Rk. Aggarwal et al., GENERIC AFFINITIES AMONG CROCODILIANS AS REVEALED BY DNA-FINGERPRINTING WITH A BKM-DERIVED PROBE, Proceedings of the National Academy of Sciences of the United Statesof America, 91(22), 1994, pp. 10601-10605
Genetic fingerprint profiles have been successfully used for establish
ing biological relationships, in linkage analysis, and in studies of p
opulation structure but have not so far been used for ascertaining phy
logenetic relationships among related groups of species and genera. Th
is is largely because these profiles are thought to evolve too rapidly
to be informative over large time intervals. However, we show here th
at among the Crocodilia, whose phylogeny is a debated issue, these pro
files can provide phylogenetically useful information. By using the pr
obe Bkm-2(8), DNA fingerprints with distinct bands distributed in the
size range 0.5-23.0 kb were obtained for individuals of 18 species bel
onging to seven of the eight genera of crocodilians. These genetic pro
files showed individual-, species-, and restriction enzyme-specific pa
tterns, In addition, striking differences were observed in the copy nu
mber of Bkm-related sequences in genomes of different crocodilian spec
ies. The qualitative data from DNA fingerprint profiles, and quantitat
ive data on copy number variation in Bkm-related sequences, suggest th
at these genera belong to two distinct groups, one of which includes A
lligator, Paleosuchus, and Caiman; the other includes Crocodylus, Oste
olaemus, Tomistoma, and Gavialis. A close relationship between Tomisto
ma and Gavialis is also suggested by these results.