Evolutionary histories of highly repeated DNA families among the artiodactyla (mammalia)

Abstract

Six highly repeated DNA families were analyzed using Southern blotting and fluorescence in situ hybridization in a comparative study of 46 species of artiodactyls belonging to seven of the eight extant taxonomic families. Two of the repeats, the dispersed bovine-Pst family and the localized 1.715 component, were found to have the broadest taxonomic distributions, being present in all pecoran ruminants (Giraffidae, Cervidae, Antilocapridae, and Bovidae), indicating that these repeats may be 25-40 million years old. Different 1.715 restriction patterns were observed in different taxonomic families, indicating that independent concerted evolution events have homogenized different motifs in different lineages. The other four satellite arrays were restricted to the Bovini and sometimes to the related Boselaphini and Tragelaphini. Results reveal that among the two compound satellites studied, the two components of the 1.711a originated simultaneously, whereas the two components of the 1.711b originated at two different historical times, perhaps as many as 15 million years apart. Systematic conclusions support the monophyly of the infraorder Pecora, the monophyly of the subfamily Bovinae (containing the Boselaphini, Bovini, and Tragelaphini), an inability to resolve any interrelationships among the other tribes of bovids, paraphyly of the genus Bos with respect to Bison, and a lack of molecular variation among two morphologically and ecologically distinct subspecies of African buffaloes (Syncerus caffer cafer and S. c. nanus). Cytogenetically, a reduction in diploid chromosome numbers through centric fusion in derived karyotypes is accompanied by a loss of centromeric satellite DNA. The nilgai karyotype contains an apparent dicentric chromosome as evidenced by the sites of 1.715 hybridization. Telomeric sequences have been translocated to the centromeres without concomitant chromosomal rearrangement in Thompson's gazelle.

Phylogenetic relationships and the primitive X chromosome inferred from chromosomal and satellite DNA analysis in Bovidae

“…The 1.715 satellite from B. taurus and the 1.714 satellite from O. aries proved to be informative markers (Modi et al 1996;Chaves et al 2000a) for studying the nature and amplification of the satellite DNA families on the autosomes and the X chromosome of the Bovidae family (figures 1,2,4 and 5; table 1) and allowed phylogeny to be inferred. Where we investigated several genera within a tribe, hybridization patterns were similar with the exception of the biarmed chromosomes, where satellite DNA reshuffling occurs (Chaves et al 2000b(Chaves et al , 2003b.…”

“…Sika (Cervus nippon) and white-tailed deer (Odocoileus virginianus) in the Cervidae family also carry 1.715-like satellite I sequences on the X chromosome (cited as unpublished observation by Gallagher et al (1999)) and these authors suggest that an acrocentric X chromosome with heterochromatin (and the 1.715 satellite I sequence) at the centromeres is the primitive condition. Modi et al (1996) hybridized a sequence representative of satellite I from Bos taurus (1.715 family) to different artiodactyl metaphases, and they found that this sequence was present in all pecoran animals analysed.…”

“…Both Modi et al (1993Modi et al ( , 1996 and Chaves et al (2000a) observed different satellite DNA in situ hybridization patterns within a small number of tribes in the Bovidae family, and we considered that the sequences had potential as phylogenetic markers to increase the resolution of the evolutionary tree at the base of the Artiodactyla (Chaves et al 2000a). Here we aimed to analyse the presence and distribution of satellites to address evolutionary and phylogenetic questions with respect to the X chromosome (and its primitive state), karyotype, species and tribal evolution.…”

Bov‐B Long Interspersed Repeated DNA (LINE) Sequences are Present in Vipera Ammodytes Phospholipase A2 Genes and in Genomes of Viperidae Snakes

“…Jobse et al [16] studied the history of the Bov-B SINE elements by comparative hybridisation and PCR, and found that they emerged just after the diver-gence of the Camelidae and the true ruminants. Recently, Modi et al [17] used Southern blot hybridisation and fluorescent in situ hybridisation (FISH) to study the distribution of ART-2 retroposon in 46 species of artiodactyls, and found that it is specific for all pecoran ruminants (fam. Bovidae, Antilocapridae, Cervidae and Giraffidae).…”

“…Szemraj proposed that the ART-2 retroposons should be considered as truncated BDDF (LINE-like) elements. Copy number estimates of ART-2 retroposon in the bovine genome range from 50000 [I41 to 200000 [17] copies/genome.…”