XB-ART-57528PLoS One January 1, 2020; 15 (11): e0241625.
A laboratory investigation into features of morphology and physiology for their potential to predict reproductive success in male frogs.
Amphibian populations are declining globally, however, the contribution of reduced reproduction to declines is unknown. We investigated associations between morphological (weight/snout-vent length, nuptial pad colour/size, forelimb width/size) and physiological (nuptial pad/testis histomorphology, plasma hormones, gene expression) features with reproductive success in males as measured by amplexus success and fertility rate (% eggs fertilised) in laboratory maintained Silurana/Xenopus tropicalis. We explored the robustness of these features to predict amplexus success/fertility rate by investigating these associations within a sub-set of frogs exposed to anti-androgens (flutamide (50 μg/L)/linuron (9 or 45 μg/L)). In unexposed males, nuptial pad features (size/colour/number of hooks/androgen receptor mRNA) were positively associated with amplexus success, but not with fertility rate. In exposed males, many of the associations with amplexus success differed from untreated animals (they were either reversed or absent). In the exposed males forelimb width/nuptial pad morphology were also associated with fertility rate. However, a more darkly coloured nuptial pad was positively associated with amplexus success across all groups and was indicative of androgen status. Our findings demonstrate the central role for nuptial pad morphology in reproductive success in S. tropicalis, however, the lack of concordance between unexposed/exposed frogs complicates understanding of the utility of features of nuptial pad morphology as biomarkers in wild populations. In conclusion, our work has indicated that nuptial pad and forelimb morphology have potential for development as biomarkers of reproductive health in wild anurans, however, further research is needed to establish this.
PubMed ID: 33175903
PMC ID: PMC7657548
Article link: PLoS One
Species referenced: Xenopus tropicalis
Article Images: [+] show captions
|Fig 3. Synopsis of correlations between nuptial pad colour and reproductive physiology in S. tropicalis males using GLM (Gaussian) for all males from the second breeding trial (n = 63).Morphological/physiological traits were removed sequentially until the lowest AIC value was achieved (see S9 Table in S1 File for details of model).|
References [+] :
Berg, Xenopus tropicalis as a test system for developmental and reproductive toxicity. 2009, Pubmed, Xenbase