Effects of cytoplasmic genes on sperm viability and sperm morphology in a seed beetle: implications for sperm competition theory?
Article first published online: 31 JUL 2006
Journal of Evolutionary Biology
Volume 20, Issue 1, pages 358–368, January 2007
How to Cite
DOWLING, D. K., NOWOSTAWSKI, A. L. and ARNQVIST, G. (2007), Effects of cytoplasmic genes on sperm viability and sperm morphology in a seed beetle: implications for sperm competition theory?. Journal of Evolutionary Biology, 20: 358–368. doi: 10.1111/j.1420-9101.2006.01189.x
- Issue published online: 18 DEC 2006
- Article first published online: 31 JUL 2006
- Received 21 March 2006; revised 26 May 2006; accepted 2 June 2006
- adaptive evolution;
- maternal age;
- maternal effects;
- maternal inheritance;
- mitochondrial DNA;
- sperm quality
Sperm competition theory predicts that sperm traits influencing male fertilizing ability will evolve adaptively. However, it has been suggested that some sperm traits may be at least partly encoded by mitochondrial genes. If true, this may constrain the adaptive evolution of such traits because mitochondrial DNA (mtDNA) is maternally inherited and there is thus no selection on mtDNA in males. Phenotypic variation in such traits may nevertheless be high because mutations in mtDNA that have deleterious effects on male traits, but neutral or beneficial effects in females, may be maintained by random processes or selection in females. We used backcrossing to create introgression lines of seed beetles (Callosobruchus maculatus), carrying orthogonal combinations of distinct lineages of cytoplasmic and nuclear genes, and then assayed sperm viability and sperm length in all lines. We found sizeable cytoplasmic effects on both sperm traits and our analyses also suggested that the cytoplasmic effects varied across nuclear genetic backgrounds. We discuss some potential implications of these findings for sperm competition theory.