Wide dispersion of B chromosomes in Rhammatocerus brasiliensis (Orthoptera, Acrididae)

Abstract

The grasshopper Rhammatocerus brasiliensis shows polymorphism of B chromosomes, but the magnitude of B-chromosome occurrence and the factors that may contribute to their dispersion in the species remain unknown thus far. The present study analyzed the occurrence and dispersion of B chromosomes in R. brasiliensis individuals from 21 populations widely distributed in the Brazilian Northeast. The genetic connectivity between 10 populations was verified through analysis of ISSR markers from 200 individuals. Of the 21 populations, 19 presented individuals with one B chromosome, three with two, and one with three B chromosomes. The B chromosome is of medium size and constitutive heterochromatin (CH) located in the pericentromeric region. A variant B chromosome was observed in three populations, similar in size to that of chromosome X, gap and CH, and located in the terminal region. B chromosome frequencies in different populations varied from 0% to 18,8%, mean 8,5%. The wide distribution of the B chromosome is likely a consequence of the positive gene flow among the analyzed populations. B-chromosome occurrence in populations of R. brasiliensis possibly follows the population genetic structure of the species and, owing to the existence of a variant, its origin may not be recent.

Aplicação de marcadores moleculares ISSRs em estudos de conservação e ecologia

“…Os artigos encontrados para a aplicação da técnica ISSR em invertebrados (09) teve por característica o conhecimento ecológico de espécies consideradas pragas (BORBA et al, 2005;MELO et al, 2020). Resultados semelhantes foram encontrados nas pesquisas que utilizaram este marcador no grupo de fungos (05), sendo grande parte dos trabalhos analisados objetivando compreender as relações ecológicas e evolutivas das espécies (DARIVA et al, 2005;JING et al, 2017;UMAÑA-CASTRO et al, 2019;LONGYA;TALUMPHAI;JANTASURIYARAT, 2020).…”

First Report of B Chromosomes in Caecilians (Amphibia: Gymnophiona)

“…chromosomes are one of the most widespread numerical polymorphisms, or a type of aneuploidy, in the karyotypes of many eukaryotic organisms (Green, 1988;Camacho, 2005;Jones, 2017). B chromosomes occur in approximately 15% of all extant eukaryotes, fungi, animals, and plants that are karyologically known (Melo et al, 2020). B chromosomes do not pair meiotically with A chromosomes but are instead inherited in a non-Mendelian mode and typically composed of constitutive heterochromatin, consisting of highly repetitive DNA sequences characteristic of satellite DNA, ribosomal DNA, and transposable elements (Douglas and Birchler, 2017).…”