Evolution of Pre- and Post-Copulatory Traits in Male Drosophila melanogaster as a Correlated Response to Selection for Resistance to Cold Stress

Abstract

BackgroundIn Drosophila melanogaster the fitness of males depends on a broad array of reproductive traits classified as pre- and post-copulatory traits. Exposure to cold stress, can reduce sperm number, male mating ability and courtship behavior. Therefore, it is expected that the adaptation to cold stress will involve changes in pre- and post-copulatory traits. Such evolution of reproductive traits in response to cold stress is not well studied.MethodsWe selected replicate populations of D. melanogaster for resistance to cold shock. Over 37–46 generations of selection, we investigated pre- and post-copulatory traits such as mating latency, copulation duration, mating frequency, male fertility, fitness (progeny production) and sperm competitive ability in male flies subjected to cold shock and those not subjected to cold shock.ResultsWe found that post cold shock, the males from the selected populations had a significantly lower mating latency along with, higher mating frequency, fertility, sperm competitive ability and number of progeny relative to the control populations.ConclusionWhile most studies of experimental evolution of cold stress resistance have documented the evolution of survivorship in response to selection, our study clearly shows that adaptation to cold stress involves rapid changes in the pre- and post-copulatory traits. Additionally, improved performances under stressful conditions need not necessarily trade-off with performance under benign conditions.

Evolution of pre- and post-copulatory traits in female Drosophila melanogaster as a correlated response to selection for resistance to cold stress

“…Reduction in egg/progeny production in response to cold shock has been previously reported (Rinehart et al, 2000, Irwin and Lee, 2003, Anderson et al, 2005, Jakobs, 2014, Mockett and Matsumoto, 2014and Singh et al, 2015, 2016. Our results are in agreement with these studies.…”

“…Similar to the effect of extreme temperature shock in males (Kvelland, 1965, Denlinger and Yocum, 1998, Rinehart et al, 2000, Rohmer et al, 2004, Malmendal et al, 2006, Yenisetti et al, 2006, reviewed in Hance et al, 2007, Jakobs, 2014and Singh et al, 2016, we observed higher mating latency and lower mating success in females exposed to cold shock compared to females not exposed to cold shock. Both traits improved as females were allowed more time to recover from the cold shock.…”

“…The FSB and FCB females were not different in any of these traits when assayed under no-shock condition. Multiple studies have documented the negative effects of temperature shock on male reproductive traits (Rohmer et al, 2004, Zizzari and Ellers, 2011, Lieshout et al, 2013, Nguyen et al, 2013, Rinehart et al, 2000and Singh et al, 2015, 2016 and female fecundity (Irwin andLee, 2003, reviewed in Hance et al, 2007;Sinclair, 2010 andRinehart et al, 2000). To the best of our knowledge, our study is the first to assess the evolution of female reproductive traits in response to cold shock.…”

“…Our previous study (Singh et al, 2015) found that populations selected for resistance to cold shock lay more viable eggs 24 hours post cold shock (compared to controls). They have also evolved a higher mating rate (Singh et al, 2015(Singh et al, , 2016.…”

“…Apart from its effects on survival at various life stages, cold shock also affects reproductive traits in both males and females of several insect species (Tucic, 1979, Chen and Walker, 1994, Watson and Hoffmann, 1996, Anderson et al, 2005, Bubliy and Loeschcke, 2005, Colinet and Hance, 2009, Schnebel and Grossfield, 1984, Carriere and Boivin, 1997, Rinehart et al, 2000, Fischer et al, 2003, Jakobs, 2014and Singh et al, 20152016.…”