The use of molecular genetic analyses to examine mating patterns and paternal care in the pumpkinseed sunfish

This dissertation presents a series of studies that describe the mating behavior and parental care of the pumpkinseed sunfish (Lepomis gibbosus ). Data on reproductive behaviors, age and size of reproductive males confirmed the existence two alternative reproductive strategies. Sneaker males comprised 39% of the males observed spawning, and they intruded on 43% of all observed matings. On average four females spawn at each nest and sneakers fertilized on average 15% of the eggs. The analysis suggests that the two reproductive strategies represent a balanced polymorphism with average equal fitnesses.; In agreement with predictions from optimization models, pumpkinseed sunfish brood size was positively correlated with fanning effort, and fanning and patrolling effort were more frequent in late breeders. Contrary to predictions of optimization models, brood size and future reproduction were not correlated with nest defense. In agreement with predictions from the effect of sexual selection on parental care, fanning, patrolling and defense rates peaked the first day of the parental care period and subsequently decreased with brood age. This suggests a strong mating effort component that may favor higher levels of defense than those expected by optimization models of parental care.; I examined the three main factors that affect the relation between paternity and parental care by male pumpkinseed sunfish. Parental effort was costly. Paternity was variable among broods. The proportion of paternity by parental males was not associated with fanning frequency or defense of hatched young. However, parental males with higher paternity showed higher levels of nest defense during the egg stage. The cues pumpkinseed males used to assess paternity are not clear.; Nest cover and depth did not affect the number of eggs received. Deeper nests had higher rates of sneaking intrusions, but parental male paternity was not affected by nest vegetation or depth. Large pumpkinseed males built nest in deep waters and this appeared to be related to high nesting success. Depth may be an important factor affecting the evolution of the pumpkinseed sunfish breeding system. Overall, this series of studies provides valuable information that improves our understanding of the processes affecting the evolution of breeding systems.