Immunological Relationship of Western Palearctic Water Frogs (Salientia: Ranidae)

Abstract

AbstractReciprocal immunological distances between six albumins of five taxa (Rana lessonae, Italian non-hybrids, R. perezi, the slow and fast albumins of R. ridibunda, and a sample possibly representing R. saharica) were determined with microcomplement fixation. The immunological distances determined by each antiserum were scaled so that the sum of distances to each albumin was identical to the sum of distances from that albumin. The scaled reciprocal values were then averaged and used to generate 39 Fitch-Margoliash phenograms. The three lowest percent standard deviations (% SD) for phenograms were 5.7, 8.3 and 8.6; the next lowest was 12.1; eight phenograms had % SD less than 20. The three phenograms with lowest (% SD agreed in grouping (a) the two albumins of Rana ridibunda; (b) Rana lessonae and the Italian non-hybrid; and (c) Rana perezi and R. "saharica ". In the lowest % SD phenogram, the two ridibunda alleles are linked to the R. lessonae-Italian non-hybrid pair; in the next, the two ridibunda albumins were linked first to the R. perezi-R. "saharica" pair; in the third, the R. lessonae-Italian non-hybrid pair was linked first to the R. perezi-R. "saharica" pair. These latter two phenograms include legs of -5.8 and -4.7, respectively. Five triads of data among the 35 possible in the lowest% SD phenogram fail to conform to the triangle inequality; this is associated with the failure of the antiserum to the rapidly migrating ridibunda albumin to distinguish between the two ridibunda albumins. This posed no problem in grouping the albumins. The negative legs in the second and third ranked phenograms are like those generated by the Fitch-Margoliash algorithm when additive data are forced into a tree other than that specified by the additive data. The three lowest % SD phenograms agree with other data suggesting groupings of the taxa represented. They all place the two ridibunda albumins together, and they all group R. lessonae with the I talian non-hybrid form; these latter two share numerous electrophoretic markers. The data suggest a divergence ofwestern Palearctic water frogs from the eastern North American R. catesbeiana ofabout 43 x 106 years ago. R. lessonae and the Italian non-hybrid may have shared a common ancestor with R. ridibunda some 12 x 106 years ago; R. lessonae and the Italian non-hybrids may have diverged as recently as 4 x 106 years ago. The two ridibunda albumins may differ by as little as one amino acid residue. The Iberian R. perezi and saharica may have diverged from the central European cluster about 16 x 166 years ago, and from each other about 6 x 106 years ago; this latter divergence may reflect the refilling of the Mediterranean Sea following a dry period some 7-5.5 x 106 years ago.