Meeting Abstract
Novel pressures introduced to an environment due to human interaction disrupts the native biodiversity. Thus, it is important to understand the evolutionary trajectory resulting from novel selective pressures introduced by anthropogenic activities in making informative conservation efforts. Rainbow trout (Oncorhynchus mykiss) is a species routinely stocked in Alaskan lakes previously devoid of the species, altering the predation regime to which native threespine stickleback (Gasterosteus aculeatus) are exposed. Here we examine effects of trout introduction on brain structure and overall brain size. This study evaluated two Alaskan lake populations, Whale Lake (not stocked) and Bear Paw Lake (stocked), that were sampled from the years 1993 until 2019. The telencephalon, optic tecta, and cerebellum will be quantified using the ellipsoid model between these populations and across time. The ellipsoid model assumes the lobes of the brain maintain an ellipsoid shape, by taking the length, height, and width of these lobes volumetric quantities can be calculated through the formula 0.167πlwh. Previous studies are in conflict, suggesting that predators select for either an increase or decrease in brain size related to specific predator-prey interactions. Due to the high metabolic cost of brain tissue, a selective trade-off exists. Selection in favor of increased brain size is thought to increase cognition and sensory abilities utilized in predator detection. However, selection in favor of decreased brain size allows for the allocation of energy to structures that aid in predator evasion and defense, as well as reproduction and feeding. This study addresses the possibility that introduction of rainbow trout has led to alterations in brain structure and size, and if so, in what directions.
