Ecologists have traditionally regarded evolution as a process that played out long ago with limited consequences for the current dynamics of natural communities. However, one of the most exciting developments in biology over the past two decades has been the growing awareness that contemporary evolutionary processes can have a far greater influence on ecological processes than has been generally appreciated. Species consist of populations that often encounter very different conditions over broad geographic ranges, and thus populations may be fine-tuned to their local environments by natural selection. In addition, recent studies suggest that evolutionary change can occur over rapid timescales and may alter which ecological traits are common in a population. Despite increased recognition of these processes, we have little understanding of how feedbacks between evolution and ecology might change the way that co-occurring species in marine communities interact with each other through time and over large distances along coastlines. In this project, we studied how feedbacks between evolution and ecology shape a predator-prey interaction in rocky shore communities along the Pacific coast of the United States. Specifically, we studied the interaction between a predatory drilling snail (the Channeled Dogwhelk, Nucella canaliculata) and the mussel Mytilus californianus, an important foundation species that forms expansive mid-intertidal mussel beds. The dogwhelk preys on mussels by drilling a small hole through their shell. We conducted laboratory experiments to quantify the drilling capacity of snails from six populations along the coast. Our findings reveal that California and Oregon dogwhelks have evolved divergent abilities to prey on mussels. Relative to snails from Oregon, those from California populations successfully drilled mussels that were substantially larger and thicker. Given that all snails were raised under common conditions in the laboratory, these differences in drilling capacity likely have a genetic basis and may have evolved in response to regional variation in mussel shell thickness. To characterize possible differences in mussel shell thickness, in 2019, we collected mussels from the same six study sites. We analyzed the thickness of these shells and also compared these values to mussels collected at the same sites in 2001 and 2008-2009. Shells from California were substantially thinner than those from the central Oregon coast in 2001 and 2008/09. Historically thinner mussels in California may have imposed selection on California dogwhelks to capitalize on this prey resource. In addition, the 2019 samples suggest that mussel shells have become thinner over the last decade, especially in Oregon. We also tested whether short-term variation in prey can impose rapid selection on the drilling traits of dogwhelks within a single population (Bodega Marine Reserve). We raised snails in the laboratory under four different diet treatments, which included a range of prey species and differences in shell thickness. We hypothesized that the diet treatments would impose selection on the drilling traits of newly hatched snails. As predicted, hatchling snails that survived on a diet of thick juvenile mussels led to the group of adult snails with the greatest percentage of strong drillers. We then outplanted a subset of snails from each diet treatment to field cages and monitored these plots for one year to test whether these snails had divergent impacts on mussel bed communities. We predicted that snails raised on a diet of thick mussels (which had the greatest frequency of strong drillers) would consume more mussels and slow the process of ecological succession to a mature mussel bed. At the end of the experiment, the most apparent effect was that the reference cages (with no snail predation) had the fastest rate of succession (i.e., the highest cover of mussels). However, there were not strong differences among the four treatments with snails raised in the laboratory on different diet treatments. Thus, although our laboratory results suggest that prey can impose selection that leads to rapid adaptation and divergent predator traits, these feedbacks were not strong enough to result in clear community-level effects in the field. We propose that a variety of factors may dampen the potential for strong feedbacks between evolution and ecology in this community. Given that eco-evolutionary feedbacks have been studied mostly in the laboratory, our contrasting results from a more realistic field setting are an important finding. Overall, our results highlight the importance of understanding feedbacks between evolution and ecology within a geographic context of changing environmental conditions. Beyond the scientific contributions, this project also supported the training of Ph.D. students and undergraduate research assistants. To broaden the scientific communication skills of the next generation of researchers, we developed training to provide UC Davis undergraduate and graduate students with the skills to produce engaging and accessible short films for the general public. These student films were shown in public film festivals, and have been shared broadly with the public through YouTube, other websites, and social media. Last Modified: 05/23/2024 Submitted by: EricDSanford