Abstract
BackgroundAbility to resist temperature shock is an important component of fitness of insects and other ectotherms. Increased resistance to temperature shock is known to affect life-history traits. Temperature shock is also known to affect reproductive traits such as mating ability and viability of gametes. Therefore selection for increased temperature shock resistance can affect the evolution of reproductive traits.MethodsWe selected replicate populations of Drosophila melanogaster for resistance to cold shock. We then investigated the evolution of reproductive behavior along with other components of fitness- larval survivorship, adult mortality, fecundity, egg viability in these populations.ResultsWe found that larval survivorship, adult mortality and fecundity post cold shock were not significantly different between selected and control populations. However, compared to the control populations, the selected populations laid significantly higher percentage of fertile eggs (egg viability) 24 hours post cold shock. The selected populations had higher mating frequency both with and without cold shock. After being subjected to cold shock, males from the selected populations successfully mated with significantly more non-virgin females and sired significantly more progeny compared to control males.ConclusionsA number of studies have reported the evolution of survivorship in response to selection for temperature shock resistance. Our results clearly indicate that adaptation to cold shock can involve changes in components of reproductive fitness. Our results have important implications for our understanding of how reproductive behavior can evolve in response to thermal stress.
Highlights
Environmental stress such as extreme temperatures, desiccation, crowding can have major consequences for fitness of organisms
We found that larval survivorship, adult mortality and fecundity post cold shock were not significantly different between selected and control populations
Our results clearly indicate that adaptation to cold shock can involve changes in components of reproductive fitness
Summary
Environmental stress such as extreme temperatures, desiccation, crowding can have major consequences for fitness of organisms. Using Drosophila, a large number of studies have investigated the evolution of resistance to various environmental stresses such as larval crowding [1], increased urea and ammonia content in larval food [2], adult desiccation, starvation [3, 4] and extreme temperatures [5,6,7,8,9]. Temperature is one of the most important ecological factors that affect the fitness of an organism [10] This is especially true of insects which are ectothermic [11, 12]. Ability to resist temperature shock is an important component of fitness of insects and other ectotherms. Increased resistance to temperature shock is known to affect life-history traits. Selection for increased temperature shock resistance can affect the evolution of reproductive traits
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