Evolution, divergence, and convergence in the mandibles of opossums (Didelphidae, Didelphimorphia).

Didelphid marsupials are considered a morphologically unspecialized group with a generalist diet that includes vertebrates, invertebrates, and plant matter. While cranium and scapula variation has already been examined within Didelphidae, variation in mandible shape, usually associated with diet or phylogeny in other mammalian groups, has not yet been properly assessed in the family. We evaluated the variation in mandible shape and size of didelphids (2470 specimens belonging to 94 species) using 2D geometric morphometrics.

Old specimens for old branches: Assessing effects of sample age in resolving a rapid Neotropical radiation of squirrels.

Ultraconserved Elements (UCEs) have been useful to resolve challenging phylogenies of non-model clades, unpuzzling long-conflicted relationships in key branches of the Tree of Life at both deep and shallow levels. UCEs are often reliably recovered from historical samples, unlocking a vast number of preserved natural history specimens for analysis. However, the extent to which sample age and preservation method impact UCE recovery as well as downstream inferences remains unclear.

Museomics of tree squirrels: a dense taxon sampling of mitogenomes reveals hidden diversity, phenotypic convergence, and the need of a taxonomic overhaul.

Background: Tree squirrels (Sciuridae, Sciurini), in particular the highly diverse Neotropical lineages, are amongst the most rapidly diversifying branches of the mammal tree of life but also some of the least known. Negligence of this group by systematists is likely a product of the difficulties in assessing morphological informative traits and of the scarcity or unavailability of fresh tissue samples for DNA sequencing. The highly discrepant taxonomic arrangements are a consequence of the lack of phylogenies and the exclusive phenotypic-based classifications, which can be misleading in a group with conservative morphology.

Molecular phylogeny of short-tailed opossums (Didelphidae: Monodelphis): taxonomic implications and tests of evolutionary hypotheses.

Short-tailed opossums (genus Monodelphis) represent one of the most speciose clades of New World marsupials, with 26 currently recognized species that collectively range from eastern Panama to northern Argentina. Here we present the first phylogenetic analyses of the genus based on dense taxonomic sampling and multiple genes. From most sampled species we obtained >4800bp of DNA sequence from one mitochondrial gene (CYTB), two autosomal exons (IRBP exon 1, BRCA1 exon 11), one autosomal intron (SLC38 intron 7), and one X-linked intron (OGT intron 14).