Alpine environments in mid-latitudes are main refugia of glacial relict species, but some relict species are distributed also below the timberline. Vaccinium vitis-idaea is a typical glacial relict, growing in alpine areas in Japan. However, they occasionally form small populations at low-altitudes in Hokkaido. Since environmental conditions of low-altitude populations are different from alpine, they may possess some unique characteristics, which are not seen in alpine populations. To reveal the habitat specific variations of V. vitis-idaea populations, we studied (1) population genetics, (2) mating system, and (3) morphological traits of 18 V. vitis-idaea populations in Hokkaido.
There were two ploidy types in V. vitis-idaea. All alpine populations were diploid, while most low-altitude populations were tetraploid. Diploid and tetraploid populations were genetically different. Although the low-altitude populations were self-compatible, the alpine populations were generally self-incompatible. Furthermore, annual stem length and leaf size were larger in the low-altitude populations, especially in tetraploids. These results indicate the existence of different ecotypes between the alpine and low-altitude populations.