Massive horizontal gene transfer by parasites challenges Neodarwinism

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The paper "Massive horizontal gene transfer and the evolution of nematomorph-driven behavioral manipulation of mantids" by Tappei Mishina and colleagues, published in Current Biology in October 2023, reports the discovery of a massive horizontal gene transfer (HGT) event from mantids to nematomorph parasites. This HGT event has enabled the parasites to evolve the ability to manipulate their hosts' behavior, a phenomenon known as host manipulation.

Mantids are a type of insect that are known for their predatory behavior. They have long, powerful legs and sharp claws that they use to catch and kill their prey. Mantids are also known for their ability to camouflage themselves, which helps them to avoid being preyed upon themselves.

Nematomorph parasites are a group of worms that live in the bodies of insects. They are known for their ability to induce their hosts to enter bodies of water, where the parasites then reproduce. This behavior is fatal to the host, but it is essential for the parasite's life cycle.

Mishina and colleagues found that the nematomorph parasite Chordodes horsehair worms has acquired over 100 genes from its mantid hosts. These genes are involved in a variety of functions, including neuromodulation, attraction to light, and circadian rhythms. The researchers believe that these genes play a role in the parasite's ability to manipulate its host's behavior.

This study is significant because it is the first to provide evidence of massive HGT from one multicellular eukaryote to another. HGT was previously thought to be rare in multicellular eukaryotes, but this study suggests that it may be more common than previously thought.

The study also has implications for our understanding of host manipulation. Host manipulation is a widespread phenomenon, but the molecular mechanisms underlying it are not well understood. This study suggests that HGT may play a role in the evolution of host manipulation in a variety of parasites.

Future implications of this research

This research has a number of potential implications for future research and applications. For example, a better understanding of the molecular mechanisms of host manipulation could lead to the development of new ways to control parasitic infections. Additionally, the discovery of massive HGT from mantids to nematomorphs could lead to new insights into the evolution of multicellular eukaryotes.

Here are some specific examples of future research directions:

  • Investigate the mechanisms by which nematomorphs acquire genes from their mantid hosts.

  • Identify the specific host-derived genes that are involved in host manipulation.

  • Determine how the expression of host-derived genes is regulated in nematomorphs.

  • Develop new methods to control parasitic infections by targeting the molecular mechanisms of host manipulation.

  • Investigate the role of HGT in the evolution of multicellular eukaryotes more broadly.

This research is still in its early stages, but it has the potential to revolutionize our understanding of host manipulation and the evolution of multicellular eukaryotes.

Mishina's work challenges the neodarwinian paradigm of evolution in several ways. First, it suggests that evolution is not always a gradual process, but can occur through sudden jumps as a result of HGT events. Second, it suggests that parasites can play a major role in the evolution of their hosts, by stealing genes from their hosts and using them to manipulate them. Third, it suggests that HGT may be a more common phenomenon than previously thought, and that it may play a role in the evolution of a wide range of organisms.

The implications of Mishina's work are still being explored, but it is clear that it has the potential to revolutionize our understanding of evolution.

Here are some specific examples of how Mishina's work challenges neodarwinism:

  • Neodarwinism emphasizes the gradual accumulation of small changes over time. HGT, on the other hand, can allow organisms to acquire new genes and functions rapidly.

  • Neodarwinism typically views parasites as passive victims of their hosts' evolution. Mishina's work suggests that parasites can actively shape the evolution of their hosts by stealing genes from them.

  • Neodarwinism has traditionally focused on vertical gene transfer, or the transmission of genes from parents to offspring. Mishina's work shows that HGT, or the transfer of genes between unrelated organisms, can also play an important role in evolution.

Overall, Mishina's work provides strong evidence that HGT is a major force in evolution, and it challenges several key tenets of neodarwinism. It will be interesting to see how the scientific community responds to Mishina's work in the coming years.

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