Abstracts (first author)
No strain no gain: genetic investigation of adaptive phenotypic plasticity in teleost jaws
Through incorporating environmental signals into ontogenetic pathways, phenotypically plastic species can fine-tune their phenotypes to precisely match local environmental conditions. In spite of its importance in the generation of adaptive phenotypes, the molecular basis of phenotypic plasticity remains poorly characterised. We are establishing a new molecular model for phenotypic plasticity research: the East African cichlid fish, Astatoreochromis alluaudi, which has been the subject of morphological studies of plasticity for 50 years. In response to a hard diet, its Lower Pharyngeal Jaw (LPJ) develops a ‘molariform’ morphology, with molar-like teeth set in an enlarged, dense jaw, compared with the smaller, finer ‘papilliform’ morphology which represents the ground state for this species. We performed a common garden experiment where siblings were fed either whole snails (hard diet), or finely minced snails (soft diet) and analysed the resulting morphological and transcriptional phenotypes. Genome-wide transcriptome analysis was performed on the LPJs of molariform and papilliform morphs that resulted from the diet treatments, shedding light on the environmentally sensitive pathways that modulate LPJ morphology. Numerous genes of mechanically responsive pathways (such as fos and jun) were upregulated in the molariform LPJs, indicating that mechanical strain intersects with bone developmental pathways that shape the molariform morphology. Intriguingly we also observe the down-regulation of various inflammatory factors and redox pathway members, suggesting that microenvironmental changes within the LPJ medullary cavity may alter cellular differentiation and proliferation. Through identifying numerous pathways involved with plasticity in the LPJ of A. alluaudi, our research opens the door to assess the role of phenotypic plasticity in generating morphological novelties amongst the explosive radiation of East African cichlid fishes.