Fecundity, offspring longevity, and assortative mating: parametric tradeoffs in sexual and life history strategy.

Genetic diversification of offspring represents a bet-hedging strategy that evolved as an adaptation to unpredictable environments. The benefits of sexual reproduction come with severe costs. For example, each offspring only carries half of each parent's genetic makeup through direct descent. The lower the reproductive rate, the more substantial the cost when considering the proportion of genes represented in subsequent generations. Positive assortative mating represents a conservative bet-hedging strategy that offsets some of these costs and preserves coadapted genomes in stable and predictable environments, whereas negative assortative mating serves the inverse function of genetic diversification in unstable and unpredictable environments.