Doi: 10.1159/000056820 The species and chromosomal distribution of the centromeric-satellite I sequence from sheep in the tribe Caprini and other Bovidae R. Chaves, a,b H. Guedes-Pinto, b J.S. Heslop-Harrison a and T. Schwarzacher a a Department of Biology, University of Leicester, Leicester (UK); b Department of Genetics and Biotechnology, ICETA – UTAD, University of Tra ´ s-os-Montes and Alto Douro, Vila Real (Portugal) Dedicated to Professor Dr. Ulrich Wolf on the occasion of his retirement. Abstract. The evolution of chromosomes in species in the family Bovidae includes fusion and fission of chromosome arms (giving different numbers of acrocentric and metacentric chromosomes with a relatively conserved total number of arms) and evolution in both DNA sequence and copy number of the pericentromeric · -satellite I repetitive DNA sequence. Here, a probe representing the sheep · -satellite I sequence was isolated and hybridized to genomic DNA digests and meta- phase chromosomes from various Bovidae species. The probe was highly homologous to the centromeric sequence in all spe- cies in the tribe Caprini, including sheep (Ovis aries), goat (Ca- pra hircus) and the aoudad or Barbary sheep (Amnotragus ler- via), but showed no detectable hybridization to the · -satellite I sequence present in the tribe Bovini and at most very weak to species in the tribes Hippotragini, Alcelaphini or Aepycerotini. The sex chromosomes of sheep, goat and aoudad did not con- tain detectable · -satellite I sequence; in sheep, one of the three metacentric autosomal chromosomes does not carry the se- quence, while in aoudad, it is essentially absent in three large autosomal pairs as well as the large metacentric chromosome pair. The satellite probes can be used as robust chromosome and karyotype markers of evolution among tribes and increase the resolution of the evolutionary tree at the base of the Artio- dactyla. Introduction The family Bovidae in the order Artiodactyla (even-toed ungulates) includes some 124 species in 45 genera (Vaughan, 1986). Many of these are of economic importance (including cattle, sheep and goats), and some significant landraces and species are endangered or threatened with extinction. A taxo- nomic division of the Bovidae has been made by Gentry (1992) based on morphological and karyotypic criteria, and this classi- fication, recognizing tribes (rather than subfamilies), is used here (Table 1). However, there are areas where phylogenetic relationships are unclear, and molecular data, including mitochondrial and ribosomal DNA sequences (Gatesby, 1992; Al- lard et al., 1992), is increasing the resolution of the phylogeny. Data from examining the distribution of satellite DNA se- quences (Modi et al., 1996; Jobse et al., 1995) has resolved fur- ther ambiguities within the Tribe Bovini. The number of auto- somal chromosome arms in the karyotypes of the Bovidae is almost constant with 56 to 58 arms, plus the X and Y chromo- somes (Wurster and Benirschke, 1968). Because of the varia- tion in the number of biarmed chromosomes, the number of autosomes varies from 28 to 58 (Bunch, 1978, Bunch et al., 1976). Differences in number of monobrachial and biarmed chromosomes have been particularly evident within the tribe Caprini (Table 1), which contains ten genera (Franklin, 1997) including sheep (Ovis), goats (Capra), aoudads (Amnotragus), and bharals (Pseudois). The thars (Hemitragus) maintain be- havioural and morphological similarities to the aoudad and may be ancestral to sheep and goats (Bunch, 1978). Now, evolu- tion of Ovis, Amnotragus and Pseudois karyotypes from a sug- gested ancestral karyotype of 2n = 60 is postulated to involve a series of Robertsonian translocations (also referred to as