Occurrence of Drosophilids in the Pernambuco's coastal region (years 2000-2001) and the frequency of chromosomal inversions found in Drosophila malerkotliana

Drosophilids were collected in the campus of UFPE (Recife), Rio Doce (Olinda), Vila Velha (Itamaraca), Parque de dois Irmaos (Recife) and Charles Darwin Ecological Refuge (Igarassu), in the years 2000 and 2001, seeking to establish the frequency of occurrence of the various species of the genus Drosophila. In these collections, D. malerkotliana occurred in an average frequency of 64%, followed by D. melanogaster, with an average frequency of 23%. The frequency of D. malerkotliana was higher than that of D. melanogaster in localities with high and medium degree of urbanization. Despite the great distance from the distribution center of the species (Africa), D. malerkotliana presented high polymorphism of chromosomal inversions. In the locality of Rio Doce, inversions In(IIL)24B-39A and In(IIL)21-25, occurred with frequencies of 18.5% and 100%, respectively, while inversion In(IIIR)84-88B occurred with a frequency of 100%. In the population of campus UFPE (Recife), also with high urbanization, two inversions were found, In(IIIR)93C-94A and In(IIIL)64A-72A with frequencies of 37.1 and 60%, respectively. In the population of The Parque de Dois Irmaos (Recife), with medium urbanization, four inversions were visualized: In(IIIL)70C-73B (66%); In(IIIR)93C-94A (52%); In(IIL)24B-39A (33%); and In(IIR)50B-51A (33%). In the population of the Charles Darwin Ecological Refuge (Igarassu), of low urbanization, only the inversion In(IIIR)100A-98B(?) was found. -88(?), with 100% frequency. These data suggest that the polymorphism of inversions is higher in localities with greater urbanization, possibly due to the longer colonization time, which allowed the accumulation of genetic variations.