Transcriptomic bases of a polyphenism.

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Molecular Biology

Background:

• Polyphenism, where one genotype produces multiple phenotypes based on environmental cues, is common but its molecular underpinnings are unclear.
• Mexican spadefoot toads (Spea multiplicata) exhibit polyphenism, with tadpoles developing into either omnivore or carnivore morphs.

Purpose of the Study:

• To investigate the transcriptomic basis of polyphenism in Spea multiplicata tadpoles.
• To identify molecular mechanisms underlying the development of the novel carnivore morph.

Main Methods:

• Comparative transcriptomics of Spea multiplicata tadpoles reared in conditions inducing carnivore morph versus non-inducing conditions.
• Analysis of gene expression patterns in body and head tissue samples.

Main Results:

• Development of the carnivore morph involved fewer gene expression changes than maintaining the omnivore morph in inducing environments, with tissue-specific differences observed.
• Significant alterations in lipid metabolism, particularly cholesterol biosynthesis, and peroxisome function were associated with morph determination.
• The carnivore morph appears to arise from a breakdown of robustness mechanisms maintaining the omnivore phenotype.

Conclusions:

• Carnivore morph development is developmentally regulated by lipid metabolism and peroxisomal pathways.
• This study provides insights into the evolution of phenotypic plasticity and identifies Spea multiplicata as a model system for further research.