From hybrids to 'virgin birth,' stick insects reveal stepwise loss of sex

The evolution of sex remains one of biology's greatest puzzles. While sexual reproduction dominates across the animal kingdom, scientists still debate why it persists despite its high costs. The science-journalism coverage adds useful context, while the strongest evidential footing still comes from the underlying data, papers or institutional documentation.

It matters because biology becomes more informative when an observed effect begins to look like a mechanism rather than an isolated pattern. The gap between identifying a correlation in biological data and understanding the causal chain that produces it is routinely underestimated, and the history of biomedical research is populated with associations that collapsed when the mechanism was sought and not found. A result that comes with a proposed mechanism, even a partial one, is more useful than a purely descriptive finding because it generates testable predictions that can narrow the hypothesis space. This article has been reviewed according to Science X's editorial process and policies. In parthenogenesis, also called "virgin birth," a form of asexual reproduction common among animals, both copies can be clonally inherited from mother to offspring, without any.

Because evolutionary transitions between sex and parthenogenesis are rarely observed, understanding how sex is lost is very challenging. To investigate this, the researchers turned to one of nature's most extraordinary masters of disguise: stick insects.

To uncover their history of reproduction, researchers from the Universities of Lausanne, Lund and Rostock analyzed genomic data from more than 500 wild stick insects that they. The paper is published in the Proceedings of the National Academy of Sciences.

Everything started with one initial hybridization event after the end of the last ice age, about 8, 000 years ago. Discover the latest in science, tech, and space with over 100, 000 subscribers who rely on Phys. org for daily insights.

The broader interest lies in whether the reported effect points toward a real mechanism and not merely a reproducible but unexplained association. Biology has learned from decades of biomarker failures that correlation, even robust correlation, is not a substitute for mechanistic understanding. A pathway that can be traced from molecular interaction to cellular response to organismal phenotype provides a far stronger foundation for intervention than a statistical association discovered in a large dataset, however well the statistics are done.

What makes this system so fascinating is that we were able to reconstruct every single transition in the lab which we inferred from the evolutionary histories of the wild stick. Instead, the new results suggest that hybridization and the loss of sex can create opportunities for further innovation, possibly helping asexuals persist despite the negative.

Because this item comes through Phys. org Biology as science journalism, it should be treated as contextual reporting rather than primary evidence. Good science reporting can identify why a result matters, connect it to the wider literature and make technical work readable, but the decisive evidence remains in the original paper, dataset, mission release or technical record. That distinction is especially important when a story is later repeated by aggregators, because repetition increases visibility, not evidential strength.

The next step is to test whether the effect repeats across different methods, cell types, model organisms and experimental conditions. Reproducibility is the first test, but mechanistic dissection is the second, and a result that passes both has a substantially better chance of translating into something clinically or biotechnologically useful. The path from a laboratory finding to an applied outcome typically takes a decade or more, and most findings do not complete it; the current result sits at the beginning of that process.

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