Evolution, pollination biology, and biogeography of the grape relative Leea (Leeaceae, vitales):

Leea D. Royen ex L. is the sole member of the tropical family Leeaceae, which is closely related to the economically important grape family, Vitaceae. Both comprise the order Vitales. In spite of its affinity with the grape family, Leea's molecular systematics has remained unexplored. This study presents the first phylogeny (chapter 1) of Leeaceae using molecular markers to provide an evolutionary framework to understand its taxonomy, morphological evolution (chapter 2), ecology (chapter 3), and biogeography (chapter 4). Ridsdale (1974, 1976) estimated that there are 34 Leea species inhabiting the tropics of Africa and Asia. DNA sequences for the internal transcribed spacer (ITS) and the 5S non-transcribed spacer (NTS) were extracted and amplified from leaf material of 22 species, representing the morphological and geographical diversity of Leea. The ITS secondary structure for the type species, L. aequata L., facilitated homology assessments in ITS sequence alignments, while 5S-NTS data helped resolve terminal relationships. The concatenated matrix was used to estimate the phylogeny and divergence times and generate the topology for ancestral area reconstructions. Area optimization was also performed on the Vitales topology estimated from previously published sequences to locate the geographic origin of Leeaceae, but either an out-of-Asia (i.e. Indochina) or out-of-India origin was inferred possible. The molecular phylogeny recovered four major clades, with the Indian/Indochinese L. asiatica (L.) Ridsdale (clade I) diverging 65.5 mya from the rest of the family. Its primitive trait of free stamens supports its position as the earliest-diverging clade. Clades II, III, and IV form a monophyletic group that had evolved in the Eocene (50.8 mya) in Indochina and/or West Malesia and exhibit the derived feature of fused stamens. Clade II, the spine-bearing species, is sister to Clade III, whose species have large flowers. Clade IV, which is unique in having multi-pinnate leaves and small stipules, evolved by the end of the Oligocene (25.6 mya) and comprise the polyphyletic 'species' (sensu Ridsdale) L. guineensis G. Don and L. indica (Burm. f.) Merr. nested among other morphologically discernible species. The radiation of Leea species mostly occurred in the Neogene (1.8-23.0 mya) during a time of dynamic geological and environmental changes in Southeast Asia. Africa and Australia were also colonized by Neogene dispersals of Asian Leea. Current species circumscriptions of L. guineensis and L. indica underestimate the genetic diversity of the genus and need to be revised. An updated checklist of 47 species reflecting clades recovered by the molecular phylogeny is presented including resurrected and putative new species. Field studies of three sympatric Philippine Leea morphospecies have revealed that habit and ecology must be considered in species circumscriptions.Ph.D.Includes bibliographical references (p. 95-107)by Jeanmaire E. Molin