Cytogenetic survey of eight ant species from the Amazon rainforest

Abstract

The scarce information regarding ant diversity in the state of Amapá and lack of cytogenetic data of species from the Amazon region can hide ant biodiversity information that may be detectable with affordable cytogenetic techniques. In this study, we describe the karyotypes of eight ant taxa collected from Amazonian localities in French Guiana and Brazil. Chromosome numbers ranged from 2n = 18 to 2n = 68. The following chromosome numbers were observed for each species: Azteca sp. group chartifex 2n = 28; Dolichoderus bidens (Linnaeus, 1758) 2n = 18; Gnamptogenys tortuolosa (Smith, 1858) 2n = 44; Camponotus renggeri Emery, 1894 n = 20; Pseudomyrmex unicolor (Smith, 1855) 2n = 68 and n = 34; Apterostigma sp. pilosum complex 2n = 46; Odontomachus bauri Emery, 1892 2n = 44, and Wasmannia auropunctata (Roger, 1863) 2n = 32. The karyotypes of P. unicolor, G. tortuolosa, and O. bauri are reported here for the first time. Our data enabled comparisons between chromosomal data of some species from Amazon and Atlantic rainforests. We also highlight the methods used for the ant chromosome classification.

Physical chromosomal mapping of major ribosomal genes in 15 ant species with a review of hypotheses regarding evolution of the number and position of NORs in ants

“…Although the karyotypes of these two Azteca species were organized according to different chromosomal classification systems, it is possible to observe that the data from FISH with rDNA probe in A. andreae and the Ag-NOR banding in A. trigona were similar with rDNA clusters located in the terminal region of the short arm of a medium-sized chromosome pair (this study, Cardoso et al 2012). Regarding classical cytogenetic data, six Azteca species, including A. andreae in this study, had 2n=28 chromosomes, and only A. alfari Emery, 1893 had 2n=26 (Mariano et al 2019;Barros et al 2021c). Increasing the efforts to physically map rDNA clusters in other Azteca species may unveil variations in the location of rDNA sites, similarly to the observed chromosome number in A. alfari, thereby enhancing our understanding of karyotypic evolution in this genus.…”

“… andreae in this study, had 2n=28 chromosomes, and only A. alfari Emery, 1893 had 2n=26 ( Mariano et al 2019 ; Barros et al 2021c ). Increasing the efforts to physically map rDNA clusters in other Azteca species may unveil variations in the location of rDNA sites, similarly to the observed chromosome number in A.…”

“…The subfamily Dolichoderinae includes 22 genera and more than 900 species, grouped into four monophyletic tribes: Tapinomini , which is sister to the clade encompassing Bothriomyrmecini , Dolichoderini , and Leptomyrmecini ( Ward et al 2010 ). Data on the distribution of rDNA clusters in this subfamily are available for two species in Tapinomini and some species in Dolichoderini (reviewed in Teixeira et al 2021a ; Barros et al 2022b ). All these species had only one pair of chromosomes bearing rDNA sites.…”

“…In Formicidae , molecular cytogenetic studies involving fluorescence in situ hybridization ( FISH ) for physical mapping of major ribosomal genes, 45S ribosomal DNA ( rDNA ), here referred to as rDNA clusters, were first conducted in Australian ants of the genus Myrmecia Fabricius, 1804 ( Imai et al 1992 ; Hirai et al 1994 , 1996 ). In recent years, FISH has been widely employed in several ant species, particularly in the Neotropical region ( Santos et al 2016 ; Aguiar et al 2017 ; Micolino et al 2019 , 2022 ; Barros et al 2021a , b , 2022a , b ; Murakami et al 2021 ; Silveira 2022 ; Teixeira et al 2022 , 2023 ; Jacintho et al 2023 ). These molecular cytogenetic studies have provided valuable insights into various biological aspects of these insects, including evolution, taxonomy, and reproduction.…”