应用无尾两栖类蝌蚪进行污染物毒理实验设计的常见问题

无尾两栖类的幼体蝌蚪是很好的水体污染指示物种,近年来,国内这方面的研究也越来越多.本文总结了研究生论文和部分已发表论文中本类研究的常见错误,指出实验设计中需要注意的重要问题.在实验动物的选择上可以尽量选择发育迅速的常见种蝌蚪以缩短实验周期、减少实验成本.为保证各个处理组之间结果的可比较性和实验的可重复性,需要选择发育期相近、体型大小相似的个体进行实验.我们建议使用Gosner于1960年提出的发育分期方法描述蝌蚪发育期;在试剂选用上,建议根据农药成分购买相应化学试剂进行针对性实验,以掌握各种药物对蝌蚪的影响;在对实验材料描述时必须采用通用名,并说明组成成分及浓度,而且对于主要成分应该用化学名描述;实验设计中应该注意设置合理的对照;数据分析上需要注意参数与非参数统计方法的选择,对于重复测量的符合假设数据应该使用重复测量的方差分析.     

无尾两栖类的简易标记法

在动物学、动物生理学和生态学等学科的研究中 ,常常需要对所研究的动物个体进行标记 ,以便于对其个体活动的追踪研究观察。在有关研究工作中 ,目前使用多种标记法 ,如烙印法、同位素示踪法等。在对蛙类的研究实践过程中 ,我们找到了针对蛙类研究的一种简单易行的标记法——划蹼法和切趾 (指 )法。由于蛙类个体小 ,较为脆弱。烙印等方法容易对其造成伤害 ,影响其生存 ,同时也不易进行操作。尤其是在蝌蚪变态期不易进行有效的标记 ,给追踪观察造成极大的困难。我们经过对中国林蛙的标记试验探索 ,找到了一种简单易行的标记方法。即采用划去蛙…     

无尾两栖类繁殖生态研究的内容和方法

广大中学生物学教师都有进行科学研究的愿望,但往往限于条件和苦于不熟悉方法,愿望难以实现。现就无尾两栖类繁殖生态研究的内容和方法作一介绍,供教师在进行当地某种无尾两栖类研究时参考。 (一)繁殖地点一般讲无尾两栖类的繁殖地点并不太隐蔽,多数种类是在水中繁殖,有的在静水内,有     

四种无尾两栖类SCE分析

本文应用腹腔注射活性炭吸附1dUR的方法制成骨髓细胞SCE标本;测定出泽蛙、虎纹蛙、黑斑蛙和中华大蟾蛛的SCE值（雄雌）分别为7.81士0.42,8.02土0.45,4.76士0.28,4.54士0.32,8.79士0.34,8.38士0.42和7.42士0.48、7.91士0.46;表明无尾两栖类体细胞的SCE值是比较高的。本文还观察了SCE在染色体上的分布;结果表明SCE的分布与染色体的长度有一定的关系。     

无尾两栖类性腺发育研究进展

脊椎动物的性腺发育一直是生物学领域研究的热点,无尾两栖动物因其胚胎发育的独立性和易观察性而成为发育生物学研究领域的良好材料,并取得了许多成果.本文综述了无尾两栖类原始性腺形成、性腺分化、精巢和卵巢的发育,以及配子发生等方面的研究进展.无尾两栖类原始性腺形成主要发生在鳃盖褶和后肢芽形成时期,不同物种略有不同;性腺分化通常...     

无尾两栖类食物资源利用研究进展

食物资源的利用是无尾两栖类生态学研究的一个重要组成部分,针对食物资源的竞争策略和食物资源竞争对群落结构的影响都有比较深入的研究,本文总结近年来本领域的理论成果与发展动态,并对我国的研究现状和未来作了讨论.     

十一种无尾两栖类分带核型的比较研究

本文比较研究11种无尾两栖类的c带型和人Ag-NORs,并报道三种核型（淡肩角蟾,秦岭雨蛙和湖北金线蛙）,结果：（1） 弹琴蛙仅大型染色体着丝点区C带正染,其余10个物种的所有染色体均有明显的着丝点C带,并分别具有数目不等的端部C带或插入型C带。其中天台蛙的C带尤为发达。（2） 中华大蟾蛛有3对Ag-NORs,大树蛙两对,其余9个种均显示1对。（3）新报三种核型中,淡肩角蟾租湖北金线蛙2n=26,N．F=52。淡肩角蟾由6对大型的和7对小型的染色休组成,湖北金线蛙大小型染色体分别为5对和8对。秦岭雨蛙2n=24,含大小型染色休各6对,其N．F=48。三个物种均未见有异型性染色体。     

中国无尾两栖类寄生肠肾虫的考种依据及其讨论

寄生蛙类肠道的肠肾虫)Nyctotheran),国外报道较多,特别是印度和亚洲其他国家的研究较多 ,记述了近 100种[1-5].     

雄激素对无尾两栖类鸣叫行为的调控及机制

鸣叫行为是无尾两栖类常见的行为,对其生存和繁殖具有重要意义.虽然目前没有一致的证据,但研究结果暗示了很多无尾两栖类动物的广告和攻击鸣叫行为与其体内雄激素水平密切相关.已有的研究表明,雄激素对无尾类发声器官的肌肉以及运动神经元有重要影响.另外,在无尾类脑部与发声的相关核团中发现雄激素受体的表达.注射精氨酸加压素(AVT)也可以增加蛙类的广告鸣叫及降低释放鸣叫.这些都暗示了激素对无尾类鸣叫行为具有重要作用,但其确切机制尚不清楚.本文通过对已做相关研究的所有物种进行系统发育分析,发现中枢神经与鸣叫行为相关的精氨酸加压素系统具有高度的进化保守性,而与鸣叫相关的性激素作用系统可能是多次独立起源的.     

无尾两栖类在不同生活史阶段的栖息环境

无尾目的生活史分为卵、蝌蚪和成体3个不同的阶段,它们分别生活在迥异的环境中,形成了各自阶段的生态适应。本文综述了无尾目3个阶段的栖息环境,以繁殖模式描述卵的栖息环境,以发育序列和生态表型描述蝌蚪的栖息环境,以生活类型描述成体的栖息环境。无尾目的环境选择策略集中表现了进化的关键趋向：由水向陆的运动。利用生活史对水陆两种环境的适应优势,无尾目成功地分布到除南极洲之外的所有大陆。     

A morphological re-examination of the frog genus Nannophrys (Anura: Ranidae) with comments on its biology, distribution and relationships

The morphology of Nannophrys Günther, 1869, a genus of ranid frogs endemic to Sri Lanka, is reexamined. The three species comprising the genus are redescribed, and a detailed account of the osteology of the type-species, N. ceylonensis Günther, is given for the first time. Adults of two species show heavy secondary cranial ossification, a feature known in only one other ranid genus, the Solomon Islands Ceratobatrachus. New information on the tapdole of N. ceylonensis is provided. N. marmorata Kirtisinghe, 1946, is accorded full species status. Reference is made to the ecological niches of N. ceylonensis and N. marmorata. The resemblance of Nannophrys to the myobatrachine leptodactylids is noted, both groups possessing a cartilaginous omosternum and dilated sacral diapophyses. On the basis of this resemblance and other data presented in the present paper, it is suggested that Nannophrys may be interpreted as a primitive ranid genus which has independently acquired a large number of derived features. Comparison is made with a selected group of related Indian ranid genera, and with Ceratobatrachus. Results indicate that Nannophrys show some affinity with the southern Indian genera Nannobatrachus and Nyctibatrachus , and also with Ceratobatrachus. Comment is made on the correlation of the zoogeographical subdivision of the southern Indian region and Nannophrys relationships.     

Evolution of reproduction in the Rhacophoridae (Amphibia, Anura)

Rhacophorid treefrogs have different reproductive modes: some go through a tadpole stage and some have direct development, and the adults of some species produce foam nests. Philautus is the only genus characterized by direct development. The production of foam nests has been reported in the genera Polypedates, Rhacophorus, Chiromantis and Chirixalus. Recent molecular studies did not provide a robust hypothesis concerning the origin of these reproductive modes in the Rhacophoridae. In order to better understand the evolution of these reproductive modes, we tried to clarify relationships within this group, using DNA sequencing. Our data set consists in a large number of new sequences (1676 base pairs corresponding to threee genes) for five outgroup ranoids and 48 Rhacophoridae, including 16 undescribed species from Sri Lanka and southern India, and all homologous data available in Genbank. After the inclusion of Philautus from India, our data show that the separation of Philautus into clades does not coincide with their geographic distribution. Our data point to the existence of a clade, including the genera Rhacophorus, Polypedates, Chiromantis and Chirixalus, which confirms the results of Wilkinson et al. (2002) and suggests that the ability to produce foam nests has emerged only once in the Rhacophoridae, as already stated by these authors.     

PATTERNS OF POSTZYGOTIC ISOLATION IN FROGS

From literature data on 116 taxa crosses involving 46 species of frogs, we found a positive correlation between degree of divergence (measured as Nei's genetic distance, D) and degree of postzygotic isolation. In anurans, hybrid sterility appears to evolve more quickly than inviability, which is consistent with the conclusions of other studies that involved Drosophila species. The lower threshold of D = 0.30 for evolution of hybrid inviability that we found is similar to that observed for Drosophila. This consistency suggests that there may be a general pattern in the acquisition of reproductive isolation in animals.     

不同程度的尾损伤对镇海林蛙(Rana zhenhaiensis)蝌蚪游泳速度的影响

无尾两栖类蝌蚪的尾巴通过产生强大的游泳速度在反捕食中起到了重要的作用。以镇海林蛙(Rana zhenhaiensis)蝌蚪为实验动物来评估断尾的运动代价。以74尾具有完整尾蝌蚪作为实验组,通过截去不同尾长片段,人为分成轻微尾损伤组(30%)和严重尾损伤组(30%)并测定两组蝌蚪在断尾前后的游泳速度。以16尾完整尾蝌蚪作为对照组在实验组断尾前后同时进行游泳速度的测定。实验结果显示断尾影响蝌蚪的游泳速度,但仅在尾损伤程度达到尾长的30%以上时才产生不利的影响。这表明轻微尾损伤并不对镇海林蛙蝌蚪的游泳速度产生严重影响。在断尾前后实验组蝌蚪的游泳速度均与尾长呈正相关。在相同尾长状态下,尾损伤蝌蚪的相对游泳速度明显快于完整尾蝌蚪。因此,尾损伤的镇海林蛙蝌蚪有可能通过改变尾和身体的摆动频次等方式在断尾后对游泳速度进行了一定的补偿。尾损伤在野外频繁发生于蝌蚪的尾远端,据此推测镇海林蛙蝌蚪在自然条件下的尾损伤并不会产生严重运动代价。     

Oviposition site choice under conflicting risks demonstrates that aquatic predators drive terrestrial egg-laying

Laying eggs out of water was crucial to the transition to land and has evolved repeatedly in multiple animal phyla. However, testing hypotheses about this transition has been difficult because extant species only breed in one environment. The pantless treefrog, Dendropsophus ebraccatus, makes such tests possible because they lay both aquatic and arboreal eggs. Here, we test the oviposition site choices of D. ebraccatus under conflicting risks of arboreal egg desiccation and aquatic egg predation, thereby estimating the relative importance of each selective agent on reproduction. We also measured discrimination between habitats with and without predators and development of naturally laid aquatic and arboreal eggs. Aquatic embryos in nature developed faster than arboreal embryos, implying no cost to aquatic egg laying. In choice tests, D. ebraccatus avoided habitats with fish, showing that they can detect aquatic egg predators. Most importantly, D. ebraccatus laid most eggs in the water when faced with only desiccation risk, but switched to laying eggs arboreally when desiccation risk and aquatic predators were both present. This provides the first experimental evidence to our knowledge that aquatic predation risk influences non-aquatic oviposition and strongly supports the hypothesis that it was a driver of the evolution of terrestrial reproduction.