Sex Allocation in Nonstandard Haplodiploids

AbstractThe value that a mother places on the production of a son or daughter depends critically on how genes are transmitted between parents and offspring. The inheritance system shapes both the reproductive value of males and females and the relatedness between parents, offspring, and other interacting individuals. Recently, a new form of haplodiploidy was discovered in Varroa mites, where although sons are produced asexually, they are diploid rather than haploid. A similar system, albeit with a different mechanism of diploid male production, is also known in Lecanoid scales. This diploid arrhenotoky may be expected to have consequences for the evolutionary dynamics of social traits, such as sex allocation. To investigate this, we extend current sex allocation theory to consider this genetic system, exploring classic models of local mate and local resource competition. We find that diploid males lead to reduced relatedness between sisters and thus results in less biased sex ratios. This difference is most exaggerated when interacting females descend from the same father (e.g., polygyny) and is reduced either when females are unlikely to share the same father or when males are highly homozygous.