Abstract Detail

Systematics

Domenech, Boris [1], Bruneau, Anne [2].

Biogeography of the genus Crudia (Detarieae, Leguminosae).

Relative importance of long-distance oceanic dispersal vs. ancient continental pathways is a prevalent question in the biogeographical history of tropical post-gondwanian lineages. We test these hypotheses by reconstructing a phylogeny of the genus Crudia Schreb., a genus nested in the Detarieae, one of the first diverging lineages in the large family Leguminosae – a post-gondwanian family, dated from 64 My. Most of the 82 genera of Detarieae are found exclusively in Africa. However, Crudia, with about 55 species, occurs on three continents in West Africa, South America and Southeast Asia. This genus is morphologically homogenous (alternate leaflets, twisted petiolules, apetalous flowers) and all species grow along tropical rivers banks. Furthermore, it is one of the three most species-rich genera within Detarieae, where the majority of genera have fewer than ten species. To reconstruct the biogeographical history of Crudia, six nuclear markers (ITS, ETS, AIGP, AGT1, MMK1, CALTL) and two plastid markers (spacer trnH-psbA and trnD-E) were sequenced, for an unprecedented taxonomic sampling of this group. Our analyses include all 10 American species, 70% of the 10 African species and more than 50% of the 35 Asian species. Phylogenetic analyses were conducted on individual matrices to check the congruence between the several markers and on a concatenated matrix of the eight loci using a Bayesian approach. The nuclear loci and plastid matrix were compared for evidence of contradictory phylogenetic signals. Biogeographical analyses were conducted with a reduced number (3) vs. a higher number (6) of hypothetic ancestral areas, to test how dispersal routes could be highlighted with a variable areas number. Phylogenetic analyses resolve the widespread genus Crudia as monophyletic. Our analyses recover a strongly supported clade of all Asian species, in all independent analyses of the loci, and another clade of all American species. However, the African species are not resolved together in a monophyletic group, occurring instead as many small clades spread across the phylogeny. Preliminary biogeographical results suggest that Africa is the ancestral distribution area for Crudia species. From there, a split between Asian species and all other species occurred, followed later by a second dispersal event from Africa to America (occurring during Eocene, according to a 45 My old fossil of Crudia found in North America). Based upon known environmental factors and intrinsic morphological features, we surmise that this distribution could be explained by oceanic long distance dispersal rather than continental dispersal, during the Eocene.

1 - Université de Montréal - Institut de Recherche en Biolog, Biological Sciences, 4101 Sherbrooke Est, Montreal, QC, H1X2B2, CANADA
2 - INSTI DE RECHERCHE BIO VEGETAL, 4101 CUE SHERBROOKE EST, Montréal, QC, H1X 2B2, Canada

Keywords:
Biogeography
long-distance dispersal
Crudia
Leguminosae
low-copy nuclear markers
fossil datation.

Presentation Type: Oral Paper
Session: 21, Cooley Awards I
Location: 201/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 8:45 AM
Number: 21004
Abstract ID:293
Candidate for Awards:George R. Cooley Award