In:
Cytogenetic and Genome Research, S. Karger AG, Vol. 146, No. 4 ( 2015), p. 296-305
Abstract:
〈 i 〉 Neacomys 〈 /i 〉 (Sigmodontinae) comprises 8 species mainly found in the Amazonian region. We describe 5 new karyotypes from Brazilian Amazonia: 2 cytotypes for 〈 i 〉 N. paracou 〈 /i 〉 (2n = 56/FNa = 62-66), 1 for 〈 i 〉 N. dubosti 〈 /i 〉 (2n = 64/FNa = 68), and 2 for 〈 i 〉 Neacomys 〈 /i 〉 sp. (2n = 58/FNa = 64-70), with differences in the 18S rDNA. Telomeric probes did not show ITS. We provide a phylogeny using 〈 i 〉 Cyt 〈 /i 〉 b, and the analysis suggests that 2n = 56 with a high FNa is ancestral for the genus, as found in 〈 i 〉 N. paracou 〈 /i 〉 , being retained by the ancestral forms of the other species, with an increase in 2n occurring independently in 〈 i 〉 N. spinosus 〈 /i 〉 and 〈 i 〉 N. dubosti 〈 /i 〉 . Alternatively, an increase in 2n may have occurred in the ancestral taxon of the other species, followed by independent 2n-reduction events in 〈 i 〉 Neacomys 〈 /i 〉 sp. and in the ancestral species of 〈 i 〉 N. tenuipes 〈 /i 〉 , 〈 i 〉 N. guianae 〈 /i 〉 , 〈 i 〉 N. musseri 〈 /i 〉 , and 〈 i 〉 N. minutus 〈 /i 〉 . Finally, a drastic reduction event in the diploid number occurred in the ancestral species of 〈 i 〉 N. musseri 〈 /i 〉 and 〈 i 〉 N. minutus 〈 /i 〉 which exhibit the lowest 2n of the genus. The karyotypic variations found in both intra- and interspecific samples, associated with the molecular phylogeny, suggest a chromosomal evolution with amplification/deletion of constitutive heterochromatin and rearrangements including fusions, fissions, and pericentric inversions.
Type of Medium:
Online Resource
ISSN:
1424-8581
,
1424-859X
Language:
English
Publisher:
S. Karger AG
Publication Date:
2015
detail.hit.zdb_id:
2061918-2
SSG:
12
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