The taxonomic status of Bufo species in East Asia,particularly those closely related to B.gargarizans,has been controversial for over half a century,and recent molecular studies further fueled the dispute.Whether B.an...The taxonomic status of Bufo species in East Asia,particularly those closely related to B.gargarizans,has been controversial for over half a century,and recent molecular studies further fueled the dispute.Whether B.andrewsi,B.bankorensis,B.minshanicus,B.sachalinensis,B.tibetanus,and B.tuberculatus constitute valid species or are geographic or ecological variants of B.gargarizans is at the centre of the discussion.Most of these forms possess morphological diagnostic traits,but those differences are minimal and often inconsistent.Molecular data produced many contradictory patterns.Lack of clear diagnostic characters,different usage or definition of various names,mis-identified specimens,limited amount of data or samples,and frequent inter-specific hybridization may all have contributed to the current controversies.Some contradiction may also result from differences between similarity-based clustering and gene tree-based branching patterns.Nevertheless,a dominant allopatric differentiation pattern within this species complex is apparent,and several regional population groups have been identified.Some of the groups resemble old names(e.g.B.minshanicus,B.tibetanus),while others are new.These groups may represent geographic or ecological variants,incipient species,or valid species,and the current data do not warrant a convincing taxonomic revision.To move forward,a single study with comprehensive sampling and genomic data is needed to establish a solid framework,which will define naturally existing population clusters/lineages,and detect their levels of divergence and approximate geographic boundaries.Morphological and ecological examination will follow to understand their biology,determine their taxonomic status,and identify consistent diagnostic characters if necessary.展开更多
Microelectrode technique was used to record the spontaneous electrical activities of the neurons in olfactory bulb of the Bufo bufo gargarizans, both in hibernation and after hibemation. This study investigated the el...Microelectrode technique was used to record the spontaneous electrical activities of the neurons in olfactory bulb of the Bufo bufo gargarizans, both in hibernation and after hibemation. This study investigated the electrophysiological characteristics of amphibian olfactory bulb in the period of hibernation and after hibernation and its effects on the start of hibernation and spontaneous awakening. The research showed four forms of spontaneous firings： single spontaneous firing, burst spontaneous firing, irregular spontaneous firing and consecutive single spontaneous firing. The single spontaneous firing includes slow depolarized spontaneous firing and fast depolarized spontaneous firing, and the slow depolarized spontaneous firing occurs only during the hibernation period. In hibernation, the low amplitude and low frequency firing with a longer duration may be relevant to maintaining the tonicity of the central nervous system in toads that are in hibernation, and this kind of firing may also provide an excited basis for their arousal from hibernation. After hibernation, the amplitude and frequency of firing increase, but the firing duration gets shorter. This form of short-term firing, which may be a phenomenon of sensory neurons fast adapting, is one of the neuronal mechanisms for the arousal of hibernating animals.展开更多
In many anurans, the forelimb muscles of males are used to grasp females and are often heavier than those of females despite the larger female body size. Such sexual dimorphism in forelimb musculature is thought to re...In many anurans, the forelimb muscles of males are used to grasp females and are often heavier than those of females despite the larger female body size. Such sexual dimorphism in forelimb musculature is thought to result from sexual selection. In addition, the hindlimbs of frogs and toads play an important role in the reproductive process as amplectant males can expel rivals with robust hindlimbs through kicking. In this study, the sexual dimorphism in dry mass for six hindlimb muscles of the Asiatic toad （Bufo gargarizans） was investigated. The results showed that, when controlled for body size, the hindlimb muscle mass of males significantly exceeded that of females for every muscle. The hindlimb muscle mass of amplectant males was also significantly larger than that of non-amplectant males. These results suggested that if strong hindlimb muscles could improve mating success of males, sexual selection would promote the evolution of dimorphism in this character.展开更多
Three anti-keratin MAbs were used to identifykeratins expressed in early embryos of Bufo bufogargarizans.MAb AF5 recognized three polypeptides ofkeratin in oocytes,fertilized eggs,up to neurula withMr of 68,65 and 60K...Three anti-keratin MAbs were used to identifykeratins expressed in early embryos of Bufo bufogargarizans.MAb AF5 recognized three polypeptides ofkeratin in oocytes,fertilized eggs,up to neurula withMr of 68,65 and 60Kd respectively.At tailbud stage,three other keratins(62,58 and 54Kd)began to expressand could be detected by AF5.MAbs D10 and K12 gavedifferent results,both of them could identify four keratin-like molecules with unusual molecular weights(Mr 98,95,30 and 27 Kd).Moreover,D10 could also detect a 54 Kdkeratin in neurula and tailbud stage embryos,while K12could reveal,beside 54Kd keratin,other four more kera-tins(68,65,62 and 60 Kd).The possible interpretation ofthese results and their implications are discussed.展开更多
Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of ...Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of B.gargarizans from Zhoushan Archipelago and adjacent continents and 71 published specimens of B.gargarizans from China's Mainland were studied.Phylogeographical and dating analyses of B.gargarizans were performed using mitochondrial DNA sequencing with a length of 1436 bp.A mt DNA tree that indicated seven major clades was obtained.The earliest split in the mt DNA tree corresponding to the divergence of populations from the western highland region occurred approximately 4.0 million years ago（mya）.A subsequent clade occurred about 3.4 mya,with cladogenesis continuing toward the end of the Pleistocene.The continental clades were distributed in the western,central and northeastern regions of China.Zhoushan Archipelago clades consisted of two largely geographically overlapping subclades with the mt DNA divergence time of 0.73 mya.These results indicated there was extensive dispersal after vicariance.The B.gargarizans populations on Zhoushan Archipelago most probably originated from populations in nearby eastern continental regions of China.It was concluded that geological uplifting during the Pliocene and several sea-level changes in Pleistocene might have influenced the divergence and population demographical history of this species.展开更多
A three-dimensional motion force tester for animal was used to measure the reaction forces of the feet of a Chinese toad (B. gargarizans) against a horizontal solid surface on which it crawled. The motion behavior of ...A three-dimensional motion force tester for animal was used to measure the reaction forces of the feet of a Chinese toad (B. gargarizans) against a horizontal solid surface on which it crawled. The motion behavior of the Chinese toad was recorded by a high-speed camera on line. The motor function of every foot was analyzed. It was found that the lateral force represents the control ability of side-to-side locomotion, controls the lateral movement, and maintains a stable state for the sustainable creeping gesture. The forefeet play the assistant role and the hind feet play the main role in driving. The normal force of the forefeet is significantly greater than that of the hind feet, so the forefeet play the main role in supporting the body and the hind feet play the assistant role. The normal force is significantly greater than the lateral force and the driving force as well. There is little change for the friction force and the support angle of the all four feet. The average value of the support angle is 70°–80°. The Chinese toad’s vola friction coefficient of the forefeet is less than that of the hind feet. The above results indicate that the difference in kinematics and the material characteristic of the contact skin of the Chinese toad. The results could be useful to the structure design and gait optimization of some robots.展开更多
Three new C-3 dehydrated bufadienolides were isolated from the venom of Bufo bufo gargarizans. Their structures were elucidated as 5β,12β-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide （1）, 5β,12β- 12,14-dihydrox...Three new C-3 dehydrated bufadienolides were isolated from the venom of Bufo bufo gargarizans. Their structures were elucidated as 5β,12β-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide （1）, 5β,12β- 12,14-dihydroxy-11 -oxobufa-2,20,22-trienolide （2）, and 5β,12β-12,14-dihydroxy-11 -oxobufa-2,20,22- trienolide （3） on the basis of extensive spectroscopic analysis, especially 1D NMR and 2D NMR data. In addition, all three compounds were tested for their cytotoxic activities against A549 and HepG2 cancer cell lines. Compounds 2 and 3 showed significant cytotoxicities with IC50 values less than 10 μmol/L on both cancer cells.展开更多
Two new bufotoxins,tolocinobufagin-3-succinoylarginine ester and tolocinobufagin-3-hemisuberate, were isolated from the skin of Bufo bufo gargarizans Cantor.Cinobufagin-3-hemisuberate was also isolated from the natura...Two new bufotoxins,tolocinobufagin-3-succinoylarginine ester and tolocinobufagin-3-hemisuberate, were isolated from the skin of Bufo bufo gargarizans Cantor.Cinobufagin-3-hemisuberate was also isolated from the natural source for the first time.Their structures were established using spectroscopic methods.展开更多
Anuran skin is a typical natural biomaterial with multifunctional features.A specific comparison of mechanical performance and morphology related to them was performed in the skin of Rana dybowskii and Bufo gargarizan...Anuran skin is a typical natural biomaterial with multifunctional features.A specific comparison of mechanical performance and morphology related to them was performed in the skin of Rana dybowskii and Bufo gargarizans using the tensile testing technique and morphological equipment.Rana dybowskii's skin has soft smooth surface covered by polygonal epidermal cells,while the Bufo gargarizans species has tough and uneven skin surface due to numerous verrucae structures.The collagen fibre bundles in lower dermis of Bufo gargarizans have wavelike organisation while the bundles of Rana dybowskii show a parallel arrangement.The mean elastic modulus of Rana dybowskii was nine times higher than that of Bufo gargarizans.This study clarified that the arrangement of collagen fibres play an important role in the strength and elasticity of skin material.展开更多
The pace-of-life syndrome(POLS) hypothesis predicts that most variation in life history, physiology,and behavior among individuals, popula tions, and species falls along a continuum from slow to fast pace of life. Whi...The pace-of-life syndrome(POLS) hypothesis predicts that most variation in life history, physiology,and behavior among individuals, popula tions, and species falls along a continuum from slow to fast pace of life. While there is evidence for climatic gradientmediated POLS patterns among species, this approach has rarely been explicitly used to study POLS patterns among-and within-populations. In addition, the roles of sex in POLS evolution among-or within-populations are largely unknown. In this study, we investigated the effects of altitudinal gradient and sex on the covariations between growth rate and several physiological traits closely associated with POLS(blood glucose, baselineand stress-induced glucocorticoids(GCs), hemolysis and hemagglutination) in the Asiatic toad Bufo gargarizans.Contrary to our expectation, altitudinal gradient had no influence on the covariations between growth rate and physiological traits, neither at the among-nor withinpopulation level, indicating that these trait integrations have similar fitness payoffs across hierarchical levels.In contrast, we found evidence for sex-specific POLS composition: there was a negative covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and hemagglutination-but only in males. This observation indicates that these trait associations differ dramatically in advancing fitness for each sex, and supports the idea that sex-specific POLS composition could evolve in species in which the reproductive roles largely differ between the sexes.展开更多
The 16S rDNA amplicon high-throughput sequencing technique provides a robust and inexpensive approach to detect the gut microbiota of amphibians. Since different experimental protocols generate technical biases in dra...The 16S rDNA amplicon high-throughput sequencing technique provides a robust and inexpensive approach to detect the gut microbiota of amphibians. Since different experimental protocols generate technical biases in drawing the gut microbiota profiles, the integrative analysis of gut microbiota produced by different studies must be performed with circumspection. In this study, we compared the efficacy of two DNA extraction methods （i.e., a phenol-chloroform method and TIANamp Stool DNA Kit） in describing intestinal and fecal bacterial communities of transplanted Asiatic toad （Bufo gargarizans） tadpoles. In terms of the DNA extraction quality （i.e., DNA purity and yield rate） and the consistency in between fecal and intestinal microbiota structures （i.e., a and 13 diversity indices）, the phenol-chloroform method was more robust than this commercial stool kit in profiling gut microbiota of tadpoles with feces.展开更多
Age and growth rate are critical parameters determining the body size of adult anurans,which grow indeterminately.Therefore,evaluating their relative importance and selective pressures acting on them may help to expla...Age and growth rate are critical parameters determining the body size of adult anurans,which grow indeterminately.Therefore,evaluating their relative importance and selective pressures acting on them may help to explain variation in body size of anurans across geographical populations.Based on the data on body size and skeletochronological age of 4 Asiatic toad(Bufo gargarizans)populations that are widely separated in latitude,the present study showed that toads at the northern extremity of the range were the oldest,on average,and grew relatively fast,toads at the southern end of the range were relatively old but grew fastest,whereas mid-latitude toads were intermediate in both traits.These results indicated that relative contributions of age and growth rate to body size differed among populations.From a life history perspective,greater age attained by toads at higher latitudes should result from delayed maturation,and faster growth from an adaptive response to strong seasonal time constraints;in contrast,selective pressures on the 2 parameters at lower latitudes might be associated,respectively,with low adult death rates and longer favorable growing seasons.展开更多
文摘The taxonomic status of Bufo species in East Asia,particularly those closely related to B.gargarizans,has been controversial for over half a century,and recent molecular studies further fueled the dispute.Whether B.andrewsi,B.bankorensis,B.minshanicus,B.sachalinensis,B.tibetanus,and B.tuberculatus constitute valid species or are geographic or ecological variants of B.gargarizans is at the centre of the discussion.Most of these forms possess morphological diagnostic traits,but those differences are minimal and often inconsistent.Molecular data produced many contradictory patterns.Lack of clear diagnostic characters,different usage or definition of various names,mis-identified specimens,limited amount of data or samples,and frequent inter-specific hybridization may all have contributed to the current controversies.Some contradiction may also result from differences between similarity-based clustering and gene tree-based branching patterns.Nevertheless,a dominant allopatric differentiation pattern within this species complex is apparent,and several regional population groups have been identified.Some of the groups resemble old names(e.g.B.minshanicus,B.tibetanus),while others are new.These groups may represent geographic or ecological variants,incipient species,or valid species,and the current data do not warrant a convincing taxonomic revision.To move forward,a single study with comprehensive sampling and genomic data is needed to establish a solid framework,which will define naturally existing population clusters/lineages,and detect their levels of divergence and approximate geographic boundaries.Morphological and ecological examination will follow to understand their biology,determine their taxonomic status,and identify consistent diagnostic characters if necessary.
基金Liaoning Provincial Department of Education-Funded Project, No. 20068040the Experimental Center of Shenyang Normal University Foundation, No. 2008007
文摘Microelectrode technique was used to record the spontaneous electrical activities of the neurons in olfactory bulb of the Bufo bufo gargarizans, both in hibernation and after hibemation. This study investigated the electrophysiological characteristics of amphibian olfactory bulb in the period of hibernation and after hibernation and its effects on the start of hibernation and spontaneous awakening. The research showed four forms of spontaneous firings： single spontaneous firing, burst spontaneous firing, irregular spontaneous firing and consecutive single spontaneous firing. The single spontaneous firing includes slow depolarized spontaneous firing and fast depolarized spontaneous firing, and the slow depolarized spontaneous firing occurs only during the hibernation period. In hibernation, the low amplitude and low frequency firing with a longer duration may be relevant to maintaining the tonicity of the central nervous system in toads that are in hibernation, and this kind of firing may also provide an excited basis for their arousal from hibernation. After hibernation, the amplitude and frequency of firing increase, but the firing duration gets shorter. This form of short-term firing, which may be a phenomenon of sensory neurons fast adapting, is one of the neuronal mechanisms for the arousal of hibernating animals.
基金supported by the National Natural Science Foundation of China(31101633)the Innovative Team Foundation of China West Normal University
文摘In many anurans, the forelimb muscles of males are used to grasp females and are often heavier than those of females despite the larger female body size. Such sexual dimorphism in forelimb musculature is thought to result from sexual selection. In addition, the hindlimbs of frogs and toads play an important role in the reproductive process as amplectant males can expel rivals with robust hindlimbs through kicking. In this study, the sexual dimorphism in dry mass for six hindlimb muscles of the Asiatic toad （Bufo gargarizans） was investigated. The results showed that, when controlled for body size, the hindlimb muscle mass of males significantly exceeded that of females for every muscle. The hindlimb muscle mass of amplectant males was also significantly larger than that of non-amplectant males. These results suggested that if strong hindlimb muscles could improve mating success of males, sexual selection would promote the evolution of dimorphism in this character.
文摘Three anti-keratin MAbs were used to identifykeratins expressed in early embryos of Bufo bufogargarizans.MAb AF5 recognized three polypeptides ofkeratin in oocytes,fertilized eggs,up to neurula withMr of 68,65 and 60Kd respectively.At tailbud stage,three other keratins(62,58 and 54Kd)began to expressand could be detected by AF5.MAbs D10 and K12 gavedifferent results,both of them could identify four keratin-like molecules with unusual molecular weights(Mr 98,95,30 and 27 Kd).Moreover,D10 could also detect a 54 Kdkeratin in neurula and tailbud stage embryos,while K12could reveal,beside 54Kd keratin,other four more kera-tins(68,65,62 and 60 Kd).The possible interpretation ofthese results and their implications are discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.41541002 and 31372183)Natural Science Foundation of Zhejiang Province(Grant No.LY13C030002),China
文摘Relatively little is known about the relationship between Bufo gargarizans populations from Zhoushan Archipelago and nearby continental regions on the Pacific coast of eastern China.In this paper,155 new specimens of B.gargarizans from Zhoushan Archipelago and adjacent continents and 71 published specimens of B.gargarizans from China's Mainland were studied.Phylogeographical and dating analyses of B.gargarizans were performed using mitochondrial DNA sequencing with a length of 1436 bp.A mt DNA tree that indicated seven major clades was obtained.The earliest split in the mt DNA tree corresponding to the divergence of populations from the western highland region occurred approximately 4.0 million years ago（mya）.A subsequent clade occurred about 3.4 mya,with cladogenesis continuing toward the end of the Pleistocene.The continental clades were distributed in the western,central and northeastern regions of China.Zhoushan Archipelago clades consisted of two largely geographically overlapping subclades with the mt DNA divergence time of 0.73 mya.These results indicated there was extensive dispersal after vicariance.The B.gargarizans populations on Zhoushan Archipelago most probably originated from populations in nearby eastern continental regions of China.It was concluded that geological uplifting during the Pliocene and several sea-level changes in Pleistocene might have influenced the divergence and population demographical history of this species.
基金supported by the Development Foundation of Science and Technology in Jilin Province of China (Grant No 20100711)the National 985 Project in Jilin University of China and the Graduate Innovation Foundation of National 985 Project in Jilin University of China (Grant No 20080105)
文摘A three-dimensional motion force tester for animal was used to measure the reaction forces of the feet of a Chinese toad (B. gargarizans) against a horizontal solid surface on which it crawled. The motion behavior of the Chinese toad was recorded by a high-speed camera on line. The motor function of every foot was analyzed. It was found that the lateral force represents the control ability of side-to-side locomotion, controls the lateral movement, and maintains a stable state for the sustainable creeping gesture. The forefeet play the assistant role and the hind feet play the main role in driving. The normal force of the forefeet is significantly greater than that of the hind feet, so the forefeet play the main role in supporting the body and the hind feet play the assistant role. The normal force is significantly greater than the lateral force and the driving force as well. There is little change for the friction force and the support angle of the all four feet. The average value of the support angle is 70°–80°. The Chinese toad’s vola friction coefficient of the forefeet is less than that of the hind feet. The above results indicate that the difference in kinematics and the material characteristic of the contact skin of the Chinese toad. The results could be useful to the structure design and gait optimization of some robots.
基金supported by National Natural Science Foundation of China(No.81102518)Postdoctoral Granted Financial Support(No.20110490915)the Guangdong High Level Talent Scheme(R.W.J.)
文摘Three new C-3 dehydrated bufadienolides were isolated from the venom of Bufo bufo gargarizans. Their structures were elucidated as 5β,12β-12,14-dihydroxy-11-oxobufa-3,20,22-trienolide （1）, 5β,12β- 12,14-dihydroxy-11 -oxobufa-2,20,22-trienolide （2）, and 5β,12β-12,14-dihydroxy-11 -oxobufa-2,20,22- trienolide （3） on the basis of extensive spectroscopic analysis, especially 1D NMR and 2D NMR data. In addition, all three compounds were tested for their cytotoxic activities against A549 and HepG2 cancer cell lines. Compounds 2 and 3 showed significant cytotoxicities with IC50 values less than 10 μmol/L on both cancer cells.
基金supported by the National Construction Project of Traditional Chinese Medicine
文摘Two new bufotoxins,tolocinobufagin-3-succinoylarginine ester and tolocinobufagin-3-hemisuberate, were isolated from the skin of Bufo bufo gargarizans Cantor.Cinobufagin-3-hemisuberate was also isolated from the natural source for the first time.Their structures were established using spectroscopic methods.
文摘Anuran skin is a typical natural biomaterial with multifunctional features.A specific comparison of mechanical performance and morphology related to them was performed in the skin of Rana dybowskii and Bufo gargarizans using the tensile testing technique and morphological equipment.Rana dybowskii's skin has soft smooth surface covered by polygonal epidermal cells,while the Bufo gargarizans species has tough and uneven skin surface due to numerous verrucae structures.The collagen fibre bundles in lower dermis of Bufo gargarizans have wavelike organisation while the bundles of Rana dybowskii show a parallel arrangement.The mean elastic modulus of Rana dybowskii was nine times higher than that of Bufo gargarizans.This study clarified that the arrangement of collagen fibres play an important role in the strength and elasticity of skin material.
基金financially supported by grants for the Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment of China (2019HJ2096001006) to J. F. CHENthe National Natural Science Foundation of China (31370431) to,the National Natural Science Foundation of China (31729003) to J. F. CHENthe Sichuan Provincial Science and Technology Department (2018JY0617) to J. F. CHEN。
文摘The pace-of-life syndrome(POLS) hypothesis predicts that most variation in life history, physiology,and behavior among individuals, popula tions, and species falls along a continuum from slow to fast pace of life. While there is evidence for climatic gradientmediated POLS patterns among species, this approach has rarely been explicitly used to study POLS patterns among-and within-populations. In addition, the roles of sex in POLS evolution among-or within-populations are largely unknown. In this study, we investigated the effects of altitudinal gradient and sex on the covariations between growth rate and several physiological traits closely associated with POLS(blood glucose, baselineand stress-induced glucocorticoids(GCs), hemolysis and hemagglutination) in the Asiatic toad Bufo gargarizans.Contrary to our expectation, altitudinal gradient had no influence on the covariations between growth rate and physiological traits, neither at the among-nor withinpopulation level, indicating that these trait integrations have similar fitness payoffs across hierarchical levels.In contrast, we found evidence for sex-specific POLS composition: there was a negative covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and hemagglutination-but only in males. This observation indicates that these trait associations differ dramatically in advancing fitness for each sex, and supports the idea that sex-specific POLS composition could evolve in species in which the reproductive roles largely differ between the sexes.
基金supported by the National Natural Science Foundation of China (NSFC 31600104)Key Scientific Research Project of Higher Education in Henan Province (No. 17B180004)+2 种基金National Undergraduate Training Program for Innovation and Entrepreneurship (No. 201610477013)Ph.D. Research Startup Foundation of Xinyang Normal University (No. 0201424)Nanhu Scholars Program for Young Scholars of Xinyang Normal University
文摘The 16S rDNA amplicon high-throughput sequencing technique provides a robust and inexpensive approach to detect the gut microbiota of amphibians. Since different experimental protocols generate technical biases in drawing the gut microbiota profiles, the integrative analysis of gut microbiota produced by different studies must be performed with circumspection. In this study, we compared the efficacy of two DNA extraction methods （i.e., a phenol-chloroform method and TIANamp Stool DNA Kit） in describing intestinal and fecal bacterial communities of transplanted Asiatic toad （Bufo gargarizans） tadpoles. In terms of the DNA extraction quality （i.e., DNA purity and yield rate） and the consistency in between fecal and intestinal microbiota structures （i.e., a and 13 diversity indices）, the phenol-chloroform method was more robust than this commercial stool kit in profiling gut microbiota of tadpoles with feces.
基金The National Sciences Foundation of China provided financial support(Grant 30425036).
文摘Age and growth rate are critical parameters determining the body size of adult anurans,which grow indeterminately.Therefore,evaluating their relative importance and selective pressures acting on them may help to explain variation in body size of anurans across geographical populations.Based on the data on body size and skeletochronological age of 4 Asiatic toad(Bufo gargarizans)populations that are widely separated in latitude,the present study showed that toads at the northern extremity of the range were the oldest,on average,and grew relatively fast,toads at the southern end of the range were relatively old but grew fastest,whereas mid-latitude toads were intermediate in both traits.These results indicated that relative contributions of age and growth rate to body size differed among populations.From a life history perspective,greater age attained by toads at higher latitudes should result from delayed maturation,and faster growth from an adaptive response to strong seasonal time constraints;in contrast,selective pressures on the 2 parameters at lower latitudes might be associated,respectively,with low adult death rates and longer favorable growing seasons.
