Fitness correlates of sex reversal
Among the wild-caught adults, XX sex-reversed males had similar body mass as normal males (LME, slope ± SE = 1.47 ± 1.29, t98= 1.15, p = 0.254; Figure 2). However, among the lab-raised animals we found several signs of reduced fitness and/or increased physiological stress in the XX sex-reversed males, including reduced body mass, increased spleen size, and liver abnormalities (see details in Supporting Information, pages 11-12, Table S5, Figures S6-7). In 2 out of the 6 individuals that were genetically female but had testes with normal anatomy, histological analysis revealed oogonia in otherwise normal testicular tissue (Figure S3), in contrast to the 17 males dissected in 2016 that all had testes without oogonia. These two individuals had small testes relative to their body size and age (Figure S8). The remaining 4 sex-reversed individuals showed completely normal testicular histology in the examined sections (Figure S3). In those two individuals that had XX siblings only (possibly sired by an XX male; see above), testis size was large relative to their body size and age (Figure S8), and testis histology showed a more mature developmental stage than in the rest of the histologically examined individuals (Figure S3).