Maternal inheritance, epigenetics
and the evolution of polyandry
by
Zeh JA, Zeh DW.
Department of Biology and Program in Ecology,
Evolution and Conservation Biology,
University of Nevada, Reno, NV, USA.
jaz@unr.edu
Genetica. 2008 Sep;134(1):45-54.

ABSTRACT

Growing evidence indicates that females actively engage in polyandry either to avoid genetic incompatibility or to bias paternity in favor of genetically superior males. Despite empirical support for the intrinsic male quality hypothesis, the maintenance of variation in male fitness remains a conundrum for traditional "good genes" models of sexual selection. Here, we discuss two mechanisms of non-Mendelian inheritance, maternal inheritance of mitochondria and epigenetic regulation of gene expression, which may explain the persistence of variation in male fitness traits important in post-copulatory sexual selection. The inability of males to transmit mitochondria precludes any direct evolutionary response to selection on mitochondrial mutations that reduce or enhance male fitness. Consequently, mitochondrial-based variation in sperm traits is likely to persist, even in the face of intense sperm competition. Indeed, mitochondrial nucleotide substitutions, deletions and insertions are now known to be a primary cause of low sperm count and poor sperm motility in humans. Paradoxically, in the field of sexual selection, female-limited response to selection has been largely overlooked. Similarly, the contribution of epigenetics (e.g., DNA methylation, histone modifications and non-coding RNAs) to heritable variation in male fitness has received little attention from evolutionary theorists. Unlike DNA sequence based variation, epigenetic variation can be strongly influenced by environmental and stochastic effects experienced during the lifetime of an individual. Remarkably, in some cases, acquired epigenetic changes can be stably transmitted to offspring. A recent study indicates that sperm exhibit particularly high levels of epigenetic variation both within and between individuals. We suggest that such epigenetic variation may have important implications for post-copulatory sexual selection and may account for recent findings linking sperm competitive ability to offspring fitness.

Biohappiness
Genospirituality
Private eugenics
'Designer babies'
Personal genomics
Genetic enhancement
Ashkenazi intelligence
Eugenics before Galton
Scandanavian eugenics
The literature of eugenics
Human self-domestication
Germline genetic engineering
Preimplantation genetic diagnosis
A life without pain? Hedonists take note'
Francis Galton and contemporary eugenics
Gene therapy and performance enhancement
5-HTT and AP-2beta gene polymorphism/spirituality
Developmental and environmental variation in genomes

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