Detecting genetic adaptation during marine invasions

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Overview:Biological introductions, defined as the establishment of species in geographic regions outside the reach of their natural dispersal mechanisms, have dramatically increased in frequency during the 20th century and are now altering community structure and ecosystem function of virtually all marine habitats. To date, studies on marine invasions focus principally on demographic and ecological processes, and the importance of evolutionary processes has been rarely tested. This knowledge gap has implications for management policies, which attempt to prevent biological introductions and mitigate their impacts. The Asian seaweed Gracilaria vermiculophylla has been introduced to every continental margin in the Northern Hemisphere, and preliminary data indicate that non-native populations are both more resistant to heat stress and resistant to snail herbivory. The project will integrate population genetics, field survey and common-garden laboratory experiments to comprehensively address the role of rapid evolutionary adaptation in the invasion success of this seaweed. Specifically, the PIs will answer the following. What is the consequence of introductions on seaweed demography and mating systems? How many successful introductions have occurred in North America and Europe? Where did introduced propagules originate? Do native, native-source and non-native locations differ in environmental conditions? Do native, native-source and non-native populations differ in phenotype?Intellectual Merit:The intellectual merit of this project is based on three gaps in the literature. First, while biological invasions are widely recognized as a major component of global change, there are surprisingly few studies that compare native and non-native populations in their biology or ecology. Native and non-native populations will be surveyed in a similar manner, allowing assessment of differences in population dynamics, mating system, epifaunal and epiphytic communities, and the surrounding abiotic and biotic environment. Second, G. vermiculophylla exhibits a life cycle typical of other invasive species (including some benthic invertebrates), yet we still lack data on the effects of decoupling the haploid and diploid stages on genetic structure, and in turn, on the evolvability of their populations. Finally, this project will provide unequivocal evidence of an adaptive shift in a marine invasive. To our knowledge, such evolutionary change has been described previously for only a complex of marine copepod species. G. vermiculophylla will serve as a model for understanding evolution in other nuisance invasions, and perhaps lead to novel methods to counter future invasions or their spread.Broader Impacts:There are several broader impacts afforded by this project. The postdoctoral researcher will receive extensive training in population and ecological genetics, develop skills necessary to further development as an independent researcher, and develop career-enhancing interpersonal skills by leading the field trips and mentoring undergraduates. At least four undergraduates will be recruited, all of whom will generate data and will be encouraged to pursue independent projects. The results will be published in peer-reviewed journals and be presented at national and international meetings of both applied and basic scientists, during lectures and seminars at our home universities and at other universities. Finally, a co-PI has successfully implemented after-school hands on plant-ecology programs at the urban public library in their after-school programming for K-5 students (http://www.cclpl.org) with undergraduate research apprentices and collaboration with undergraduate senior education majors. Offerings will be expanded in this after-school program by developing hands on quantitative inquiry based modules on marine invasive species, marine algae and other topics. Undergraduate students on this project will have the opportunity to interact with undergraduate students in other ongoing projects in our group (see http://arabidopsisunpak.org). Thus research students across different areas of ecological-genetics will have the opportunity to share experiences and expertise.