Cordiaceae, Ehretiaceae (probably including Lennoaceae), and
Heliotropiaceae are pantropically distributed clades of the
Boraginales. Their representatives' distribution is limited primarily
by climatic factors such as water availability and minimum
temperature. They very rarely enter temperate regions (e.g.,
Ehretia, Heliotropium). Since we have well resolved
phylogenies of these groups based on both molecular (ITS1) and
morphological data we can infer their historical biogeography.
Cordiaceae, Ehretiaceae, and Heliotropiaceae constitute a monophylum,
their major clades have a primarily Gondwanian distribution. Laurasian
taxa are only sporadically found in, e.g., Ehretia and
Heliotropium. The molecular phylogenies of the respective taxa
clearly show paraphyly of the New World species and a monophyly of the
Old World species. Based on early Tertiary fossils found in, e.g.,
Cordia (from Asia), Ehretia (from Europe), or
Tournefortia (Central America) we assume a high geological age
of the corresponding groups. Thus a late cretaceous vicariance event
(separation of Africa and South America) is the likely explanation for
current distribution patterns (demonstrated for Bourreria,
Cordia, Euploca, and Heliotropium). Laurasian
species of Ehretia occur presently in Central America and
Eastern Asia (with a secondary colonization of Australia). The
disjunction can be also explained by vicariance (separation of North
America and Eurasia). This hypothesis is supported by fossils from
Europe, which close the present day distribution gap. Old World
Cordia subcordata is closely allied to Caribbean Cordia
sebestena and its relatives. Similar patterns are observed in
Tournefortia (closely allied species in Africa, Asia and the
New World) and Heliotropium.Their ITS1 sequences have only a
few differences that make an early separation by plate tectonics
implausible. The fleshy fruits found in many taxa suggest possible
long-distance dispersal by animals (endozoochory) in this case.
Key words: Cordiaceae, distribution, Ehretiaceae, Heliotropiaceae, ITS1