隆肛蛙幼体脊椎骨骼的发育

无尾两栖类幼体在水栖到陆栖环境的转变过程中,脊椎骨会发生重塑来适应陆栖环境。本研究采用茜素红和阿利新蓝对不同发育阶段的隆肛蛙Feirana quadranus幼体的脊椎骨进行双染色,描述幼体发育中脊椎骨形态发生过程。本研究结果显示,在Gosner 26期,荐前椎Ⅰ~Ⅷ的椎弓和椎体开始骨化,提示无尾两栖类幼体发育持续时间越长,其骨化起始时期可能越早。在Gosner 42期,脊椎骨前后关节形成。在Gosner 46期,荐后椎和底索愈合形成尾杆骨。前后关节和尾杆骨的形成时期与大多无尾两栖类幼体基本一致。本研究推测,脊椎骨前后关节的形成有利于前肢和后肢的协调运动;尾杆骨的出现有利于后肢力量的传递。     

中华大蟾蜍蝌蚪变态过程中肩带与前肢的发育及骨化次序

本文采用骨骼双染色法,对中华大蟾蜍(Bufo gargarizans)33~46期蝌蚪的肩带及前肢骨的发育和骨化次序进行了研究。结果显示,中华大蟾蜍蝌蚪的肩带从36期开始出现,39期通过肌肉与荐前椎Ⅱ、Ⅲ连接,在45期胸骨出现,肩带各结构的出现和骨化起始于肩臼窝邻近的范围;前肢骨出现及骨化的方向是从近端到远端、从轴后到轴前的。肩带和前肢骨的出现有助于缓冲无尾两栖类登陆后运动产生的振动,反映了无尾类蝌蚪在变态过程中由水栖生活到陆栖生活的适应。     

中华大蟾蜍蝌蚪后肢骨的发育及骨化顺序研究

本研究对中华大蟾蜍Bufo gargarizans不同发育时期蝌蚪的腰带和后肢骨进行双染色。结果显示,在中华大蟾蜍蝌蚪中,后肢软骨化和骨化顺序都是由近端到远端,但在远端肢体的发育模式则呈轴后支配的特征。中华大蟾蜍蝌蚪Gosner 40期,两侧髂骨作合掌式对接融合,提示髂骨融合为无尾类由水生到陆生栖息环境的转换做准备。     

浙江丽水中华大蟾蜍和黑眶蟾蜍蝌蚪对水位变化的表型响应

全球气候变暖引发栖息地干涸将对生活在水中的无尾类幼体提出了挑战。通过浙江丽水中华大蟾蜍(Bufo gargarizans)和黑眶蟾蜍(Duttaphrynus melanosticus)蝌蚪在实验条件下对不同水位变化的表型响应,检测表型可塑性的遗传性和环境近因性影响。结果表明,水位变化对中华大蟾蜍蝌蚪早期发育历期、头宽和体重影响不显著,对体长影响显著,其中逐减水位最大、恒低水位最小,慢波、恒高与快波、逐增水位依次减少;水位变化对黑眶蟾蜍蝌蚪早期发育历期、体长、头宽和体重影响均显著;发育历期以恒高水位最大,恒低水位最小;体长以逐减水位最大,恒低、快波和慢波水位显著偏小,逐增和快波水位居中;头宽以恒低水位最小,逐增水位居中,其余较大;体重以恒低水位最小、恒高水位最大,其余居中。水位变化对中华大蟾蜍蝌蚪的变态时间、体长、头宽和体重影响均不显著;水位变化对黑眶蟾蜍蝌蚪的变态时间、体长和体重影响均显著,对头宽影响不显著;恒低水位的变态时间最长,恒高水位的变态时间最短,其他水位变化之间差异不显著;恒高水位的体长最大,恒低和快波水位最小,其他居中;逐增和快波水位的体重最大,恒低水位最小。研究结果表明,繁殖季节不同的中华大蟾蜍和黑眶蟾蜍蝌蚪响应水位变化的表型可塑性差异显著,长期在容易发生干旱和水位变化的冬季繁殖的中华大蟾蜍蝌蚪的表型可塑性低,在雨水充沛的春季繁殖的黑眶蟾蜍蝌蚪的表型可塑性高,表现出表型可塑性的种间差异和遗传性;在早期发育过程中,两种蝌蚪体长的共同的表型变异与缺乏遗传基础的环境近因性影响有关;黑眶蟾蜍蝌蚪对低水位或水位下降作出减速分化的消极响应,响应程度与环境信号的强弱直接相关。     

中国林蛙与中华蟾蜍蝌蚪颅骨形态的系统进化比较

对无尾两栖动物系统进化的研究,主要是基于经典的形态学、现代分子生物学等技术。无尾两栖动物蝌蚪的进化与成体的进化可能是两个独立的过程,所以无尾两栖类蝌蚪形态及发育特征也可以作为研究系统进化的重要指征。本文对中国林蛙(Rana chensinensis)及中华蟾蜍(Bufo gargarizans)变态前蝌蚪的软骨性颅骨及鳃部骨骼进行形态学描述,基于幼体形态特征,进行系统建树。建树结果支持Orton将无尾两栖类蝌蚪划分为4种类型,认为最原始的类群为Ⅲ型蝌蚪,与Tihen的观点一致。新蛙亚目的中国林蛙和中华蟾蜍蝌蚪属Ⅳ型,是最进化的类群。     

新疆北鲵骨骼系统及骨骼发育时序特征

为揭示新疆北鲵(Ranodon sibiricus)骨骼系统特征及骨骼发育时序规律,采用“软骨-硬骨”双染色法对2月龄、3月龄、4月龄、6月龄、1龄、2龄、3龄和9龄8个不同年龄段新疆北鲵骨骼系统进行详细观察和对比分析。结果表明新疆北鲵骨骼系统分为头骨、脊椎骨和附肢骨三大部分,共(217±1)块骨,其中头骨骨骼53块脊椎骨(48±1)块,附肢骨116块。此外,新疆北鲵头颅外形宽扁,犁骨齿排列幼体呈“/”型,成体则呈“■”型颅顶同时具有额顶囟和前颌囟,且前颌囟长与鼻骨长之比达或大于1/2,翼骨前端与上颌骨后端较接近等显著区别于其他小鲵科物种的骨骼特征,可作为种间分类重要依据。基于骨骼发育时序和骨化时间特征对比分析,北鲵骨骼数量和形态发生重大改变主要在6月龄幼体和2龄幼体两个时期。6月龄幼体的骨骼变化主要体现在头骨:新生出上颌骨、泪骨和前额骨,前颌囟形状逐渐清晰,腭骨退化,翼骨向后回缩,鳞骨向外延展。此外,腰带新生出前耻骨,暗示其进入骨骼变态发育阶段。2龄幼体的骨骼变化主要体现在舌器:第三、第四鳃弓退化,外鳃消失,暗示其变态发育接近尾声或结束。研究结果表明新疆北鲵变态发育时期从6月龄起至2...     

辽宁产中华大蟾蜍和花背蟾蜍蝌蚪形态特征的比较和分析

对中华大蟾蜍 Bufo gargarizans和花背蟾蜍B. raddei 第36期蝌蚪外形和口部形态结构进行详细观察和描述,并进行了定量比较和分析.中华大蟾蜍蝌蚪体背观呈长卵圆形,全身黑褐色;尾呈桨形,背腹鳍透明无斑;唇齿式为2(2)/3 (即Ⅰ:1+1/Ⅲ).花背蟾蜍蝌蚪体背观呈卵圆形,体背面和侧面为灰黑色或深灰色,腹面灰色有金属光泽;尾呈纺锤形,背鳍近透明,其上有黑色细纹,腹鳍透明无色;唇齿式为2(2)/3(即Ⅰ:1+1/Ⅲ),个别为2(2)/3(1)(即Ⅰ:1+1/1+1:Ⅱ).两种蟾蜍蝌蚪在体色、体型、尾色、尾型、口盘形态结构以及繁殖等方面有着明显区别.对辽宁和华西产的中华蟾蜍蝌蚪的分析表明两地蝌蚪在形态特征方面基本相同,显示出蝌蚪在种内的稳定性.编制了两种蟾蜍蝌蚪的简明检索表,供野外调查和监测参考.     

变态前后花背蟾蜍蝌蚪消化器官大小及各型白细胞百分比的适应性变化

以戈斯纳(Gosner,1960)分期表为标准,测定了28、38、42、44、45和46期野生花背蟾蜍(Pseudepidalea raddei)身体和消化器官的大小,并通过断尾或心脏穿刺采血技术,测定了各型白细胞的百分比及嗜中性粒细胞和淋巴细胞的比值(N/L的比值)的变化。结果表明:体重、体全长及尾长随发育阶段先升后降,而重长比和体长则一直增加;小肠长度和湿重均在38期最高,后者显著高于42期;肝湿重从28期至45期逐渐增加,但46期时下降;嗜中性粒细胞的百分比45期显著高于38期,嗜酸性粒细胞的百分比44期显著高于42和45期;淋巴细胞、嗜碱性粒细胞和单核细胞的百分比及N/L的比值均不随发育阶段而变化。这些结果提示,花背蟾蜍蝌蚪能量获取器官和能量贮存器官的大小分别在变态高峰期和登陆前达到最大值,嗜中性粒细胞和嗜酸性粒细胞的比例变化有助于蝌蚪从水生过渡到陆地生活、完成变态发育过程。     

同水塘分布两种无尾两栖类蝌蚪的竞争策略

实验室条件下,通过活动性水平,变态时的体重、增长率和完成变态所需时间考察同水塘分布的中华蟾蜍(Bufo gargarizans)和高原林蛙蝌蚪(Rana kukunoris)的竞争策略。实验按照2×3因子设计,即:食物资源2个水平(高、低),组合方式3个水平(10只中华蟾蜍蝌蚪,记为B组;5只中华蟾蜍蝌蚪和5只高原林蛙蝌蚪,记为BR组;10只高原林蛙蝌蚪,记为R组)。中华蟾蜍蝌蚪的活动性在食物水平低时显著低于食物水平高时,而高原林蛙蝌蚪的活动性在不同食物水平下无显著差异;食物水平低时,混合组的高原林蛙蝌蚪变态时体重和体重增长率都显著高于R组,而混合组中华蟾蜍蝌蚪与B组相比无显著差异;在不同处理组中,食物水平低时混合组中华蟾蜍蝌蚪幼体期最短。这些结果表明:中华蟾蜍蝌蚪在不同食物资源条件下所选择的生存策略可能不同,即食物资源充足时,增加活动性获取更多食物;食物资源有限时,降低活动性且提前完成变态;与中华蟾蜍蝌蚪相比,在食物资源有限时高原林蛙蝌蚪获取食物能力更强。     

五种蝌蚪口器及舌鳃骨的结构比较

采用体视显微镜和骨骼双染色法对5种不同栖息环境的无尾两栖动物蝌蚪的口器和舌鳃骨的形态结构特征进行了观察。5种蝌蚪口器由唇齿行、唇乳突和角质颌等组成。舌鳃骨是由关联骨Ⅰ、关联骨Ⅱ、角舌骨、舌鳃骨盘和角鳃骨等骨骼组成。蝌蚪的梅氏软骨若较发达,其摄食方式可能为刮食;蝌蚪的舌鳃骨发达,其摄食方式则可能为滤食。角质颌、唇齿以及角鳃骨上鳃耙的出现显著增强了蝌蚪主动摄食能力和对食物与非食物的主动选择性。     

中华蟾蜍蝌蚪颅骨发育的形态计量学分析

采用TPS(thin-plate spline)形态计量软件计量了中华蟾蜍Bufogargarizans幼体蝌蚪发育中软骨性颅骨的11项形态指标的变化,采用颅骨总长(TLC,the total length of chondrocranium)线性回归分析了各形态特征与颅骨总长的关系。通过对中华蟾蜍幼体蝌蚪颅骨的线性形态测量,结果表明喙上软骨、内睑部关节距等呈负异速生长,外睑部关节距呈同速生长;听囊等感受结构呈正异速生长,与Emerson等人的观点有所不同。基于中华蟾蜍幼体蝌蚪各期样本之间颅骨的发育存在着较大的差异,在实验样本的选取中既要考虑Gosner的分期,还要考虑同期蝌蚪个体体型大小。     

Effects of Predation by Invasive Western Mosquitofish(Gambusia affinis) on Survival of Eggs,Embryos and Tadpoles of Pelophylax nigromaculatus and Duttaphrynus melanostictus in South China

Alien species are one of the most serious threats to the decline and extinction of native amphibian populations. In this study, we examined the predation of invasive Western Mosquitofish Gambusia affinis on the eggs, embryos, and tadpoles of Duttaphrynus melanostictus and Pelophylax nigromaculatus in south China. Our results suggested that the survival of eggs and embryos remaining in the egg capsules of P. nigromaculatus and D. melanostictus was significantly higher than those removed from the egg capsule at 12-h intervals within 72 h in the presence of G. affinis. The survival of P. nigromaculatus eggs and embryos without egg capsules was significantly lower than those of D. melanostictus without egg capsules. The survival of P. nigromaculatus eggs and embryos with egg capsules was significantly higher than those of D. melanostictus with egg capsules from 24 h to 72 h except for 12 h. The survival of D. melanostictus tadpoles was significantly higher than that of P. nigromaculatus tadpoles in the presence of G. affinis. The survival of Gosner stage 26 tadpoles of P. nigromaculatus was significantly higher than that of Gosner stage 30 tadpoles from 12 h to 60 h, but there were no significant differences at 72 h. In contrast, the survival of Gosner stage 26 tadpoles of D. melanostictus was significantly lower than that of Gosner stage 30 tadpoles within 72 h, recording every 12 h. The increasing temperature caused a significant increase in predation by G. affinis on P. nigromaculatus eggs and embryos. The outer jelly capsule surrounding anurans eggs might serve as a mechanical defense against predation by G. affinis due to its large diameter, relatively stationary state and unpalatability. The differences in the vulnerability of P. nigromaculatus and D. melanostictus embryos and tadpoles to G. affinis probably due to differences in the unpalatability, black skin and activity. Based on the magnitude of predation by G. affinis on the eggs, embryos and tadpoles of these two species and the combined impact of temperature, we might speculate that invasive G. affinis and global warming would have more detrimental impacts on population viability of P. nigromaculatus than D. melanostictus in China.     

Effects of light intensity on activity in four sympatric anuran tadpoles

Though light conditions are known to affect the development and anti-predation strategies of several aquatic species, relatively little is known about how different species react to light, or how light can affect these species during different points in their life-cycle. In this study, we used four sympatric anuran tadpoles(Bufo gargarizans, B. melanostictus, Pelophylax nigromaculatus and Microhyla fissipes) as animal system to examine species-specific activities of the underdoing different light intensity treatments, so as to better understand how they respond to light. We exposed four different species of tadpoles to 1660 and 14 lux light intensity treatments and then measured several parameters including development stage, body length and tail length, and as well as their basic activities. The results of this observation and analysis showed that the activities of tadpoles were significantly greater in B. gargarizans and B. melanostictus than in P. nigromaculatus and M. fissipes; and were also significantly greater during times of high light intensity as compared to during low light intensity. Moreover, the observed relationship between species and light intensity was significant. The activities of B. gargarizans and B. melanostictus tadpoles were greater in high light, while the activity of P. nigromaculatus tadpoles was greater in low light intensity, while M. fissipes tadpoles showed no differences in either low or high intensity light. Furthermore, the activities of B. gargarizans, B. melanostictus and M. fissipes tadpoles in terms of developmental stage, body size or tail length did not seem to differ with light intensity, but during early larval developmental period of P. nigromaculatus, the activity of tadpoles was negatively correlated with development stage, but irrelevant to either body size or tail length in different light intensities. These results lead us to conclude the observed activities of the four sympatric anuran tadpoles are closely correlated with their specific anti-predation strategies.     

Community structure of vestimentiferan-generated habitat islands from Gulf of Mexico cold seeps

Biologically generated structures create habitat and influence the distribution and abundance of species in many marine systems. In the rather monotonous and nutrient-poor environment of the deep-sea, cold seep environments and their associated chemosynthetic communities offer islands of primary production and habitat to a generally sparsely distributed macrofauna. In this study, we investigate the structure of macrofaunal assemblages associated with vestimentiferan aggregations on the upper Louisiana slope of the Gulf of Mexico and the relationships between assemblage composition and the size and complexity of the vestimentiferan-generated habitat. Using custom-designed and custom-built devices, we collected seven whole vestimentiferan aggregations along with their associated fauna during the summers of 1997 and 1998. Sixty-five species were found associated with the four vestimentiferan aggregations collected in 1998, more than doubling the number of species previously reported for seeps in this region. Individual aggregations contained between 23 and 44 different non-vestimentiferan species. General trends of increasing species richness with increasing habitat size and increasing faunal density with increasing habitat complexity were identified, but substantial variability suggested other factors also control the composition of faunal associates. Faunal abundances decreased with increasing aggregation age. Seep endemics dominated the communities of younger aggregations, but non-endemic species dominated communities of older aggregations. Relative dominance of the heterotrophic community by primary consumers decreased, while predatory secondary and higher-order consumers increased with increasing aggregation age. These trends are discussed in terms of successional changes in aggregation structure, habitat heterogeneity and environmental conditions.     

Phylogeographic analysis of the Bufo gargarizans species complex: a revisit

Using mtDNA sequencing and allozyme electrophoresis data, we tested the "vicariance followed by dispersal" hypothesis of the Bufo gargarizans species group and re-evaluated the species status in the general lineages species concept. A phylogenetic analysis suggested that dispersal, instead of vicariance, dominated the history of the species group. There was a general trend of west to east dispersal, while some lineages from the east subsequently returned to the west. The secondary admixture of those previously allopatric lineages produced substantial levels of sympatric genetic diversity, often as high as 7.0% pairwise difference within populations. The phylogenetic hypothesis does not support the current two species designation. Neither B. andrewsi nor B. gargarizans represents an independent evolutionary lineage, and monophyletic groups did not correspond to geographically discrete groups. Allozyme data also failed to reveal any fixed allelic difference among the populations. Therefore, we recommend regarding the complex as a single species, Bufo gargarizans, without subspecies division.     

唐家河自然保护区高山姬鼠和中华姬鼠夏季生境选择的比较

为揭示影响高山姬鼠和中华姬鼠夏季空间分布的生态因素,采用样线法和样方取样法,于2009年6—8月在四川省唐家河国家级自然保护区内对两种姬鼠的生境选择进行了比较研究。结果表明:两种姬鼠主要利用坡度平缓,郁闭度、落叶层盖度、乔木胸径和高度较小,灌木、竹子和草本密度适中而草本盖度较大的生境;高山姬鼠频繁出现在海拔较低(1400 m左右)、草本植物较大(平均高度为16—30 cm)的生境中,而中华姬鼠频繁出现在海拔较高(1900 m左右)、草本植物较小(平均高度<15 cm)的生境中。此外,高山姬鼠频繁出现在竹林较矮(平均高度<1 m)、水源距离较近(<50 m)、植被演替阶段较低(小树林)的常绿-落叶阔叶混交林中,而中华姬鼠对这4种生态因子无明显的选择性。两种姬鼠在对生境的利用上虽具一定重叠性,但对诸多生境变量选择上的差异表明各自具有不同的生境利用模式。海拔、植被演替阶段、郁闭度和草本高度4个生境变量判别函数系数的绝对值明显大于其他变量,表明高山姬鼠和中华姬鼠在生境上的分割可能主要与这4个变量有关。生境利用模式的不同有助于两种姬鼠同域共存。     

Skull development during anuran metamorphosis: I. Early development of the first three bones to form--the exoccipital, the parasphenoid, and the frontoparietal

In anuran amphibians, cranial bones typically first form at metamorphosis when they rapidly invest or replace the cartilaginous larval skull. We describe early development of the first three bones to form in the Oriental fire-bellied toad, Bombina orientalis--the parasphenoid, the frontoparietal, and the exoccipital--based on examination of serial sections. Each of these bones is fully differentiated by Gosner stage 31 (hindlimb in paddle stage) during premetamorphosis. This is at least six Gosner developmental stages before they are first visible in whole-mount preparations at the beginning of prometamorphosis. Thus, developmental events that precede and mediate the initial differentiation of these cranial osteogenic sites occur very early in metamorphosis--a period generally considered to lack significant morphological change. Subsequent development of these centers at later stages primarily reflects cell proliferation and calcified matrix deposition, possibly in response to increased circulating levels of thyroid hormone which are characteristic of later metamorphic stages. Interspecific differences in the timing of cranial ossification may reflect one or both of these phases of bone development. These results may qualify the use of whole-mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.     

Thermal tolerance and heat shock protein synthesis during development in the anuran Lepidobatrachus laevis

Development of the Paraguayan anuran Lepidobatrachus laevis is unusual in that the larvae are obligate carnivores, facultative cannibals and apparently exist at high environmental temperatures in their natural habitat. In the present study, the effect of environmental temperature on the rate of anuran development was investigated. The larvae have a thermotolerance range of 18°C for normal development between 19 and 37°C. The effect of temperature on the rate of development was dramatic; larvae that were incubated at 36.8°C develop to stage 24 (Gosner) in approximately 9 h compared with 24 h for larvae incubated at 19°C. The ability of larvae to survive heat shock was also examined; larvae did not survive a shock of 45°C for 15 min when it was administered at stages 3, 5, 9, 10 or 20. However, using the same heat shock conditions, 50% survival was observed when larvae were shocked at stage 16. To study protein synthesis during heat shock, larvae were pulsed with [³⁵S]-methionine during heat shock and labeled proteins were analyzed by electrophoresis under reducing and denaturing conditions. Larvae synthesized two sets of heat-shock proteins at doublet molecular weights of 83/78 and 62/59 kDa. These proteins were synthesized independently of the stage of development at which the shock was administered or the magnitude of the heat shock.     

Induction of metamorphosis in the Asian shore crab Hemigrapsus sanguineus: Characterization of the cue associated with biofilm from adult habitat

Recruitment of crabs to nursery habitat requires settlement of the megalopal stage on suitable substratum followed by metamorphosis into the first juvenile stage. Reducing the time to metamorphosis may result in higher recruitment and survival. Previous work has shown that metamorphosis of the Asian shore crab is accelerated by cues from three different sources: (a) water-soluble exudate produced by conspecific adult crabs; (b) biofilm covering rocks in natural habitat for this species; and (c) abiotic rock from natural habitat. The objective of the present investigation was to characterize the metamorphic cue associated with biofilm from rocky intertidal habitat and to compare the three metamorphic cues (exudate from conspecific adults, biofilm from rocky intertidal, and texture of substratum) that have been identified for H. sanguineus. Results of our study show that megalopae of the Asian shore crab respond strongly to biofilm associated with rocky intertidal habitat that has developed for at least 8 days. We also found that megalopae respond to textured rock surfaces from natural habitat, even when those surfaces had been rendered abiotic. The cue remains active after the biofilm has been exposed to − 20 ºC for 12 h, but is de-activated by a few minutes exposure to 100 °C. Moreover, the biofilm cue appears to work in synergy with cues from other sources, but requires actual contact with the biofilm. Our findings show that addition of biofilm to an abiotic textured rock surface significantly decreases mean time to metamorphosis, and simultaneous exposure of megalopae to biofilm-covered rock and to exudate from adult H. sanguineus decreases mean time to metamorphosis even further. The response of this species to multiple cues—and particularly to biofilm in the absence of adult conspecifics—provides a clear advantage in the colonization of virgin habitat and helps explain the very rapid spread of this invasive species along the majority of the east coast of the United States in only two decades.     

纳帕海环湖公路交通噪声对鸟类的影响

为研究纳帕海环湖公路交通噪声对冬季鸟类的影响域和对敏感物种黑颈鹤(Grus nigricollus)行为的影响,于2009年和2010年冬季沿环湖公路以自驾车匀速行驶调查(40 km/h)与徒步定点观测两种形式对路域鸟类的回避距离及黑颈鹤的行为反应进行了研究.结果显示:(1)纳帕海环湖公路路域一共记录到鸟类36种,其中...