Chromosomal evolution and phylogenetic considerations in cuckoos (Aves, Cuculiformes, Cuculidae)

Abstract

The Cuckoos have a long history of difficult classification. The species of this order have been the subject of several studies based on osteology, behavior, ecology, morphology and molecular data. Despite this, the relationship between Cuculiformes and species of other orders remains controversial. In this work, two species of Cuculidae, Guira guira (Gmelin, 1788) and Piaya cayana (Linnaeus, 1766), were analyzed by means of comparative chromosome painting in order to study the chromosome evolution of this group and to undertake the first chromosome mapping of these species. Our results demonstrate high chromosomal diversity, with 2n = 76 in G. guira, with fission and fusion events involving ancestral syntenies, while P. cayana presented only fissions, which were responsible for the high diploid number of 2n = 90. Interestingly, there were no chromosomal rearrangements in common between these species. Our results, based on Giemsa staining, were compared with previous data for other cuckoos and also with taxa proposed as sister-groups of Cuculiformes (Otidiformes, Musophagiformes and Opisthocomiformes). Cytogenetic comparisons demonstrated that cuckoo species can be divided into at least three major groups. In addition, we found no evidence to place Cuculiformes close to the groups proposed previously as sister-groups.

Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation

“…The comparison of our results with the data of G . guira from dos Santos et al [ 30 ] suggests a very similar karyotype between these species, with several chromosomal rearrangements shared between both species ( Table 1 ). On the other hand, no chromosomal rearrangements were shared between these species and P .…”

“…Since the first reports, cytogenetic studies on cuckoos have revealed karyotype variation both in chromosomal number and morphology, with 2n ranging from 64 to 90 [ 28 , 29 , 30 ]. This indicates that interchromosomal rearrangements, such as fusion, fission, and intrachromosomal rearrangements, such as pericentric inversion and centromere repositions, have played an important role in the chromosome evolution of these species.…”

“…Cytogenetics studies with cuckoos’ species are still scarce and based mostly on conventional cytogenetics approaches [ 28 , 29 , 30 ]. These studies demonstrated a variation in karyotype organizations with 2n ranging from 64 in Crotophaga major (Crotophaginae) [ 29 ] to 90 in Piaya cayana (Cuculinae) [ 30 ].…”

“…Cytogenetics studies with cuckoos’ species are still scarce and based mostly on conventional cytogenetics approaches [ 28 , 29 , 30 ]. These studies demonstrated a variation in karyotype organizations with 2n ranging from 64 in Crotophaga major (Crotophaginae) [ 29 ] to 90 in Piaya cayana (Cuculinae) [ 30 ]. WCP experiments using Gallus gallus and Leucopternis albicollis macrochromosomes probes have been applied only to two species: Guira guira (Cuculinae) and Piaya cayana (30), revealing that the chromosome evolution in cuckoos involved mainly fissions and fusions events when compared with G .…”

“…guira , resulting in a low diploid number (2n = 76) in contrast with a high diploid number in P . cayana (2n = 90) [ 30 ]. Besides, some gaps in the macrochromosomes of both species were not hybridized by the G .…”