The karyotype of the Iberian imperial eagle (Aquila adalberti) analyzed byclassical and DNA replication banding

We report here for the first time the karyotype of the Iberian imperial eag le (Aquila adalberti). All eagles examined had a diploid number of 82 chrom osomes and a greater number of microchromosomes (12 pairs) than has been fo und in all other species of the Accipitridae family. This karyotypic eviden ce corroborates the recent separation of A. adalberti from A. heliaca on th e basis of molecular data. RB-FPG banding induced a specific banding patter n that allowed us to identify homologous chromosome pairs and revealed feat ures about late and early replicating regions. Several chromosome banding t echniques (C-, CMA(3)-, and restriction endonuclease banding and silver sta ining) were used to characterize the karyotype more accurately. Two GC-rich , late-replicating heterochromatin regions were found in the W chromosome. These regions are AluI resistant and can be used for sex determination in t his species. All microchromosomes were heterochromatic, GC rich, and late r eplicating. Silver staining revealed active nucleolus organizing regions on a pair of microchromosomes that were entirely heterochromatic and stained intensely after CMA3-banding. Different chromosome rearrangements are discu ssed in order to establish the phylogenetic relationship between A. adalber ti and its most closely related species, A. heliaca.