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38 <br />THE BREEDING SYSTEM OF THE BOTTOMLESS LAKES PUPFISH (CYPRINODON <br />PECOSENSIS). <br />Astrid Kedric-Brown and Renee Vestal, Department of Ecology & <br />Evolutionary Biology, University of Arizona. <br />At high population density the breeding system of Cyprinodon <br />pecosensis is one of male territoriality. Males established breeding <br />territories on substrates with significant topographic complexity, <br />such as rocky embankments, mats of submerged aquatic vegetation or <br />single rocks scattered over a featureless silty bottom. <br />Females preferred oviposition substrates which coincided with <br />male preferences for territorial sites. Females preferred to oviposit <br />on rocky substrates (93% of a total of 365 spawnings). <br />Male reproductive success depended on territory quality and <br />individual characteristics. Males with territories on rocky <br />substrates had the highest spawning success (13 females mated per <br />30 min.). Occupants of territories situated primarily on silty <br />substrate had lower spawning success (7 males mated per 30 min.). <br />There was a positive correlation between male reproductive success <br />and the topographic complexity of the habitat (r = 0.57; P <0.005; <br />N = 40). Topographic complexity was defined as the ratio of the area <br />occupied by prominent topographic features to total area of a territory. <br />Both individual characteristics of males and the number of breeding <br />males in an area enhance reproductive success. Males with fully <br />developed breeding colorations had higher spawning rates (4 females <br />mated per 30 min.) than pale males (0.5 females mated per 30 min.). <br />Males defending territories in areas where there were several adjacent <br />territories had a higher reproductive success (1.8 females mated per <br />30 min.) than solitary territorial males (0.9 females mated per <br />30 min.).