Malesia

The broadly defined area used in Flora Malesiana consists of the countries of Malaysia, Singapore, Indonesia, Brunei, the Philippines, Timor-Leste and Papua New Guinea.

[1] The original definition by the World Geographical Scheme for Recording Plant Distributions (WGSRPD) covered a similar area, but New Guinea and some offshore islands were split off as Papuasia in its 2001 version.

[2] Van Steenis defined the area of Malesia through the concept of 'demarcation knots': lines across which there are major changes in the genera present in the flora.

[citation needed] The first edition of the World Geographical Scheme for Recording Plant Distributions (WGSRPD) used the same definition, but in the second edition of 2001, New Guinea and the Bismarck Archipelago were removed from Malesia and united with the Solomon Islands, previously placed in the WGSRPD's Southwestern Pacific region, and placed into a new region, Papuasia, whose eastern boundary extends to line 5 in map 2.

[5] Western Malesia includes the Malay Peninsula and the islands of Sumatra, Java, Bali, and Borneo (area A in map 2).

The Sahul component is now understood to include substantial two-way exchanges with Sunda inclusive of lowland taxa.

Evidence for the relative contributions of the great Asiatic floristic interchanges (GAFIs) with India and Sahul, respectively, to the flora of Malesia comes from contemporary lineage distributions, the fossil record, time-calibrated phylogenies, functional traits, and the spatial structure of genetic diversity.

Functional trait and biome conservatism are noted features of montane austral lineages from Sahul (e.g., diverse Podocarpaceae), whereas the abundance and diversity of lowland lineages, including groups such as Syzygium (Myrtaceae) and the Asian dipterocarps (Dipterocarpoideae), reflect a less well understood combination of dispersal, ecology, and adaptive radiations.