C-RUI: Cellular, Physiological and Life-history Responses of a Stream Fish, Blacknose Dace (Rhinichthys atromaculatus), to Urbanization

Towson University, Towson MD

Investigators

Abstract

Scientists are in general agreement with the idea that urbanization and its accompanying habitat loss and fragmentation will result in a reduced communities of organisms-often referred to as opportunistic, generalist or weedy species-that are able to cope with the novel selection pressures and stressors of the urban environment through rapid evolution or plasticity, or both. Evidence for this point of view comes from the disproportionate persistence of broadly distributed species in urban environments, the rapid evolution of resistance to toxins by fungi, bacteria, plants, insects, and even mammals, and the rapid evolution among some invertebrate groups of preference for introduced plant hosts. While it is clear that specific selection pressure in the urban environment can result in rapid evolution of specific traits, it remains unclear how and by what mechanisms the overall physiology and life history characteristics of populations will change with urbanization. Specifically, will populations in urban environments become more "opportunistic," and if so what roles will phenotypic plasticity and evolution play? To address these questions this project will investigate the response of a common stream fish, blacknose dace, to watershed urbanization. Past comparative studies have documented increased growth rates, younger age and size at maturity, increased swimming performance, and reduced predator avoidance behavior in populations occupying streams draining heavily urbanized watersheds (>90 % urban land use). The general goals of this project are to continue comparative studies in greater detail, including extending them to the cellular level, and to investigate the relative roles of phenotypic plasticity and evolution in producing the differences observed in urban populations. Field studies will involve comparison of cellular and tissue structure, protein expression, metabolism, lipid storage, diet, and survival across a series of streams draining watersheds with 20 to > 90 % urban land use. A common garden experiment will be conducted to investigate the potential genetic basis of any of the differences observed in past studies, or discovered during this study. By conducting programs to enhance undergraduate retention in the project over multiple years the investigators hope to increase undergraduate understanding of, and desire to pursue multidisciplinary studies in graduate school.