title: Cryptic Species in Proechimys goeldii (Rodentia, Echimyidae)? A Case of Molecular and Chromosomal Differentiation in Allopatric Populations.
abstract: The spiny rats of the genus Proechimys have a wide distribution in the Amazon, covering all areas of endemism of this region. We analyzed the karyotype and cytochrome b (Cyt b) sequences in Proechimys goeldii from 6 localities representing 3 interfluves of the eastern Amazon. A clear separation of P. goeldii into 2 monophyletic clades was observed, both chromosomally and based on Cyt b sequences: cytotype A (2n = 26x2640;/27x2642;, NF = 42) for samples from the Tapajos-Xingu interfluve and cytotype B (2n = 24x2640;/25x2642;, NF = 42) for samples from the Xingu-Tocantins interfluve and east of the Tocantins River. The karyotypes differ in a pericentric inversion and a centric fusion/fission and an average nucleotide divergence of 6.1%, suggesting cryptic species. Meiotic analysis confirmed the presence of a XX/XY1Y2 multiple sex chromosome determination system for both karyotypes. The karyotypes also vary from the literature (2n = 24, NF = 42, XX/XY). The autosome translocated to the X chromosome is different both in size and morphology to P. cf. longicaudatus, which also has a multiple sex chromosome determination system (2n = 14x2640;/15x2640;x2642;/16x2640;/17x2642;, NF = 14). The Xingu River is a barrier that separates populations of P. goeldii, thus maintaining their allopatric nature and providing an explanation for the molecular and cytogenetic patterns observed for the Xingu River but not the Tocantins River.
authors.affiliation: Centro de Estudos Avanx00E7;ados da Biodiversidade, Universidade Federal do Parx00E1;, Belx00E9;m, Brazil.
authors.forename: Marlyson J
authors.initials: MJ
authors.lastname: Rodrigues da Costa
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Siqueira do Amaral
authors.forename: Julio C
authors.initials: JC
authors.lastname: Pieczarka
authors.forename: Maria I
authors.initials: MI
authors.lastname: Sampaio
authors.forename: Rogério V
authors.initials: RV
authors.lastname: Rossi
authors.forename: Ana C
authors.initials: AC
authors.lastname: Mendes-Oliveira
authors.forename: Renata C
authors.initials: RC
authors.lastname: Rodrigues Noronha
authors.forename: Cleusa Y
authors.initials: CY
authors.lastname: Nagamachi
mesh_terms: D000818:Animals; D001938:Brazil; D007446:Chromosome Inversion; D045303:Cytochromes b / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D005260:Female; D049810:Genetic Speciation; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D008297:Male; D010802:Phylogeny; D045483:Rivers; D012377:Rodentia / Q000145:classification* / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*; D013045:Species Specificity; D014178:Translocation, Genetic
chemical_list: D045303:Cytochromes b