Relation of Infection to Population Structure in Drosophila melanogaster

Extrachromosomal Element Delta in Drosophila melanogaster. IV. Variation and Persistence of Delta-Associating Second Chromosomes in a Natural Population

“…The frequency of infected flies with the killing agent was still higher in the summer collection and decreased in the autumn collection made in 1966 (Table 6), as observed in the collection made in 1964 and 1965 (Minamori and Tatsukawa, 1968). It suddenly decreased to a negligible percent in the summer and autumn collections made in 1967, and again increased in the summer and autumn collection made in 1968.…”

“…The population dealt with in this study has been surveyed since 1961, with regard to frequencies of lethal and semilethal second chromosomes and of infected flies with a killing agent (Minamori and Saito, 1964;Minamori and Tatsukawa, 1968). According to the surveys made in 1964 and 1965, the lethal frequency of this population was significantly reduced under the condition of infection.…”

INCREASING TREND IN FREQUENCIES OF LETHAL AND SEMILETHAL CHROMOSOMES IN A NATURAL POPULATION OF <i>DROSOPHILA MELANOGASTER</i>

“…3) The lethal plus semilethal frequency increased and allelism frequency decreased from early summer to fall in each year. 4) An infective agent was discovered in this population in 1964, and it was recognized to reduce lethal frequencies, but not semilethal frequencies (Minamori 1967;Minamori and Tatsukawa 1968) . 5) An extrachromosomal element denoted by delta was found in this population in 1965 (Minamori 1969) .…”

“…The results obtained in surveys made in the 1961-1968 period were reported (Minamori and Saito 1964;Minamori and Tatsukawa 1968;Minamori et al 1970) . The characteristics observed in this population during the period are as follows.…”