title: Genomic distribution of P elements in Drosophila willistoni and a search for their relationship with chromosomal inversions.
abstract: According to the recent-invasion hypothesis, Drosophila melanogaster may have acquired its P elements in a fairly recent process of horizontal transmission between species. Drosophila willistoni has been identified as the potential donor species in that transfer process. A most remarkable feature of D. willistoni is its extensive chromosomal polymorphism due to inversions-the adaptiveness of which has been the subject of many classical studies on evolutionary genetics. In this article, we further extend the study of P elements in D. willistoni, focusing on the possible role they may play in the generation of chromosomal inversions. Our results may be summarized as follows. P-homologous sequences were detected in South American populations of D. willistoni. In two of them, a recently collected wild population and an old laboratory stock, the P insertion sites were located in the polytene chromosomes. Several hybridization sites were mapped in all major chromosome arms of the natural population, which was also chromosomally polymorphic; in the laboratory population, nearly devoid of inversions, hybridization sites were found to be confined to the chromocenter. In the wild population, 10 of the 24 P hybridized sites coincided with several inversions break points and another five sites located themselves very close to those points. The results are discussed within the context of evolutionary hypotheses.
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: L P
authors.initials: LP
authors.lastname: Regner
authors.forename: M S
authors.initials: MS
authors.lastname: Pereira
authors.forename: C E
authors.initials: CE
authors.lastname: Alonso
authors.forename: E
authors.initials: E
authors.lastname: Abdelhay
authors.forename: V L
authors.initials: VL
authors.lastname: Valente
mesh_terms: D000818:Animals; D007446:Chromosome Inversion; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004330:Drosophila / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics; D005260:Female
chemical_list: D004251:DNA Transposable Elements