(
Oplegnathus fasciatus) was transported from
Japan to the
United States inside a fishing boat that was washed out to sea by the
2011 Tohoku earthquake and tsunami. Rafting has played an important role in the colonization of isolated land masses by mammals. Prominent examples include
Madagascar, which has been isolated for ~120 million years (
Ma), and
South America, which was isolated for much of the
Cenozoic. Both land masses, for example, appear to have received their
primates by this mechanism. According to genetic evidence, the common ancestor of the
lemurs of Madagascar appears to have crossed the
Mozambique Channel by rafting between 50 and 60 Ma ago. Likewise, the
New World monkeys are thought to have originated in
Africa and rafted to
South America by the
Oligocene, when the continents were much closer than they are today. (an alternative theory involves dispersal of a putative now-extinct iguana lineage from Australia or Asia). Similarly, a number of
clades of American
geckos seem to have rafted over from Africa during both the Paleogene and Neogene.
Skinks of the related genera
Mabuya and
Trachylepis also apparently both floated across the Atlantic from Africa to South America and
Fernando de Noronha, respectively, during the last 9 Ma. Skinks from the same group have also rafted from Africa to
Cape Verde, Madagascar, the
Seychelles, the
Comoros and
Socotra. and
blind snakes appear to have rafted from Africa to South America. An example of a bird that is thought to have reached its present location by rafting is the weak-flying South American
hoatzin, whose ancestors apparently floated over from Africa. Colonization of groups of islands can occur by an
iterative rafting process sometimes called island hopping. Such a process appears to have played a role, for example, in the colonization of the
Caribbean by
mammals of South American origin (i.e., caviomorphs, monkeys and
sloths). A remarkable example of iterative rafting has been proposed for spiders of the genus
Amaurobioides. Members of this genus inhabit coastal sites and build silken cells which they seal at high tide; however, they do not
balloon.
DNA sequence analysis suggests that ancestors of the genus dispersed from southern South America to South Africa about 10 Ma ago, where the most
basal clade is found; subsequent rafting events then took the genus eastward with the
Antarctic Circumpolar Current to Australia, then to New Zealand and finally to Chile by about 2 Ma ago. However, oceanic dispersal of terrestrial species may not always take the form of rafting; in some cases, swimming or simply floating may suffice. Tortoises of the genus
Chelonoidis arrived in South America from Africa in the Oligocene; they were probably aided by their ability to float with their heads up, and to survive up to six months without food or fresh water. ==Observation==