Convergent Gene Losses Explain Evolution of Stomachless Fishes

Researchers at Tokyo Tech identified four key genes required for gastric functions that are co-deleted or pseudogenized in stomachless ray-finned fishes. The convergent gene losses explain the adaptation of agastric fishes to ecological niches, shedding light on the evolution of unique anatomical features.

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Nitish Verma
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Convergent Gene Losses Explain Evolution of Stomachless Fishes

Convergent Gene Losses Explain Evolution of Stomachless Fishes

Researchers at Tokyo Tech have uncovered the genetic basis for the evolution of stomachless ray-finned fishes, revealing convergent gene losses that explain their adaptation to ecological niches. The study, published in Communications Biology, compared gene losses between agastric and gastric fishes, identifying four key genes required for gastric functions that are co-deleted or pseudogenized in agastric fishes: slc26a9, kcne2, cldn18a, and vsig1.

Why this matters: This study sheds light on the intricate relationship between genetic adaptations and the evolution of unique anatomical features, providing insights into the mechanisms that shape the diversity of life on Earth. Understanding these mechanisms can also inform our approaches to conservation and the management of ecosystems.

These genes are essential for secretions of gastric acids, stomach development, and protection of gastric cells. Their absence or inactivation in agastric fishes results in the reduction or loss of stomach structure. The research team, led by Associate Professor Akira Kato, suggests that these convergent gene losses represent a genotypic convergence, where similar genetic changes occurred independently in different agastric fish groups.

The researchers also discovered that agastric egg-laying mammals, such as echidna and platypus, have kcne2 and vsig1 either deleted or pseudogenized. Additionally, if cldn18 is present in agastric bony fishes, it is mutated compared to gastric fishes. Interestingly, the study found that gastric fish, like stickleback, express kcne2, pga, pgc, vsig1, and cldn18a in organs other than the stomach, indicating gene functions beyond gastric functions.

"We identified novel genes absent in agastric fishes among four major bony fish lineages, which suggests a convergent evolution scenario in the context of stomach loss," said Kato. "Our findings, thus, imply that a similar cassette of gene losses occurred independently during or after stomach loss in the several agastric fish groups."

This groundbreaking study provides significant insights into the genotypic convergence that has fine-tuned the agastric fish body to suit its specific ecological niche. The convergent loss of key gastric genes across multiple independent lineages of stomachless fishes highlights the intricate relationship between genetic adaptations and the evolution of unique anatomical features. As researchers continue to explore the genetic basis of evolutionary changes, studies like this shed light on the complex mechanisms shaping the diversity of life on Earth.

Key Takeaways

  • Researchers uncover genetic basis for stomachless ray-finned fishes.
  • Four key genes required for gastric functions are co-deleted or pseudogenized in agastric fishes.
  • Convergent gene losses occurred independently in different agastric fish groups.
  • Agastric egg-laying mammals also show similar gene losses or mutations.
  • Study sheds light on genetic adaptations and evolution of unique anatomical features.