflects the functional divergence of the transformed tissue to either its male or female character. Α common "crew" of well-known molecular players is acting to preserve either sex identity of the gonad in these fish. Lastly, this study lays the ground for a deeper understanding of the complex process of sex differentiation in two species with an evolutionary significant reproductive system.

Nervous systems display intriguing patterns of sexual dimorphisms across the animal kingdom, but the mechanisms that generate such dimorphisms remain poorly characterized. In the nematode Caenorhabditis elegans, a number of neurons present in both sexes are synaptically connected to one another in a sexually dimorphic manner as a result of sex-specific synaptic pruning and maintenance [1-3]. We define here a mechanism for the male-specific maintenance of the synaptic connections of the phasmid sensory neuron PHB and its male-specific target, the sex-shared AVG interneuron. We show that the C. elegans Netrin ortholog UNC-6, signaling through its cognate receptor UNC-40/DCC and the CED-5/DOCK180 guanine nucleotide exchange factor, is both required and sufficient for male-specific synaptic maintenance. The dimorphism of unc-6 activity is brought about by sex-specific regulation of unc-6 transcription. Although unc-6 is transcribed in the AVG neuron of males and hermaphrodites during juvenile stages, unc-6 expression is downregulated in AVG in hermaphrodites during sexual maturation but is maintained during sexual maturation of males. unc-6 downregulation in hermaphrodites is conferred by the master regulator of hermaphrodite sexual identity, the Gli/CI homolog TRA-1, which antagonizes the non-sex-specific function of the LIM homeobox gene lin-11, a terminal selector and activator of unc-6 in AVG. Preventing the downregulation of unc-6 in AVG of hermaphrodites through ectopic expression of unc-6 in transgenic animals results in the maintenance of the PHB>AVG synapses in hermaphrodites. Taken together, intersectional transcriptional regulation of unc-6/Netrin is required and sufficient to cell autonomously pattern sexually dimorphic synapses., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study uses histological techniques to make a detailed comparison of the reproductive morphologies of four gobiid genera, Amblyeleotris, Ctenogobiops, Fusigobius and Kraemeria. Three distinct reproductive morphological patterns were observed. All species examined in the genus Fusigobius exhibit either an ovariform or testiform gonad and precursive accessory gonadal structures (pAGS) associated with each of the gonadal lobes, regardless of gonadal state. In contrast, among species of Amblyeleotris, Ctenogobiops and Kraemeria examined, pAGS were not found. Furthermore, Amblyeleotris and Ctenogobiops differ from both Kraemeria and Fusigobius in lacking AGS associated with the testiform gonad. These findings, based solely on reproductive morphology, suggest that Kraemeria and Fusigobius may be more closely related to each other than either is to Amblyeleotris and Ctenogobiops. Findings of this study support the view that reproductive morphological patterns could prove informative in elucidating evolutionary relationships within the family Gobiidae., (© 2017 The Fisheries Society of the British Isles.)

Caenorhabditis elegans contains 25 Argonautes, of which, ALG-1 and ALG-2 are known to primarily interact with miRNAs. ALG-5 belongs to the AGO subfamily of Argonautes that includes ALG-1 and ALG-2, but its role in small RNA pathways is unknown. We analyzed by high-throughput sequencing the small RNAs associated with ALG-5, ALG-1 and ALG-2, as well as changes in mRNA expression in alg-5, alg-1 and alg-2 mutants. We show that ALG-5 defines a distinct branch of the miRNA pathway affecting the expression of genes involved in immunity, defense, and development. In contrast to ALG-1 and ALG-2, which associate with most miRNAs and have general roles throughout development, ALG-5 interacts with only a small subset of miRNAs and is specifically expressed in the germline where it localizes alongside the piRNA and siRNA machinery at P granules. alg-5 is required for optimal fertility and mutations in alg-5 lead to a precocious transition from spermatogenesis to oogenesis. Our results provide a near-comprehensive analysis of miRNA-Argonaute interactions in C. elegans and reveal a new role for miRNAs in the germline., (© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.)

The fourfinger threadfin Eleutheronema tetradactylum is reported as a protandrous hermaphrodite from Australian waters, while being a gonochorist in reports from Singapore and India, with a single report of protandrous hermaphroditism from the latter. Histological analysis of gonads of fish from Indian waters confirms protandrous hermaphroditism in E. tetradactylum. The study was based on 480 fish examined from eight locations along the Indian coast. Mean total length (L T ) of male fish was 240 mm with the transition to female starting from 280 mm L T . Specimens confirmed as mature females were >380 mm L T ., (© 2017 The Fisheries Society of the British Isles.)

Dead end (dnd), vertebrate-specific germ cell marker, had been demonstrated to be essential for primordial germ cell (PGC) migration and survival, and the link between PGC number and sex change had been revealed in some teleost species, but little is known about dnd in hermaphroditic vertebrates. In the present study, a protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides) dnd homologue (Ecdnd) was identified and characterized. Quantitative real-time PCR and in situ hybridization analysis revealed a dynamic and sexually dimorphic expression pattern in PGCs and germ cells of gonads. During sex changing, the Ecdnd transcript sharply increased in early transitional gonad, reached the highest level at late transitional gonad stage, and decreased after testis maturation. Visualization of zebrafish PGCs by injecting with RFP-Ecdnd-3'UTR RNA and GFP-zfnanos3-3'UTR RNA confirmed importance of Ecdnd 3'UTR for the PGC distribution. In addition, knockdown of EcDnd by using antisense morpholinos (MO) caused the ablation of PGCs in orange-spotted grouper. Therefore, the current data indicate that Ecdnd is essential for PGCs survival and may serve as a useful germ cell marker during gametogenesis in hermaphroditic grouper., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Environmental conditions experienced during animal development are thought to have sustained impact on maturation and adult lifespan. Here we show that in the model organism C. elegans developmental rate and adult lifespan depend on larval population density, and that this effect is mediated by excreted small molecules. By using the time point of first egg laying as a marker for full maturity, we found that wildtype hermaphrodites raised under high density conditions developed significantly faster than animals raised in isolation. Population density-dependent acceleration of development (Pdda) was dramatically enhanced in fatty acid β-oxidation mutants that are defective in the biosynthesis of ascarosides, small-molecule signals that induce developmental diapause. In contrast, Pdda is abolished by synthetic ascarosides and steroidal ligands of the nuclear hormone receptor DAF-12. We show that neither ascarosides nor any known steroid hormones are required for Pdda and that another chemical signal mediates this phenotype, in part via the nuclear hormone receptor NHR-8. Our results demonstrate that C. elegans development is regulated by a push-pull mechanism, based on two antagonistic chemical signals: chemosensation of ascarosides slows down development, whereas population-density dependent accumulation of a different chemical signal accelerates development. We further show that the effects of high larval population density persist through adulthood, as C. elegans larvae raised at high densities exhibit significantly reduced adult lifespan and respond differently to exogenous chemical signals compared to larvae raised at low densities, independent of density during adulthood. Our results demonstrate how inter-organismal signaling during development regulates reproductive maturation and longevity.

Many metazoans start germ cell development during embryogenesis, while some metazoans possessing pluripotent stem cells undergo postembryonic germ cell development. The latter reproduce asexually but develop germ cells from pluripotent stem cells or dormant primordial germ cells when they reproduce sexually. Sexual induction of the planarian Dugesia ryukyuensis is an important model for postembryonic germ cell development. In this experimental system, hermaphroditic reproductive organs are differentiated in presumptive gonadal regions by the administration of a crude extract from sexual planarians to asexual ones. However, the substances involved in the first event during postembryonic germ cell development, i.e., ovarian development, remain unknown. Here, we aimed to identify a bioactive compound associated with postembryonic ovarian development. Bioassay-guided fractionation identified ʟ-tryptophan (Trp) on the basis of electrospray ionization-mass spectrometry, circular dichroism, and nuclear magnetic resonance spectroscopy. Originally masked by a large amount of ʟ-Trp, ᴅ-Trp was detected by reverse-phase high-performance liquid chromatography. The ovary-inducing activity of ᴅ-Trp was 500 times more potent than that of ʟ-Trp. This is the first report describing a role for an intrinsic ᴅ-amino acid in postembryonic germ cell development. Our findings provide a novel insight into the mechanisms of germ cell development regulated by low-molecular weight bioactive compounds.

Multiple nanos genes have been characterized in several fishes, but the functional implications of their various expression patterns remain unclear. In this study, we identified and characterized four nanos genes from a hermaphroditic fish orange-spotted grouper, Epinephelus coioides . Ecnanos1a and Ecnanos1b show divergent expression patterns, and the dynamic expression change of Ecnanos1a in pituitaries during sex change is associated with testis differentiation and spermatogenesis. Ecnanos2 and Ecnanos3 might be germline stem cells (GSCs) and primordial germ cells (PGCs)-specific markers, respectively. Significantly, Ecnanos3 3'-untranslated region (UTR) is necessary for PGC specific expression, where a non-canonical "GCACGTTT" sequence is required for miR-430-mediated repression of Ecnanos3 RNA. Furthermore, grouper Dead end (Dnd) can relieve miR-430 repression in PGCs by associating with a 23 bp U-rich region (URR) in Ecnanos3 3'-UTR. The current study revealed the functional association of multiple nanos genes with PGC formation and germ cell development in orange-spotted grouper, and opened up new possibilities for developing biotechnologies through utilizing the associations between Ecnanos3 and PGCs or between Ecnanos2 and GSCs in the hermaphroditic fish.

Premise of the Study: It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female-biased allocation increases with plant size in the hermaphroditic-gynomonoecious herb Eremurus anisopterus ., Methods: Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types of E. anisopterus ., Key Results: Frequency of gynomonoecious plants varied from 2-17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites., Conclusions: Although the prediction of an increase in female flower number with plant size was not observed in E. anisopterus , the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female-biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants., (© 2017 Botanical Society of America.)

Males and females pursue different reproductive strategies, which often bring them into conflict-many traits exist that benefit one sex at a cost to another [1]. Decreased female survival following mating dramatically demonstrates one aspect of this phenomenon [2-5]. Particularly intriguing is the evidence that secreted compounds can shorten lifespan of members of the opposite sex in Drosophila [6] and Caenorhabditid nematodes [7] even without copulation taking place. The purpose of such signals is not clear, however. While it is possible that they could limit subsequent mating with competitors or hasten post-reproductive demise, thus decreasing competition for resources, they are also likely to harm unmated individuals. Why would a system exist that reduces the vigor of potential mates prior to mating? Addressing this question could provide insights into mechanisms and evolution of sexual conflict and reveal sensory inputs that regulate aging. Here, we describe two distinct ways in which Caenorhabditis elegans males cause faster somatic aging of hermaphrodites but also manipulate different aspects of their reproductive physiology. The first, mediated by conserved ascaroside pheromones, delays the loss of germline progenitor cells. The second accelerates development, resulting in faster sexual maturation. These signals promote male reproductive strategy and the effects harmful to hermaphrodites appear to be collateral damage rather than the goal., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Hermaphroditic organisms are key models in sex allocation research, yet the developmental processes by which hermaphrodite sex allocation can evolve remain largely unknown. Here we use experimental evolution of hermaphrodite-male (androdioecious) Caenorhabditis elegans populations to quantify the developmental changes underlying adaptive shifts in hermaphrodite sex allocation. We show that the experimental evolution of increased early-life self-fertility occurred through modification of a suite of developmental traits: increased self-sperm production, accelerated oogenesis and ovulation, and increased embryo retention. The experimental evolution of increased self-sperm production delayed entry into oogenesis-as expected, given the sequentially coupled production of self-spermatogenesis and oogenesis. Surprisingly, however, delayed oogenesis onset did not delay reproductive maturity, nor did it trade-off with gamete or embryo size. Comparing developmental time dynamics of germline and soma indicates that the evolution of increased sperm production did not delay reproductive maturity due to a globally accelerated larval development during the period of self-spermatogenesis. Overall, heterochrony in gametogenesis and soma can explain adaptive shifts in hermaphrodite sex allocation., (© 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.)

Developmental plasticity, the ability of one genotype to produce distinct phenotypes in different environments, has been suggested to facilitate phenotypic diversification, and several examples in plants and animals support its macroevolutionary potential [1-8]. However, little is known about associated molecular mechanisms, because environmental effects on development are difficult to study by laboratory approaches. One promising system is the mouth dimorphism of the nematode Pristionchus pacificus [9-12]. Following an irreversible decision in larval development, these nematodes form moveable teeth that occur in either of two discrete morphs. The "eurystomatous" (Eu) form has a wide mouth and two teeth, allowing predatory feeding on other nematodes. In contrast, the alternative ("stenostomatous"; St) form has diminutive mouthparts that largely constrain its diet to microbes. The sulfatase EUD-1 was previously discovered to execute a polyphenism switch based on dosage of functional alleles [13] and confirmed a prediction of evolutionary theory about how developmental switches control plasticity [1, 3]. However, the genetic context of this single gene, and hence the molecular complexity of switch mechanisms, was previously unknown. Here we use a suppressor screen to identify factors downstream of eud-1 in mouth-form regulation. We isolated three dominant, X-linked mutants in the nuclear hormone receptor gene nhr-40 that are haploinsufficient. Both eud-1 nhr-40 double and nhr-40 single mutants are all Eu, whereas transgenic overexpression of nhr-40 does not restore the wild-type phenotype but instead results in nearly all-St lines. Thus, NHR-40 is part of a developmental switch, suggesting that switch mechanisms controlling plasticity consist of multi-component hormonal signaling systems., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This paper presents results on the age, growth and population structure of a small grouper, the mutton hamlet Alphestes afer, and discusses the observed size and age structure patterns in relation to reproductive strategies among the epinephelids. Ages were determined by examination of sectioned otoliths, which showed a distinct pattern of alternating translucent and opaque zones that formed annually, as validated with tetracycline labelling. The von Bertalanffy growth function was adjusted to the length-at-age data of the males and females, but no significant differences were observed between the resulting parameters. The females, however, were older at given sizes and attained larger sizes and ages, with a maximum observed longevity of 13 years and a total length (LT ) of 26 cm, while the males attained maximum longevities of only 10 years and a 22 cm maximum LT . The LT and age range for the sex change was 16-25 cm and 3-11 years. The total mortality rate (Z) was estimated to be 0·55 for females and 0·82 for males. With the males younger and smaller than the females, this species differed from the pattern commonly observed for protogynous epinephelids. Males had slower growth after maturation, probably due to energy allocation to sperm production during sexual development. This study shows that demography is an important tool to understand the pathways for reproductive strategies in grouper populations., (© 2016 The Fisheries Society of the British Isles.)

Gonad ontogeny of the Hong Kong grouper Epinephelus akaara (a bi-directional sex changer) and the yellow grouper Epinephelus awoara (a protogynous hermaphrodite) was examined for the first time from post-larval phase until first sexual maturation, by histology. Approximately 20 specimens of each species were collected randomly every 2-7 weeks from rearing tanks with natural sea water and temperature between June 2013 and June 2014. The paired gonadal primordia (GP) were observed at 6 weeks after hatching (wah) for both species; however, gonia were first observed in GP at 16 wah for E. akaara and at 8 wah for E. awoara. The timings for the appearance of primary-growth stage oocytes (O1) and the completion of ovarian lumen (OL) varied; both at 27 wah for E. akaara, and at 18 and 23 wah for E. awoara respectively. A bisexual-phase gonad with an OL, O1 and scattered spermatogenic cysts (SC) was observed at 27-29 wah for both E. akaara and E. awoara. Sexual differentiation was subsequently observed from the bisexual-phase gonad at 34 wah for E. akaara, and 41 wah for E. awoara, with the appearance of cortical-alveolus stage oocytes (O2) for developing female and the proliferation of SC for developing primary male (i.e. from juvenile directly). Ovaries of mature females contained the vitellogenic stage oocytes (O3) and scattered SC; testes of mature primary males had sperm in sperm sinuses within the gonadal wall and remained O1. Minimum age of first sexual maturation for both female and primary male of E. akaara was at 41 wah; minimum total length (LT ) of female (143 mm) was larger than that of primary male (137 mm L(T)). Minimum age and size of first sexual maturation for female of E. awoara (47 wah and 149 mm L(T), respectively) were larger than those of E. akaara. Developing primary males of E. awoara were found at 41-58 wah, however, mature males were not observed, indicating inconsistency in first sexual maturation for E. awoara. This study provided strong evidences of primary male pathway in E. akaara and E. awoara; the latter is confirmed to be diandric., (© 2016 The Fisheries Society of the British Isles.)

Thermal developmental plasticity represents a key organismal adaptation to maintain reproductive capacity in contrasting and fluctuating temperature niches. Although extensively studied, research on thermal plasticity has mainly focused on phenotypic outcomes, such as adult life history, rather than directly measuring plasticity of underlying developmental processes. How thermal plasticity of developmental phenotypes maps into plasticity of resulting final phenotypes, and how such mapping relationships evolve, thus remain poorly understood. Here we address these questions by quantifying thermal plasticity of Caenorhabditis hermaphrodite germline development. We integrate measurements of germline development and fertility at the upper thermal range in isolates of C. briggsae, C. elegans, and C. tropicalis. First, we compare intra- and interspecific variation in thermal germline plasticity with plasticity in reproductive output. Second, we ask whether the developmental errors leading to fertility break-down at upper thermal limits are evolutionarily conserved. We find that temperature variation modulates spermatogenesis, oogenesis and germ cell progenitor pools, yet the thermal sensitivity of these processes varies among isolates and species, consistent with evolutionary variation in upper thermal limits of hermaphrodite fertility. Although defective sperm function is a major contributor to heat-induced fertility break-down, high temperature also significantly perturbs oogenesis, germline integrity, and mitosis-meiosis progression. Remarkably, the occurrence and frequency of specific errors are strongly species- and genotype-dependent, indicative of evolutionary divergence in thermal sensitivity of distinct processes in germline development. Therefore, the Caenorhabditis reproductive system displays complex genotype-by-temperature interactions at the developmental level, which may remain masked when studying thermal plasticity exclusively at the life history level., (© 2015 Wiley Periodicals, Inc.)

Background and Aims: Variation in the relative female and male reproductive success of flowering plants is widespread, despite the fundamental hermaphroditic condition of the majority of species. In many hermaphroditic populations, environmental conditions and their influence on development and size can influence the gender expression of individuals through the formation of hermaphroditic and unisexual flowers. This study investigates the hypothesis that the bulbous, animal-pollinated, perennial Lilium apertum (Liliaceae) exhibits a form of size-dependent gender modification known as gender diphasy, in which the sexual expression of individuals depends on their size, with plants often changing sex between seasons., Methods: Variation in floral traits was examined in relation to their size using marked individuals in natural populations, and also under glasshouse conditions. Measurements were taken of the height, flower number, floral sex expression, flower size, flower biomass and pollen production of individuals over consecutive years between 2009 and 2012 in seven populations in south-west China., Key Results: Flowers of L. apertum are either perfect (hermaphroditic) or staminate (male) and, in any given season, plants exhibit one of three sex phenotypes: only hermaphrodite flowers, a mixture of hermaphroditic and male flowers, or only male flowers. Transitions between each of these sex phenotypes were observed over consecutive years and were commonly size-dependent, particularly transitions from small plants bearing only male flowers to those that were taller with hermaphroditic flowers. Hermaphroditic flowers were significantly larger, heavier and produced more pollen than male flowers., Conclusions: The results for L. apertum are consistent with the 'size advantage hypothesis' developed for animal species with sex change. The theory predicts that when individuals are small they should exhibit the sex for which the costs of reproduction are less, and this usually involves the male phase. L. apertum provides an example of gender diphasy, a rare sexual system in flowering plants., (© The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Nematodes have many different reproductive strategies along with their divergent life histories; the ability of hermaphrodite to self- and cross-fertilize is useful for genetic manipulation. Here, we demonstrate the hermaphroditism of the fungal feeding nematode Bursaphelenchus okinawaensis, which was formerly described as a parthenogenetic nematode, and we show its other unique sexual characteristics. To determine that it is hermaphroditic, we performed the following experiments: observation of the pronuclear and chromosome behavior during oogenesis and early embryogenesis; observation of spermatogenesis during the fourth larval stage; investigation of sperm utilization; and investigation of phenotypic segregation after cross-mating using a chemically induced visible mutant. We then investigated the mating preferences and spermatid size difference between males and hermaphrodites. B. okinawaensis males successfully mated only with sperm-depleted old hermaphrodites, and the spermatid sizes of males were almost the same as those of hermaphrodites. Moreover, the sex ratio of cross-fertilized progeny was highly skewed toward hermaphrodites. B. okinawaensis is phylogenetically distant from established model nematodes such as C. elegans and is more closely related to some economically relevant parasitic nematodes. This newly discovered hermaphroditic nematode has great potential for evolutionary and parasitological research., (Copyright © 2014 Shinya et al.)

All undifferentiated gonads of anemonefish first differentiate into ovaries, and then testicular tissue appear among ovarian tissue, and finally form ambisexual gonads with both ovarian and testicular tissues. The role of estradiol-17beta (E2) in differentiation of ovarian cells is well conserved across phyla; however, its role in development of ambisexual gonads is poorly understood. Here we demonstrate that the E2 produced during the differentiation of ovarian cells does not allow testicular cells to differentiate in the prospective ambisexual gonad. We examined the immunolocalization of the steroidogenic enzyme cytochrome aromatase (P450(arom)), which is involved in E2 production. In the gonads, numbers of the P450(arom) -positive cells increased during ovarian differentiation. However, immunopositive cells with weak signal intensity were seen in the interstitial areas among oocytes and between oocytes and testicular tissue undergoing testicular differentiation. In contrast, P450(arom) -positive cells were not found in any testicular tissues of the ambisexual gonads. We also examined changes in E2 production in vitro in the gonads during testicular differentiation. E2 was high in the ovaries before the appearance all of testicular tissue, and decreased accompanying the differentiation of testicular tissue. These results suggest a balance of estrogen/androgen seems to be important during sex differentiation, and then a shift from estrogen to androgen production may induce testicular differentiation in the ovary. Further, exogenous E2 treatment suppressed naturally occurring differentiation of testicular cells forming exclusively ovarian tissues in the gonad in vivo, suggesting the increase of estrogen blocks the differentiation of testicular tissue and the formation of ambisexual gonad., (© 2013 Wiley Periodicals, Inc.)

To elucidate the action mechanism of environmental androgenic chemicals on fish reproductive activity by transient stimulation in heavily polluted areas, individuals of the hermaphrodite fish Kryptolebias marmoratus were injected once with six concentrations of methyltestosterone (MT) (0.1, 1, 5, 10, 50, and 100 μg/g BW) intraperitoneally. The fish were sampled at intervals of 7, 15, and 30 days after a single injection. At 7 days after injection, mature oocytes were not observed in the MT-exposed groups except for the group exposed to 0.1 μg MT, while testicular development was not remarkably different between any of the groups. Also, at 7 days after injection, hepatic estrogen receptor α (ERα) and vitellogenin (VTG) mRNA abundance decreased significantly in the MT-exposed groups despite no significant difference in plasma 17β-estradiol (E2) levels between any of the groups. This significant difference in VTG mRNA between the control and the MT-exposed groups persisted until 30 days after injection, although ERα mRNA abundance was not statistically different between any groups at 30 days after injection. Our results clearly show that a single injection of MT inhibits ovarian development rather than testicular development in the hermaphroditic gonad of K. marmoratus. Furthermore, our results demonstrate that a single injection of MT interfered with hepatic VTG mRNA synthesis mediated by the suppression of hepatic ERα mRNA transcription.

Many zoophilous plants attract their pollinators by offering nectar as a reward. In gynodioecious plants (i.e. populations are composed of female and hermaphrodite individuals) nectar production has been repeatedly reported to be larger in hermaphrodite compared to female flowers even though nectar production across the different floral phases in dichogamous plants (i.e. plants with time separation of pollen dispersal and stigma receptivity) has rarely been examined. In this study, sugar production in nectar standing crop and secretion rate were investigated in Geranium sylvaticum, a gynodioecious plant species with protandry (i.e. with hermaphrodite flowers releasing their pollen before the stigma is receptive). We found that flowers from hermaphrodites produced more nectar than female flowers in terms of total nectar sugar content. In addition, differences in nectar production among floral phases were found in hermaphrodite flowers but not in female flowers. In hermaphrodite flowers, maximum sugar content coincided with pollen presentation and declined slightly towards the female phase, indicating nectar reabsorption, whereas in female flowers sugar content did not differ between the floral phases. These differences in floral reward are discussed in relation to visitation patterns by pollinators and seed production in this species.

Sex change is known from various fish species. In many polygynous species, the largest female usually changes sex to male when the dominant male disappeared, as predicted by the classical size-advantage model. However, in some fishes, the disappearance of male often induces sex change by a smaller female, instead of the largest one. The halfmoon triggerfish Sufflamen chrysopterum is one of such species. We conducted both field investigation and theoretical analysis to test the hypothesis that variation in female fecundity causes the sex change by less-fertile females, even if they are not the largest. We estimated the effect of body length and residual body width (an indicator of nutrition status) on clutch size based on field data. Sex-specific growth rates were also estimated from our investigation and a previous study. We incorporated these estimated value into an evolutionarily stable strategy model for status-dependent size at sex change. As a result, we predict that rich females change sex at a larger size than poor ones, since a rich fish can achieve high reproductive success as a female. In some situations, richer females no longer change sex (i.e. lifelong females), and poorer fish changes sex just after maturation (i.e. primary males). We also analyzed the effect of size-specific growth and mortality., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Kryptolebias marmoratus is a synchronous hermaphroditic vertebrate that utilizes an ovotestis for reproduction. This fish develops externally, is easy to maintain, and has about a 100-day life cycle, making it a desirable developmental genetic model organism. Here, we present a pilot zygotic mutant screen utilizing the common chemical mutagen, N-ethyl-N-nitrosourea (ENU) to establish genetics in this model species. Selection of clonal stocks and optimal conditions for mutagenizing this fish are presented and the types and frequencies of zygotic mutants are documented in comparison to other fish models. Kryptolebias marmoratus is an exemplar model organism that will complement future developmental genetic screens in vertebrates.

The mangrove rivulus (Kryptolebias marmoratus) is a small fish native to mangrove ecosystems in Florida, the Caribbean, Central America, and South America. This species is one of only two self-fertilizing, hermaphroditic vertebrates capable of producing offspring that are genetically identical to both the parent and all siblings. Long bouts of selfing result in individuals with completely homozygous genotypes, effectively allowing for the production of "clones." Rivulus is also extremely sensitive to environmental change, both during development and adulthood. Life-history traits, behavior, physiology, morphology, and even sexual phenotype are shaped to a large extent by the interaction of genes with the environment, and many of these traits appear to co-vary. True reaction norms can be generated for this species in much the same way as has been done for clonally reproducing invertebrates and plants that have contributed immensely to our understanding of the evolution of phenotypic plasticity. That is, rivulus provides the opportunity to place individuals with identical genotypes in many different environments at any point during ontogeny or adulthood. In addition, rivulus populations are characterized by high genotypic diversity, a luxury not afforded by many clonal vertebrates, which allows us to evaluate variation among genotypes in the shape of reaction norms and in patterns of covariance among traits. We provide background information on phenotypic plasticity and phenotypic integration, coupled with a description of characteristics that we feel qualify rivulus as a potentially powerful model in which to study the evolution of reaction norms and covariance among traits.

Although first described in 1880, Kryptolebias marmoratus avoided scientific scrutiny until 1961, when it was identified as the only known selfing hermaphroditic vertebrate. The subsequent intense interest in this fish as a laboratory animal, continuing to this day, might explain the paucity of wild collections, but our collective knowledge now suggests that the inherent difficulty of wild collection is more a matter of "looking in all the wrong places." Long thought to be rare in the mangroves, and it is rare in certain human-impacted habitats, K. marmoratus can be quite abundant, but in microhabitats not typically targeted by ichthyologists: ephemeral pools at higher elevations in the swamp, crab burrows, and other fossorial or even terrestrial haunts. Field studies of this enigmatic fish have revealed almost amphibious behaviors. During emersion these fish tolerate extended dry periods. In water, they are exposed to temperature extremes, high levels of hydrogen sulfide, and depleted dissolved oxygen. Finally, their catholic diet and a geographically variable sex life completes a portrait of an unusual animal. A clearer picture is emerging of adult life, with initial population density estimates now known and some indication of high population turnover in burrows, but juvenile habitat and adult oviposition sites remain unknown.

Interest in the occurrence and fate of trace organic contaminants in the aquatic environment and their potential effects on all organisms has increased over the past two decades. Researches on contaminants have included both natural and synthetic estrogenic contaminants, neuroactive pharmaceuticals, and other endocrine disrupting chemicals that are mediated by the androgen and progesterone receptors. Exposure to very low concentrations (ng/L or parts per trillion) of compounds such as 17α-ethynylestradiol (EE(2)), a synthetic estrogen, can affect gonadal development, viability and production of eggs, fertilization rate, and sexual differentiation in fishes. Researchers and aquaculturists have used exposures to relatively higher concentrations of androgens and estrogens, for example 17α-methyltestosterone and EE(2), respectively, to direct sexual differentiation in a number of fishes. Rivulus is an androdioecious teleost that in nature exists mostly as selfing, simultaneous hermaphrodites as well as a small number of males that outcross with hermaphrodites. No one has either collected females in the wild or created functional females in the laboratory. This study had two goals: (1) to develop a reliable protocol to produce female rivulus to enable downstream technologies such as embryo injections and (2) to investigate developmental effects of EE(2) on the sexual outcome, reproductive health, and relevant gene expression in rivulus. With these goals in mind, we exposed newly hatched rivulus to nominal concentrations of 0.1, 0.5, or 1.0 parts per million (ppm) EE(2) for 4 weeks, grew them to maturity in control water, and then compared egg production; production and viability of embryos; age of reproductive maturity; and gene expression in the brain, gonad, and liver. Expression levels of seven genes with known relevance to gonadal development and function (cyp19a1b, cyp19a1a, dmrt1, figα, ERα, ERβ, and vtg) were measured using quantitative polymerase chain reaction (PCR). There was a significant decrease in cyp19a1a gene expression in the brain, corresponding to increased exposure to EE(2). Gonadal gene expression for cyp19a1a, ERα, and dmrt1 also decreased in response to EE(2). Vtg expression in the liver was unaffected. Our hypothesis that exposure to EE(2) during gonadal differentiation would direct female development was not supported by the data. However, treated fish exhibited impaired reproductive health that included reduced expression of relevant genes and, importantly, decreased fertility, increased sterility, and delay of age of reproductive maturity. The results of this study suggest that the development and maintenance of a simultaneous hermphrodite ovotestis may be particularly sensitive to its hormonal milieu.

Melampus coffeus belongs to a primitive group of pulmonate mollusks found mainly in the upper levels of the marine intertidal zone. They are common in the neotropical mangroves. Little is known about the biology of this species, particularly about its reproduction. The aim of this study was to 1) characterize the morphology and histology of M. coffeus' gonad; 2) describe the main gametogenesis events and link them to a range of maturity stages; 3) chronologically evaluate the frequency of the different maturity stages and their relation to environmental factors such as water, air and sediment temperatures, relative humidity, salinity and rainfall; and 4) characterize M. coffeus' spawning, eggs and newly hatched veliger larvae. Samples were collected monthly between February, 2007 and January, 2009 from the mangroves of Praia de Arpoeiras, Acaraú County, State of Ceará, northeastern Brazil. The characterization of the gonad development stages was carried out using routine histological techniques. The results of this study show that Melampus coffeus is a simultaneous hermaphrodite. The follicles have masculine and feminine elements, interleaved within the gonad. M. coffeus presents a well-defined synchronous reproductive cycle, showing successive maturation, release and resting periods. The average diameter of the oocytes was negatively correlated with salinity and positively correlated with rainfall. The results show that no reproductive activity occurs during periods of drought. After the dry season, the increasing rainfall levels and reduced salinity lead to the appearance of very dense populations, predominantly composed of small individuals.

Cell migration and morphogenesis are key events in tissue development and organogenesis. In Caenorhabditis elegans, the migratory path of the distal tip cells determines the morphology of the hermaphroditic gonad. The distal tip cells undergo a series of migratory phases interspersed with turns to form the gonad. A wide variety of genes have been identified as crucial to this process, from genes that encode components and modifiers of the extracellular matrix to signaling proteins and transcriptional regulators. The connections between extracellular and transmembrane protein functions and intracellular pathways are essential for distal tip cell migration, and the integration of this information governs gonad morphogenesis and determines gonad size and shape.

In Opuntia stenopetala, flowers initiate as hermaphrodite; however, at maturity, only the stamens in male flowers and the gynoecium in female flowers become functional. At early developmental stages, growth and morphogenesis of the gynoecium in male flowers cease, forming a short style lacking stigmatic tissue at maturity. Here, an analysis of the masculinization process of this species and its relationship with auxin metabolism during gynoecium morphogenesis is presented. Histological analysis and scanning electron microscopy were performed; auxin levels were immunoanalyzed and exogenous auxin was applied to developing gynoecia. Male flower style-tissue patterning revealed morphological defects in the vascular bundles, stylar canal, and transmitting tissue. These features are similar to those observed in Arabidopsis thaliana mutant plants affected in auxin transport, metabolism, or signaling. Notably, when comparing auxin levels between male and female gynoecia from O. stenopetala at an early developmental stage, we found that they were particularly low in the male gynoecium. Consequently, exogenous auxin application on male gynoecia partially restored the defects of gynoecium development. We therefore hypothesize that, the arrest in male flower gynoecia patterning could be related to altered auxin homeostasis; alternatively, the addition of auxin could compensate for the lack of another unknown factor affecting male flower gynoecium development.

Sex allocation theory for simultaneous hermaphrodites predicts increases in relative allocation to male-specific function as competition for fertilizations increases. Theoretical models developed specifically for competing acorn barnacles predict that the proportional allocation to male function increases toward an asymptote of 50% as the number of competitors for fertilizations increases. Experimental manipulations were used to investigate how mate competition affected both relative and absolute allocation to the sex functions for two species of acorn barnacle: Semibalanus balanoides and Balanus glandula. The ratio of male to female allocation did not increase with the number of competitors for either species. However, both species showed increased allocation to male function (estimated as total mass of sex-specific tissues) with increased crowding. Allocation to female function seemed to be limited by other factors and did not vary with mating group size as predicted. Allocation to male and female function were both positively related to body size, but a trade-off between male and female function, a key assumption of prior models, was not observed., (© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.)

Salinity is an important parameter that affects survival and metabolism in fish. In fish, pituitary growth hormone (GH) regulates physiological functions including adaptation to different salinity as well as somatic growth. GH is stimulated by growth hormone-releasing hormone (GHRH) and exerts its function via binding to growth hormone receptor (GHR). As Kryptolebias marmoratus is a euryhaline fish, this species would be a useful model species for studying the adaptation to osmotic stress conditions. Here, we cloned GH, -GHR, somatolactin (SL), and somatolactin receptor (SLR) genes, and analyzed their expression patterns in different tissues and during early developmental stages by using real-time RT-PCR. We also further examined expression of them after acclimation to different salinity. Tissue distribution studies revealed that Km-GH and -SL mRNAs were remarkably expressed in brain and pituitary, whereas Km-GHR and -SLR mRNAs were predominantly expressed in liver, followed by gonad, muscle, pituitary, and brain. During embryonic developmental stages, the expression of their mRNA was increased at stage 3 (9 dpf). The Km-GH and -SL mRNA transcripts were constantly elevated until stage 5 (5h post hatch), whereas Km-GHR and -SLR mRNA levels decreased at this stage. After we transferred K. marmoratus from control (12 psu) to hyper-osmotic condition (hyperseawater, HSW; 33 psu), Km-GH, -SL, and GHR mRNA levels were enhanced. In hypo-osmotic conditions like freshwater (FW), Km-GH and -SL expressions were modulated 24 h after exposure, and Km-SLR transcripts were significantly upregulated. This finding suggests that Km-GH and -SL may be involved in the osmoregulatory mechanism under hyper-osmotic as well as hypo-osmotic stress. This is the first report on transcriptional modulation and relationship of GH, GHR, SL, and SLR during early development and after salinity stress. This study will be helpful to a better understanding on molecular mechanisms of adaptation response to salt stress in euryhaline fish., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background and Aims: How and why plants evolve to become selfing is a long-standing evolutionary puzzle. The transition from outcrossing to highly selfing is less well understood in self-compatible (SC) mixed-mating (MM) species where potentially subtle interactions between floral phenotypes and the environment are at play. We examined floral morphological and developmental traits across an entire SC MM genus, Collinsia, to determine which, if any, predict potential autonomous selfing ability when pollinators are absent (AS) and actual selfing rates in the wild, s(m), and to best define the selfing syndrome for this clade., Methods: Using polymorphic microsatellite markers, we obtained 30 population-level estimates of s(m) across 19 Collinsia taxa. Species grand means for the timing of herkogamy (stigma-anther contact) and dichogamy (stigmatic receptivity, SR), AS, floral size, longevity and their genetic correlations were quantified for 22 taxa., Key Results: Species fell into discrete selfing and outcrossing groups based on floral traits. Loss of dichogamy defines Collinsia's selfing syndrome. Floral size, longevity and herkogamy also differ significantly between these groups. Most taxa have high AS rates (>80 %), but AS is uncorrelated with any measured trait. In contrast, s(m) is significantly correlated only with SR. High variance in s(m) was observed in the two groups., Conclusions: Collinsia species exhibit clear morphological and developmental traits diagnostic of 'selfing' or 'outcrossing' groups. However, many species in both the 'selfing' and the 'outcrossing' groups were MM, pointing to the critical influence of the pollination environment, the timing of AS and outcross pollen prepotency on s(m). Flower size is a poor predictor of Collinsia species' field selfing rates and this result may apply to many SC species. Assessment of the variation in the pollination environment, which can increase selfing rates in more 'outcrossing' species but can also decrease selfing rates in more 'selfing' species, is critical to understanding mating system evolution of SC MM taxa.

Background and Aims: Within Chenopodioideae, Atripliceae have been distinguished by two bracteoles enveloping the female flowers/fruits, whereas in other tribes flowers are described as ebracteolate with persistent perianth. Molecular phylogenetic hypotheses suggest 'bracteoles' to be homoplastic. The origin of the bracteoles was explained by successive inflorescence reductions. Flower reduction was used to explain sex determination. Therefore, floral ontogeny was studied to evaluate the nature of the bracteoles and sex determination in Atripliceae., Methods: Inflorescences of species of Atriplex, Chenopodium, Dysphania and Spinacia oleracea were investigated using light microscopy and scanning electron microscopy., Key Results: The main axis of the inflorescence is indeterminate with elementary dichasia as lateral units. Flowers develop centripetally, with first the formation of a perianth primordium either from a ring primordium or from five individual tepal primordia fusing post-genitally. Subsequently, five stamen primordia originate, followed by the formation of an annular ovary primordium surrounding a central single ovule. Flowers are either initially hermaphroditic remaining bisexual and/or becoming functionally unisexual at later stages, or initially unisexual. In the studied species of Atriplex, female flowers are strictly female, except in A. hortensis. In Spinacia, female and male flowers are unisexual at all developmental stages. Female flowers of Atriplex and Spinacia are protected by two accrescent fused tepal lobes, whereas the other perianth members are absent., Conclusions: In Atriplex and Spinacia modified structures around female flowers are not bracteoles, but two opposite accrescent tepal lobes, parts of a perianth persistent on the fruit. Flowers can achieve sexuality through many different combinations; they are initially hermaphroditic, subsequently developing into bisexual or functionally unisexual flowers, with the exception of Spinacia and strictly female flowers in Atriplex, which are unisexual from the earliest developmental stages. There may be a relationship between the formation of an annular perianth primordium and flexibility in floral sex determination.

The mechanisms by which new modes of reproduction evolve remain important unsolved puzzles in evolutionary biology. Nematode worms are ideal for studying the evolution of mating systems because the phylum includes both a large range of reproductive modes and large numbers of evolutionarily independent switches [1, 2]. Rhabditis sp. SB347, a nematode with sexual polymorphism, produces males, females, and hermaphrodites [3]. To understand how the transition between mating systems occurs, we characterized the mechanisms that regulate female versus hermaphrodite fate in Rhabditis sp. SB347. Hermaphrodites develop through an obligatory nonfeeding juvenile stage, the dauer larva. Here we show that by suppressing dauer formation, Rhabditis sp. SB347 develops into females. Conversely, larvae that under optimal growth conditions develop into females can be respecified toward hermaphroditic development if submitted to dauer-inducing conditions. These results are of significance to understanding the evolution of complex mating systems present in parasitic nematodes., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Sexual reproduction may be divided into two main categories: hermaphroditism and dioecy (Botany)/gonochorism (Zoology). Simultaneous hermaphrodites can function in both male and female roles whereas a dioecious/gonochorist population consists of distinct male and female individuals. Mean-field calculations, which ignore spatial aspects, suggest that self-incompatible hermaphrodites should have a twofold advantage over dioecious population when reproduction is limited by mating encounters. By use of stochastic spatial simulations we demonstrate that hermaphroditism has an even greater advantage when local interactions are considered. This result provides further support for the observation that hermaphroditism is associated with sedentary species, such as plants and animals with poor mate search efficiency. We also investigate the finite size effects associated with the well-known quadratic contact process.