Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

Full text
Author(s):
Lofeu, Leandro ; Brandt, Renata ; Kohlsdorf, Tiana
Total Authors: 3
Document type: Journal article
Source: BMC Evolutionary Biology; v. 17, AUG 2 2017.
Web of Science Citations: 6
Abstract

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. (AU)

FAPESP's process: 16/01558-3 - Facultative sex allocation in response to Operational or Juvenile Sex Ratios in the brown anole, Anolis sagrei
Grantee:Renata Brandt Nunes
Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
FAPESP's process: 13/14125-0 - Integrative analysis of sexual dimorphism in lizards: morphology, functional significance and selection
Grantee:Renata Brandt Nunes
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 15/07650-6 - Ecology, evolution and development (Eco-Evo-Devo) in the Brazilian herpetofauna
Grantee:Tiana Kohlsdorf
Support Opportunities: Research Projects - Thematic Grants