title: Offspring sex in a TSD gecko correlates with an interaction between incubation temperature and yolk steroid hormones.
abstract: We incubated eggs of the Japanese gecko Gekko japonicus at three temperatures, and measured yolk testosterone (T) and 17β-estradiol (E2) levels at three time points in embryonic development (oviposition, 1/3 of incubation, and 2/3 of incubation), to examine whether maternal influence on offspring sex via yolk steroid hormone deposition is significant in the species. Eggs incubated at 24 °C and 32 °C produced mostly females, and eggs incubated at 28 °C almost a 50:50 sex ratio of hatchlings. Female-producing eggs were larger than male-producing eggs. Clutches in which eggs were incubated at the same temperature produced mostly same-sex siblings. Yolk T level at laying was negatively related to eggs mass, and yolk E2/T ratio was positively related to egg mass. Results of two-way ANOVA with incubation temperature and stage as the factors show that: yolk E2 level was higher at 32 °C than at 24 °C; yolk T level was higher, whereas yolk E2/T ratio was smaller, at 28 °C than at 24 °C; yolk E2 and T levels were higher at 2/3 than at 1/3 of incubation. Our data in G. japonucus show that: (1) maternal influence on offspring sex via yolk steroid hormone deposition is significant; (2) incubation temperature affects the dynamics of developmental changes in yolk steroid hormones; (3) influences of yolk steroid hormones on offspring sex are secondary relative to incubation temperature effects; and (4) offspring sex correlates with an interaction between incubation temperature and yolk steroid hormones.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210046, Jiangsu, China.
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Ding
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Ji
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004530:Egg Yolk / Q000737:chemistry / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D004958:Estradiol / Q000378:metabolism; D005260:Female; D006728:Hormones / Q000378:metabolism*; D008116:Lizards / Q000502:physiology*; D008297:Male; D019849:Sex Determination Processes / Q000502:physiology*; D012744:Sex Ratio; D013696:Temperature; D013739:Testosterone / Q000378:metabolism
chemical_list: D006728:Hormones; D013739:Testosterone; D004958:Estradiol