Molecular Biology and Evolution, Vol 8, 71-84, Copyright © 1991 by Society for Molecular Biology and Evolution
MW Allard and RL Honeycutt
Patterns of restriction-endonuclease site and length variation at the
nuclear rDNA locus (18S + 28S rRNA gene complex) were examined in rodents.
Of the 164 restriction sites mapped for seven species, 22 were conserved
(mapping to the 18S, 28S, and 5.8S genes and ITS1) in all three Onychomys
species as well as in Mus musculus and in three closely related peromyscine
rodents, Peromyscus boylii, P. eremicus, and Reithrodontomys megalotis. The
nontranscribed spacer (NTS) region revealed most of the variation among
these taxa, with the patterns of variation grouping into the following
categories, (1) intraindividual variation revealing as many as four
site-specific repeat types within an individual, (2) intraspecific and
interspecific site variation confined to the NTS, and (3) length variation
in both the transcribed and NTS regions. Length variation in the 28S rRNA
gene was also examined in 17 additional rodent species, and most size
differences mapped to the divergent domain, D8, found in sequence
comparisons between Mus and Rattus. The systematic implications of rDNA
variation are discussed using the perspective gained from these rodent
comparisons.
ORIGINAL ARTICLE
Ribosomal DNA variation within and between species of rodents, with emphasis on the genus Onychomys
Department of Organismic and Evolutionary Biology, Harvard University.
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