Abstract for presentation at 11th International Congress of Human Genetics

Do Mitochondrial Mutations Affect Population Viability?: The Effect Of Mitochondrial DNA Mutations On Sperm Function

  • Dr Neil Gemmell, University of Canterbury, New Zealand
  • Dr Victoria Metcalf, University of Canterbury, New Zealand
  • Ms Patrice Irvine, University of Canterbury, New Zealand
  • Dr Felicity Jones, University of Canterbury, New Zealand
  • Ms Katherine McBride, University of Canterbury, New Zealand
  • Prof Fred Allendorf, University of Montana, United States

    • The mitochondrial genome (mtDNA) is generally considered an innocent bystander in adaptive evolution; however, there is increasing evidence that mtDNA maybe an important contributor to viability and fecundity. Recent work in humans and other species indicates that mtDNA mutations play a role in sperm function, male fertility and male fitness. Ironically, deleterious mtDNA mutations that affect only males, such as those that impair sperm function, will not be subject to natural selection because mitochondria are generally maternally inherited. Thus, such mutations may reach high frequencies affecting the viability of natural populations. To determine if mtDNA mutations do affect population viability we have begun a comprehensive research program to identify mitochondrial mutations and then determine whether these mutations impact on sperm function and male reproductive performance. We have screened a semi-wild population of New Zealand chinook salmon (Oncorhynchus tshawytscha) for mutations in the mtDNA NADH genes. Five main haplogroups have been identified from a screen of >350 fish from two cohorts (2003, 2004) across ND1-5. In total, 19 SNPs have been identified, 5 of which encode amino acid changes. Representative fish from each of the 5 haplogroups have then been used to assess the effect of mitochondrial haplogroup on key male fertility factors such as longevity, sperm velocity, and fertilisation success. There is significant variation in sperm longevity among males, but this is not related to mtDNA haplogroup. In contrast, we find that mtDNA haplogroup explains a significant amount of the variation observed in sperm velocity. Recent studies of sperm competition in fish, birds and mammals indicate that sperm velocity is the primary determinant of fertilization success, which suggests that these mtDNA variants likely have fitness consequences. Competitive fertilization experiments are underway to explore this possibility.

    Conference Organiser - ICMS Pty Ltd