Data from: Patterns of male fitness conform to predictions of evolutionary models of late-life

We studied lifetime male virility, a male fitness component, in five
populations of Drosophila melanogaster. Virility was measured as the
number of females, out of eight total, that a male could fertilize in 24
hours. Individual males were measured at weekly intervals until they died.
Virility declined in an approximately linear fashion for the first three
weeks of adult life. It then stayed low but relatively constant for
another three weeks, exhibiting a clear plateau. These observations are
consistent with the evolutionary theories of late-life.The results were
not consistent with a simple heterogeneity theory of late-life. This is
the first demonstration of a late-life plateau for a male fitness
component. We also found that the virility of males that were within seven
days of death was significantly lower than similarly aged males that were
not about to die. This rapid deterioration of virility prior to death, or
death spiral, is similar to a decline in fecundity that we had previously
documented.