Phylogenetic conservation and diversification of 18S rDNA loci in leaf-cutting ants (Hymenoptera, Formicidae): insights from molecular validation and chromosomal mapping using FISH

By

Cardoso, Danon Clemes
Cristiano, Maykon P

Type

Article

Date of Publication

2026-1-5

Original Publication

Comparative cytogenetics : international journal of plant & animal cytogenetics, karyosystematics and molecular systematics

Volume

20

Pages

1--20

Subjects

18S rDNA , 45S ribosomal DNA , comparative phylogenetics , FISH-probe , leafcutting ants , rDNA

Contributed by

Pensoft Publishers

Language

English

Published by

St. Petersburg, Russia [Published] with technical support of Zoological Institute RAS [2007]-

Identifiers

DOI: https://doi.org/10.3897/compcytogen.20.162616

 

Abstract

<br> Ribosomal DNA (rDNA) clusters are important cytogenetic markers that can inform both taxonomic delimitation and chromosomal evolution in ants. In this study, we molecularly characterize and validate the widely used 18S rDNA probe applied in cytogenetic studies of Hymenoptera and provide new FISH-based chromosomal data for two previously unstudied leaf-cutting ant species (<br> Acromyrmex ambiguus<br> (Emery, 1888) and<br> Ac. crassispinus<br> (Forel, 1909)). While the general distribution of 45S rDNA loci in leafcutting is relatively well documented (copy number and site), we expand the comparative framework by testing the phylogenetic structure of rDNA positioning across genera. Our results confirm the conserved number of rDNA loci per species but reveal lineage-specific variation in chromosomal location, including both subterminal and pericentromeric arrangements. Phylogenetic signal analyses suggest non-random patterns consistent with evolutionary constraints in locus positioning. Together, our findings refine current cytogenetic models for leafcutting ants and demonstrate the utility of rDNA as a cytotaxonomic character and evolutionary marker for assessing chromosomal diversification.<br>