Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months unti...Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months until the egg mature in ovary,while the adaptive evolution of fertilization-related genes remains to be studied.In the present study,based on the genome and transcriptome information of black rockfish,a total of 10 hyaluronidase genes were identified by phylogenetic and sequence analyses,including hyal1,hyal2,hyal3,hyal4,hyal6 and spam1a,spam1b,spam1c and spam1d.The spam1 subfamilies,including spam1a,spam1b,spam1c and spam1d,were significantly expanded compared to other species.The adaptive evolution of hyaluronidase was further investigated by selection pressure analysis of branch model and branch site model.The results showed that only spam1 subfamily was positively selected with a large number of positive selection sites,and the evolution rate was significantly higher thanthose of other teleosts.Two positively selected sites,LYS-171 and GLY-164,were located in the neutral hyaluronidase activity domain,which was pivotal for SPAM1 to participate in enzymatic hydrolysis of the extracellular hyaluronic acid matrix and mediate acrosome reaction in mammals.Furthermore,spam1 was mainly expressed in spermatocytes,secondary spermatocytes,and spermatids of testis,whereas it was not found in metamorphic sperm and mature sperm based on the spatiotemporal expression analysis.All results indicated that spam1 might originate from the testis and might be an adaptation of viviparous trait in black rockfish.展开更多
Aims: Aim was to evaluate the anti-osteoporotic and anti-osteoarthritic activity of fresh water snail (Viviparous bengalensis) (VB) flesh extract (VBE) in experimental model. Settings and Design: Experimental osteopor...Aims: Aim was to evaluate the anti-osteoporotic and anti-osteoarthritic activity of fresh water snail (Viviparous bengalensis) (VB) flesh extract (VBE) in experimental model. Settings and Design: Experimental osteoporosis (OSP) was developed in female Wistar rats by bilateral overectomy and Osteoarthritis (OA) was developed in male Wistar rats by bacterial collagenase injection. Methods and Material: VB was collected locally and authenticated, then homogenized in 3500 rpm × 15 mins and supernatant was collected. Rats were divided into-Group-1: Sham control, Group-2: OSP/OA control, Group-3: Standard (vitD3 200 mg·kg -1;p.o., calcium i.p. 1500 mg·kg -1?× 15 days in OSP and indomethacin 0.25 mg·kg-1, p.o. × 5 alternative days in OA), Group-4: VBE treated (1 gm·kg-1;p.o. × 15 days), Group-5: VBE treated (2 mg·kg-1;p.o. × 15 days). Anti-osteoporotic and anti-osteoarthritic activity of VBE was examined through physical, urinary and serum parameters. Statistical use: Data were expressed in terms of mean ± SEM (n = 6). ANOVA was performed, p Key findings: It was observed that the body weight, ankle/ knee diameters, urinary markers hydroxyproline/glucosamine/calcium/phosphate/creatinine, serum ACP/ALP/TRAP, calcium/creatinine, cytokines (TNF-α/IL-1β/CINC-1) levels were changed significantly and restored after VBE treatment. Significance: Fresh water snail flesh extract possess anti-osteoporosis and anti-osteoarthritic activity in experimental animal models.展开更多
We studied the cycles of reproduction and fat bodies of a blue-tailed skink population of an undescribed species of the Plestiodon brevirostris group.Sexual maturity is attained by females and males as they both reach...We studied the cycles of reproduction and fat bodies of a blue-tailed skink population of an undescribed species of the Plestiodon brevirostris group.Sexual maturity is attained by females and males as they both reach about 59 mm of SVL.Vitellogenesis started in June-July,with ovulation occurring during late-October to mid-November,and parturition in mid-spring.Litter size varied from two to six,with a mean of 3.86±0.15 embryos in uterus,and showed a positive correlation with female body mass and SVL.During gestation,a significant increase in the average wet mass of embryos in uterus was evident.In comparison,there were no notable changes in the average dry mass.Juvenile growth data suggest that sexual maturity,both males and females,is reached at 16-17 months of age.Testicles and epididymides exhibited maximal weight during August-September.Testicular regression occurred in September.Mating apparently takes place from mid-summer to early fall.Lipids stored in female fat bodies are used for vitellogenesis and for nutrition during the winter months.In males,the stored lipids appear to be used in reproductive activities during the mating season.展开更多
We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-...We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-Burma hotspot region. A regular method of field sampling of various forest types was used to map the bamboo species in Assam, India. Moreover, people＇s perception on bamboo blooming was investigated at 17 sample plots covering 258 respondents inhabiting at the site at an average of 15 in each plots. A floral clump （inflorescence） emerged and developed into a giant panicle comprising of numerous florets. Two types of seeds viz. bacea and caryopsis were recorded in different species. Viviparous germination was noticed in few bacca seeds produced by M. baccifera and this has unusual occurrence in bamboo. Seed viability test shows that 75% caryopsis seeds were viable; these seeds had the potential of germination and can be used for mass regen- eration. Most local respondents believe that bamboo flowering can result in population explosion of rodent, therefore, they think bamboo flower- ing is positively correlated with famine. This traditional belief results in massive destruction of bamboo clumps, which significantly impacts on rural economy.展开更多
Many species are shifting towards higher altitudes in response to global wa rming, but how these upslope-shifting species will respond to hypoxic environments at high altitudes remains unclear. Hypoxia can be especial...Many species are shifting towards higher altitudes in response to global wa rming, but how these upslope-shifting species will respond to hypoxic environments at high altitudes remains unclear. Hypoxia can be especially challenging for viviparous reproduction because of the limitation of oxygen supply to the female and her developing embryos. To investigate the effect of hypoxia on viviparous females and their offspring we acclimated pregnant females of a high-altitude dwelling vivipa rous liza rd(Phr ynocephalus vlangalii) to local oxygen and hypoxia conditions, respectively. We then recorded maternal body temperatures, postpartum body condition, as well as offspring morphology and locomotor performance. We found that pregnant females had higher body temperatures and advanced their parturition under hypoxic acclimation. However, maternal body condition, offspring morphology and locomotor performance were unaffected by the hypoxic conditions during gestation. Our study suggests that upslope-shifting viviparous lizards respond to hypoxic environments by plastically adjusting their body tempera tures to reduce parturition time, without short-term costs to offspring traits.展开更多
The process of rooting of propagules is one of the critical aspects fordiscussing the ecological expansion of mangrove populations.By the experimentsof culture,we found out that this process was controlled by light in...The process of rooting of propagules is one of the critical aspects fordiscussing the ecological expansion of mangrove populations.By the experimentsof culture,we found out that this process was controlled by light in the viviparoushypocotyl of Kandelia candel.This discovery supplies a favourable access toexplain why the floating propagules of K.candel can remain alive for a long timeon the sea and be successfully dispersed by tides.展开更多
Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with ...Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if mor- phological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact dif- ferences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection [Current Zoology 58 （3）： 440-452, 2012].展开更多
To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five t...To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five thermally different natural nests and at two constant temperatures （18℃ and 21 ℃）. Our manipulation of incubation temperature had significant effects on incubation length and several hatchling traits （snout-vent length, tail length, fore-limb length, and sprint speed）, but not on hatching success and other hatchling traits examined （body mass, head size, and hind-limb length）. Incubation length was nonlinearly sensitive to temperature, but it was not correlated with the thermal variance when holding the thermal mean constant. The 18 ℃ treatment not only produced smaller sized hatchlings but also resulted in decreased sprint speed. Eggs in the nest with the greatest proportion of temperatures higher than 28 ℃ also produced smaller sized hatchlings. None of the hatchling traits examined was affected by the thermal variance. Thermal fluctuations did result in longer incubation times, but females would benefit little from maintaining stable body temperatures or selecting thermally stable nests in terms of the reduced incubation length. Our data show that the mean rather than the variance of temperatures has a key role in influencing incubation length and hatchling phenotypes, and thus do not support the hypothesis tested .展开更多
Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identi...Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identify which factors are associated with such differences. The dataset included 732 effect size estimates from 100 articles （82 species）. Larger unsigned effect size （meaning larger sexual differences in a given marker） occurred in： reptiles and fish; those species that do not pro- vide parental care; and oviparous species. Estimates of signed effect size （positive values meaning higher oxidative stress in males） indicated that females were less resistant to oxidative stress than males in： reptiles while males and females were similar in fish, birds, and mammals; those species that do not provide parental care; and oviparous species. There was no evidence for a significant sexual differentiation in oxidative balance in fish, birds, and mammals. Effect size was not associ- ated with： the number of offspring; whether the experimental animals were reproducing or not; biomarker （oxidative damage, non-enzymatic, or enzymatic antioxidant）, the species body mass; the strain （wild vs. domestic）; or the study environment （wild vs. captivity）. Oxidative stress tended to be higher in females than males across most of the tissues analyzed. Levels of residual heterogeneity were high in all models tested. The findings of this meta-analysis indicate that diversification of reproductive strategies might be associated with sexual differences in oxidative balance. This explorative meta-analysis offers a starting platform for future research to investigate the rela-tionship between sex and oxidative balance further.展开更多
Rensch’s rule relates to a pattern whereby sexual size dimorphism is more female-biased in small-sized species and more male-biased in large-sized ones.We collected literature and museum data on the body size of male...Rensch’s rule relates to a pattern whereby sexual size dimorphism is more female-biased in small-sized species and more male-biased in large-sized ones.We collected literature and museum data on the body size of males and females belonging to 4032 lizard species,as well as data on their reproductive modes and clutch sizes.We used phylogenetic comparative analyses,and general linear mixed models,to test Rensch’s rule and examined how re-productive mode and clutch size affect sexual size dimorphism.Sexual size dimorphism was independent of clutch size in lizard species with variable clutch sizes and in oviparous lizards.Large litters were associated with female-biased sexual dimorphism in viviparous and in scincomorph lizards.Inference regarding Rensch’s rule depended on the analytical method used to identify it.The widely used,but less conservative,reduced major axis regression usually support Rensch’s rule while ordinary least squares regressions mostly show isometric relationships.The rule tended to apply more to oviparous than to viviparous lizards.We infer that Rensch’s rule is,at best,a weak pattern in lizards.This is especially true in viviparous lineages where females reproduce infrequently and therefore evolve large sizes to maximise fecundity,resulting in female-biased dimorphism.展开更多
Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil r...Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil record. The Peltopleuriformes from the Middle to Late Triassic of Europe and South China are a stem group of Neopterygii that may have first evolved internal fertilization and viviparity in this clade because they show a highly modified anal fin in presumed males resembling the intromittent organ in living viviparous teleosts. Until recently, Peltopleurus lissocephalus and P. rugosus from the Ladinian/Anisian boundary(*242 Ma) of Monte San Giorgio area in Switzerland and Italy represent the oldest record of Peltopleuriformes, and the phylogenetic interrelationships of this group remain controversial. Here, we report the discovery of a new peltopleuriform, Peltopleurus nitidus sp. nov., based on eleven well-preserved specimens from the early Middle Triassic(Pelsonian, Anisian, *244 Ma)of Luoping, eastern Yunnan, China. The discovery documents the oldest convincing peltopleuriform, extending the geological range of this clade by proximately two million years. Results of the phylogenetic analysis recover P.nitidus at the base of Peltopleuridae, and provide robust support for the sister-group relationships of Peltopleuridae with Thoracopteridae within the Peltopleuriformes. The male anal fin of P. nitidus shows a primitive condition unknown in other peltopleuriforms. Comparative studies of the male anal fin in P. nitidus and other peltopleuriforms shed new light on the internal fertilization in this group.展开更多
基金supported by the National Natural Science Foundation of China(Nos.32273133,31970492).
文摘Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months until the egg mature in ovary,while the adaptive evolution of fertilization-related genes remains to be studied.In the present study,based on the genome and transcriptome information of black rockfish,a total of 10 hyaluronidase genes were identified by phylogenetic and sequence analyses,including hyal1,hyal2,hyal3,hyal4,hyal6 and spam1a,spam1b,spam1c and spam1d.The spam1 subfamilies,including spam1a,spam1b,spam1c and spam1d,were significantly expanded compared to other species.The adaptive evolution of hyaluronidase was further investigated by selection pressure analysis of branch model and branch site model.The results showed that only spam1 subfamily was positively selected with a large number of positive selection sites,and the evolution rate was significantly higher thanthose of other teleosts.Two positively selected sites,LYS-171 and GLY-164,were located in the neutral hyaluronidase activity domain,which was pivotal for SPAM1 to participate in enzymatic hydrolysis of the extracellular hyaluronic acid matrix and mediate acrosome reaction in mammals.Furthermore,spam1 was mainly expressed in spermatocytes,secondary spermatocytes,and spermatids of testis,whereas it was not found in metamorphic sperm and mature sperm based on the spatiotemporal expression analysis.All results indicated that spam1 might originate from the testis and might be an adaptation of viviparous trait in black rockfish.
文摘Aims: Aim was to evaluate the anti-osteoporotic and anti-osteoarthritic activity of fresh water snail (Viviparous bengalensis) (VB) flesh extract (VBE) in experimental model. Settings and Design: Experimental osteoporosis (OSP) was developed in female Wistar rats by bilateral overectomy and Osteoarthritis (OA) was developed in male Wistar rats by bacterial collagenase injection. Methods and Material: VB was collected locally and authenticated, then homogenized in 3500 rpm × 15 mins and supernatant was collected. Rats were divided into-Group-1: Sham control, Group-2: OSP/OA control, Group-3: Standard (vitD3 200 mg·kg -1;p.o., calcium i.p. 1500 mg·kg -1?× 15 days in OSP and indomethacin 0.25 mg·kg-1, p.o. × 5 alternative days in OA), Group-4: VBE treated (1 gm·kg-1;p.o. × 15 days), Group-5: VBE treated (2 mg·kg-1;p.o. × 15 days). Anti-osteoporotic and anti-osteoarthritic activity of VBE was examined through physical, urinary and serum parameters. Statistical use: Data were expressed in terms of mean ± SEM (n = 6). ANOVA was performed, p Key findings: It was observed that the body weight, ankle/ knee diameters, urinary markers hydroxyproline/glucosamine/calcium/phosphate/creatinine, serum ACP/ALP/TRAP, calcium/creatinine, cytokines (TNF-α/IL-1β/CINC-1) levels were changed significantly and restored after VBE treatment. Significance: Fresh water snail flesh extract possess anti-osteoporosis and anti-osteoarthritic activity in experimental animal models.
基金funded by the Biology Major of the Facultad de Estudios Superiores Zaragoza,Universidad Nacional Autónoma de México(UNAM)Scientific collecting permit issued by Semarnat(SGPA/DGVS 12013/12)。
文摘We studied the cycles of reproduction and fat bodies of a blue-tailed skink population of an undescribed species of the Plestiodon brevirostris group.Sexual maturity is attained by females and males as they both reach about 59 mm of SVL.Vitellogenesis started in June-July,with ovulation occurring during late-October to mid-November,and parturition in mid-spring.Litter size varied from two to six,with a mean of 3.86±0.15 embryos in uterus,and showed a positive correlation with female body mass and SVL.During gestation,a significant increase in the average wet mass of embryos in uterus was evident.In comparison,there were no notable changes in the average dry mass.Juvenile growth data suggest that sexual maturity,both males and females,is reached at 16-17 months of age.Testicles and epididymides exhibited maximal weight during August-September.Testicular regression occurred in September.Mating apparently takes place from mid-summer to early fall.Lipids stored in female fat bodies are used for vitellogenesis and for nutrition during the winter months.In males,the stored lipids appear to be used in reproductive activities during the mating season.
文摘We recorded gregarious flowering of three bamboo species viz. Bambusa arundinacea, Bambusa tulda and Melocanna baccifera during rainy season from early March to late May, 2008 at lowland forest of Bajali area of Indo-Burma hotspot region. A regular method of field sampling of various forest types was used to map the bamboo species in Assam, India. Moreover, people＇s perception on bamboo blooming was investigated at 17 sample plots covering 258 respondents inhabiting at the site at an average of 15 in each plots. A floral clump （inflorescence） emerged and developed into a giant panicle comprising of numerous florets. Two types of seeds viz. bacea and caryopsis were recorded in different species. Viviparous germination was noticed in few bacca seeds produced by M. baccifera and this has unusual occurrence in bamboo. Seed viability test shows that 75% caryopsis seeds were viable; these seeds had the potential of germination and can be used for mass regen- eration. Most local respondents believe that bamboo flowering can result in population explosion of rodent, therefore, they think bamboo flower- ing is positively correlated with famine. This traditional belief results in massive destruction of bamboo clumps, which significantly impacts on rural economy.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA20050201 and XDB31000000)the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0501)the National Natural Science Fund of China (31801987 and 31870391)。
文摘Many species are shifting towards higher altitudes in response to global wa rming, but how these upslope-shifting species will respond to hypoxic environments at high altitudes remains unclear. Hypoxia can be especially challenging for viviparous reproduction because of the limitation of oxygen supply to the female and her developing embryos. To investigate the effect of hypoxia on viviparous females and their offspring we acclimated pregnant females of a high-altitude dwelling vivipa rous liza rd(Phr ynocephalus vlangalii) to local oxygen and hypoxia conditions, respectively. We then recorded maternal body temperatures, postpartum body condition, as well as offspring morphology and locomotor performance. We found that pregnant females had higher body temperatures and advanced their parturition under hypoxic acclimation. However, maternal body condition, offspring morphology and locomotor performance were unaffected by the hypoxic conditions during gestation. Our study suggests that upslope-shifting viviparous lizards respond to hypoxic environments by plastically adjusting their body tempera tures to reduce parturition time, without short-term costs to offspring traits.
文摘The process of rooting of propagules is one of the critical aspects fordiscussing the ecological expansion of mangrove populations.By the experimentsof culture,we found out that this process was controlled by light in the viviparoushypocotyl of Kandelia candel.This discovery supplies a favourable access toexplain why the floating propagules of K.candel can remain alive for a long timeon the sea and be successfully dispersed by tides.
文摘Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if mor- phological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact dif- ferences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection [Current Zoology 58 （3）： 440-452, 2012].
基金The work was carried out in compliance with the current laws of China, and was supported by grant from Priority Academic Program Development of Jiangsu Higher Education Institutions to Ji＇s group, the Natural Science Foundation of the Jiangsu Higher Education Institutions of China （Project No. llKJB180004）, Jiangsu Provincial Foundation of Natural Science （No. BK2012849） and the Natural Science Foundation of China （No. 31070339）. We would like to thank Long-Hui Lin, Jian-Fang Gao, Lai-Gao Luo andYan-Fu Qu for their assistance both in the field and in the laboratory.
文摘To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five thermally different natural nests and at two constant temperatures （18℃ and 21 ℃）. Our manipulation of incubation temperature had significant effects on incubation length and several hatchling traits （snout-vent length, tail length, fore-limb length, and sprint speed）, but not on hatching success and other hatchling traits examined （body mass, head size, and hind-limb length）. Incubation length was nonlinearly sensitive to temperature, but it was not correlated with the thermal variance when holding the thermal mean constant. The 18 ℃ treatment not only produced smaller sized hatchlings but also resulted in decreased sprint speed. Eggs in the nest with the greatest proportion of temperatures higher than 28 ℃ also produced smaller sized hatchlings. None of the hatchling traits examined was affected by the thermal variance. Thermal fluctuations did result in longer incubation times, but females would benefit little from maintaining stable body temperatures or selecting thermally stable nests in terms of the reduced incubation length. Our data show that the mean rather than the variance of temperatures has a key role in influencing incubation length and hatchling phenotypes, and thus do not support the hypothesis tested .
文摘Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identify which factors are associated with such differences. The dataset included 732 effect size estimates from 100 articles （82 species）. Larger unsigned effect size （meaning larger sexual differences in a given marker） occurred in： reptiles and fish; those species that do not pro- vide parental care; and oviparous species. Estimates of signed effect size （positive values meaning higher oxidative stress in males） indicated that females were less resistant to oxidative stress than males in： reptiles while males and females were similar in fish, birds, and mammals; those species that do not provide parental care; and oviparous species. There was no evidence for a significant sexual differentiation in oxidative balance in fish, birds, and mammals. Effect size was not associ- ated with： the number of offspring; whether the experimental animals were reproducing or not; biomarker （oxidative damage, non-enzymatic, or enzymatic antioxidant）, the species body mass; the strain （wild vs. domestic）; or the study environment （wild vs. captivity）. Oxidative stress tended to be higher in females than males across most of the tissues analyzed. Levels of residual heterogeneity were high in all models tested. The findings of this meta-analysis indicate that diversification of reproductive strategies might be associated with sexual differences in oxidative balance. This explorative meta-analysis offers a starting platform for future research to investigate the rela-tionship between sex and oxidative balance further.
基金supported by funds provided to L.S.by the National Natural Science Foundation of China(31660613).
文摘Rensch’s rule relates to a pattern whereby sexual size dimorphism is more female-biased in small-sized species and more male-biased in large-sized ones.We collected literature and museum data on the body size of males and females belonging to 4032 lizard species,as well as data on their reproductive modes and clutch sizes.We used phylogenetic comparative analyses,and general linear mixed models,to test Rensch’s rule and examined how re-productive mode and clutch size affect sexual size dimorphism.Sexual size dimorphism was independent of clutch size in lizard species with variable clutch sizes and in oviparous lizards.Large litters were associated with female-biased sexual dimorphism in viviparous and in scincomorph lizards.Inference regarding Rensch’s rule depended on the analytical method used to identify it.The widely used,but less conservative,reduced major axis regression usually support Rensch’s rule while ordinary least squares regressions mostly show isometric relationships.The rule tended to apply more to oviparous than to viviparous lizards.We infer that Rensch’s rule is,at best,a weak pattern in lizards.This is especially true in viviparous lineages where females reproduce infrequently and therefore evolve large sizes to maximise fecundity,resulting in female-biased dimorphism.
基金supported by the National Natural Science Foundation of China (41672001 and 41272002)State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (143114)supported by a grant from the Chinese Academy of Sciences
文摘Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil record. The Peltopleuriformes from the Middle to Late Triassic of Europe and South China are a stem group of Neopterygii that may have first evolved internal fertilization and viviparity in this clade because they show a highly modified anal fin in presumed males resembling the intromittent organ in living viviparous teleosts. Until recently, Peltopleurus lissocephalus and P. rugosus from the Ladinian/Anisian boundary(*242 Ma) of Monte San Giorgio area in Switzerland and Italy represent the oldest record of Peltopleuriformes, and the phylogenetic interrelationships of this group remain controversial. Here, we report the discovery of a new peltopleuriform, Peltopleurus nitidus sp. nov., based on eleven well-preserved specimens from the early Middle Triassic(Pelsonian, Anisian, *244 Ma)of Luoping, eastern Yunnan, China. The discovery documents the oldest convincing peltopleuriform, extending the geological range of this clade by proximately two million years. Results of the phylogenetic analysis recover P.nitidus at the base of Peltopleuridae, and provide robust support for the sister-group relationships of Peltopleuridae with Thoracopteridae within the Peltopleuriformes. The male anal fin of P. nitidus shows a primitive condition unknown in other peltopleuriforms. Comparative studies of the male anal fin in P. nitidus and other peltopleuriforms shed new light on the internal fertilization in this group.
