Evaluating the existence and benefit of major histocompatibility complex‐based mate choice in an isolated owl population

How mate preferences evolve in the first place has been a major conundrum for sexual selection. Some hypotheses explaining this assume fitness benefit derived from subsequent generations. Major histocompatibility complex (MHC)‐based mate choice is a representative example of the mate choice that is associated with such trans‐generational mechanisms. To provide evidences for fitness benefit of MHC‐based mate choice, previous studies assessed the association between own MHC genotype and own fitness components. However, the association between MHC‐based mate choice in the parental generation and fitness components in the resultant offspring generation has only rarely been measured in wild populations. Focusing on the isolated population of the monogamous Ryukyu Scops Owl (Otus elegans interpositus) on Minami‐daito Island, Japan, we found evidence of MHC‐based mate choice. However, we found no evidence of MHC‐based mate choice increasing own reproductive success or offspring survival. This is a rare case study that directly examines the existence of the trans‐generational indirect benefit of MHC‐based mate choice for genetic compatibility from trans‐generational data in a wild bird population. By investigating the fitness benefits of mate choice, this study serves to facilitate our understanding of the evolution of MHC‐based mate choice. We tested the existence of MHC‐based mate choice and its fitness benefit for an isolated population of Ryukyu Scops Owl (Otus elegans interpositus), using trans‐generational data. We reported an evidence of MHC‐based mate choice and inbreeding avoidance. However, we did not get evidence of the mating bias having either direct fitness benefit at present generation and/or indirect fitness benefit across multiple generations. Although fitness benefit of the mating bias was not supported, testing it using trans‐generational data per.se. is important because such trans‐generational indirect fitness benefit is often assumed in MHC studies but rarely tested directly in wild populations.