Tiemann Inga, Rehkämper Gerd
Study Group Behaviour and Brain, C. & O. Vogt Institute of Brain Research, University of Duesseldorf, Germany.
Brain Res Bull. 2008 Jun 15;76(3):300-3. doi: 10.1016/j.brainresbull.2008.03.013. Epub 2008 Apr 18.
White Crested Polish (WCP) chickens are an interesting breed because of skull anatomy (crest), brain size and composition. This makes them attractive to investigate processes of selection that could parallel a step towards speciation in terms of ethological isolation. Lohmann Brown Classic (BL) and Red Leghorn (RL) were selected as comparative breeds to detect whether WCPs flock together as shown by shorter inter-individual distances within WCP than across breeds. WCP and BL were observed in the first year whereas RL served as comparative breed to WCP in the second year. Eggs of both breeds of each year were incubated at the same time, and chicks hatched and were raised together. Three young hens of each breed were randomly chosen and observed weekly in an open field situation for 20 min between the first and 31st week of life. Intra-breed distances differed significantly from those distances measured across breeds. Results demonstrate breed-specific flocking within observed breeds. This flocking behaviour may reflect breed-specific social and sexual preferences. Our observations indicate that domestic breeds may represent an ethological entity. Selective processes controlled by human intervention as given in domestication may therefore to be set in parallel to evolutionary processes.
白冠波兰鸡（WCP）因其头骨解剖结构（鸡冠）、脑容量和组成而成为一个有趣的品种。这使得它们对于研究选择过程具有吸引力，这些选择过程在行为隔离方面可能类似于物种形成的一个步骤。罗曼褐经典品系（BL）和红来航鸡（RL）被选作比较品种，以检测WCP鸡是否如所显示的那样聚集在一起，即WCP鸡之间的个体间距比不同品种之间的间距短。第一年观察WCP和BL，而第二年RL作为WCP的比较品种。每年两个品种的鸡蛋同时孵化，雏鸡一起孵化并饲养。在出生后的第1周和第31周之间，每周在开阔场地随机挑选每个品种的三只年轻母鸡，观察20分钟。品种内的距离与不同品种间测量的距离有显著差异。结果表明在观察的品种内存在特定品种的聚集行为。这种聚集行为可能反映了特定品种的社会和性偏好。我们的观察表明，家养品种可能代表一个行为学实体。因此，驯化中由人类干预控制的选择过程可能与进化过程并行。
