The occurrence and abundance of plants with extrafloral nectaries, the basis for antiherbivore defensive mutualisms, along a latitudinal gradient in east Asia

The occurrence and abundance of indigenous plants with extrafloral nectarie s was evaluated within local communities and regional floras along a north to south gradient from tundra in northeastern Russia (64-70 degrees N) thro ugh temperate types in eastern Russia and Korea to subtropical vegetation i n the Bonin Islands (26-27 degrees N) south of Japan. Moving from tundra to subtropical vegetation, there is a pattern of increasing abundance of extr afloral bearing plants as a function of total plant cover (from 10.25 to 40 .18%), number of species per sampled area (from 0.11 to 1.13/100m), and pro portion of species within regional floras (from 0.32 to 7.46%). There were some plants with extrafloral nectaries in all communities but their abundan ce varied greatly, c. 1-25% in the four:northern latitudes and c.7-70% in t he subtropical region. Ants, the primary mutualists associated with plants bearing extrafloral nectaries, have a similar pattern of increasing abundan ce (species richness, nest density, and colony size) along the same north-s outh latitudinal gradient.