Rate of Ageing in Drosophila suhohscura 279 



of females (Maynard Smith, 1959). This can be shown in two 

 ways. Table VI shows the lifespans of males and of females 

 of nine inbred lines, two kinds of F^ hybrids between inbred 

 lines, and the offspring of two groups of wild-caught females, 

 one from Kent and one from Galilee. In eight of these 13 

 populations there was a significant difference between the 



Tables VI 

 Relative longevities of males and females, in days, at 20° c. 



+ +, significant at 0-001 level; +, significant at 10 level. 



longevities of the two sexes, but in four cases it was the males 

 and in four cases the females which lived for longer. This can 

 only be explained by the presence of genes which affect the 

 longevity of the two sexes differently. The same conclusion 

 emerges from a study of the correlations between the longevi- 

 ties of relatives in a population derived from females caught in 

 Galilee (Table VII). All the correlations are rather low; this 

 means only that many differences between members of the 



