Phylogeny and chromosomal diversification in the Dichroplus elongatus species group (Orthoptera, Melanoplinae)

Abstract

In an attempt to track the chromosomal differentiation in the Dichroplus elongatus species group, we analyzed the karyotypes of four species with classical cytogenetic and mapping several multigene families through fluorescent in situ hybridization (FISH). We improved the taxon sampling of the D. elongatus species group adding new molecular data to infer the phylogeny of the genus and reconstruct the karyotype evolution. Our molecular analyses recovered a fully resolved tree with no evidence for the monophyly of Dichroplus. However, we recovered several stable clades within the genus, including the D. elongatus species group, under the different strategies of tree analyses (Maximum Parsimony and Maximum Likelihood). The chromosomal data revealed minor variation in the D. elongatus species group’s karyotypes caused by chromosome rearrangements compared to the phylogenetically related D. maculipennis species group. The karyotypes of D. intermedius and D. exilis described herein showed the standard characteristics found in most Dichroplini, 2n = 23/24, X0♂ XX♀, Fundamental number (FN) = 23/24. However, we noticed two established pericentric inversions in D. intermedius karyotype, raising the FN to 27♂/28♀. A strong variation in the heterochromatic blocks distribution was evidenced at interespecific level. The multigene families’ mapping revealed significant variation, mainly in rDNA clusters. These variations are probably caused by micro chromosomal changes, such as movement of transposable elements (TEs) and ectopic recombination. These observations suggest a high genomic dynamism for these repetitive DNA sequences in related species. The reconstruction of the chromosome character “variation in the FN” posits the FN = 23/24 as the ancestral state, and it is hypothesized that variations due to pericentric inversions has arisen independently three times in the evolutionary history of Dichroplus. One of these independent events occurred in the D. elongatus species group, where D. intermedius is the unique case with the highest FN described in the tribe Dichroplini.

Cytogenomic analysis unveils mixed molecular evolution and recurrent chromosomal rearrangements shaping the multigene families onSchistocercagrasshopper genomes

“…The statistical significance observed only for U2 snDNA may also be indicative of that the homogenization events occurred more efficiently in this multigene family than in 18S rDNA and H3 histone. Despite the observed variations, U2 snDNA chromosomal patterns in Schistocerca were less dynamic than what was previously reported in grasshoppers (Palacios-Gimenez et al 2013;Castillo et al 2017). In these cases, transpositions plus chromosome inversions were also involved in dynamisms of U2 snDNA.…”

“…2013; Castillo et al. 2017). In these cases, transpositions plus chromosome inversions were also involved in dynamisms of U2 snDNA.…”

Repetitive DNAs in Melipona scutellaris (Hymenoptera: Apidae: Meliponidae): chromosomal distribution and test of multiple heterochromatin amplification in the genus

“…This is the first effort to locate this sequence in Hymenoptera. The presence of a unique chromosomal cluster of U2 snDNA was also observed in true bugs (Bardella et al 2016) and the grasshoppers Abracris flavolineata and Schistocerca gregaria (Bueno et al 2013;Camacho et al 2015), although multiple clusters were also noticed in other species, like grasshoppers (Palacios-Gimenez et al 2013;Castilho et al 2017). The use of this probe in other Melipona and Hymenoptera will elucidate the organization and evolution patterns of this sequence, which could be a good tool for understanding chromosome evolution.…”

Chromosome evolution and phylogeny in Ronderosia (Orthoptera, Acrididae, Melanoplinae): clues of survivors to the challenge of sympatry?

“…When compared with other Dichroplini genera, where established and polymorphic autosome‐autosome centric fusions are an important source of chromosome variation (e.g. Dichroplus ) (Mesa et al ., ; Colombo et al ., ; Castillo et al ., ), chromosome variation through A‐A centric fusion seems to have played a secondary role in Ronderosia .…”