Analysis of multiple chromosomal rearrangements in the genome of Willisornis vidua using BAC-FISH and chromosome painting on a supposed conserved karyotype

Talita Fernanda Augusto Ribas,Julio Cesar Pieczarka,Alexandre Aleixo,Darren K Griffin,Fengtang Yang,Patricia Caroline Mary O´Brien,Malcolm Andrew Ferguson-Smith,Lucas G Kiazim,Rebecca E O’Connor,Cleusa Yoshiko Nagamachi

doi:10.1186/s12862-021-01768-y

Abstract

BackgroundThamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes. They are a diverse group of 225 species and 45 genera and occur in lowlands and lower montane forests of Neotropics. Despite the large degree of diversity seen in this family, just four species of Thamnophilidae have been karyotyped with a diploid number ranging from 76 to 82 chromosomes. The karyotypic relationships within and between Thamnophilidae and another Passeriformes therefore remain poorly understood. Recent studies have identified the occurrence of intrachromosomal rearrangements in Passeriformes using in silico data and molecular cytogenetic tools. These results demonstrate that intrachromosomal rearrangements are more common in birds than previously thought and are likely to contribute to speciation events. With this in mind, we investigate the apparently conserved karyotype of Willisornis vidua, the Xingu Scale-backed Antbird, using a combination of molecular cytogenetic techniques including chromosome painting with probes derived from Gallus gallus (chicken) and Burhinus oedicnemus (stone curlew), combined with Bacterial Artificial Chromosome (BAC) probes derived from the same species. The goal was to investigate the occurrence of rearrangements in an apparently conserved karyotype in order to understand the evolutionary history and taxonomy of this species. In total, 78 BAC probes from the Gallus gallus and Taeniopygia guttata (the Zebra Finch) BAC libraries were tested, of which 40 were derived from Gallus gallus macrochromosomes 1–8, and 38 from microchromosomes 9–28.ResultsThe karyotype is similar to typical Passeriformes karyotypes, with a diploid number of 2n = 80. Our chromosome painting results show that most of the Gallus gallus chromosomes are conserved, except GGA-1, 2 and 4, with some rearrangements identified among macro- and microchromosomes. BAC mapping revealed many intrachromosomal rearrangements, mainly inversions, when comparing Willisornis vidua karyotype with Gallus gallus, and corroborates the fissions revealed by chromosome painting.ConclusionsWillisornis vidua presents multiple chromosomal rearrangements despite having a supposed conservative karyotype, demonstrating that our approach using a combination of FISH tools provides a higher resolution than previously obtained by chromosome painting alone. We also show that populations of Willisornis vidua appear conserved from a cytogenetic perspective, despite significant phylogeographic structure.

Highlights

Thamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes
We show that populations of Willisornis vidua appear conserved from a cytogenetic perspective, despite significant phylogeographic structure
We report 14 interchromosomal differences in Willisornis vidua when compared to Taeniopygia guttata and Gallus gallus, using the latter as the reference (Figs. 4 and 5; Table 2)

Summary

Introduction

Thamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes. Recent studies have identified the occurrence of intrachromosomal rearrangements in Passeriformes using in silico data and molecular cytogenetic tools These results demonstrate that intrachromosomal rearrangements are more common in birds than previously thought and are likely to contribute to speciation events. In Brazil, there are approximately 1900 species of Passeriformes, with 1300 occurring in the Amazon, of which 265 are endemic [2, 3] This order represents one of the largest adaptive radiations among vertebrates, with representative species in all continents except Antarctica, and with the most diversity found in the tropics [1]. The Thamnophilidae family (typical antbirds), are a widespread radiation of insectivorous Passeriformes birds They are a monophyletic and diverse group [4] of species and 45 genera with many occurring in upland forests of the Neotropics [5, 6]. In Brazil as a whole, there have been 31 new species described in the last decade, 15 of which were found in the Amazon region [17]

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