Mori A, Burghardt G M
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Japan.
J Comp Psychol. 2000 Dec;114(4):408-13. doi: 10.1037/0735-7036.114.4.408.
Rhabdophis tigrinus, which typically forages on toads, has unusual nuchal glands on its dorsal neck region containing secretions chemically comparable to cardiac steroids found in toads. R. tigrinus also has several peculiar antipredator displays involving the neck region. If the nuchal gland secretions of R. tigrinus are derived from toads obtained as prey, populations of R. tigrinus that have not eaten toads over an evolutionary time scale would be expected to lose antipredator displays related to the nuchal glands. We found that laboratory-hatched R. tigrinus from a small toad-free island exhibited displays related to nuchal glands less frequently and flight responses more frequently than hatchling snakes from areas sympatric with toads. These results are consistent with the hypothesis of the dietary origin of the nuchal gland secretions and also support the genetic origin of the behavioral differences between the populations.
颈槽蛇通常以蟾蜍为食，其颈部背面区域有特殊的颈腺，所含分泌物在化学上与蟾蜍体内发现的强心甾类物质相当。颈槽蛇还有几种涉及颈部区域的奇特反捕食行为表现。如果颈槽蛇的颈腺分泌物源自作为猎物获取的蟾蜍，那么在进化时间尺度上未食用蟾蜍的颈槽蛇种群，预计会失去与颈腺相关的反捕食行为表现。我们发现，来自一个无蟾蜍的小岛、在实验室孵化的颈槽蛇，相较于与蟾蜍同域分布地区的幼蛇，表现出与颈腺相关行为的频率更低，而逃跑反应的频率更高。这些结果与颈腺分泌物的饮食来源假说相符，也支持了不同种群间行为差异的遗传起源。
