Ideas in Ecology and Evolution (Sep 2011)
Post-plasmogamic pre-karyogamic sexual selection: mate choice inside an egg cell
Abstract
Intersexual selection is often categorized as pre-copulatory or post-copulatory mate choice by individuals of one sex over showy individuals of the other sex. We extend the framework of post-copulatory choice to include post-plasmogamic pre-karyogamic sexual selection. That is, selection of haploid nuclei within the microcosm of a single fertilized egg cell after sperm has entered an egg cell but before fusion of their nuclear membranes, in which an egg nucleus chooses a sperm nucleus with which to fuse. The role of sexual selection at this nuclear level is probably small in monospermic out-crossers, but large in polyspermic out-crossers. Post-plasmogamic pre-karyogamic sexual selection may also explain how the sperm nucleus is rejected in gynogens, and how the egg nucleus is rejected in androgens. We propose that male and female nuclei behave independently within an egg cell, and that post-plasmogamic pre-karyogamic mate choice is largely based on either (1) a pre-existing sensory bias for certain characteristics of the sperm pronuclear mem-brane, or (2) detection of good genes through signal (mRNA) detection.
