Revision and analysis of the chromosome variability in the speciose genus Akodon (Rodentia, Sigmodontinae), including new data from Argentina.

CAROLINA ALICIA LABARONI; PAEZ COLL MAIRHOFER VA; OJEDA RA; NOVILLO A; TETA P; PABLO JAYAT; OJEDA R.A.; BUSCHIAZZO, L.M; CÁLCENA, E.; BOLZÁN A; C. LANZONE

ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS.

ACAD BRASILEIRA DE CIENCIAS

Lugar: Rio de Janeiro; Año: 2023 vol. 95 p. 1 - 17

0001-3765

Rodentia has a high speciesnumber and chromosomal variability. The South American genus Akodon is one of the most speciose muroids,with more than 40 species included in several species groups. Here, wecharacterize cytogenetically specimens of Akodonfrom central-western Argentina. Subsequently, we reviewed and analyzed the cytogeneticdata for this genus, build a phylogeny and mapped chromosome changes tointerpret its evolution. Specimens of A.dolores from central-western Argentina have 2n=42-44/FNa=44 (46, 48) due toa Robertsonian rearrangement. Our data expand the distribution range known forthis polymorphism and confirm its geographic structure. Other specimens had2n=40/FNa=40, representing populations of A.oenos, A. polopi, and A. spegazzinii. All karyotypes have a lowamount of heterochromatin, concentrated in centromeres and sex chromosomes, asin other rodents. The complement with 2n=40/FNa=40 is the most frequent in Akodon and is shared by most species in somegroups. Chromosome numbers are very diverse. The FNa shows less variability; FNa=42was recovered as ancestral, excluding A.mimus, which was connected at the baseof the Akodon tree and has FNa=44. Thisindicates a complex chromosome evolution in Akodon,and suggests that reductions and increases in the 2n and FNa evolvedindependently in some lineages.