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RESEARCH PRODUCT

Euryhaline Brachionus strains (Rotifera) from tropical habitats: morphology and allozyme patterns

subject

description

The euryhaline rotifer Brachionus is a complex of sibling species. Although many investigations have been carried out in the past, the relationships among the Spanish species, the tropical SS strains and the clusters previously described, remained unknown. In this study, allozyme data for five populations from the tropics and two from Spanish lagoons — one of them B. ibericus and the other B. rotundiformis — were combined with data from the previous studies. Cluster analysis based on genetic distance allowed the 74 strains to be divided into two major groups. One group was associated with B. plicatilis-like strains, and the other group was associated with B. rotundiformis and B. ibericus. This latter group was divided into two clades. One of these clustered most with the S-morphotype strains and the B. ibericus species. The other clustered most closely with the tropical (SS) strains and the B. rotundiformis Spanish species. These results show a correspondence between the species description based on Spanish strains and the allozyme groups identified in a larger collection of strains.