Systematics of the southern Patagonian-Fueguian endemic Abrothrix lanosus (Rodentia: Sigmodontinae): Phylogenetic position, karyotypic and morphological data

A new species of fish-eating rat, genus Neusticomys (Sigmodontinae), from Ecuador

BACKGROUND

Inthis study, the genetic substructure and morphology of the species Neusticomysmonticolus was evaluated. A nuclear marker and mitochondrial maker were used to examine phylogeographic structure and to estimategenetic distances. Two statistical measurement analyses were applied to morphological data.

RESULTS

These data recovered two morphologically distinct phylogeographic groups corresponding to populations on the eastern and western slopes of the Andes. Further, these eastern and western Andean slope populations of N. monticolus are 8.5 % divergent using sequence data from cytochrome-b (0.8 % divergent in the interphotoreceptor retinoid-binding protein gene).

CONCLUSIONS

Populationscurrently assigned to N.monticolus constitutea species complex. The name N.monticolus is here restricted to western Andean slope populations. Populations on the eastern slope of the Andes are assigned to a new species, to which the authors assign the name Neusticomys vossi sp.nov.

Characterization of the kidney transcriptome of the long-haired mouse Abrothrix hirta (Rodentia, Sigmodontinae) and comparison with that of the olive mouse A. olivacea

To understand how small mammals cope with the challenge of water homeostasis is a matter of interest for ecologists and evolutionary biologists. Here we take a step towards the understanding of the transcriptomic functional response of kidney using as a model the long-haired mouse (Abrothrix hirta) a species that distributes across Patagonian steppes and Austral temperate rainforests in Argentina and Chile. Specifically, we i) characterize the renal transcriptome of A. hirta, and ii) compare it with that-already available-of the co-generic and co-distributed A. olivacea. Renal mRNA transcripts from 16 specimens of A. hirta from natural populations were analyzed. Over 500 million Illumina paired-end reads were assembled de novo under two approaches, an individual assembly for each specimen, and a single in-silico normalized joint assembly including all reads from all specimens. The total number of annotated genes was similar with both strategies: an average of 14,956 in individual assemblies and 14,410 in the joint assembly. Overall, 15,463 distinct genes express in the kidney of A. hirta. Transcriptomes of A. hirta and A. olivacea were similar in terms of gene abundance and composition: 95.6% of the genes of A. hirta were also found in A. olivacea making their functional profiles also similar. However, differences in the transcriptome of these two species were observed in the set of highly expressed genes, in terms of private genes for each species and the functional profiles of highly expressed genes. As part of the novel transcriptome characterization, we provide distinct gene lists with their functional annotation that would constitute the basis for further research on these or any other species of the subfamily Sigmodontinae, which includes about 400 living species distributed from Tierra del Fuego to southern United States.

The phylogenetic position of the enigmatic Atlantic forest-endemic spiny mouse Abrawayaomys (Rodentia: Sigmodontinae)

Background

The phylogenetic position of the sigmodontine genus Abrawayaomys, historically assigned to the tribe Thomasomyini or considered a sigmodontine incertae sedis, was assessed on the basis of nuclear and mitochondrial DNA sequences obtained from four individuals from different localities in the Atlantic forest of Brazil. Sequences of Abrawayaomys were analyzed in the context of broad taxonomic matrices by means of maximum-likelihood (ML) and Bayesian analyses (BA).

Results

The phylogenetic position of Abrawayaomys differed depending on the gene analyzed and the analysis performed (interphotoreceptor retinoid-binding protein (IRBP) ML: sister to Thomasomyini; IRBP BA: sister to Akodontini; cytochrome (Cyt) b ML: sister to Neotomys; and Cyt b BA: sister to Reithrodontini). With the sole exception of the BA based on Cyt b sequences, where the Abrawayaomys-Reithrodon clade had strong support, all sister-group relationships involving Abrawayaomys lacked any significant support.

Conclusions

As such, Abrawayaomys constitutes the only representative so far known of one of the main lineages of the sigmodontine radiation, differing from all other Atlantic forest sigmodontine rodents by having a unique combination of morphological character states. Therefore, in formal classifications, it should be regarded as a Sigmodontinae incertae sedis.