P.I.. Snell, Terry W. Proposal #: 9503521 P.I.. Lonsdale, Darcy, L. Proposal #: 9505803 PROJECT ABSTRACT Pheromonal regulation of invertebrate reproduction influences several fundamental ecological processes in the sea, e.g., recruitment, fecundity, and population growth rate. Chemical communication is also crucial to locating conspecifics, recognizing potential mates, and transferring sperm. Despite the evolutionary significance of these chemical signals, little is known about the type of molecules employed and the basis for discrimination. The main objectives of this research are: 1)to identify one class of chemicals (=glycoproteins) responsible for mate recognition in marine copepods, 2) to investigate their range of polymorphism within and between species, and 3) to examine their role in the maintenance of productive isolation among species.