154 / FIELDS OF INSTRUCTION on populations, successions, microhabitat, distribution, pre- dation, evolution, and other aspects. Offered in Costa Rica as part of the program of the Organization for Tropical Stud- ies. ZOO 6905-Individual Studies (1-8; max: 14) ZOO 6910-Supervised Research (1-5; max: 5) S/U. ZOO 6927-Special Topics in Zoology (1-4) ZOO 6939-Seminar in Animal Behavior (1-3) Prereq: PCB 5415C or consent of instructor. Special behavioral topics. ZOO 6940-Supervised Teaching (1-5; max: 5) S/U. ZOO 6971-Research for Master's Thesis (1-15) S/U. ZOO 7979--Advanced Research (1-9) Research for doctoral students before admission to candidacy. Designed for stu- dents with a master's degree in the field of study or for stu- dents who have been admitted for a doctoral program. Not open to students who have been admitted to candidacy. S/U. ZOO 7980-Research for Doctoral Dissertation (1-15) S/U.