Ecogeographical Differentiation in Nectandra (Lauraceae), and its Historical Implications

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Abstract
Following a taxonomic revision of Nectandra, a genus of about 114 species of neotropical trees, character gradients are compared against geographical distribution, habitat preferences, and reproductive phenology of individual species, with the aim of reconstructing the spatial and temporal diversification of the genus. It is shown that Nectandra, together with Ocotea, Persea, and other genera of the Lauraceae, originated from a northern hemisphere matrix that immigrated into South America, perhaps as late as after the closure of the Central American land bridge in the Pliocene. The dramatic diversification of the genus within South America was facilitated by its ornithochorous dispersal system, implying ample processes of allopatric speciation. At present, speciation seems to take place preferably by processes of ecotypic (mostly edaphic) specialization, by which widely distributed, ecologically polymorphic species give rise to swarms of ecologically narrowly specialized satellite species.