【作者】 张方；

【导师】 吴孝兵；

【作者基本信息】 安徽师范大学 ， 动物学， 2004， 硕士

【摘要】 本论文对涉及饲养条件下夏秋两季扬子鳄的行为和活动时间分配进行了研究，同时基于NT-3和BDNF基因部分序列探讨了扬子鳄的分类地位和爬行动物的系统发生。2003年夏秋两季，采用扫描取样法和目标动物取样法，对饲养条件下扬子鳄的个体行为和活动时间分配进行了研究。结果表明：夏秋两季饲养条件下扬子鳄的个体行为主要包括休息、游泳、潜水、吼叫、嬉戏、摄食和晒太阳等，同时也记录其他行为如：漱口、挠痒、排泄、打斗、堆积、摆尾、对视、打哈欠、伸懒腰等。夏季扬子鳄花费在休息的时间最多，秋季花费在晒太阳的时间最多。夏季扬子鳄的日变化规律显示早晨6:00～7:00为休息高峰期；下午12:30到13:30为潜水高峰期，秋季在早晨6:00～7:30这一时间段为潜水高峰期，且一天中扬子鳄晒太阳活动出现三次高峰即10:30～11:00，13:30～14:00，16:30～17:00。统计结果表明，扬子鳄的潜水、晒太阳和休息三种个体行为在夏秋两季有着较为显著的差异性。在30℃~36℃之间，扬子鳄潜水频次或潜水时间和温度之间近乎呈线性关系。在25℃~30℃之间，潜水时间或频次受温度影响不大。研究结果同时表明长期的人工饲养对扬子鳄的某些弹性行为如摄食行为等产生了较大影响。例如扬子鳄的摄食时间已由原来的晚间改为白天摄食；人工饲养条件下扬子鳄种群密度较大，作者对扬子鳄摄食行为的观测中未见先潜水靠近猎物，再浮出水面将猎物俘获的偷袭动作。另外观察过程中也未见扬子鳄表现出贪食性，尽管是两天进行一次人工投食，但扬子鳄一次取食并不多，同时观察到每次投食并非所有的扬子鳄来投料台摄取投喂的食物，也未见扬子鳄一次取食量可达体重的10%左右现象。扬子鳄的四种吼叫以第四种最为常见。该种吼叫，时间一般不定，昼夜都有可能发生。夏季一般早晨居多，群体参与并且吼叫时间较长；秋季，吼叫时间较短且一般为个别个体参与。这种吼叫声雌雄个体有较大差别，一般雄性(圈养个体同样雄性比雌性少)发出声音较破的“吐---吐”声（发出此种声音的个体较少，这也可作为判断雌雄的信号之一），不如雌性的“哄---哄”声洪亮。在行为描述的基础上，对扬子鳄的有关行为机制进行了探讨，而影响扬子鳄行为表达的生物因素主要包括年龄、食物资源和人为干扰；非生物因素主要包括空间、温度和生境等。在爬行动物的系统发生研究中，鳄类与鸟类和哺乳类的系统发生关系一直是争议的焦点问题之一，同时鳄类中扬子鳄的分类地位也存在着很多争议。神经营养因子-3(Neroutrophin-3 NT-3)和脑源性神经营养因子(Brain derived neroutrophin factor BDNF)是神经生长因子(Nerve growth factor, NGF)家族中两个主要成员。用 NT-3和BDNF基因分析动物的系统发生，已被用于两栖爬行类及鸟类等类群。经过对扬子鳄、尼罗鳄和泰国鳄等物种序列的比对，其NT-3和BDNF基因的同源序列长度分别为647 bp和586 bp，其中NT-3基因多态位点277个，占位点总数的42.81%；BDNF多态位点213个，占位点总数的36.35%。据此构建系统发生树，结果显示NT-3基因序列和BDNF基因序列及两序列合并数据的MP树和NJ树均支持鸟类和鳄类为姐妹群关系；同样NT-3基因、BDNF基因及其合并数据的MP树也支持扬子鳄与密西西比鳄亲缘关系较近；但基于NT-3基因所构建的NJ树中扬子鳄与密西西比鳄并没有聚为一支，所以有关扬子鳄与密西西比鳄的分类地位问题仍有必要做进一步探讨。更多还原

【Abstract】 This paper researched the behaviors and time budgets of captive-bred Chinese alligator，and discussed the taxonomical status of Chinese alligator (Alligator sinensis) and the phylogeny of the reptiles based on the sequences of NT-3 and BDNF genes. In summer and autumn of 2003, the author introduced target objective observation and scan sampling methods to research behaviors and time budgets of Chinese alligator. The results showed that the main individual behaviors include resting, swimming, diving, roaring, playing, basking, feeding and so on, at the same time recorded others behaviors such as gargling, tickling, excreting, fighting, swing tail, pileup, staring, yawning, stretching waist etc. After reproduction in summer, resting is the main behavior of daily rhythm, basking becomes the main behavior in autumn. The daily varying rhythm of main behaviors of Chinese alligator showed that from 6:00 to 7:00 in summer morning, there is a resting fastigium and a diving fastigium from 12:30 to 13:30 in the afternoon. In autumn, there was a diving fastigium from 6:00 to 7:30 and three basking fastigiums in a day, that was 10:30～11:00，13:30～14:00，16:30～17:00. The analysis showed there were significantly differences among the diving, basking and resting in summer and autumn. During the temperature of 30℃~36℃, the relationship between frequency and temperature approximately abide by linearity relations. During the temperature of 25℃~30℃, the temperature was not the most important factor . Because of the long time breeding, some elastic behaviors, such as feeding, were affected. Except for the description for behavior, this paper also discussed the mechanism of behaviors. Biological factors affecting alligators’ behaviors were described, including age, food resources, human impacts. Non-biological factors were demonstrated also in the study, such as space, temperature and living habitats. The phylogenetic relationships among crocodiles, Aves and mammals always were the focus of study and debate. Neroutrophin-3 (NT-3) and brain derived neurotrophic factor (BDNF) are the main members of nerve growth factor (NGF). The NT-3 and BDNF genes have been applied to analyze the phylogeny of amphibians, reptiles, Aves and so on. Based on the alignment for sequences from some species, including Alligator sinensis, Crocodylus niloticus and Crocodylus <WP=6>siamensis etc., 647-bp homologous sequences of NT-3 gene and 586-bp homologous sequences of BDNF gene were obtained. It was detected that 277 polymorphic loci with 42.81% proportion of polymorphic loci were found in NT-3 gene, and 213 polymorphic loci with 36.35% proportion of polymorphic loci in BDNF gene. Based on the NT-3 or BDNF gene, phylogenetic trees constructed by Neighbor-joining method in MEGA and Maximum-parsimony in PAUP all showed that crocodile was clustered as the sister group of Aves. In addition, based on the combination data, phylogenetic trees also supported the results above. On the other hand, the results from the MP phylogenetic trees constructed by PAUP4.0a supported the American alligator was more closed to Chinese alligator. But the results from the NJ tree in MEGA based on NT-3 gene did not support this result. So the classification status about American alligator and Chinese alligator should be studied in the future.更多还原