Characterization of chromosome structures of Falconinae (Falconidae, Falconiformes, Aves) by chromosome painting and delineation of chromosome rearrangements during their differentiation

Abstract

Karyotypes of most bird species are characterized by around 2n=80 chromosomes, comprising 7-10 pairs of large-and medium-sized macrochromosomes including sex chromosomes and numerous morphologically indistinguishable microchromosomes. The Falconinae of the Falconiformes has a different karyotype from the typical avian karyotype in low chromosome numbers, little size difference between macrochromosomes and a smaller number of microchromosomes. To characterize chromosome structures of Falconinae and to delineate the chromosome rearrangements that occurred in this subfamily, we conducted comparative chromosome painting with chicken chromosomes 1-9 and Z probes and microchromosome-specific probes, and chromosome mapping of the 18S-28S rRNA genes and telomeric (TTAGGG)n sequences for common kestrel (Falco tinnunculus) (2n=52), peregrine falcon (Falco peregrinus) (2n=50) and merlin (Falco columbarius) (2n=40). F. tinnunculus had the highest number of chromosomes and was considered to retain the ancestral karyotype of Falconinae; one and six centric fusions might have occurred in macrochromosomes of F. peregrinus and F. columbarius, respectively. Tandem fusions of microchromosomes to macrochromosomes and between microchromosomes were also frequently observed, and chromosomal locations of the rRNA genes ranged from two to seven pairs of chromosomes. These karyotypic features of Falconinae were relatively different from those of Accipitridae, indicating that the drastic chromosome rearrangements occurred independently in the lineages of Accipitridae and Falconinae.

Intrachromosomal rearrangements in avian genome evolution: evidence for regions prone to breakpoints

“…Larkin et al (2009) suggested that homologous synteny blocks and evolutionary breakpoint regions are subject to different evolutionary pressures. As further avian genomes are published, especially those with atypical karyotypes (for example, Falconiformes and Psittaciformes (de Oliveira et al, 2005(de Oliveira et al, , 2010Nanda et al, 2007;Nishida et al, 2008;Nie et al, 2009), we will be able to test the hypothesis that blocks of ordered genes have been preserved through evolution, and that these are reflected in the syntenic blocks seen here. Further species that have been of interest in zoo-FISH studies and would thus be likely candidates for studies in addition to the Falconiformes and Psittaciformes mentioned above include other Galliformes (Shibusawa et al, 2004a, b) and a range of species from orders such as Anseriformes and Passeriformes (Guttenbach et al, 2003).…”

Karyotypes and recombination patterns of the Common Swift (Apus apus Linnaeus, 1758) and Eurasian Hobby (Falco subbuteo Linnaeus, 1758)

“…In the Needle-tailed Swift (Hirundapus caudacutus), the species distantly related the Common Swift, Z chromosome is the smallest of metacentric macrochromosomes (Christidis 1990). In all Falco species examined it is middle-sized acrocentric chromosome (Nishida et al 2008). …”

“…Falconids show a very wide variation in diploid chromosome numbers (from 40 to 92) (Christidis 1990). Eurasian Hobby has 2n = 50 (Christidis 1990; Wang and Chen 1998;Nishida et al 2008).…”

Upgrading short-read animal genome assemblies to chromosome level using comparative genomics and a universal probe set

“…The first, the peregrine falcon (Falco peregrinus), has an atypical karyotype (2n = 50) (Nishida et al 2008). The falcon's ability to fly at speeds >300 km/h and its enhanced visual acuity make it the fastest predator on earth (Tucker et al 1998).…”

“…DNA was isolated using DNeasy blood and tissue kit Hansmann et al (2009) and the remaining chromosomes according to their chicken homeologs. Falcon chromosomes 1-13 and Z were numbered accordingly to the method of Nishida et al (2008). The remaining chromosomes were numbered by decreasing combined length of the placed PCFs.…”