ISSN:
1615-6110
Keywords:
Rubiaceae
;
Exostema
;
Morphology
;
ITS sequences
;
cladistics
;
phylogeny
;
diversity
;
Caribbean biogeography
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The neotropical genusExostema comprises 25 species of trees and shrubs, ranging in distribution from Bolivia to Mexico and throughout the West Indies, with most species endemic to the Greater Antilles. Infrageneric relationships and species-level patterns of evolution were investigated in phylogenetic analyses using morphological, molecular, and combined data sets. All data sets resolved three main species groups which correspond to the three sections recognized byMcDowell (1996). However, the analyses of ITS sequence data placed the two South American species basal to the three main clades. Otherwise, the morphological and molecular data are highly compatible, and produce a more robust yet consistent phylogeny in the combined data analysis. Morphological evolution inExostema involves many specializations for xeric habitats, reflecting repeated ecological shifts from moist forest to exposed, seasonally dry environments during the diversification of the genus. Both moth and bee pollination syndromes are found inExostema, and shifts in pollination ecology appear pivotal to the differentiation of the three sections. Biogeographically,Exostema likely originated in South America and migrated via Central America to the Greater Antilles, where the morphological diversification and speciation are most extensive.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01089740
