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External parental care is uncommon among actiniarians but common in Epiactis species. Here, several aspects of reproduction are analyzed for of one of them, Epiactis georgiana. Samples were collected in December, January, February, March, and April in the Antarctic Peninsula and the eastern Weddell Sea, during 1998, 2000, 2002, and 2003. Most sexually mature individuals of E. georgiana are male or female, but some are hermaphrodites. This is the first report of hermaphroditism in E. georgiana, which is the third species of the genus with this sexual pattern. The results suggest that oogenesis starts in December and that at least two generations of oocytes overlap; a third generation is often brooded externally. Putative fertilization is likely internal, and larvae and/or embryos are externally brooded on the distal part of the adult column until an advanced developmental stage. Apparently E. georgiana reproduces seasonally, probably releasing the embryos/larvae in the last months of the austral spring (December). Inter-individual variability was observed in gametogenesis. In addition, specimens from the Antarctic Peninsula were larger than those from the Weddell Sea. This study represents the first step in understanding the reproductive mode of E. georgiana., Introduction The diversity and number of clades of marine benthic invertebrates employing parental care in the Southern Ocean is unusually high, leading to a wide array of hypotheses to explain [...]

Protandrous hermaphrodites are predicted to change sex from male to female when relative reproductive fitness of females surpasses that of males. How size at sex transition varies with population, mating group and individual parameters was investigated for five populations of the protandrous hermaphrodite slipper snail, Crepidula fornicata. The populations varied for density, size distribution, average mating group size and sex ratio. Size at sex-change was correlated with the population sex ratio. Comparisons of multiple hypotheses revealed that variables predicting the sex of a snail vary among positions in the mating group. The variables included body size, the relative size of the snail sitting atop the focal snail and population density. Our data support the conclusions that size at sex-change (and by inference, the size at which one sex has relatively greater fitness) is not fixed for these hermaphrodites and that individual size, social conditions and population differences all influence variation in relative fitness., Introduction Sequential hermaphroditism is a reproductive strategy whereby organisms change sex at some point in their lifetime. The size-advantage hypothesis for sequential hermaphroditism posits the existence of a threshold size [...]

One of the main goals of sex allocation theory is understanding sex ratio evolution. However, theoretical studies predicting sex ratios in species with unusual sexual systems, such as protandric simultaneous (PS) hermaphroditism, are rare. In PS hermaphrodites, juveniles first develop into functional males that mature into simultaneous hermaphrodites later in life. Here, we report on the sex ratio (males/males + hermaphrodites) in the PS hermaphroditic shrimp Exhippolysmata oplophoroides. A 2-year study demonstrated that hermaphrodites dominated the population in two different bays. This skewed sex ratio may be explained by limited encounter rates among conspecifics. In agreement with this idea, the density of shrimps was extremely low ([less than or equal to]1 shrimp km.sup.-2) at the two study sites. Size at sex phase change and sex ratios remained relatively stable through time at the two bays. The stability of these parameters might be explained by the rather steady population structure of this species during the study period. A review of sex ratios in PS hermaphroditic shrimps (Lysmata and Exhippolysmata) revealed considerable variation; some species have male- and others hermaphrodite-skewed sex ratios. The conditions explaining inter- and intra-specific sex ratio variation in protandric simultaneous hermaphroditic species remain to be addressed., Author(s): J. A. Baeza [sup.1] [sup.2] [sup.3] , A. A. Braga [sup.4] , L. S. López-Greco [sup.5] , E. Perez [sup.3] [sup.6] , M. L. Negreiros-Fransozo [sup.7] , A. Fransozo [...]

The protandric simultaneous hermaphrodite shrimp Lysmata wurdemanni (Gibbes 1850) has a pure searching mating system, i.e., males are continually searching for receptive females and copulation is brief. To examine whether size-based advantage in male--male competition occurs and whether the mating ability of male-phase (M) shrimp equals that of euhermaphrodite-phase shrimp serving as males (Em), mating performance, including mating frequency and precopulatory behavior, of M and Em shrimp was compared using two M:Em ratios. Two experiments were carried out from March 2004 to August 2004 at Florida Institute of Technology's Vero Beach Marine Laboratory using laboratory-cultured shrimp that originated from Port Aransas, TX, USA. In the two experiments, one parturial euhermaphrodite-phase shrimp acting as a female (Ef) was maintained with one M and two Em shrimp (one with and one without an egg mass), and two M and two Em shrimp, respectively. The M shrimp used were always smaller than the Em shrimp. Experiment 1 showed that there was no significant difference in mating ability between Em with and without egg mass. In both experiments, the M shrimp gained mating partners more frequently than the Em shrimp did. In the experiment with two M and two Em shrimp, mating frequencies of the small M and large M shrimp were similar. Precopulatory behaviors of the M shrimp were more active than those of the Em shrimp. Mating between the small M and larger Ef shrimp was sometimes successful even when the size difference was 20.0 mm total length (TL). Mating between a larger M shrimp and smaller Ef shrimp sometimes failed when the size difference was only 13.0 mm TL. Mating frequency of M shrimp over that of Em shrimp with Ef shrimp increased significantly with increasing density and operational sex ratio. The advantage of M over Em shrimp in obtaining mating partners is probably a result of sexual selection and adaptation, and may partially explain the observed delayed sex change in some L. wurdemanni, i.e., some male-phase shrimp grow very large and never become hermaphrodites.

Recent reports have demonstrated a cost associated with intersexuality in Amphipoda, including reduced fecundity and fertility. In this study, the gross morphology of the gonads in normal and intersex Echinogammarus marinus (Amphipoda) were compared to determine whether resource allocation to gonadal tissue accounted for this reduced fitness. Evidence for the presence of the male sex-determining hormone, androgenic gland hormone (AGH), was compared between sexual phenotypes using MALDI mass spectrometry. Two distinct intersex phenotypes ('male' intersex and 'female' intersex) were found, with variation in gonadal structure corresponding with external phenotype. Examination of male intersexes revealed normal testicular development (testes, seminal vesicles and vas deferens), but also revealed the formation of an oviduct. Ovaries of intersex females showed normal ovarian development, but were reduced in length by approximately 20% due to the presence of vas deferens. The number of vas deferens in intersex females was equal to the number (one or two) of genital papillae. We hypothesise that the reduced ovarian length observed in intersex females is a likely cause of the reduced brood size previously reported in intersex females of this species. Variation in the sexual phenotype corresponded both to development of the androgenic gland and to expression of a peptide fragment corresponding to the A chain of androgenic gland hormone (AGH). Androgenic glands and a putative AGH peptide were present in males. However, in both normal and intersex females, the androgenic glands were only present in a rudiment form and the peptide was not detected. Intersex males were found to possess abnormal glands that appeared hypertrophied. However, AGH peptides were not detected, supporting the suggestion that the intersex phenotype is manifested via perturbations of AGH., Introduction Intersexuality is widespread throughout the Amphipoda, having been reported in many families (Sexton and Huxley 1921; Sexton 1924; Ginsberger-Vogel 1975; Hastings 1981; Ford et al. 2003). Recent reports demonstrate [...]

The reproductive biology of the Mediterranean vermetid gastropod Serpulorbis arenarius, a subtidal sessile solitary species that lives in shady rocky communities, was studied at two localities south-east of the Iberian Peninsula. Its population density is usually low, with specimens sometimes sparsely distributed. Its shell often appears to be covered by epibiotic organisms. The sex ratio is biased toward males (63%) in the populations of SE Spain, and the results point towards hermaphroditism with alternating sexuality. The results obtained suggest that all specimens are first males, change to females under some as yet unknown condition and, after the ovogenesis cycle has been completed, revert to the original sexual state (male). The possible adaptive forces that favour hermaphroditism in this species are discussed, and we hypothesise that the seizure of a spermatophore by males may stimulate sex change to female. Brooding females (51% of females studied) were found from March to December. In males, histological study of testes revealed that spermatogenesis seems to occur throughout the year. Females brooded between 5 and 28 ([bar.x]= 15) egg capsules, which were attached by stalks to the inner surface of the shell. It is noteworthy that the gonads of two of the specimens brooding egg capsules were developing testes. The newly laid egg capsules were filled with an organic intracapsular matrix, in which 40-153 (2=94) eggs were embedded. The mean diameter of the uncleaved ova was 352.5 [micro]m. The organic intracapsular matrix and some nurse eggs were used as an extra-embryonic food source. Hatching occurred at an advanced veliger stage, immediately followed by metamorphosis. Therefore, the larval development of S. arenarius is of a lecithotrophic intracapsular type, with a short, free-swimming/crawling phase.

Increasing concerns over rising intersexuality in the animal kingdom and the ability of certain chemicals to disrupt the endocrine system have demanded a better understanding of the costs associated with such conditions. Whilst intersexuality appears relatively wide-spread throughout gonochoristic crustaceans, i.e. those crustacean species with two separate sexes, the 'fitness' costs have rarely been reported. Through comparable investigation of normal and intersex specimens of the highly abundant marine/estuarine amphipod Echinogammarus marinus (Leach) these 'fitness costs' were determined. Measurements taken to assess fitness costs included fecundity, fertility and embryonic development, maturation period, and any morphological deformities that might result in reduced pairing success. Results from this study suggest that intersex E.marinus suffer from reduced fecundity and fertility, and mature at a larger size than normal specimens. These fitness costs can also, to a certain extent, be related to the degree of intersexuality. It is suggested that the increased size and morphological abnormalities observed in intersexes may result in reduced pairing success. Investigations into intersex organisms, i.e. those organisms with known dysfunctional endocrine systems, and the costs associated with such conditions, should aid researchers in assessing effects at the population and community level.

Byline: R. Wiersma (1) Keywords: Abnormal genitalia; Infertility; True hermaphroditism Abstract: This is an 18-year (1985--2001) retrospective review of 85 patients with true hermaphroditism, with the aim of facilitating early recognition of this condition. Presentation of neonates and infants 6 months or younger, constituting 54% of this cohort, were different from the older children. The presentation, clinical features and investigative results of all patients diagnosed with true hermaphroditism at a single South African paediatric surgical unit were reviewed. This paper highlights the previously reported high incidence (51%) of this condition, as well as some of the unusual features of true hermaphroditism in this region. Diagnosis of true hermaphroditism requires a high index of suspicion for subtle anomalies of the genitalia. Although there were no pathognomonic clinical features, the true hermaphrodite presents as a patient of either gender with a congenital anomaly of the genitalia. The child is likely to have a normal male phallus, bifid labio-scrotal folds, a perineal hypospadias and in 53% of patients there was a palpable gonad. The method of investigation, together with the results and some of the management dilemmas associated with true hermaphroditism in a Third World population are presented. Author Affiliation: (1) Department of Paediatric Surgery, University of Natal, Private Bag 7, 4013 , Congella Durban, South Africa Article History: Registration Date: 30/03/2004 Accepted Date: 16/02/2004 Online Date: 26/05/2004

Byline: Josiane Courteau (1), Sabin Lessard (2) Keywords: Optimal sex ratio; Diffusion approximation; Stationary distribution; Group competition Abstract: We consider a haploid, hermaphrodite population subdivided into an infinite number of demes of finite size N. Assuming recurrent mutation, random union of gametes, partial dispersal, genetic drift, and incorporating group competition, a diffusion approximation is used to describe the evolution of sex ratio, corresponding to sex allocation to male versus female functions. The stationary distribution is deduced. In presence of group selection, a female-biased sex ratio in the whole population is found to be optimal in the sense that an allele coding for this sex ratio is always more frequent at equilibrium when segregating with another allele coding for a different sex ratio than for the same sex ratio. Numerical studies are presented to check the validity and accuracy of this prediction. Author Affiliation: (1) Centre de recherche clinique, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4 (2) Departement de mathematiques et de statistique, Universite de Montreal, Montreal, Quebec, Canada H3C 3J7 Article History: Registration Date: 01/01/2003 Received Date: 19/03/2003 Online Date: 27/10/2003 Article note: Research supported in part by grants from NSERC of Canada and FCAR of Quebec. This work is part of the first author's Ph.D. thesis at the Universite de Montreal under the supervision of the second author. Send offprint requests to: Sabin Lessard

Byline: J.A. Vargas (1), R.F. del Castillo (2) Keywords: aAndrodioecy; Gynodioecy; Fitness; Pollen discounting; Rational map; Projective plane Abstract: We formulate two single-locus Mendelian models, one for androdioecy and the other one for gynodioecy, each with 3 parameters: t the male (female) fertility rate of males (females) to hermaphrodites, s the fraction of the progeny derived from selfing and g the fitness of inbreeders. Each model is expressed as a transformation of a 3 dimensional zygotic algebra, which we interpret as a rational map of the projective plane. We then study the dynamics for the evolution of each reproductive system and compare our results with similar published models. In this process, we introduce a general concept of fitness and list some of its properties, obtaining a relative measure of population growth, computable as an eigenvalue of a mixed mating transformation for a population in equilibrium. Our results concur with previous models of the evolution of androdioecy and gynodioecy regarding the threshold values above which the sexual polymophism is stable, although the previous models assume constant the fraction of ovules from hermaphrodites that are self pollinated, while we assume constant the fraction of the progeny derived from selfing. A stable androdioecy requires more stringent conditions than a stable gynodioecy if the amount of pollen used for selfing is negligible in comparison with the total amount of pollen produced by hermaphrodites. Otherwise, both models are identical. We show explicitly that the genotype fitnesses depend linearly on their frequencies. Simulations show that any population not at equilibrium always converges to the equilibrium point of higher fitness. However, at intermediate steps, the fitness function occasionally decreases. Author Affiliation: (1) Independent scholar, Constitucion 204, (centro), Oaxaca, Oaxaca, Mexico, 68000 (2) CIIDIR IPN Oaxaca, Calle Hornos 1003, Xoxocotlan, Oaxaca, Mexico, 71230 Article History: Received Date: 07/05/1999 Online Date: 23/04/2003

Gonad morphology and colony composition support the existing supposition that the obligate coral-dwelling damselfish Dascyllus aruanus has a protogynous hermaphroditic sexual pattern. Adults had either an active ovary containing vitellogenic oocytes, an ovotestis, or a spermiated testis and were classified as adult female, hermaphrodite, or adult male, respectively. Among individuals having male function, the testis (or testis portion of the ovotestis) takes the form of an unrestricted spermatogonial lobular testis. Among hermaphrodites having an ovotestis, a small proportion of individuals had a gonad in which both the ovarian and testicular portions were inactive (inactive hermaphrodites), whereas the majority had a predominantly testicular ovotestis that contained spermatozoa (male-active hermaphrodites). The size range of individuals within gonadal classes indicates that all D. aruanus first develop an ovariform gonad. Some individuals then undergo ovarian maturation to become adult females while others develop testicular tissue to form an ovotestis and become male-active hermaphrodites. Subsequently, progressive loss of ovarian tissue results in the development of a secondary testis from an ovotestis with the retention of a residual, afunctional lumen among adult males. The wide size range of individuals having an ovotestis suggests that some hermaphrodites function as adult females before developing testicular tissue while other individuals do not pass through an adult female stage. If this is the case, D. aruanus exhibits a diandric protogynous hermaphroditic sexual pattern. The apparent prolonged retention of an ovotestis with both healthy oocytes and an ovarian-type lumen in a spermiated ovotestis, as well as a functional sex ratio of 1:1 for adult females:adult males plus male-active hermaphrodites also raises the possibility that D. aruanus may be capable of bidirectional sex change during the hermaphroditic stage. Such a capability would be highly adaptive for a species having limited mobility and unpredictable recruitment of new colony members resulting in unpredictable mating opportunities.

The caridean shrimp Lysmata wurdemanni (Gibbes) displays protandric simultaneous hermaphroditism with out-crossing, but not all males become simultaneous hermaphrodites (euhermaphrodites). In this laboratory study, we attempted to determine why some shrimp remain males. In our experiment, we grew L. wurdemanni from postlarvae to adults in several group sizes and observed their reproductive function. We found that all shrimp reared in isolation become euhermaphrodites. When cultured in a group, the proportion of shrimp remaining male decreased with increasing group size. Except for those that mated within a day, inter-molt euhermaphrodite-phase shrimp (with or without embryos) and inter-molt male-phase shrimp fertilized eggs successfully. On the other hand, euhermaphrodite shrimp can only mate as females and have their eggs fertilized during a narrow post-molt window (less than 12 h) in each molt cycle (10 days). The fertilization rate of male-euhermaphrodite pairs was similar to that of euhermaphrodite-euhermaphrodite pairs. There are at least two non-exclusive explanations for the persistence of male shrimp in a group. In certain group compositions, an individual may gain more reproductive fitness as a large male with multiple mating partners than as a small female with low clutch size. Alternatively, the presence of male-phase individuals, with variable molt-cycle duration (5-8 days), may be necessary to ensure mating. This study is the first direct experimental demonstration of social control of sex change in the decapod crustaceans.

Byline: Satoki Sakai (1) Keywords: Keywords: Evolutionarily stable strategy, Female-biased sex allocation, Hermaphroditic plants, Male-biased sex allocation, Sink-limited growth, Source-limited growth Abstract: Author Affiliation: (1) Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Aoba, Sendai, 980--8578 Japan, JP Article note: Received 8 June 2000/ Accepted in revised form 7 July 2000

Imposex or pseudohermaphroditism in Hydrobia ulvae results mostly from exposure to the biocide tributylin. In a recent study by Schulte-Oehlmann et al, the percentage of imposex-affected females reached 44.3%, with about 12.9% sterilized. No signs of sex change of females were noted while four stages and two paths of development were identified. Parameters to measure tributylin pollution were suggested, namely: vas deferens sequence index, imposex incidence, percentage of sterilized females and the average female penis length.

The mechanism behind the self-fertilisation in Celleporella hyalina is investigated. Results show that autogamy is normally suppressed in hermaphroditic C. hyalina where outcrossing is possible, but self-fertilization is used as an emergency alternative. However, offsprings of self-fertilization experiences frequent abortion and absence of settlement due to reduced fitness as a result of inbreeding depression.

Samples of Coryphopterus glaucofraenum were collected off the southwest coast of Puerto Rico and examined histologically to determine the sexual pattern. The sex ratios observed were female-biased. Experimental evidence showed that C. glaucofraenum is protogynous, with all-female groups undergoing sex change within 10 to 40 days.Histological studies on immature fish showed that all male fishes pass through a female stage. Ovarian, trnsitional and testis stuctures were similar to C. nichosi and C. personatus. The results indicate that protogyny is an ancestral condition in the genus Coryphopterus.

Transsexualism and homosexuality have been theorized to originate in the male from insufficient androgenization of the brain. For verification of this hypothesis clinical science must rely on subjects with an abnormal prenatal/perinatal endocrine history. A case of a 33-year-old 46,XY subject with an incomplete form of androgen insensitivity syndrome (AIS) is presented. In adulthood the only genital sign of masculinization is a clitoris of 4 cm; the vagina in normal size. The diagnosis AIS was verified by androgen receptor studies. At birth there was confusion as to the sex of the newborn. Originally, the subject was assigned to the male sex, but this decision was reversed 5 days after birth and the subject was reared as a girl. At age 30 the subject applied for gender reassignment treatment to the male sex. Upon psychological evaluation the gender identity was unambiguously male and the sexual orientation was exclusively towards women. The estrogen feedback effect on LH, regarded by some as a marker of the sexual differentiation of the neuroendocrinium was negative before orchiectomy but positive after orchiectomy. Our observation demonstrates that in 46,XY subjects a male gender identity and a sexual orientation towards women can develop with a strikingly lower-than-normal level of biological action of androgens.

A study was undertaken to investigate the true simultaneous hermaphrodite traits of female shrimps, Lysmata wurdemanni, in terms of reproductive capability during the same mating period. The simultaneous hermaphrodite characteristics were observed via the time-lapse video, reproductive morphology and population structure. It was determined that L. wurdemanni females were typical outcrossing hermaphrodites capable of copulating and inseminating as males on the same night they spawned.