RESUMEN
Natural temperature variation in many marine ecosystems is stochastic and unpredictable, and climate change models indicate that this thermal irregularity is likely to increase. Temperature acclimation may be more challenging when conditions are highly variable and stochastic, and there is a need for empirical physiological data in these thermal environments. Using the hermaphroditic, amphibious mangrove rivulus (Kryptolebias marmoratus), we hypothesized that compared with regular, warming diel thermal fluctuations, stochastic warm fluctuations would negatively affect physiological performance. To test this, we acclimated fish to: (1) non-stochastic and (2) stochastic thermal fluctuations with a similar thermal load (27-35°C), and (3) a stable/consistent control temperature at the low end of the cycle (27°C). We determined that fecundity was reduced in both cycles, with reproduction ceasing in stochastic thermal environments. Fish acclimated to non-stochastic thermal cycles had growth rates lower than those of control fish. Exposure to warm, fluctuating cycles did not affect emersion temperature, and only regular diel cycles modestly increased critical thermal tolerance. We predicted that warm diel cycling temperatures would increase gill surface area. Notably, fish acclimated to either thermal cycle had a reduced gill surface area and increased intralamellar cell mass when compared with control fish. This decreased gill surface area with warming contrasts with what is observed for exclusively aquatic fish and suggests a preparatory gill response for emersion in these amphibious fish. Collectively, our data reveal the importance of considering stochastic thermal variability when studying the effects of temperature on fishes.
Asunto(s)
Aclimatación , Branquias , Procesos Estocásticos , Animales , Branquias/fisiología , Aclimatación/fisiología , Ciprinodontiformes/fisiología , Temperatura , Cambio Climático , Organismos Hermafroditas/fisiología , CalorRESUMEN
Sperm competition is a potent mechanism of postcopulatory sexual selection that has been found to shape reproductive morphologies and behaviours in promiscuous animals. Especially sperm size has been argued to evolve in response to sperm competition through its effect on sperm longevity, sperm motility, the ability to displace competing sperm, and ultimately fertilization success. Additionally, sperm size has been observed to co-evolve with female reproductive morphology. Theoretical work predicts that sperm competition may select for longer sperm but may also favour shorter sperm if sperm size trades-off with number. In this study, we studied the relationship between sperm size and postmating success in the free-living flatworm, Macrostomum lignano. Specifically, we used inbred isolines of M. lignano that varied in sperm size to investigate how sperm size translated into the ability of worms to transfer and deposit sperm in a mating partner. Our results revealed a hump-shaped relationship with individuals producing sperm of intermediate size having the highest sperm competitiveness. This finding broadens our understanding of the evolution of sperm morphology by providing empirical support for stabilizing selection on sperm size under sperm competition.
Asunto(s)
Espermatozoides , Animales , Masculino , Espermatozoides/fisiología , Femenino , Organismos Hermafroditas/fisiología , Turbelarios/fisiología , Platelmintos/fisiologíaRESUMEN
Many 'hard-wired', innate animal behaviors are related to reproduction. So what happens when reproductive systems evolve? New research in nematodes has identified principles underlying the co-evolution of reproductive strategy and sexual behavior, revealing some surprises and raising intriguing new questions.
Asunto(s)
Evolución Biológica , Conducta Sexual Animal , Animales , Conducta Sexual Animal/fisiología , Reproducción , Organismos Hermafroditas/fisiología , Caenorhabditis elegans/fisiología , Masculino , FemeninoRESUMEN
Pathogens generate ubiquitous selective pressures and host-pathogen interactions alter social behaviours in many animals1-4. However, very little is known about the neuronal mechanisms underlying pathogen-induced changes in social behaviour. Here we show that in adult Caenorhabditis elegans hermaphrodites, exposure to a bacterial pathogen (Pseudomonas aeruginosa) modulates sensory responses to pheromones by inducing the expression of the chemoreceptor STR-44 to promote mating. Under standard conditions, C. elegans hermaphrodites avoid a mixture of ascaroside pheromones to facilitate dispersal5-13. We find that exposure to the pathogenic Pseudomonas bacteria enables pheromone responses in AWA sensory neurons, which mediate attractive chemotaxis, to suppress the avoidance. Pathogen exposure induces str-44 expression in AWA neurons, a process regulated by a transcription factor zip-5 that also displays a pathogen-induced increase in expression in AWA. STR-44 acts as a pheromone receptor and its function in AWA neurons is required for pathogen-induced AWA pheromone response and suppression of pheromone avoidance. Furthermore, we show that C. elegans hermaphrodites, which reproduce mainly through self-fertilization, increase the rate of mating with males after pathogen exposure and that this increase requires str-44 in AWA neurons. Thus, our results uncover a causal mechanism for pathogen-induced social behaviour plasticity, which can promote genetic diversity and facilitate adaptation of the host animals.
Asunto(s)
Caenorhabditis elegans , Feromonas , Pseudomonas aeruginosa , Reproducción , Conducta Sexual Animal , Animales , Femenino , Masculino , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/microbiología , Caenorhabditis elegans/fisiología , Proteínas de Caenorhabditis elegans/metabolismo , Glucolípidos/metabolismo , Organismos Hermafroditas/fisiología , Feromonas/metabolismo , Pseudomonas aeruginosa/patogenicidad , Pseudomonas aeruginosa/fisiología , Receptores de Feromonas/metabolismo , Reproducción/fisiología , Células Receptoras Sensoriales/metabolismoRESUMEN
We tested whether crowding stress affects the hypothalamo-pituitary-interrenal (HPI) axis of the self-fertilizing fish, Kryptolebias marmoratus, which is known to be aggressive in the laboratory conditions but sometimes found as a group from a single land crab burrow in the wild. The projection of corticotropin-releasing hormone (CRH) neurons to the adrenocorticotropic hormone (ACTH) cells in the pituitary was confirmed by dual-label immunohistochemistry; CRH-immunoreactive (ir) fibers originating from cell bodies located in the lateral tuberal nucleus (NLT) of the hypothalamus were observed to project to ACTH-ir cells in the rostral pars distalis of the pituitary. Then, fish were reared solitary or in pairs for 14 days, and the number of CRH-ir cell bodies in the NLT of the hypothalamus and cortisol levels in the body without head region were compared. The number of CRH-ir cell bodies and cortisol levels were significantly higher in paired fish. These results indicate that crowding stress affects the HPI axis in K. marmoratus which thrive in small burrows with limited water volume.
Asunto(s)
Ciprinodontiformes/fisiología , Sistema Hipotálamo-Hipofisario/fisiología , Peces Killi/fisiología , Autofecundación/fisiología , Hormona Adrenocorticotrópica/fisiología , Animales , Hormona Liberadora de Corticotropina/fisiología , Ciprinodontiformes/anatomía & histología , Femenino , Proteínas de Peces/fisiología , Organismos Hermafroditas/fisiología , Sistema Hipotálamo-Hipofisario/anatomía & histología , Inmunohistoquímica , Riñón/fisiología , Peces Killi/anatomía & histología , Masculino , Fibras Nerviosas/fisiología , Estrés FisiológicoRESUMEN
The stunning sexual transformation commonly triggered by age, size or social context in some fishes is one of the best examples of phenotypic plasticity thus far described. To date our understanding of this process is dominated by studies on a handful of subtropical and tropical teleosts, often in wild settings. Here we have established the protogynous New Zealand spotty wrasse, Notolabrus celidotus, as a temperate model for the experimental investigation of sex change. Captive fish were induced to change sex using aromatase inhibition or manipulation of social groups. Complete female-to-male transition occurred over 60 days in both cases and time-series sampling was used to quantify changes in hormone production, gene expression and gonadal cellular anatomy. Early-stage decreases in plasma 17ß-estradiol (E2) concentrations or gonadal aromatase (cyp19a1a) expression were not detected in spotty wrasse, despite these being commonly associated with the onset of sex change in subtropical and tropical protogynous (female-to-male) hermaphrodites. In contrast, expression of the masculinising factor amh (anti-Müllerian hormone) increased during early sex change, implying a potential role as a proximate trigger for masculinisation. Collectively, these data provide a foundation for the spotty wrasse as a temperate teleost model to study sex change and cell fate in vertebrates.
Asunto(s)
Peces/fisiología , Organismos Hermafroditas/fisiología , Procesos de Determinación del Sexo , Animales , Hormona Antimülleriana/genética , Hormona Antimülleriana/metabolismo , Inhibidores de la Aromatasa/farmacología , Estradiol/sangre , Femenino , Proteínas de Peces/genética , Proteínas de Peces/metabolismo , Peces/sangre , Peces/genética , Regulación de la Expresión Génica , Gónadas/fisiología , Organismos Hermafroditas/efectos de los fármacos , Organismos Hermafroditas/genética , Organismos Hermafroditas/metabolismo , Masculino , Modelos Animales , Fenotipo , Caracteres Sexuales , Procesos de Determinación del Sexo/efectos de los fármacos , Conducta Social , Testosterona/análogos & derivados , Testosterona/sangreRESUMEN
Dioecious species are a hallmark of the animal kingdom, with opposing sexes responding differently to identical sensory cues. Here, we study the response of C. elegans to the small-molecule pheromone, ascr#8, which elicits opposing behavioral valences in each sex. We identify a novel neuropeptide-neuropeptide receptor (NP/NPR) module that is active in males, but not in hermaphrodites. Using a novel paradigm of neuropeptide rescue that we established, we leverage bacterial expression of individual peptides to rescue the sex-specific response to ascr#8. Concurrent biochemical studies confirmed individual FLP-3 peptides differentially activate two divergent receptors, NPR-10 and FRPR-16. Interestingly, the two of the peptides that rescued behavior in our feeding paradigm are related through a conserved threonine, suggesting that a specific NP/NPR combination sets a male state, driving the correct behavioral valence of the ascr#8 response. Receptor expression within pre-motor neurons reveals novel coordination of male-specific and core locomotory circuitries.
Asunto(s)
Caenorhabditis elegans/fisiología , Organismos Hermafroditas/fisiología , Locomoción , Receptores de Neuropéptido/genética , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans , Proteínas Portadoras , Organismos Hermafroditas/genética , Locomoción/efectos de los fármacos , Masculino , Receptores de Neuropéptido/metabolismoRESUMEN
Photoperiod is a reliable cue to regulate growth and reproduction for seasonal adaptation. Although photoperiodism has been well studied in Chordata and Arthropoda, less is known about Mollusca. We examined photoperiodic effects on egg laying, body size, gonad-somatic index, oocyte size and relative amounts of caudodorsal cell hormone mRNA in individual rearing conditions in the pond snail Lymnaea stagnalis. Twenty-five weeks after hatching, the percentages of egg-laying snails under a photoperiod of 12 h light and 12 h darkness (12L:12D) were significantly smaller than those under longer days. The total numbers of eggs and egg masses under 12L:12D were significantly smaller than those under longer days. Significant differences between 16L:8D and 12L:12D were not observed in the soft body and ovotestis weight, and the gonad-somatic index. Photoperiodic effects were also not observed in oocyte diameters twenty-two weeks after hatching. Twenty-seven weeks after hatching amounts of caudodorsal cell hormone mRNA were significantly lower in the cerebral ganglia with commissure under 12L:12D than 16L:8D. L. stagnalis exhibited a clear photoperiodic response in egg laying and the amount of caudodorsal cell hormone mRNA, but not in gonadal development. Under 12L:12D suppression of caudodorsal cell hormone expression might suppress egg laying.
Asunto(s)
Gónadas/crecimiento & desarrollo , Hormonas de Invertebrados/biosíntesis , Lymnaea/anatomía & histología , Lymnaea/fisiología , Oviposición/fisiología , Fotoperiodo , Animales , Organismos Hermafroditas/fisiologíaRESUMEN
Vertebrates usually exhibit gonochorism, whereby their sex is fixed throughout their lifetime. However, approximately 500 species (~ 2%) of extant teleost fishes change sex during their lifetime. Although phylogenetic and evolutionary ecological studies have recently revealed that the extant sequential hermaphroditism in teleost fish is derived from gonochorism, the evolution of this transsexual ability remains unclear. We revealed in a previous study that the tunica of the ovaries of several protogynous hermaphrodite groupers contain functional androgen-producing cells, which were previously unknown structures in the ovaries of gonochoristic fishes. Additionally, we demonstrated that these androgen-producing cells play critical roles in initiating female-to-male sex change in several grouper species. In the present study, we widened the investigation to include 7 genera and 18 species of groupers and revealed that representatives from most major clades of extant groupers commonly contain these androgen-producing cells, termed testicular-inducing steroidogenic (TIS) cells. Our findings suggest that groupers acquired TIS cells in the tunica of the gonads for successful sex change during their evolution. Thus, TIS cells trigger the evolution of sex change in groupers.
Asunto(s)
Organismos Hermafroditas/fisiología , Perciformes/fisiología , Procesos de Determinación del Sexo/fisiología , Testículo/fisiología , Andrógenos/metabolismo , Animales , Femenino , MasculinoRESUMEN
Astrocytes modulate synaptic transmission; yet, it remains unclear how glia influence complex behaviors. Here, we explore the effects of Caenorhabditis elegans astrocyte-like cephalic glia (CEPglia ) and the glia-specific bHLH transcription factor HLH-17 on mating behavior and the defecation motor program (DMP). In C. elegans, male mating has been explicitly described through the male tail circuit and is characterized by coordination of multiple independent behaviors to ensure that copulation is achieved. Furthermore, the sex-specific male mating circuitry shares similar components with the DMP, which is complex and rhythmic, and requires a fixed sequence of behaviors to be activated periodically. We found that loss of CEPglia reduced persistence in executing mating behaviors and hindered copulation, while males that lacked HLH-17 demonstrated repetitive prodding behavior that increased the time spent in mating but did not hinder copulation. During the DMP, we found that posterior body wall contractions (pBocs) and enteric muscle contractions (EMCs) were differentially affected by loss of HLH-17 or CEPglia in males and hermaphrodites. pBocs and EMCs required HLH-17 activity in both sexes, whereas loss of CEPglia alone did not affect DMP in males. Our data suggest that CEPglia mediate complex behaviors by signaling to the GABAergic DVB neuron, and that HLH-17 activity influences those discrete steps within those behaviors. Collectively, these data provide evidence of glia as a link in cooperative regulation of complex and rhythmic behavior that, in C. elegans links circuitry in the head and the tail.
Asunto(s)
Proteínas de Caenorhabditis elegans/metabolismo , Copulación/fisiología , Neuronas GABAérgicas/fisiología , Organismos Hermafroditas/fisiología , Locomoción/fisiología , Neuroglía/fisiología , Factores de Transcripción/metabolismo , Animales , Animales Modificados Genéticamente , Caenorhabditis elegans , Proteínas de Caenorhabditis elegans/genética , Femenino , Masculino , Factores de Transcripción/genéticaRESUMEN
Sexual interference between male and female function in hermaphrodite plants is reduced by protandry. In environments with insufficient pollinator service, prolongation of male function owing to limited pollen removal could restrict the duration of female function and lower seed production. We provide evidence that this form of sexual conflict has played a role in the spread of females in gynodioecious populations of Cyananthus delavayi in the pollen-limited environments in which this subalpine species occurs. Using field experiments involving artificial pollen removal from the strongly protandrous flowers of hermaphrodites, we demonstrated a trade-off between male- and female-phase duration with no influence on overall floral longevity. Pollen removal at the beginning of anthesis resulted in hermaphrodite seed production matching that of females. In contrast, restricted pollen removal increased the duration of male function at the expense of female function lowering maternal fertility compared to females. This pattern was evident in five populations with females experiencing a twofold average seed fertility advantage compared to hermaphrodites. Gynodioecy often appears to evolve from protandrous ancestors and pollen limitation is widespread in flowering plants suggesting that sexual conflict may play an unappreciated role in the evolution of this form of sexual dimorphism.
Asunto(s)
Evolución Biológica , Campanulaceae/fisiología , Flores/fisiología , Aptitud Genética , Organismos Hermafroditas/fisiología , Polinización , Semillas/crecimiento & desarrolloRESUMEN
VAMP/synaptobrevin-associated protein B (VAP-B) is a type II ER membrane protein, but its N-terminal MSP domain (MSPd) can be cleaved and secreted. Mutations preventing the cleavage and secretion of MSPd have been implicated in cases of human neurodegenerative diseases. The site of VAP cleavage and the tissues capable in releasing the processed MSPd are not understood. In this study, we analyze the C. elegans VAP-B homolog, VPR-1, for its processing and secretion from the intestine. We show that intestine-specific expression of an N-terminally FLAG-tagged VPR-1 rescues underdeveloped gonad and sterility defects in vpr-1 null hermaphrodites. Immunofluorescence studies reveal that the tagged intestinal expressed VPR-1 is present at the distal gonad. Mass spectrometry analysis of a smaller product of the N-terminally tagged VPR-1 identifies a specific cleavage site at Leu156. Mutation of the leucine results in loss of gonadal MSPd signal and reduced activity of the mutant VPR-1. Thus, we report for the first time the cleavage site of VPR-1 and provide direct evidence that intestinally expressed VPR-1 can be released and signal in the distal gonad. These results establish the foundation for further exploration of VAP cleavage, MSPd secretion, and non-cell-autonomous signaling in development and diseases.
Asunto(s)
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Proteínas del Helminto/metabolismo , Proteínas de la Membrana/metabolismo , Animales , Animales Modificados Genéticamente , Caenorhabditis elegans/embriología , Caenorhabditis elegans/genética , Caenorhabditis elegans/crecimiento & desarrollo , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Retículo Endoplásmico/metabolismo , Genes de Helminto , Gónadas/química , Gónadas/crecimiento & desarrollo , Gónadas/metabolismo , Proteínas del Helminto/química , Organismos Hermafroditas/genética , Organismos Hermafroditas/metabolismo , Organismos Hermafroditas/fisiología , Infertilidad , Intestinos/citología , Intestinos/fisiología , Leucina/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Fenotipo , Mutación Puntual , Dominios Proteicos , Procesamiento Proteico-PostraduccionalRESUMEN
For the first 25 years after the landmark 1974 paper that launched the field, most C. elegans biologists were content to think of their subjects as solitary creatures. C. elegans presented no shortage of fascinating biological problems, but some of the features that led Brenner to settle on this species-in particular, its free-living, self-fertilizing lifestyle-also seemed to reduce its potential for interesting social behavior. That perspective soon changed, with the last two decades bringing remarkable progress in identifying and understanding the complex interactions between worms. The growing appreciation that C. elegans behavior can only be meaningfully understood in the context of its ecology and evolution ensures that the coming years will see similarly exciting progress.
Asunto(s)
Caenorhabditis elegans/fisiología , Etología/historia , Organismos Hermafroditas/fisiología , Animales , Conducta Alimentaria/fisiología , Femenino , Glucolípidos/fisiología , Historia del Siglo XX , Historia del Siglo XXI , Masculino , Feromonas/fisiología , Conducta Sexual Animal/fisiología , Conducta SocialRESUMEN
MAIN CONCLUSION: Better seed germination of females than of hermaphrodites is not a major contributor to the greater geometric lifetime fitness that females require to be maintained in a gynodioecious population. Gynodioecy is a sexually dimorphic breeding system in which females (F, male sterile) and hermaphrodites (H) coexist in the same population. For plants with nuclear (biparental) inheritance of male sterility, theory predicts that except when the product of selfing rate (s) and inbreeding depression (δ) in H is high (sδ > 0.50), F must compensate (female advantage) for the loss of gene transmission via pollen production by producing more or higher-quality offspring than H to be maintained in the population. For species with cytoplasmic (maternal) inheritance of male sterility, the female requires only a small compensation in seed production or some other offspring fitness trait to persist. Reallocation to seeds of resources saved by loss of pollen production is expected to increase the quantity (number) and/or quality (mass, germinability) of seeds produced by F, thus compensating for the lack of pollen production. The primary aim of our study was to compare seed germination of F and H via a literature review. Based on theoretical considerations, we hypothesized that seeds of F should germinate better or equally as well as those of H. We found that of 235 case studies for 47 species Fgerm > Hgerm in 48.1%, Fgerm = Hgerm in 38.3% and Fgerm < Hgerm in 13.6%. Our results are very similar to those of a previously published meta-analysis that included germination of F and H for 12 species. For 162 cases on seed size, F > H in 29.0%, F = H in 63.6% and F < H in 7.4%. Since [(Fgerm > Hgerm) < (Fgerm ≤ Hgerm)] and [(Fseedsize > Hseedsize) < (Fseedsize ≤ Hseedsize)], these results suggest that seed quality is not a major fitness component of female advantage.
Asunto(s)
Germinación , Fenómenos Fisiológicos de las Plantas , Semillas , Organismos Hermafroditas/fisiología , Reproducción , Semillas/crecimiento & desarrolloRESUMEN
The last few decades have seen the structural and functional elucidation of small-molecule chemical signals called ascarosides in C. elegans. Ascarosides mediate several biological processes in worms, ranging from development, to behavior. These signals are modular in their design architecture, with their building blocks derived from metabolic pathways. Behavioral responses are not only concentration dependent, but also are influenced by the current physiological state of the animal. Cellular and circuit-level analyses suggest that these signals constitute a complex communication system, employing both synergistic molecular elements and sex-specific neuronal circuits governing the response. In this review, we discuss research from multiple laboratories, including our own, that detail how these chemical signals govern several different social behaviors in C. elegans. We propose that the ascaroside repertoire represents a link between diverse metabolic and neurobiological life-history traits and governs the survival of C. elegans in its natural environment.
Asunto(s)
Caenorhabditis elegans/fisiología , Feromonas/fisiología , Conducta Social , Adaptación Fisiológica , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/crecimiento & desarrollo , Células Quimiorreceptoras/fisiología , Relación Dosis-Respuesta a Droga , Femenino , Genes de Helminto , Glucolípidos/química , Glucolípidos/fisiología , Organismos Hermafroditas/fisiología , Locomoción/fisiología , Masculino , Redes y Vías Metabólicas , Estructura Molecular , Nematodos/metabolismo , Vías Nerviosas/fisiología , Feromonas/química , Atractivos Sexuales/fisiología , Conducta Sexual Animal/fisiología , Transducción de Señal , InaniciónRESUMEN
Sexual dimorphism is a device that supports genetic diversity while providing selective pressure against speciation. This phenomenon is at the core of sexually reproducing organisms. Caenorhabditis elegans provides a unique experimental system where males exist in a primarily hermaphroditic species. Early works of John Sulston, Robert Horvitz, and John White provided a complete map of the hermaphrodite nervous system, and recently the male nervous system was added. This addition completely realized the vision of C. elegans pioneer Sydney Brenner: a model organism with an entirely mapped nervous system. With this 'connectome' of information available, great strides have been made toward understanding concepts such as how a sex-shared nervous system (in hermaphrodites and males) can give rise to sex-specific functions, how neural plasticity plays a role in developing a dimorphic nervous system, and how a shared nervous system receives and processes external cues in a sexually-dimorphic manner to generate sex-specific behaviors. In C. elegans, the intricacies of male-mating behavior have been crucial for studying the function and circuitry of the male-specific nervous system and used as a model for studying human autosomal dominant polycystic kidney disease (ADPKD). With the emergence of CRISPR, a seemingly limitless tool for generating genomic mutations with pinpoint precision, the C. elegans model system will continue to be a useful instrument for pioneering research in the fields of behavior, reproductive biology, and neurogenetics.
Asunto(s)
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/anatomía & histología , Proteínas de Ciclo Celular/genética , Organismos Hermafroditas/fisiología , Sistema Nervioso/anatomía & histología , Caracteres Sexuales , Estructuras Animales/crecimiento & desarrollo , Estructuras Animales/inervación , Estructuras Animales/ultraestructura , Animales , Sistemas CRISPR-Cas , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiología , Proteínas de Caenorhabditis elegans/fisiología , Cilios/química , Proteínas de Unión al ADN/fisiología , Modelos Animales de Enfermedad , Vesículas Extracelulares/fisiología , Organismos Hermafroditas/ultraestructura , Humanos , Interneuronas/fisiología , Masculino , Sistema Nervioso/crecimiento & desarrollo , Plasticidad Neuronal , Neuronas/clasificación , Neuronas/fisiología , Neuronas/ultraestructura , Neurotransmisores/fisiología , No Disyunción Genética , Riñón Poliquístico Autosómico Dominante/genética , Conducta Sexual Animal/fisiología , Canales Catiónicos TRPP/genética , Factores de Transcripción/fisiologíaAsunto(s)
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiología , Cilios/metabolismo , Vesículas Extracelulares/metabolismo , Canales Catiónicos TRPP/genética , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Organismos Hermafroditas/genética , Organismos Hermafroditas/fisiología , Masculino , Transporte de Proteínas , Reproducción , Canales Catiónicos TRPP/metabolismoRESUMEN
BACKGROUND: Flower longevity plays an important role in pollen dispersal and reproductive success in plants. In dichogamous plants, the duration of anthesis as well as the time allocated to male and female functions can vary in response to intrinsic factors (e.g., flowering time and resource allocation) and pollination context along a growth season. However, the fitness consequences of phenological dynamics have rarely been examined. This study aims to unravel the potential causes driving variation in flower longevity, duration of sex phases, and phenotypic sex during a flowering season of strongly protandrous Aconitum gymnandrum, and particularly reproductive consequences of the phenological pattern. RESULTS: Population floral sex ratio shifted from completely male at the beginning to completely female at the end of the season, as is common in other protandrous plants. Phenological dynamics of the floral sex ratio and the duration of sex phases caused a shift from femaleness to maleness in the mean phenotypic sex over the whole season. Floral longevity was negatively correlated with flower size and positively affected by temperature. Early flowers within inflorescences rather than early-flowering individuals emphasized the duration of female over male phase. Owing to the dominance of male-phase flowers, early flowering for individual flowers and plants, or female-biased sex resulted in higher pollen deposition per flower and seed set. At the flower level, flower longevity positively affected female reproductive success, while the effect of flower size was negative. By contrast, plant-level female reproductive success was negatively affected by flower longevity but positively correlated to flower size. CONCLUSIONS: The major result of this study lies in elucidating the relationship between variation in phenological sex expression and floral longevity and their fitness consequences of protandrous A. gymnandrum. The contrasting results on female fitness for individual flowers and plants contribute to our current understanding of the adaptive significance of floral longevity.
Asunto(s)
Aconitum/fisiología , Flores , Longevidad , Adaptación Fisiológica , Flores/crecimiento & desarrollo , Flores/fisiología , Organismos Hermafroditas/fisiología , Polinización/fisiología , Reproducción/fisiología , Estaciones del Año , Razón de Masculinidad , TundraRESUMEN
Egg trading-whereby simultaneous hermaphrodites exchange each other's eggs for fertilization-constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of nontrading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (cheaters who mate only in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of intermediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions, traders can invade-and resist invasion from-providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites.
Asunto(s)
Evolución Biológica , Organismos Hermafroditas/fisiología , Óvulo , Conducta Sexual Animal , Animales , Femenino , Masculino , Modelos Biológicos , ReproducciónRESUMEN
Many hermaphroditic organisms possess a self-incompatibility system to avoid inbreeding. Although the mechanisms of self-incompatibility in flowering plants are well known, little is known about the mechanisms of self-sterility in hermaphroditic marine invertebrates. Ascidians are hermaphroditic sessile marine invertebrates that release sperm and eggs into the surrounding seawater. Several species, including Ciona intestinalis type A (Ciona robusta), exhibit strict self-sterility. In a previous study, we found that the candidate genes responsible for self-sterility in Ciona reside in chromosome 2q (locus A) and chromosome 7q (locus B). Two pairs of multi-allelic genes, named s(sperm)-Themis-A and v(vitelline-coat)-Themis-A in locus A and s-Themis-B and v-Themis-B in locus B, are responsible for self-sterility. In this study, we identified a third multi-allelic gene pair, s-Themis-B2 and v-Themis-B2, within locus B that is also involved in this system. Genetic analysis revealed that the haplotypes of s/v-Themis-A, s/v-Themis-B and s/v-Themis-B2 play essential roles in self-sterility. When three haplotypes were matched between s-Themis and v-Themis, fertilization never occurred even in nonself crossing. Interestingly, gene targeting of either s/v-Themis-B/B2 or s/v-Themis-A by genome editing enabled self-fertilization. These results indicate that s/v-Themis-A, -B and -B2 are S-determinant genes responsible for self-sterility in the ascidian C. intestinalis type A.