Insights into the karyotype evolution and speciation of the beetle Euchroma gigantea (Coleoptera: Buprestidae)

Abstract

Euchroma Dejean, 1833 (Buprestidae: Coleoptera) is a monotypic genus comprising the species Euchroma gigantea, with populations presenting a degree of karyotypic variation/polymorphism rarely found within a single taxonomic (specific) unit, as well as drastically incompatible meiotic configurations in populations from extremes of the species range. To better understand the complex karyotypic evolution of E. gigantea, the karyotypes of specimens from five populations in Brazil were investigated using molecular cytogenetics and phylogenetic approaches. Herein, we used FISH with histone genes as well as sequencing of the COI to determine differential distribution of markers and relationships among populations. The analyses revealed new karyotypes, with variability for chromosome number and morphology of multiple sex chromosome mechanisms, occurrence of B chromosome variants (punctiform and large ones), and high dispersion of histone genes in different karyotypes. These data indicate that chromosomal polymorphism in E. gigantea is greater than previously reported, and that the species can be a valuable model for cytogenetic studies. The COI phylogenetic and haplotype analyses highlighted the formation of three groups with chromosomally polymorphic individuals. Finally, we compared the different karyotypes and proposed a model for the chromosomal evolution of this species. The species E. gigantea includes at least three cytogenetically polymorphic lineages. Moreover, in each of these lineages, different chromosomal rearrangements have been fixed. Dispersion of repetitive sequences may have favored the high frequency of these rearrangements, which could be related to both adaptation of the species to different habitats and the speciation process.

Meiotic analyses show adaptations to maintenance of fertility in X1Y1X2Y2X3Y3X4Y4X5Y5 system of amazon frog Leptodactylus pentadactylus (Laurenti, 1768)

“…Thus, when perform synapses during meiotic cycles consist of various types of multivalent associations, ranging from simple trivalent to complex forms, involving several karyotype elements 5 – 7 . These systems have also been observed in other animals, including bats 6 – 8 , rodents 3 , birds 9 , fish 10 , lizards 11 , beetles 12 , butterflies 13 , termites 14 , spiders 15 and scorpions 16 .…”

Rapid chromosomal evolution in the bush-cricket Gonatoxia helleri Hemp, 2016 (Orthoptera, Phaneropterinae)

“…Even under the assumption that fusions or inversions are frequent in orthopteran chromosomal evolutionary history (e.g. White 1973, Hewitt 1979, Warchałowska-Śliwa 1998 leading to a reduced diploid number, the karyotype of G. helleri is an extreme example compared to other phaneropterines and Gonatoxia species (Warchałowska-Śliwa et al in preparation). In specimens analyzed in this paper, probably Robertsonian translocations (centric fusion) and tandem fusions and/or inversion were the reason of the observed morphological arrangements in the 1 st chromosome pair in all investigated populations of G. helleri.…”

“…Potter et al 2017). The role of chromosomal rearrangements (translocations, inversions, changes in chromosome number) in the formation of reproductive barriers has been investigated and found to play a causal role in the isolation of species or populations in some genera of Hemiptera (Mills andCook 2014, Chirino et al 2017), Diptera (Coluzzi et al 2002), Coleoptera (Kobayashi et al 2000, Xavier et al 2018, Lepidoptera (Vershinina andLukhtanov 2017, Lucek 2018), and Orthoptera (e.g. Kawakami et al 2011, Taffarel et al 2015, Buleu et al 2019, Silva et al 2019.…”

Chromosomal dynamics in space and time: evolutionary history of Mycetophylax ants across past climatic changes in the Brazilian Atlantic coast

“…On the other hand, under a molecular cytogenetic approach, such as Fluorescence in situ Hybridization (FISH) chromosome mapping, useful diagnostic characters for morphologically conservative species may be provided as variations in the number and/or position of ribosomal DNA (rDNA) clusters or CR indications given by changes in chromosome number. Hence, the use of FISH data has become an important tool for describing and delimiting new taxa, especially for insects 28–30 . In this way, we can accurately test the assumptions made previously on the likely chromosomal evolution within the Mycetophylax lineages.…”