AN ELECTROPHORETIC INVESTIGATION OF RELATIONSHIPS OF DIPLOID AND TETRAPLOID SPECIES OF AUSTRALIAN DESERT FROGS NEOBATRACHUS (ANURA, MYOBATRACHIDAE)

Allozyme electrophoresis of 27 loci was used to characterise genetic v ariation among 29 populations of six diploid species of the myobatrach id frog genus Neobatrachus. All six species are well differentiated ge netically with the percentage of fixed differences between species ran ging from 11 to 59%. The genetic data are in agreement with the curren tly accepted species boundaries. The four tetraploid species were exam ined for 25 of the 27 loci assayed in the diploid species. In contrast to the diploid species, the tetraploid species shared electromorphs w ith each other at all the loci examined. The tetraploid species were e xamined for the presence of electromorphs specific to individual diplo id species. The majority of these electromorphs were observed in the t etraploid species. For cases in which the range of a tetraploid specie s contacts that of a diploid species and the diploid population can be characterised by unique electromorphs, then evidence of current gene flow was found in the direction of the tetraploid populations. The dat a are compatible with single or multiple discrete or hybrid origins of the tetraploids overlain by gene flow among the tetraploids and betwe en the tetraploids and some and perhaps all of the diploids by means o f geographically limited but ongoing episodes of introgressive hybridi sation.