Friday, November 2, 2012

[Mammalogy • 2005] Ecomorphological diversification among South American spiny rats (Rodentia; Echimyidae): a phylogenetic and chronological approach



Fig. 3. Phylogram inferred from the maximum-likelihood analysis of a gene supermatrix combining the vWF, cyt b, 12S and 16S rRNAs markers. Numbers above branches are ML bootstrap values. Black circles and white squares indicate polyphyly for, respectively, the Heteropsomyinae and Echimyinae subfamilies (McKenna and Bell, 1997).
The main ecomorphological characteristics are given on the right, with black, hatched, and white rectangles for scansorial or arboreal, semi-fossorial, and terrestrial taxa. Myocastor (∼) is semi-aquatic.
Pictures represent from top to bottom: Capromys piloridesEuryzygomatomys spinosusTrinomys setosusThrichomys aperoidesMyocastor coypusHoplomys gymnurusProechimys guyannensisLonchothrix emiliaeIsothrix bistriataKannabateomys amblyonyx, and Echimys chrysurus. The scale is given in substitutions per site (s. p. s.).

Abstract
The phylogeny of South American spiny rats (Rodentia; Echimyidae) was studied using the exon 28 of the von Willebrand Factor nuclear gene (vWF). Sequences were analysed separately and in combination with a mitochondrial dataset (cyt b, 12S and 16S rRNAs) used in previous publications. The basal polytomy of echimyids was partially resolved and unexpected intergeneric clades were recovered. Thus, the intimate nested position of Myocastor within echimyids is evidenced. A well-supported clade is identified, including all the arboreal genera, and a group formed by Myocastor, Thrichomys, and Proechimys + Hoplomys. The clustering of Euryzygomatomys + Clyomys with Trinomys is also suggested. On the opposite, the phylogenetic position of Capromys as well as the relationships among arboreal genera remain unclear. Molecular divergence times were estimated using a Bayesian relaxed molecular clock and suggest a Middle Miocene origin for most of modern genera. The ecomorphological diversification of echimyids is discussed in the light of these new results and past environmental modifications in South America.

Keywords: Echimyidae; von Willebrand factor; Relaxed molecular clock; Arboreality; Vicariance


2005. Ecomorphological diversification among South American spiny rats (Rodentia; Echimyidae): a phylogenetic and chronological approach

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