Conclusion
The Mighty Males hypothesis has several attractive properties. First and foremost, it is simple, relying on only a few assumptions that are well supported. Second, a common difficulty when applying the Bull-Charnov Model to a given situation is that sex-specific benefits can be argued from the perspective of advantaging males, or advantaging females, even within the same species (e.g., compare Harlow and Taylor 2000; Warner and Shine 2005). The Mighty Males hypothesis generates the same or very similar predictions for every species, some of which already have good support, and therefore the hypothesis can be tested unambiguously. Finally, Mighty Males also implies that environmental factors other than temperature may affect sex determination, even in species traditionally known to exhibit TSD. The hypothesis may therefore help explain why species simultaneously exhibit TSD and other forms of ESD as well. More broadly, I suggest that our knowledge of TSD is less complete than is currently appreciated, and I hope in earnest that the present essay spurs further investigation into TSD and other forms of ESD in reptiles and elsewhere, perhaps guided by some of the ideas that fall naturally out of the Mighty Males hypothesis.
Acknowledgements: I sincerely thank Fred Janzen, Daniel Warner, Locke Rowe, and Melanie Massey for feedback that greatly improved an earlier draft of this paper. Funding was provided by an NSERC Discovery grant to NR.