| 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 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.
|
PDF Full Text Request