From Preferences to Choices

This chapter focuses on mate sampling and on how choosers decide among sampled mates. The thinking in this regard has largely focused on the fitness consequences for courters and choosers. For courters, how does mate sampling affect choosiness and therefore variance in courter fitness, and how do courters exploit sampling and decision mechanisms? For choosers, how does fitness depend on different putative sampling schemes and decision algorithms? Much of this literature flows back to an influential paper that explored the fitness consequences of several hypothetical sampling schemes. The chapter describes what we know about the heuristic rules that animals use to evaluate finite pools of courters, and about the cognitive constraints underlying mate assessment and comparisons among mates.

Sperm as moderators of environmentally induced paternal effects in a livebearing fish

Until recently, paternal effects—the influence of fathers on their offspring due to environmental factors rather than genes—were largely discarded or assumed to be confined to species exhibiting paternal care. It is now recognized that paternal effects can be transmitted through the ejaculate, but unambiguous evidence for them is scarce, because it is difficult to isolate effects operating via changes to the ejaculate from maternal effects driven by female mate assessment. Here, we use artificial insemination to disentangle mate assessment from fertilization in guppies, and show that paternal effects can be transmitted to offspring exclusively via ejaculates. We show that males fed reduced diets produce poor-quality sperm and that offspring sired by such males (via artificial insemination) exhibit reduced body size at birth. These findings may have important implications for the many mating systems in which environmentally induced changes in ejaculate quality have been reported.