Extraction of DNA and genotyping
The extraction of DNA, microsatellite genotyping, and a mitochondrial DNA haplotype analysis were conducted using the procedure described in previous studies (Shimozuru, et al. , 2019; Shirane, et al. , 2018). Briefly, DNA was extracted using the DNeasy Blood & Tissue Mini Kit (Qiagen Inc., Tokyo, Japan) for blood and tissue samples, the DNA Extractor FM Kit (Wako, Osaka, Japan) or Isohair Easy (Nippon Gene, Inc., Tokyo, Japan) for hair samples, and the QIAamp DNA Stool Mini Kit (Qiagen Inc.) for feces samples. Twenty-one microsatellite markers and one sex marker, amelogenin (Yamamoto, et al. , 2002), were analyzed by a multiplex PCR assay (Shimozuru, et al. , 2020; Shimozuru, et al. , 2019; Shimozuru, et al. , 2020). Allele size was determined using an ABI PRISM 310 genetic analyzer or SeqStudio Genetic Analyzer (Thermo Fisher Scientific K.K., Tokyo, Japan). In addition, eight Y-linked microsatellite alleles (Y318.1, Y318.2, Y318.4, Y318.6, Y318.9, Y369.1, Y369.4, and 15020.1; Hirata, et al. , 2017) were determined by a multiplex PCR assay, using the same primer sets as those used in previous studies (Bidon, et al. , 2014; Hirata, et al. , 2017). The mitochondrial and Y chromosome haplotype information were used to select candidate mothers for offspring, and candidate fathers for male offspring, respectively.