426 Isoptera Figure 19 Life cycle of the fungus-growing termite, Macrotermes michaelseni, in the grassland of Kenya Reproduced from Abe, 1995 Many fossil species of the Kalotermitidae whose living species are mostly of the one-piece type have been found in the Tertiary period It is probable that the second major event, the expansion and diversification of separate type termites and the diversification of the one-piece type termites driven by the expanding separate type termites into fragmented habitats, occurred in the Tertiary Only a few fossil species of the higher termites are known from the Tertiary The third event, the radiation of higher termites, may have occurred in the late Tertiary or the Quarternary On the other hand, the worldwide distribution of higher termites suggests their early evolution and dispersal before the breakdown of Gondwanaland in the Cretaceous As shown later, it is quite difficult for termites to cross the oceans It is probable that the radiation of higher termites may have occurred in the late Tertiary or the Quarternary, although the origin of higher termites may be before the breakdown of Gondwanaland in the Cretaceous Dispersal Ability of Termites Islands sterilized by volcanic eruption are good for studying the process of colonization In 1883, Krakatau, located about 60 km from Java and 40 km from Sumatra, erupted violently and more than half of the island disappeared, leaving the remaining Krakatau and two neighboring islands The entire flora and fauna of the islands were almost destroyed, but they were rapidly colonized by organisms of Java and Sumatra In the Krakatau Islands, three, three, and seven species of termite were collected in 1908, 1919–1933, and 1982, respectively They were characterized by the dominance of the lower termites (Kalotermitidae and Rhinotermitidae), the one- piece type, and the absence of soil feeders, although a woodfeeding arboreal species of Nasutitermes of the higher termites was found in the Krakatau Islands On the other hand, the supposed source area (the tip of West Java) was characterized by higher species diversity (13 species), the dominance of higher termites and separate type, and the presence of soil feeders In the tip of West Java, the one-piece type termites of the Kalotermitidae are confined to the coastal forest, while soil feeders are confined to inner forests Alates of termites are specialized for dispersal within a zone of calm air near the ground The dispersal distances are short in lower termites (up to 300 m) and a little long in higher termites (a few kilometers) It is not impossible but difficult for termites to disperse widely or to reach remote islands by flight Therefore, termites usually cross the sea by rafting The Kalotermitidae, the first colonizers, have some preadaptive attributes for oversea dispersal: (a) they tend to be confined to the coastal area and may be easily swept into the sea, (b) they are more tolerant to sea water than other types, and (c) their caste differentiation is flexible On the other hand, it is difficult for soil-feeding termites to cross the sea because they have little opportunity to be in rafting wood Thus the dominance of the Kalotermitidae (onepiece type) and the Rhinotermitidae (intermediate type) in many islands is explained in terms of the differential dispersal ability of termites The Evolutionary Radiation of Original Termites The first event, the evolutionary radiation of the original termites into a new habitat of wood throughout the world, may have been driven by an efficient utilization of wood as an