Genetic markers and breeding success: Theoretical and empirical investigations in fish

One of the most active research areas in population biology is genetic relatedness and gene flow in mating systems. This thesis examines genetic relatedness and gene flow in fish mating systems using microsatellite DNA markers, and contains four sections. The first section shows how to quantify microsatellite variation, and tests assumptions made by genetic distance estimators that have long been problematic. The results enable the widespread application of microsatellites in genetic models of population biology and are important in evolutionary and conservation biology for calculating genetic distances and identifying evolutionarily significant units. The second section develops mathematical models for calculating genetic relatedness among parents and offspring using both genetic and behavioural data. The models calculate the confidence in the parentage assignments and the optimum number of loci and offspring required to provide accurate parentage inference, and enable analysis of previously intractable mating systems. The third section quantifies gene flow within a major social unit of bluegill reproduction, the colony. Higher quality parental males attain higher paternity by avoiding parasitism during spawning by small precociously maturing males called cuckolders and adaptively allocate more parental care to their young. Cuckolder success is determined by their size and reproductive behavior with small sneakers and large females mimics attaining the highest reproductive success. Females make complex mate choice decisions, adaptively trading-off direct benefits from parental male care with good genes of cuckolders. The fourth section addresses the conservation biology practice of producing hatchery fish for wild supplementation, and its effects on the genetics, behaviour and reproductive success of wild populations. Independent of hierarchy position, hatchery males obtain lower paternity, possibly due to inferior sperm or reproductive ability, and overall obtain about half the success of their wild counterparts. Hatcheries have the potential to reduce effective sizes and genetically pollute wild populations, increase extinction probabilities, and in general may be an ineffective conservation approach. Overall, this thesis provides both innovative models to understand the breeding biology and evolution of natural populations, and novel empirical results that have important consequences for the conservation and effective management of wild fish populations.