PHYLOGENETIC STUDIES ON DIDELPHID MARSUPIALS II. NONMOLECULAR DATA AND NEW IRBP SEQUENCES: SEPARATE AND COMBINED ANALYSES OF DIDELPHINE RELATIONSHIPS WITH DENSER TAXON SAMPLING
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Abstract In order to test the results of a previous study of didelphid marsupial phylogeny based on IRBP nuclear gene sequences (Jansa and Voss, 2000. Phylogenetic studies on didelphid marsupials I. Introduction and preliminary results from nuclear IRBP gene sequences. Journal of Mammalian Evolution 7: 43–77), we surveyed external, cranial, dental, and karyotypic characters among a more densely taxon-sampled didelphine ingroup. Separate maximum-parsimony analyses of these nonmolecular data and of a new (taxon-dense) IRBP matrix yielded superficially dissimilar strict-consensus topologies. However, no didelphine clade that was even moderately well supported by either separate analysis was contradicted by any equivalently well-supported clade in the other. Instead, all examples of taxonomic incongruence involved weak nodal support from one or both datasets. A maximum-likelihood analysis of the IRBP data produced a consensus topology that was completely congruent with, although slightly more resolved than, the maximum-parsimony consensus. A combined (simultaneous) maximum-parsimony analysis of both datasets (nonmolecular + IRBP) produced a consensus topology that closely resembled the results of analyzing IRBP separately. Most of the didelphine relationships previously reported by Jansa and Voss (op. cit.) are supported by these analytic exercises, with some notable exceptions. The taxon currently known as Marmosa canescens is conspicuously divergent from congeneric species and variously clusters with three different groups (“other Marmosa” + Micoureus, Monodelphis, or higher didelphines [= clade H of Jansa and Voss, op. cit.] ) in several parsimony-equivalent resolutions of a fourfold basal polytomy in the IRBP and combined-data consensus topologies. Even without canescens, however, the genus Marmosa is not demonstrably monophyletic. The nomenclatural consequences of these results are discussed, and a new genus is described for “Marmosa” canescens. Future analyses should test the monophyly of other speciose didelphine genera, but new sources of character data will be needed to offset the loss of resolution and decreased nodal support that are often caused by denser taxon sampling.
Subfields: Genetics, Molecular Biology, Paleontology
View Paper: https://www.semanticscholar.org/paper/4b102758b1ba78eaf283af583ee2ef1b4af39cf6
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Citations in the corpus
- Organization of the Olfactory and Respiratory Skeleton in the Nose of the Gray Short-Tailed Opossum Monodelphis domestica (2005, background): “…characters are formally scored in cladistic analyses, variability of this system is not well represented in phylogenetic data matrices (but see Gauthier et al., 1988; Rowe, 1988, 1993; Voss and Jansa, 2003), and our understanding of how the nose “works” and evolved in mammals remains incomplete.”
- A Brief History of South American Metatherians: Evolutionary Contexts and Intercontinental Dispersals (2016, background): “A primitive pattern of foot morphology is characteristic of didelphids and microbiotheriids, with minor deviations related to toe size and predominance (Szalay 1982a, b, 1994; Voss and Jansa 2003).”
- On the Contents of Gracilinanus Gardner and Creighton, 1989, with the Description of a Previously Unrecognized Clade of Small Didelphid Marsupials (2005, methodology): “We analyzed nonmolecular (morphological and karyotypic) characters and nuclear gene sequences to assess the relationships of Cryptonanus with other didelphid taxa previously analyzed using the same data (Voss and Jansa, 2003; Voss et al., 2004a).”
- Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals (2009, methodology): “As noted elsewhere, Kirsch and Palma’s (1995) suggestion that Marmosops is paraphyletic was based on misidentified voucher material (Voss and Jansa, 2003: 57).”