Chromosome phylogeny of the subfamily Pitheciinae (Platyrrhini, Primates) by classic cytogenetics and chromosome painting

Abstract

Background: The New World monkey (Platyrrhini) subfamily Pitheciinae is represented by the genera Pithecia, Chiropotes and Cacajao. In this work we studied the karyotypes of Pithecia irrorata (2n = 48) and Cacajao calvus rubicundus (2n = 45 in males and 2n = 46 in females) by G- and C-banding, NOR staining and chromosome painting using human and Saguinus oedipus whole chromosome probes. The karyotypes of both species were compared with each other and with Chiropotes utahicki (2n = 54) from the literature.

Results: Our results show that members of the Pitheciinae have conserved several chromosome forms found in the inferred ancestral Platyrrhini karyotype (associations of human homologous segments 3a/21, 5/7a, 2b/16b, 8a/18, 14/15a and 10a/16a). Further, the monophyly of this subfamily is supported by three chromosomal synapomorphies (2a/10b, an acrocentric 15/14 and an acrocentric human 19 homolog). In addition, each species presents several autapomorphies. From this data set we established a chromosomal phylogeny of Pitheciinae, resulting in a single most parsimonious tree.

Conclusions: In our chromosomal phylogeny, the genus Pithecia occurred in a more basal position close to the inferred ancestor of Platyrrhini, while C. c. rubicundus and C. utahicki are closely related and are linked by exclusive synapomorphies.

Figure 1

G- (A) and C-banding (B) in P. irrorata.

Figure 2

G - (A) and C-banding (B) in C. c. rubicundus.

Figure 3

NOR-staining in P. irrorata (A) and C. c. rubicundus (B). NOR-regions are highlighted by arrows.

Figure 4

Representative FISH-images from cross-species chromosome painting experiments using human probes in P. irrorata (A), human (B) and S. oedipus probes (C) in C. c. rubicundus. Beside each metaphase the respective probe composition and color assignment is given

Figure 5

Comparative karyotype analysis of P. irrorata, C. c. rubicundus and C. utahicki [19]by G-banding and FISH using human whole chromosome probes. The banded C. utahicki chromosomes were obtained from a previously unpublished metaphase [10].

Figure 6

Most parsimonious tree based on the binary chromosome character matrix (additional file 1). The analysis was made employing the maximum parsimony method using PAUP software.