Collaborative research in science has been conducted for over 300 years, which international collaboration having grown in importance throughout the past century. International collaboration offers some important opportunities and advantages in ecological research. This is because ecosystems have complexity, variety, and ubiquity across boarder, and the insights of a variety of disciplinary experts are required to understand these ecosystems. In particular, today, our societies face global problems, including biodiversity loss, climate changes, and biological invasion, in which multidisciplinary, international approaches are needed. In my talk I will introduce two topics of our collaborative studies on ecology and evolution in plant-insect interactions: (1) biodiversity and microevolutionary divergence in a community context, and (2) plant genetics and insect population dynamics of exotic species in their native range. First, we have conducted collaborative study between Japan and Finland. In this collaboration we have investigated how species diversity of herbivorous insects affects trait evolution of a community member. Despite growing concerns of biodiversity loss, the question of how biodiversity influences evolutionary dynamics within species remains understudied. Plagiodera versicolora is a specialist leaf beetle on willow trees (Salix spp), and is widely distributed across Eurasia, including Japan and Finland. We found that the leaf beetle populations in Japan evolutionally developed divergent adaptive foraging traits, depending on local herbivore community structure. We also confirmed a similar pattern in Finland. Our results suggest that changes in local biodiversity may rapidly change evolutionary trajectories of species, and that this may be ubiquitous phenomenon. Second, we have conducted collaborative study between Japan and US to investigate interactions between the tall goldenrod (Solidago altissima) and its specialist aphid (Uroleucon nigrotuberculatum), both of which are exotic species in Japan from North America. We examined consequences of genotypic diversity of the tall goldenrod for spatial population dynamics of the aphids in their native range. As a result we found that plant genotypic diversity increased population size of the aphid due to enhancement of movement. Motivation of the collaboration arises from the following reasons: (1) genetic variation and spatial spreading dynamics are important issues in biological invasion processes, (2) knowledge and collection of a variety of Solidago genotypes are accumulated in the US collaborator’s lab, and (3) comparison of ecological and evolutionary dynamics between native and introduced range may provide insights toward management of exotic species as well as fundamental ecological theory.Session 2.1: Biodiversity and Environmental Protection in the Nort
