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Raymond T Bauer - One of the best experts on this subject based on the ideXlab platform.
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persistence of reduced androgenic glands after protandric sex change suggests a basis for Simultaneous Hermaphroditism in a caridean shrimp
The Biological Bulletin, 2016Co-Authors: Jose Luis Bortolini, Raymond T BauerAbstract:The caridean shrimp Lysmata wurdemanni is a protandric Simultaneous hermaphrodite. These individuals go through a male phase (MP) before changing sex to become female-phase Simultaneous hermaphrodites (FPSH). The latter have an externally female phenotype, but retain a reduced male reproductive system and both male and female reproductive function. Previous studies have reported that the androgenic glands (AGs), whose hormones stimulate development of male characteristics in decapod crustaceans, are absent in the female phase of purely protandric species. We tested the hypothesis of androgenic gland persistence in FPSHs of L. wurdemanni by dissection and histology on the ejaculatory ducts. These glands were observed in FPSHs, although in a variably atrophied form. Androgenic glands of L. wurdemanni MPs are compact and replete with well developed cells, with large, deeply stained (hematoxylin-eosin) nuclei, as in males of gonochoric and protandric species. The AGs of Simultaneous hermaphrodites were more r...
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molecular phylogeny of shrimps from the genus lysmata caridea hippolytidae the evolutionary origins of protandric Simultaneous Hermaphroditism and social monogamy
Biological Journal of The Linnean Society, 2009Co-Authors: Antonio J Baeza, Christoph D Schubart, Petra Zillner, Soledad Fuentes, Raymond T BauerAbstract:Shrimps from the genus Lysmata are known because of their wide diversity of lifestyles, mating systems, symbiotic partnerships, and conspicuous coloration. They can occur in crowds (large aggregations), in small groups, or as socially monogamous pairs. Shrimps from this genus are rare, if not unique among crustaceans, because of their unusual sexual system. To date, the sexual system of all species investigated comprises a protandric Simultaneous Hermaphroditism: shrimps initially mature and reproduce as males and later in life turn into functional Simultaneous hermaphrodites. The evolutionary relationships of the species within the genus are unsettled. A molecular phylogeny of the group may shed light on the evolutionary origins of the peculiar sexual and social systems of these shrimps and help resolve standing taxonomic questions long overdue. Using a 647-bp alignment of the 16S rRNA mitochondrial DNA, we examined the phylogenetic relationship of 21 species of shrimps from the genus Lysmata from several biogeographical regions; the Atlantic, Pacific, and Indo-Pacific. The resulting phylogeny indicates that the genus is paraphyletic and includes the genus Exhippolysmata. The constituent species are subdivided into three well supported clades: one group exclusively composed of neotropical species; a second clade comprising the Indo-Pacific and Atlantic symbiotic fish cleaner shrimps; and a third clade including tropical and temperate species from the Atlantic and Pacific. The molecular phylogeny presented here does not support a historical contingency hypothesis, previously proposed to explain the origins of protandric Simultaneous Hermaphroditism within the genus. Furthermore, the present study shows that monogamous pair-living is restricted to one monophyletic group of shrimps and therefore probably evolved only once. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 415–424.
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same sexual system but variable sociobiology evolution of protandric Simultaneous Hermaphroditism in lysmata shrimps
Integrative and Comparative Biology, 2006Co-Authors: Raymond T BauerAbstract:Synopsis The sexual system of the decapod (caridean) shrimp Lysmata is protandric Simultaneous Hermaphroditism (PSH). Individuals first mature as males (male phase ¼ MP) and then when older (larger) change to the external phenotype of female carideans (female phase ¼ FP). However, unlike purely protandric carideans, Lysmata FPs retain reduced male gonadal tissues and ducts, and are able to mate nonreciprocally as males as well as to reproduce as females. Thus, FPs of Lysmata species are functional Simultaneous hermaphrodites although most reproductive effort is devoted to embryo production and incubation. The question explored here is, given the propensity of carideans to protandry, the apparent low cost, and high reproductive advantage of PSH, why has not PSH evolved more frequently? The mating systems and sexual selection of caridean shrimps, the original sex of protandric individuals, the cost of maleness, and sex allocation theory are discussed in relation to protandry and PSH. None of these factors adequately explains the evolution of PSH of Lysmata species. Lysmata has at least 2 species groups with very different sociobiologies; these groups do not appear to share current selective pressures that would explain PSH in both. A historical contingency hypothesis, testable in part with a phylogenetic analysis, may explain the evolution of PSH in Lysmata.
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Experimental test of socially mediated sex change in a protandric Simultaneous hermaphrodite, the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae)
Behavioral Ecology and Sociobiology, 2004Co-Authors: J. Antonio Baeza, Raymond T BauerAbstract:In Lysmata wurdemanni , individuals begin benthic life in a male phase (MP) but later change to a female phase (FP) with female external morphology, but with both male and female reproductive capacity (protandric Simultaneous Hermaphroditism). Previous studies have demonstrated that the size (timing) of sex change varies considerably in natural populations. We experimentally tested for social mediation of sex change by rearing male-phase individuals (MPs) in both large and small social groups with different sexual and size composition. In the “large group” experiment, speed of sex change was inversely related to the abundance of female-phase individuals (FPs) in the group (sex-ratio induction). Increased allocation to female function (more rapid change to FP) may occur when male mating opportunities are lower because the Simultaneous-hermaphrodite FP can immediately reproduce as a female while maintaining male mating capacity. When FPs are abundant, delayed sex change might be adaptive because the costs of female reproduction are considerable. An MP may gain reproductively by increased growth before changing to FP at a larger size (fewer but much larger broods). Size-ratio induction of sex change by small MPs was suggested but not confirmed. Experimental results from “small groups” (1–2 individuals) were qualitatively similar but not as conclusive as those from large groups. The number and complexity of social interactions in large groups may be necessary to stimulate labile sex change in this species. In L. wurdemanni , sex change may be influenced not only by abiotic factors related to breeding [Bauer (2002) Biol Bull 203:347–357] but also by social factors in certain demographic situations.
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protandric Simultaneous Hermaphroditism in the marine shrimp lysmata californica caridea hippolytidae
Journal of Crustacean Biology, 2004Co-Authors: Raymond T Bauer, William A NewmanAbstract:Abstract To investigate the extent of protandric Simultaneous Hermaphroditism (PSH) in the genus Lysmata, observations were made on the sexual system of L. californica, a species from the warm-temperate eastern Pacific. Observations on a large number of female-phase individuals (FPs) from a museum collection indicated that FPs with broods containing advanced embryos spawn again (successively) soon after brood hatching. Female-phase individuals maintained in pairs went through successive cycles of embryo brooding concomitant with gonadal vitellogenesis, hatching, molting, and spawning. Time-lapse video observations confirmed that FPs are able to copulate as males and inseminate postmolt, prespawning FPs. Prespawning FPs maintained alone did not produce successful broods of embryos. Thus, FPs of L. californica are outcrossing Simultaneous hermaphrodites. Size-frequency distributions of sexual phases showed that individuals develop first in the male phase (MP) and then change to the female phase. Individuals...
Antonio J Baeza - One of the best experts on this subject based on the ideXlab platform.
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sexual systems in shrimps infraorder caridea dana 1852 with special reference to the historical origin and adaptive value of protandric Simultaneous Hermaphroditism
2018Co-Authors: Antonio J BaezaAbstract:In this chapter, the diversity of sexual systems in the infraorder Caridea is summarized. Caridean shrimps exhibit six different sexual systems: gonochorism (separate sexes), strict protandry, partial protandry with primary females, partial protandry with primary males, partial protandry with primary males and primary females, and protandric Simultaneous Hermaphroditism. Within monophyletic clades belonging to the species-rich and ecologically dissimilar order Decapoda, gender expression is the most diverse in caridean shrimps. Additional studies on the life history and sexual system of caridean shrimps coupled with improvements on our understanding of the internal phylogenetic relationships within this species-rich clade are needed for a formal testing of transition asymmetries in the group. The historical origin of protandric Simultaneous Hermaphroditism, a sexual system that represents the “pinnacle” of evolution with respect to gender expression in the Caridea, remains to be fully understood. The conditions that maintain protandric Simultaneous Hermaphroditism include sex-dependent time commitments and sex-dependent energetic costs. The role of sexual selection in explaining the adaptive value of protandric Simultaneous Hermaphroditism needs to be addressed. Caridean shrimps represent excellent model systems to continue improving our understanding about the mechanisms explaining the diversity of gender expression patterns in nature.
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protandric Simultaneous Hermaphroditism in parhippolyte misticia clark 1989 caridea hippolytidae implications for the evolution of mixed sexual systems in shrimp
Journal of Crustacean Biology, 2012Co-Authors: Hitoshi Onaga, Curt G Fiedler, Antonio J BaezaAbstract:The sexual system of the shrimp Parhippolyte misticia (Clark, 1989), inhabiting the rocky subtidal at Okinawa, Japan and Kimbe Bay, Papua New Guinea, was examined. Dissections suggested that the population consisted of male phase (MP) and functional Simultaneous euhermaphrodite (EH) individuals. MPs have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well-developed male portion containing sperm, but an undeveloped female portion. EHs lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well-developed ovaries containing mature oocytes and testes with sperm. When EHs were maintained in pairs, both shrimp molted and spawned eggs which attached below the pleon and developed as embryos, demonstrating that EHs can reproduce as males and inseminate other EHs acting as females. These results demonstrate that P. misticia is a protandric Simultaneous hermaphrodite, as reported before for other shrimp of the genera Lysmata and Exhippolysmata. Also, these results suggest that protandric Simultaneous Hermaphroditism might have evolved more than once independently in shrimp from the diverse and species-rich Infraorder Caridea. Future research aimed at disentangling the phylogenetic relationship of Parhippolyte, Lysmata, Exhippolysmata and other closely related genera (Calliasmata, Lysmatella, Barbouria) and describing the sociobiology of additional representatives from the genera above is needed to understand the evolutionary history of sexual systems in caridean shrimp.
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molecular phylogeny of shrimps from the genus lysmata caridea hippolytidae the evolutionary origins of protandric Simultaneous Hermaphroditism and social monogamy
Biological Journal of The Linnean Society, 2009Co-Authors: Antonio J Baeza, Christoph D Schubart, Petra Zillner, Soledad Fuentes, Raymond T BauerAbstract:Shrimps from the genus Lysmata are known because of their wide diversity of lifestyles, mating systems, symbiotic partnerships, and conspicuous coloration. They can occur in crowds (large aggregations), in small groups, or as socially monogamous pairs. Shrimps from this genus are rare, if not unique among crustaceans, because of their unusual sexual system. To date, the sexual system of all species investigated comprises a protandric Simultaneous Hermaphroditism: shrimps initially mature and reproduce as males and later in life turn into functional Simultaneous hermaphrodites. The evolutionary relationships of the species within the genus are unsettled. A molecular phylogeny of the group may shed light on the evolutionary origins of the peculiar sexual and social systems of these shrimps and help resolve standing taxonomic questions long overdue. Using a 647-bp alignment of the 16S rRNA mitochondrial DNA, we examined the phylogenetic relationship of 21 species of shrimps from the genus Lysmata from several biogeographical regions; the Atlantic, Pacific, and Indo-Pacific. The resulting phylogeny indicates that the genus is paraphyletic and includes the genus Exhippolysmata. The constituent species are subdivided into three well supported clades: one group exclusively composed of neotropical species; a second clade comprising the Indo-Pacific and Atlantic symbiotic fish cleaner shrimps; and a third clade including tropical and temperate species from the Atlantic and Pacific. The molecular phylogeny presented here does not support a historical contingency hypothesis, previously proposed to explain the origins of protandric Simultaneous Hermaphroditism within the genus. Furthermore, the present study shows that monogamous pair-living is restricted to one monophyletic group of shrimps and therefore probably evolved only once. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 415–424.
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protandric Simultaneous Hermaphroditism in the shrimps lysmata bahia and lysmata intermedia
Invertebrate Biology, 2008Co-Authors: Antonio J BaezaAbstract:Abstract. The sexual system of two peppermint shrimps, Lysmata bahia and Lysmata intermedia, inhabiting intertidal fossil coral terraces at Bocas del Toro, on the Caribbean coast of Panama, was examined. Dissections suggested that the population of each species consisted of functional males and functional Simultaneous hermaphrodites. Males have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well-developed male portion full of sperm, but an undeveloped female portion. Hermaphrodites lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well-developed ovaries full of mature oocytes and testes with sperm. When hermaphrodites were maintained in pairs, both molted and spawned eggs (to beneath abdomen) that continued developing after 3 d, demonstrating that hermaphrodites can reproduce as males and inseminate other hermaphrodites acting as females. The possibility of self-fertilization or parthenogenetic reproduction was tested and disregarded, because hermaphrodites reared in isolation spawned oocytes that failed to develop, disappearing from the abdomen after 2 d. Males reared in pairs mature as hermaphrodites in <50 d, showing the ability of males to mature as hermaphrodites. These results demonstrate that L. bahia and L. intermedia are protandric Simultaneous hermaphrodites, as reported for all species of this genus whose sexual system has been examined. However, the studied species featured a lifestyle, termed “tropical-low abundance,” here not recognized previously for the genus; they occur in low abundances in tropical environments, they do not develop symbiotic associations with sessile invertebrates, and they are not conspicuously colored. Information on the sexual systems and lifestyles of more species needs to be examined before these observations can be placed into a comparative context within the genus.
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testing three models on the adaptive significance of protandric Simultaneous Hermaphroditism in a marine shrimp
Evolution, 2006Co-Authors: Antonio J BaezaAbstract:Protandric Simultaneous Hermaphroditism, as reported for shrimps in the genus Lysmata, is a sexual system in which individuals invariably reproduce as males first and later in life as Simultaneous hermaphrodites. I tested three models (i.e., sex-dependent energetic costs, sex-dependent mortality rates and sex-dependent time commitments) in an attempt to explain the adaptive value of protandric Simultaneous Hermaphroditism in the shrimp L. wurdemanni. Specific assumptions and predictions of each model were evaluated using manipulative experiments. In the laboratory, males grew faster than Simultaneous hermaphrodites of the same size and age, an indication that the female function incurs higher energetic costs of reproduction than the male function. Also, large SHPs were more successful in monopolizing food than small males. The sex-dependent growth rate and size-dependent resource holding power agree with predictions of the sex-dependent energetic cost model. The time that Simultaneous hermaphrodites required for replenishing their sperm reservoirs after mating as males was much shorter (2 days) than the time required to brood one clutch of embryos (11 days). Also, small Simultaneous hermaphrodites experienced heavier mortality due to predatory fishes than large ones. The sex-dependent reproductive time commitment and size-dependent mortality agree with predictions of the sex-dependent time commitment model. Conversely, I found no evidence that the sex-dependent mortality model explains protandric Simultaneous Hermaphroditism in the studied species. In contrast to model predictions, mortality due to predatory fishes suffered by Simultaneous hermaphrodites was not greater than that suffered by males of the same body size. In L. wurdemanni, the relationship between sex-specific investment and reproductive success seems to change during ontogeny in a way that is consistent with an adaptive adjustment of sex allocation to improve age-specific reproductive success.
J. Antonio Baeza - One of the best experts on this subject based on the ideXlab platform.
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Life history traits and reproductive performance of the caridean shrimp Lysmata boggessi, a heavily traded invertebrate in the marine aquarium industry.
PeerJ, 2020Co-Authors: Michael D. Dickson, Donald C. Behringer, J. Antonio BaezaAbstract:The most intense commercial harvest of marine aquarium species in North America occurs in the coastal waters surrounding Florida, yet very often little information exists on the life histories, population dynamics, or reproductive characteristics of these organisms. The peppermint shrimp Lysmata boggessi is one such species and is heavily targeted along the west coast of Florida. It is known primarily among aquarists for its ability to control pest anemones and in the scientific community for its unique sexual system, protandric Simultaneous Hermaphroditism. However, no study has addressed fishery interactions or long-term population dynamics for L. boggessi. We used monthly fisheries-dependent sampling, with a trained observer present, for a full year to assess seasonality in sex phase ratio (males to males + hermaphrodites), size at sex change, fecundity, embryo volume and reproductive output of an exploited L. boggessi population. L. boggessi exhibited distinct seasonality in size distribution, sex phase ratio, size at sex phase change and reproductive activity. The peak reproductive season was in spring, when the population was dominated by small but fecund hermaphrodites. Reproduction decreased during fall and winter and sex phase ratios favored male phase shrimp that exhibited delayed sex change. This population and individual level information is the first of its kind for L. boggessi and fills a much needed data gap for the informed management of this fishery.
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Molecular phylogeny of broken-back shrimps (genus Lysmata and allies): a test of the 'Tomlinson-Ghiselin' hypothesis explaining the evolution of Hermaphroditism.
Molecular Phylogenetics and Evolution, 2013Co-Authors: J. Antonio BaezaAbstract:Abstract The ‘Tomlinson–Ghiselin’ hypothesis (TGh) predicts that outcrossing Simultaneous Hermaphroditism (SH) is advantageous when population density is low because the probability of finding sexual partners is negligible. In shrimps from the family Lysmatidae, Bauer’s historical contingency hypothesis (HCh) suggests that SH evolved in an ancestral tropical species that adopted a symbiotic lifestyle with, e.g., sea anemones and became a specialized fish-cleaner. Restricted mobility of shrimps due to their association with a host, and hence, reduced probability of encountering mating partners, would have favored SH. The HCh is a special case of the TGh. Herein, I examined within a phylogenetic framework whether the TGh/HCh explains the origin of SH in shrimps. A phylogeny of caridean broken-back shrimps in the families Lysmatidae, Barbouriidae, Merguiidae was first developed using nuclear and mitochondrial makers. Complete evidence phylogenetic analyses using maximum likelihood (ML) and Bayesian inference (BI) demonstrated that Lysmatidae + Barbouriidae are monophyletic. In turn, Merguiidae is sister to the Lysmatidae + Barbouriidae. ML and BI ancestral character-state reconstruction in the resulting phylogenetic trees indicated that the ancestral Lysmatidae was either gregarious or lived in small groups and was not symbiotic. Four different evolutionary transitions from a free-living to a symbiotic lifestyle occurred in shrimps. Therefore, the evolution of SH in shrimps cannot be explained by the TGh/HCh; reduced probability of encountering mating partners in an ancestral species due to its association with a sessile host did not favor SH in the Lysmatidae. It is proposed that two conditions acting together in the past; low male mating opportunities and brooding constraints, might have favored SH in the ancestral Lysmatidae + Barbouridae. Additional studies on the life history and phylogenetics of broken-back shrimps are needed to understand the evolution of SH in the ecologically diverse Caridea.
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Protandric Simultaneous Hermaphroditism in the shrimps Lysmata bahia and Lysmata intermedia
Invertebrate Biology, 2008Co-Authors: J. Antonio BaezaAbstract:Abstract. The sexual system of two peppermint shrimps, Lysmata bahia and Lysmata intermedia, inhabiting intertidal fossil coral terraces at Bocas del Toro, on the Caribbean coast of Panama, was examined. Dissections suggested that the population of each species consisted of functional males and functional Simultaneous hermaphrodites. Males have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well-developed male portion full of sperm, but an undeveloped female portion. Hermaphrodites lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well-developed ovaries full of mature oocytes and testes with sperm. When hermaphrodites were maintained in pairs, both molted and spawned eggs (to beneath abdomen) that continued developing after 3 d, demonstrating that hermaphrodites can reproduce as males and inseminate other hermaphrodites acting as females. The possibility of self-fertilization or parthenogenetic reproduction was tested and disregarded, because hermaphrodites reared in isolation spawned oocytes that failed to develop, disappearing from the abdomen after 2 d. Males reared in pairs mature as hermaphrodites in
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Experimental test of socially mediated sex change in a protandric Simultaneous hermaphrodite, the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae)
Behavioral Ecology and Sociobiology, 2004Co-Authors: J. Antonio Baeza, Raymond T BauerAbstract:In Lysmata wurdemanni , individuals begin benthic life in a male phase (MP) but later change to a female phase (FP) with female external morphology, but with both male and female reproductive capacity (protandric Simultaneous Hermaphroditism). Previous studies have demonstrated that the size (timing) of sex change varies considerably in natural populations. We experimentally tested for social mediation of sex change by rearing male-phase individuals (MPs) in both large and small social groups with different sexual and size composition. In the “large group” experiment, speed of sex change was inversely related to the abundance of female-phase individuals (FPs) in the group (sex-ratio induction). Increased allocation to female function (more rapid change to FP) may occur when male mating opportunities are lower because the Simultaneous-hermaphrodite FP can immediately reproduce as a female while maintaining male mating capacity. When FPs are abundant, delayed sex change might be adaptive because the costs of female reproduction are considerable. An MP may gain reproductively by increased growth before changing to FP at a larger size (fewer but much larger broods). Size-ratio induction of sex change by small MPs was suggested but not confirmed. Experimental results from “small groups” (1–2 individuals) were qualitatively similar but not as conclusive as those from large groups. The number and complexity of social interactions in large groups may be necessary to stimulate labile sex change in this species. In L. wurdemanni , sex change may be influenced not only by abiotic factors related to breeding [Bauer (2002) Biol Bull 203:347–357] but also by social factors in certain demographic situations.
G J Holt - One of the best experts on this subject based on the ideXlab platform.
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Simultaneous Hermaphroditism in the marine shrimp lysmata wurdemanni caridea hippolytidae an undescribed sexual system in the decapod crustacea
Marine Biology, 1998Co-Authors: Raymond T Bauer, G J HoltAbstract:Simultaneous Hermaphroditism with out- crossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of ''female-phase'' (FP) individuals. Copulations between FPs resulted in suc- cessful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of cari- dean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovar- ian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. ''Transitionals,'' individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may medi- ate MP change into FP hermaphrodites in L. wurde- manni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sex- ual system in these species.
Dong Zhang - One of the best experts on this subject based on the ideXlab platform.
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phase specific expression of an insulin like androgenic gland factor in a marine shrimp lysmata wurdemanni implication for maintaining protandric Simultaneous Hermaphroditism
PLOS ONE, 2017Co-Authors: Dong ZhangAbstract:BACKGROUND: Shrimp in the genus Lysmata have a unique and rare sexual system referred to as protandric Simultaneous Hermaphroditism, whereby individuals mature first as male (male phase), and then the female function may also develop as the shrimp grow, so that the gonad is able to produce both eggs and sperms Simultaneously, a condition called Simultaneous Hermaphroditism (euhermaphrodite phase). To date, the mechanisms of sex control in this sexual system still remain poorly understood. Many studies indicate that an insulin-like androgenic gland factor (IAG) is involved in controlling sex differentiation in gonochoric crustaceans, but its role in the protandric Simultaneous hermaphrodite is still not clear. RESULTS: To determine whether an IAG is involved in sex control in the hermaphrodite, here we, for the first time, cloned the IAG gene cDNA sequence from Lysmata wurdemanni (termed Lw-IAG: L. wurdemanni insulin-like AG factor), a protandric Simultaneous hermaphroditic shrimp. The IAG contains an open reading frame of 528 bp, corresponding to 176 amino acids, which consists of a signal peptide, B chain, C peptide, and A chain. The organization is similar to the IAGs found in other decapods. The IAG gene was expressed in both male and euhermaphrodite phases, but the expression level was significantly higher in the male phase than in the euhermaphrodite phase. Immunofluorescence analysis and Western Blotting revealed that the IAG protein was expressed in the androgenic gland, and its expression level was higher in the male phase than in the euhermaphrodite phase. CONCLUSIONS: Data presented here suggest that the IAG gene may be a factor controlling sex in the protandric Simultaneous hermaphrodite, and that the euhermaphrodite phase is maintained by reduced gene expression, i.e., the presence of the androgenic gland (or the androgenic hormone it produces) completely inhibits ovarian development in the male phase, and incomplete degeneration of the androgenic gland in the euhermaphrodite phase results in Simultaneous Hermaphroditism. The findings presented in the current study can help to reveal how protandric Simultaneous Hermaphroditism evolved in crustaceans.
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Reproduction in a Simultaneous hermaphroditic shrimp, Lysmata wurdemanni: any two will do?
Marine Biology, 2001Co-Authors: Dong ZhangAbstract: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.
