Kajita

Research Interests †

1. Phylogeography of Pantropical Plants with Sea Drifted Seeds †

The geographic distance of seed dispersal is generally limited because of the media (winds, water, animal, etc., for example), so that the distribution areas of plants are mostly limited.

However, some plants have very wide distribution area. Pantropical Plants with Sea-drifted Seeds (PPSS) are plants that have extremely wide distribution littoral areas in tropics all over the world. About 6 species are known in total. Ipomoea pes-caprae (Convolvulaceae), Canavalia rosea (Leguminosae), and Hibiscus tiliaceus (Malvaceae) are representative species of PPSS. These three species and their allies have almost overlapping distribution range in the coastal areas of tropics and subtropics on the earth. How can a plant species that grow in the beautiful sandy beach of Rio de Janeiro can be the same one in Okinawa Island in Japan? The geographic distance between the two localities is about 20,000km! This is one of the questions we are currently working on. We focus on these three species and collect materials from their populations in tropics world wide, and to reveal the level of gene flow by Sea-Drifted seeds to keep this distribution area.

2. Molecular Phylogeny of Legumes †

Leguminosae ("Bean Family") is the third biggest family of flowering plants. So many legume plants are utilized in various ways in our daily life, especially as crops. We do not live on legume crop alone, but our life without legumes must be very hard. To understand the phylogenetic relationships of Leguminosae, we use molecular phylogenetic method. This modern method using nucleotide sequences of DNA can provide us objective ways to infer phylogenetic relationships of living organisms. In the field of legume study, many researchers are working on various taxonomic groups using various methods. I myself did phylogenetic study on whole Legume family using chloroplast rbcL gene collaborated with Jeff Doyle of Cornell University. I am working now on tribe Desmodieae that includes ca. 400 species.