GENETIC STUDIES OF NATURAL POPULATIONS OF DROSOPHILA: DROSOPHILA PSEUDOOBSCURA, A LARGE DOMINANT POPULATION

FOR several years members of this laboratory have studied the genetic structure of Drosophila populations. None of these populations has been a large dominant continental population. PROFESSOR TH. DOBZHANSKY and his colleagues have analyzed samplemf Drosophila willistoni, the major Neotropical Drosophila with the largest population of any Drosophila known, and Drosophila pseudoobscura, which is the dominant population in numbers and distribution in the western United States and extends through Mexico and Guatemala. The studies with D. pseudoobscura are summarized and extended by DOBZHANSKY, SPASSKY and TIDWELL (1963 and references therein). PROFESSOR DOBZHANSKY spent the summer of 1961 in Arizona collecting and analyzing populations of D. pseudoobscura. He provided this laboratory with large samples of two of the populations he was testing and DR. WILLIAM B. HEED collected two other populations of D. pseudoobscura so that there were four samples from as many localities to compare. These parallel investigations on samples of the same population have the added advantage that one can compare directly the results of the two methods of analysis. MATERIALS AND METHODS