Nematodes can rapidly shift to predatory behavior for survival

Nematodes are microscopic roundworms that are found in diverse environments all over the world. They have long been considered to show fixed behavioral patterns, for example feeding on a diet of bacteria and other microbes.

However, new research has revealed that they switch to predatory behavior if suitable prey (such as other nematode worms) are available in the environment. This indicates that their behavior is far more adaptable than previously thought.

Over multiple generations, these tiny organisms demonstrated a striking ability to shift entirely to a predatory lifestyle, based on environmental exposure to suitable prey.

Nematodes develop predatory instincts

Scientists at the Max Planck Institute for Biology Tübingen conducted an experiment spanning 101 generations of nematode worm lineages in which the worms were exposed to alternative food sources.

The dietary shift led to a complete transformation in their behavior, with all test lines adopting 100% predatory tendencies, and demonstrating an unprecedented level of adaptability. Interestingly, the change in diet was also accompanied by a change in the form of the mouth, with a wider mouth being associated with a predatory diet.

The rapid and consistent response contradicts the idea that predatory traits are fixed and highlights the profound role of environmental influence in shaping behavior and evolutionary pathways over extended periods.

Nematodes pass down predatory traits

The study also explored how nematodes retain behavioral changes across generations. Researchers found that at least five generations of exposure were required to establish lasting predatory behavior.

This suggests that organisms can inherit environmental responses, which could have implications in other species beyond nematodes. It potentially reshapes perspectives on adaptation and the plasticity of behavioral traits.

MicroRNAs and adaptation

A deeper look into the genetic mechanisms behind this shift revealed the involvement of microRNAs. The miR-35 family, in particular, played a key role in passing down behavioral traits by interacting with the EBAX-1 gene.

This discovery links genetic regulation to behavioral shifts, and offers a new perspective on how species adapt and evolve over time.

“This research opens new avenues in the understanding of behavioural plasticity,” said Shiela Quiobe, doctoral researcher and first author of the study.

“This discovery was completely unexpected, and now it’s exciting as we’re just scratching the surface in understanding the microRNAs’ mechanisms.”

Evolution beyond the individual

The implications of these findings extend beyond nematodes. Dr. Ralf Sommer, Director of the Department of Integrative Evolutionary Biology and lead author of the study, highlights the study’s significance.

“The long-term environmental induction experiment is a novel approach in the context of phenotypic plasticity to show that environmental responses can be important for longer evolutionary periods.”

“The fact that we see a phenomenon where you really need multi-generational exposure to induce such memory indicates that there might be more crosstalk between ecology and evolution,” he added.

These results challenge traditional views on evolution and predatory strategies, emphasizing the importance of ecological factors in shaping genetic adaptations.

They suggest that environmental pressures play a more active role in guiding evolution than previously recognized.

Lasting impact of environmental changes

The study raises intriguing questions about the mechanisms behind this inherited predatory behavior.

Scientists plan to conduct follow-up research to investigate the molecular targets of microRNAs and identify the bacterial agents responsible for triggering this adaptation.

Understanding these processes could provide new insights into the long-term impact of environmental changes on species survival.

Implications for evolutionary theory

The findings from this study challenge long-held assumptions about evolution, particularly the balance between genetic determinism and environmental influence.

Traditionally, evolutionary changes have been viewed as slow, being driven by random mutations and natural selection over thousands or millions of years. However, this research suggests that behavioral shifts can emerge much more rapidly when organisms experience sustained environmental pressure.

The discovery that nematodes require multiple generations of exposure before fully adopting a predatory lifestyle highlights the role of epigenetics in shaping evolutionary paths.

It also raises the question of how other species might exhibit similar inherited behavioral adaptations in response to environmental changes. Could this mechanism explain shifts in feeding behaviors, migration patterns, or survival strategies in larger organisms?

Understanding how microRNAs contribute to behavioral plasticity could also have applications in biotechnology and medicine.

If similar regulatory pathways exist in other species, scientists may be able to manipulate gene expression to influence adaptive traits, potentially aiding in conservation efforts or even addressing neurodevelopmental disorders linked to gene regulation.

This study paves the way for future research into the interplay between environment, genetics, and behavior, and offers new perspectives on how organisms evolve in response to their surroundings.

The study was published in the journal Science Advances.

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