By Dr. Michael A. Steele

　 H, Fenner Chair of Research Biology, Wilkes University

　 Time：3:00 pm ,　4 Nov. 2009 (Wed.) 

　 Place：Lecture Hall B517, Institute of Zoology, Chinese Academy of Sciences

　 Contact: Dr.Zhishu Xiao, 010-64807110

I will review a series of experiments from the eastern deciduous forests of the United States that demonstrate how hoarding and foraging decisions influence the dispersal of the acorns of oak, and potentially, the structure of oak forests. I will also review new experimental evidence of secondary dispersal, cache memory, and a retriever's advantage in the recovery of cached nuts by rodents. By simulating predation of scatter-hoarding tree squirrels immediately after caching, we found that cache owners have a retrieval advantage over conspecifics even in an abnormally high-density population. We also show how habitat structure influences the placement of various seed types and how this may influence spatial variation in cache pilferage. Further evidence of secondary dispersal based on radiotelemetry studies show that scatter-hoarding is a dynamic process controlled more by the cache owner than by the activity of pilferers. Based on these new studies, we suggest that the process of seed placement, coupled with predation of scatter-hoarding rodents and birds, may have a significant impact on seed dispersal and establishment in many systems.