CAREER: Testing the roles of evolutionary processes and plasticity in driving the northern range expansion of a tropical jellyfish

About This Grant

Major consequences of thermal changes in oceans globally include species movement into previously unoccupied regions and the proliferation of species that can tolerate a broad range of environments. In the oceans, jellyfish populations are increasing and expanding into new regions, which can have dramatic impacts on fisheries, tourism due to stings, and how nutrients are cycled in coastal ecosystems. However, the ability to understand how, why, and if jellyfish populations are increasing and the downstream consequences, is hindered by the lack of understanding of jellyfish basic biology and what contributes to their survival, reproduction, and movement patterns. The proposed research will track and study the upside-down jellyfish, which is expanding their range northward along both coasts of Florida. Genetics, epigenetics, and thermal tolerance of range expanding northern Florida populations will be compared to original founding populations in the Florida Keys, ultimately revealing how these jellyfish adapt, move, and establish new populations. This work involves strong collaboration with community scientist programs in Florida, who will help track these newly established populations. The research goals will also be integrated into the classroom at Texas A&M University through development of a Course-based Undergraduate Research Experience (CURE), where clonal jellyfish propagated in the lab will be used to study how different aspects of the environment promote reproduction and survival. This course will focus on developing students’ critical thinking and problem-solving skills as they tackle broad questions in the fields of ocean sciences, genomics, and molecular biology. As a consequence of rapid global environmental fluctuations, some organisms are suffering dramatic declines in populations sizes, while others are expanding their ranges into previously uninhabited regions. Range expanding populations often show evidence of adaptation and acclimation, thus providing an ideal system to ask questions about the relative roles of adaptation and plasticity in response to rapid change, and the molecular mechanisms underlying them. Prior work has documented the northward expansion of the tropical coastal jellyfish, Cassiopea xamachana, that is occurring along parallel coasts in Florida. The proposed work will examine interpopulation differences in physiological and molecular responses to thermal stress that may be driving their expansion, as well as how symbiosis and host genetic and epigenetic variation may shape evolutionary processes occurring during range expansion. Additionally, C. xamachana exhibits clonal and sexual phases of their life cycle, thus allowing experiments to tease apart mechanistic epigenetic effects from genetic background in the context of phenotypic plasticity. While well known in plants, the role of epigenetic marks on adaptive and plastic processes is not fully understood in animal systems, especially ones that are becoming invasive under global change. Therefore, population-specific clonal lines will be utilized to execute a long-term evolution experiment to understand fitness impacts of mutation accumulation and epigenetic change. Research will be directly integrated with educational aims through promotion of community science to track range expansion, and analysis of long-term clonal fitness and molecular data performed through a course-based undergraduate research experience (CURE). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.