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Abstract BackgroundLife cycle evolution includes ecological transitions and shifts in the timing of somatic and reproductive development (heterochrony). However, heterochronic changes can be tissue‐specific, ultimately leading to the differential diversification of traits. Salamanders exhibit alternative life cycle polymorphisms involving either an aquatic to terrestrial metamorphosis (biphasic) or retention of aquatic larval traits into adulthood (paedomorphic). In this study, we used gene expression and histology to evaluate how life cycle evolution impacts temporal reproductive patterns in males of a polymorphic salamander. ResultsWe found that heterochrony shifts the distribution of androgen signaling in the integument, which is correlated with significant differences in seasonal reproductive gland development and pheromone gene expression. In the testes, androgen receptor (ar) expression does not significantly vary between morphs or across seasons. We found significant differences in the onset of spermatogenesis, but by peak breeding season the testes were the same with respect to both histology and gene expression. ConclusionThis study provides an example of how seasonal heterochronic shifts in tissue‐specificargene expression can disparately impact seasonal development and expression patterns across tissues, providing a potential mechanism for differential diversification of reproductive traits.
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Modular genetic control of social status in a cichlid fish
Social hierarchies are ubiquitous in social species and profoundly influence physiology and behavior. Androgens like testosterone have been strongly linked to social status, yet the molecular mechanisms regulating social status are not known. The African cichlid fishAstatotilapia burtoniis a powerful model species for elucidating the role of androgens in social status given their rich social hierarchy and genetic tractability. DominantA. burtonimales possess large testes and bright coloration and perform aggressive and reproductive behaviors while nondominant males do not. Social status inA. burtoniis in flux, however, as males alter their status depending on the social environment. Due to a teleost-specific whole-genome duplication,A. burtonipossess two androgen receptor (AR) paralogs,ARαandARβ, providing a unique opportunity to disentangle the role of gene duplication in the evolution of social systems. Here, we used CRISPR/Cas9 gene editing to generate AR mutantA. burtoniand performed a suite of experiments to interrogate the mechanistic basis of social dominance. We find thatARβ,but notARα, is required for testes growth and bright coloration, whileARα, but notARβ, is required for the performance of reproductive behavior and aggressive displays. Both receptors are required to reduce flees from females and either AR is sufficient for attacking males. Thus, social status inA. burtoniis inordinately dissociable and under the modular control of two AR paralogs. This type of nonredundancy may be important in facilitating social plasticity inA. burtoniand other species whose social status relies on social experience.
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- Award ID(s):
- 1825723
- PAR ID:
- 10199390
- Publisher / Repository:
- Proceedings of the National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 117
- Issue:
- 45
- ISSN:
- 0027-8424
- Page Range / eLocation ID:
- p. 28167-28174
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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