Evolution of a novel female reproductive strategy in Drosophila melanogaster populations subjected to long term protein restriction

Reproductive output is often constrained by availability of
macronutrients, especially protein. Long term protein restriction,
therefore, is expected to select for traits maximizing reproduction even
under nutritional challenge. We subjected four replicate populations of
Drosophila melanogaster to a complete deprivation of yeast supplement,
thereby mimicking a protein restricted ecology. Following 24 generations,
compared to their matched controls, females from experimental populations
showed increased reproductive output early in life, both in presence and
absence of yeast supplement. The observed increase in reproductive output
was without associated alterations in egg size, development time,
pre-adult survivorship, body mass at eclosion, and lifespan of the
females. Further, selection was ineffective on lifelong cumulative
fecundity. However, females from experiment regime were found to have a
significantly faster rate of reproductive senescence following the
attainment of the reproductive peak early in life. Therefore, adaptation
to yeast deprivation ecology in our study involved a novel reproductive
strategy whereby females attained higher reproductive output early in life
followed by faster reproductive aging. To the best of our knowledge, this
is one of the cleanest demonstration of optimization of fitness by fine
tuning of reproductive schedule during adaptation to a prolonged
nutritional deprivation.