Keywords

population dynamics, population synchrony, genetic structure, local adaptation, eco-evolutionary dynamics, animal personality, long-term data, habitat fragmentation, dispersal, migration, host-parasite interactions, statistical modelling

Study species

Dolly Varden charr, white-spotted charr, Japanese tits, Eurasian red squirrels, freshwater leeches

We are looking at how dispersal among local populations affects population dynamics, genetic structure, and local adaptation. This is a fundamental question in spatial ecology and also important for conservation in fragmented landscapes. Despite the notable attention to and rapid progress in theories of metapopulations, empirical studies are still critically lacking. The main problem is obtaining long-term data from multiple local populations. We overcome this by investigating a good model system of stream-dwelling salmonid. Dolly Varden in the Sorachi River system use both small tributaries and the main stem, but spawn only in tributaries. Therefore, each tributary can be considered as local habitat. Different approaches have been employed to reveal the population dynamics of Dolly Varden (e.g. Koizumi 2011), but there are many questions still unanswered. A recent topic is host-parasite dynamics. Blood sucking leeches attach to the fish but only in some local populations. We are interested in how host behavior and dynamics affect population persistence of rare leeches, and if these ectoparasites affect migration behavior of the host.

We also started to work on Eurasian red squirrels in urban landscapes. Squirrels are very abundant in Obihiro city, central Hokkaido, even in very small highly fragmented parks. We are curious how the population persists around this area. What are the minimum habitat requirements, how much dispersal occurs among forest fragments, how much inbreeding occurs? We hypothesized that personality is a key factor for population persistence in the city. Bolder or less vigilant individuals should do well and also contribute to dispersal among forest fragments. Urban squirrels are also a good species for environmental education.

• Koizumi I. (2011) Integration of ecology, demography and genetics to reveal population structure and persistence: a mini review and case study of stream-dwelling Dolly Varden. Ecology of Freshwater Fish, 20, 352-363
• Koizumi I., Yamamoto S., Nomoto K. & Maekawa K. (2008) Synchrony in local population dynamics of stream-dwelling Dolly Varden: do genetically similar groups show similar demography? Population Ecology, 50, 367-377.
• Koizumi I., Yamamoto S. & Maekawa K. (2006) Decomposed pairwise regression analysis of genetic and geographic distances reveals a metapopulation structure of stream-dwelling Dolly Varden charr. Molecular Ecology, 15, 3175-3189.
• Koizumi I. & Maekawa K. (2004) Metapopulation structure of stream-dwelling Dolly Varden charr inferred from patterns of occurrence in the Sorachi River basin, Hokkaido, Japan. Freshwater Biology, 49, 973-981.