Islands within islands: a molecular phylogenetic study of the Leucocroton alliance (Euphorbiaceae) across the Caribbean Islands and within the serpentinite archipelago of Cuba

Authors

  • Brett Jestrow,

    Corresponding author
    1. Department of Biological Sciences, Florida International University, Miami, FL, USA
    2. Center for Tropical Plant Conservation, Fairchild Tropical Botanical Garden, Coral Gables, FL, USA
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  • Jorge Gutiérrez Amaro,

    1. Jardín Botánico Nacional, Habana, Cuba
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  • Javier Francisco-Ortega

    1. Department of Biological Sciences, Florida International University, Miami, FL, USA
    2. Center for Tropical Plant Conservation, Fairchild Tropical Botanical Garden, Coral Gables, FL, USA
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Brett Jestrow, Center for Tropical Plant Conservation, Fairchild Tropical Botanic Garden, 11935 Old Cutler Road, Coral Gables, FL 33156, USA.
E-mail: bjestrow@fairchildgarden.org

Abstract

Aim  Our aim was to investigate the historical biogeography of the three genera of the Leucocroton alliance (i.e. Garciadelia Jestrow & Jiménez Rodr., Lasiocroton Griseb., and Leucocroton Griseb., Euphorbiaceae).

Location  The alliance is restricted to the Bahamas, Cuba, Hispaniola and Jamaica.

Methods  Members of the Leucocroton alliance, along with representatives from tribe Adelieae (Adelia L. and Philyra Klotzsch.), were included in a molecular phylogenetic analysis based upon nucleotide sequences of the internal transcribed spacer region of the nuclear ribosomal DNA and the non-coding chloroplast regions psbM–trnD and ycf6–pcbM. The program s-diva was used to calculate ancestral areas based on the phylogenetic trees and present species distributions.

Results  Phylogenetic analyses support the monophyly of the three genera. The ancestral area of the Leucocroton alliance is eastern Cuba and Hispaniola. Ancestral forms of Leucocroton arose on eastern Cuba and underwent two migrations across the island. The ancestor of Lasiocroton also originated on eastern Cuba followed by later dispersal to and speciation events on the other islands. Our study also suggests that ancestral forms of the Leucocroton alliance probably occurred on limestone soils.

Main conclusions  Our study concurs with previous hypotheses suggesting that the flora of serpentinite regions of the Caribbean derives from other types of soils. The serpentine endemics of the Leucocroton alliance have a single origin and represent one of the most extraordinary examples of speciation in this unique environment of the New World. The high colonization success achieved by the members of Leucocroton on serpentine soils was not attained by the other genera of the alliance, which occur on limestone areas.

Ancillary