Micro and macroevolution of sea anemone venom phenotype

Area of Science:

• Evolutionary biology
• Genomics
• Biochemistry

Background:

• Venom composition is highly variable within and between species due to evolutionary pressures on toxic proteins.
• The mechanisms driving toxin expression dynamics and venom phenotype determination are not fully understood.

Purpose of the Study:

• To investigate the evolutionary processes shaping toxin expression in sea anemone venom.
• To analyze the genetic basis of venom variation in *Nematostella vectensis*.

Main Methods:

• Interspecific comparisons of toxin expression.
• In-depth population-level analysis of the dominant toxin (Nv1) gene copy number variation in *Nematostella vectensis*.
• Correlation analysis of gene copy number with transcript and protein expression levels.

Main Results:

• Sea anemone toxin expression evolves rapidly, with different toxin families dominating species' venoms via gene duplication.
• Significant variation in Nv1 diploid copy number (1-24 copies) exists across *Nematostella vectensis* populations, arising from independent gene expansion/contraction events.
• Nv1 copy number directly correlates with Nv1 expression at transcript and protein levels, with one population showing near-complete loss of Nv1 production.

Conclusions:

• Massive gene duplication events are a key mechanism driving venom phenotype evolution in sea anemones.
• Copy number variation of dominant toxins, like Nv1, is a major source of venom diversity and functional variation.
• The study proposes the dominant toxin hypothesis, suggesting convergent evolution of dominant toxin strategies across diverse venomous lineages.