Evolutionary cytogenetics can take confidence from methodological and analytical advances that promise to speed up data acquisition and analysis. Drastic chromosomal reshuffling has been documented in birds of prey by FISH. However, the available probes, derived from chicken, have the limitation of not being capable of determining if breakpoints are similar in different species: possible synapomorphies are based on the number of segments hybridized by each of chicken chromosome probes. Hence, we employed FACS to construct chromosome paint sets of the white hawk (Leucopternis albicollis), a Neotropical species of Accipitridae with 2n = 66. FISH experiments enabled us to assign subchromosomal homologies between chicken and white hawk. In agreement with previous reports, we found the occurrence of fusions involving segments homologous to chicken microchromosomes and macrochromosomes. The use of these probes in other birds of prey can identify important chromosomal synapomorphies and clarify the phylogenetic position of different groups of Accipitridae.

Rodentia comprises 42 % of living mammalian species. The taxonomic identification can be difficult, the number of species currently known probably being underestimated, since many species show only slight morphological variations. Few studies surveyed the biodiversity of species, especially in the Amazon region. Cytogenetic studies show great chromosomal variability in rodents, with diploid numbers ranging from 10 to 102, making it difficult to find chromosomal homologies by comparative G banding. Chromosome painting is useful, but only a few species of rodents have been studied by this technique. In this study, we sorted whole chromosome probes by fluorescence-activated cell sorting from two Hylaeamys megacephalus individuals, an adult female (2n = 54) and a fetus (2n = 50). We made reciprocal chromosome painting between these karyotypes and cross-species hybridization on Cerradomys langguthi (2n = 46). Both species belong to the tribe Oryzomyini (Sigmodontinae), which is restricted to South America and were collected in the Amazon region. Twenty-four chromosome-specific probes from the female and 25 from the fetus were sorted. Reciprocal chromosome painting shows that the karyotype of the fetus does not represent a new cytotype, but an unbalanced karyotype with multiple rearrangements. Cross-species hybridization of H. megacephalus probes on metaphases of C. langguthi shows that 11 chromosomes of H. megacephalus revealed conserved synteny, 10 H. megacephalus probes hybridized to two chromosomal regions and three hybridized to three regions. Associations were observed on chromosomes pairs 1-4 and 11. Fluorescence in situ hybridization with a telomeric probe revealed interstitial regions in three pairs (1, 3, and 4) of C. langguthi chromosomes. We discuss the genomic reorganization of the C. langguthi karyotype.

The Neotropical Phyllostomidae family is the third largest in the order Chiroptera, with 56 genera and 140 species. Most researchers accept this family as monophyletic but its species are anatomically diverse and complex, leading to disagreement on its systematics and evolutionary relationships. Most of the genera of Phyllostomidae have highly conserved karyotypes but with intense intergeneric variability, which makes any comparative analysis using classical banding difficult. The use of chromosome painting is a modern way of genomic comparison on the cytological level, and will clarify the intense intergenus chromosomal variability in Phyllostomidae. Whole chromosome probes of species were produced as a tool for evolutionary studies in this family from two species from different subfamilies, Phyllostomus hastatus and Carollia brevicauda, which have large morphological and chromosomal differences, and these probes were used in reciprocal chromosome painting. The hybridization of the Phyllostomus probes on the Carollia genome revealed 24 conserved segments, while the Carollia probes on the Phyllostomus genome detected 26 segments. Many chromosome rearrangements have occurred during the divergence of these two genera. The sequence of events suggested a large number of rearrangements during the differentiation of the genera followed by high chromosomal stability within each genus.