English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background  Developmental associations often explain phenotypic integration. The intersected hormonal regulation of ontogenetic processes fosters predictions of steroid-mediated phenotypic integration among sexually dimorphic traits, a statement defied by associations between classical dimorphism predictors (e.g. body size) and traits that apparently lack sex-specific functions (e.g. ratios between the lengths of Digits II and IV - 2D:4D). Developmental bases of female-biased 2D:4D have been identified, but these remain unclear for taxa presenting male-biased 2D:4D (e.g.  anura ). Here we propose two alternative hypotheses to investigate evolution of male-biased 2D:4D associated with sexually dimorphic body size using  Leptodactylus  frogs: I)‘ hypothesis of sex-specific digit responses ’ - Digit IV would be reactive to testosterone but exhibit responses in the opposite direction of those observed in female-biased 2D:4D lineages, so that Digit IV turns shorter in males; II) ‘ hypothesis of identity of the dimorphic digit’ - Digit II would be the dimorphic digit.    Results  We compiled the following databases using  Leptodactylus  frogs: 1) adults of two species from natural populations and 2) testosterone-treated  L. fuscus  at post-metamorphic stage. Studied traits seem monomorphic in  L. fuscus ;  L. podicipinus  exhibits male-biased 2D:4D. When present, 2D:4D dimorphism was male-biased and associated with dimorphic body size; sex differences resided on Digit II instead of IV, corroborating our ‘ hypothesis of identity of the dimorphic digit’ . Developmental steroid roles were validated: testosterone-treated  L. fuscus  frogs were smaller and exhibited masculinized 2D:4D, and Digit II was the digit that responded to testosterone.    Conclusion  We propose a model where evolution of sexual dimorphism in 2D:4D first originates from the advent, in a given digit, of increased tissue sensitivity to steroids. Phenotypic integration with other sexually dimorphic traits would then occur through multi-trait hormonal effects during development. Such process of phenotypic integration seems fitness-independent in its origin and might explain several cases of steroid-mediated integration among sexually dimorphic traits.    Electronic supplementary material  The online version of this article (doi:10.1186/s12862-017-1021-0) contains supplementary material, which is available to authorized users.

Phenotypic integration mediated by hormones: associations among digit ratios, body size and testosterone during tadpole development