Predictable transcriptome evolution in the convergent and complex bioluminescent organs of squid

Area of Science:

• Evolutionary Biology
• Genomics
• Molecular Biology

Background:

• Convergent evolution often results in similar traits arising independently.
• The genetic basis, specifically gene expression (transcriptomes), underlying these convergent traits is less understood.
• Symbiotic bioluminescent organs (photophores) in squid offer a model for studying convergent organ evolution.

Purpose of the Study:

• To investigate whether the overall gene expression patterns (transcriptomes) of convergent traits are also convergent.
• To determine the extent of parallel evolution in transcriptomes of symbiotic bioluminescent organs in divergent squid species.

Main Methods:

• Comparative transcriptomic analysis of bioluminescent organs (photophores) from two distinct squid species.
• Statistical modeling to assess the predictability of organ identity based on gene expression levels.

Main Results:

• Strong statistical evidence for convergent evolutionary origins of entire transcriptomes in squid photophores.
• Demonstrated massively parallel evolution of gene expression in these organs.
• Gene expression profiles were highly similar, allowing accurate prediction of organ identity across species.

Conclusions:

• Convergent evolution extends to the overall gene expression levels underlying complex organs.
• Predictable solutions likely influence not only the evolution of novel organs but also their underlying transcriptomic architecture.
• This highlights widespread parallel changes in gene expression during the evolution of complex, convergent structures.