ArticleZoological letters2015
Variation in the ontogeny of sex steroid levels between latitudinal populations of the medaka.
Article in Zoological letters, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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5 citing papers in PubMed, 9 citations in OpenAlex.
- Sexual Dimorphism in Fin Size and Shape in Bluefin Killifish.Ecology and evolution · 2026Article
- Population Variation in Steroid Hormone-Related Gene Expression and Sexually Dimorphic Communication in the Electric Fish Apteronotus albifrons.Journal of experimental zoology. Part A, Ecological and integrative physiology · 2025Article
- Sexual Dimorphism in Fin Size and Shape in North American Killifish.Ecology and evolution · 2025Article
- Genetic analysis of body weight in wild populations of medaka fish from different latitudes.PloS one · 2020Article
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5 authors at 3 institutions in 1 country.
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Abstract
introductionSex steroids mediate the expression of sexual dimorphism during ontogeny, and populations that differ in the magnitudes of sexual dimorphism may accordingly differ in the ontogenetic patterns of their sex steroid levels. The medaka, Oryzias latipes species complex, shows geographic variation in the magnitude of sexual dimorphism with respect to the lengths of their anal and dorsal fins; dimorphism is greater in low-latitude populations than in high-latitude populations. However, sexual differences in the ontogenetic dynamics of sex steroids, and its interpopulation variation, have not been examined.
resultsWe measured testosterone (T), estradiol-17β (E2), and 11-ketotestosterone (11-KT) concentrations throughout ontogeny of laboratory-reared fish from two latitudinal populations: Aomori (northern) and Okinawa (southern). In both populations, the levels of all three steroids were high during early ontogenetic stages and decreased with growth. After reaching about 15 mm in standard length, when sexual dimorphisms in fin lengths became apparent, steroid levels increased and tended to plateau. Sexual differences in the steroid levels were observed only in the later ontogenetic stages; T and 11-KT levels were higher in males, while E2 levels were higher in females. Accordingly, interpopulation differences also became clearer; the southern fish tended to show higher T levels and lower E2 levels than the northern fish.
conclusionsThe ontogenetic patterns of sex steroid levels paralleled the ontogeny of anal and dorsal fins in the two latitudinal populations, suggesting that interpopulation variation in the degree of sexual dimorphisms in fin lengths is mediated by sex steroid-dependent regulation of fin elongation.
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