ESTIMATING GENETIC-VARIATION FROM LARVAE AND ADULTS OF MAYFLIES - AN ELECTROPHORETIC ANALYSIS OF 3 SPECIES OF HEPTAGENIIDAE (EPHEMEROPTERA)

Genetic variation in larvae and imagines of three species of Heptageni idae from central Italy, Ecdyonurus sp. (venosus group), Electrogena g randiae (Belfiore, 1981), and Electrogenn lateralis (Curtis, 1834) was studied by starch-gel electrophoresis. Thirteen enzyme systems were a nalysed for a total of 20 loci (Aat, Ada, Adk-1, Adk-2, Ck-1, Ck-2, Es t-1, Est-2, alpha-Gpdh, Gpi, La-1, La-2, Mdh-1, Mdh-2, Me-1, Me-2, Mpi , Pap, Pgm-1, Pgm-2), 15 of which were expressed in adults and 16 in t he larvae. Only 11 loci (Aat, Ada, Est-2, Gpi, La-2, Mdh-1, Me-2, Mpi, Pap, Pgm-1, Pgm-2) were shared by larvae and adults. Observed heteroz ygosities were always lower than expected values; higher values were o bserved in larvae than in adults. Fixation indices and genetic distanc es were higher in the adults; however, the two genera were better disc riminated using the larval samples. In conclusion, comparisons using l arvae and adults simultaneously should be avoided, and absolute values of genetic identities and genetic distances to assess systematic leve ls have to be considered with caution, since they can vary from one de velopmental stage to another.