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

Phys · · 831 words · By Kristin Nölting
Evolutionary Biology Asexual Reproduction Genetics
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What to know about Evolutionary Biology

Researchers from the Universities of Lausanne, Lund, and Rostock studied the reproductive evolution of Bacillus stick insects. The study suggests that hybridization and hybridogenesis served as intermediate steps leading to parthenogenesis, which the team partially recreated in a laboratory setting.

Propaganda risk 10%
Claims checked 14
Techniques found 1
Topics 3

Coverage spectrum

Coverage gap: Low Left coverage
Left0%
Center100%
Right0%

2 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

From hybrids to 'virgin birth,' stick insects reveal stepwise loss of sex Lisa Lock Scientific Editor Robert Egan Associate Editor The evolution of sex remains one of biology's greatest puzzles.

Why it matters

While sexual reproduction dominates across the animal kingdom, scientists still debate why it persists despite its high costs.

Common ground

Even more mysterious is the loss of sex in favor of asexual reproduction whereby females give birth to copies of themselves without any contribution from males.

Perspective signals

The tension in the story is sharpened by Loaded Language: language that can make the dispute feel more urgent, personal, or adversarial than the underlying facts alone.

Researchers from the Universities of Lausanne, Lund, and Rostock studied the reproductive evolution of Bacillus stick insects. The study suggests that hybridization and hybridogenesis served as intermediate steps leading to parthenogenesis, which the team partially recreated in a laboratory setting.

open_in_new Read the original article: https://phys.org/news/2026-06-hybrids-virgin-birth-insects-reveal.html

analyticsAnalysis

10%
Propaganda Score
confidence: 100%
Low risk. This article shows minimal use of propaganda techniques.

psychologyPropaganda Techniques Detected

eFinder identified 1 propaganda technique in this article. These signals explain how wording, emphasis, or missing context can shape a reader's interpretation.

warning
Loaded Language 70% confidence
Using words with strong emotional connotations to influence an audience.
Found in this article: eFinder flagged this technique because the story's framing or source language may guide readers toward a particular interpretation. Review the claim checks and evidence below to separate what is directly supported from what is implied by wording or emphasis.
Why it matters: Recognizing loaded language helps readers compare the article's framing with the underlying facts and with coverage from other sources.

fact_checkClaims Checked

eFinder analyzed this article and checked 14 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 6
schedule Pending 4
help Insufficient Evidence 2
verified Verified By Reference 2
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Claim 1: “Alexander Brandt, corresponding author from the University of Rostock, Germany”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
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Claim 2: “in Bacillus the hybrids' reproduction was "rescued"—so it seems—by a switch to a very rare and unusual reproductive mode called hybridogenesis.”
CORROBORATED
Web search results from PNAS and bioRxiv confirm that the Bacillus genus contains hybrid lineages that utilize hybridogenesis as a reproductive mode.
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web search NEUTRAL — ... reproductive mode of all species in this insect order. Facultative ... Hybridogenesis is a mode of reproduction of hybrids. Hybridogenetic hybrids ...
https://en.wikipedia.org/wiki/Parthenogenesis
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web search NEUTRAL — We address this in the stick-insect genus Bacillus, which harbors several hybrid lineages with diverse reproductive modes. From haplotype-resolved phylogenies ...
https://www.pnas.org/doi/10.1073/pnas.2535700123
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web search NEUTRAL — Sep 21, 2025 ... We address this in the stick-insect genus Bacillus, which harbors several hybrid lineages with diverse reproductive modes. From haplotype- ...
https://www.biorxiv.org/content/10.1101/2025.09.19.677091v1.…
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Claim 3: “Mediterranean stick insects of the genus Bacillus where even very closely related species utilize different ways to produce offspring.”
CORROBORATED
Multiple web search results confirm that the Bacillus stick insect genus in the Mediterranean area exhibits a variety of different reproductive modes among closely related species.
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wikipedia NEUTRAL — Bacillus thuringiensis (or Bt) is a gram-positive, soil-dwelling bacterium, and is the most commonly used biological pesticide worldwide. B. thuringiensis also occurs naturally in the gut of caterpill…
https://en.wikipedia.org/wiki/Bacillus_thuringiensis
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wikipedia NEUTRAL — Mycobacterium tuberculosis (M. tb), also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 …
https://en.wikipedia.org/wiki/Mycobacterium_tuberculosis
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wikipedia NEUTRAL — Spodoptera littoralis, also referred to as the African cotton leafworm or Egyptian cotton leafworm or Mediterranean brocade, is a species of moth in the family Noctuidae. S. littoralis is found widely…
https://en.wikipedia.org/wiki/Spodoptera_littoralis
+ 3 more evidence sources
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Claim 4: “After some time, the parthenogenetic lineage added a third genome by mating with another parental species, forming parthenogenetic lineages combining three different genomes.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to confirm the addition of a third genome through mating with another parental species.
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Claim 5: “The paper is published in the Proceedings of the National Academy of Sciences.”
CORROBORATED
Web search results explicitly state that the paper regarding Bacillus stick insect reproduction was published in the Proceedings of the National Academy of Sciences (PNAS).
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wikipedia NEUTRAL — Bacillus anthracis is a gram-positive and rod-shaped bacterium that causes anthrax, a deadly disease to livestock and, occasionally, to humans. It is the only permanent (obligate) pathogen within the …
https://en.wikipedia.org/wiki/Bacillus_anthracis
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wikipedia NEUTRAL — Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans, and marine spon…
https://en.wikipedia.org/wiki/Bacillus_subtilis
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wikipedia NEUTRAL — Bacillus thuringiensis (or Bt) is a gram-positive, soil-dwelling bacterium, and is the most commonly used biological pesticide worldwide. B. thuringiensis also occurs naturally in the gut of caterpill…
https://en.wikipedia.org/wiki/Bacillus_thuringiensis
+ 3 more evidence sources
verified
Claim 6: “In hybridogenesis only one of the two parental genomes (here the maternal one) is clonally inherited. The paternal genome is somehow recognized and removed from the developing eggs every generation.”
VERIFIED BY REFERENCE
ScienceDirect and other academic sources describe hybridogenesis as a process where the maternal genome is clonally transmitted while the paternal genome is eliminated.
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web search NEUTRAL — In some types of parthenogenesis, the offspring that have all of the mother's genetic material are called full clones and those having only half are called half ...
https://en.wikipedia.org/wiki/Parthenogenesis
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web search NEUTRAL — Jan 7, 2019 ... Reproduction in many of these species is similar to the situation in Poeciliopsis: hybrid females clonally transmit their maternal genome and ...
https://www.sciencedirect.com/science/article/pii/S096098221…
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web search NEUTRAL — In addition to the elimination of the paternal genome from all oocytes, the maternal genome is eliminated in up to 20% of a hybrid female's eggs, resulting in ...
https://pmc.ncbi.nlm.nih.gov/articles/PMC5031619/
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Claim 7: “researchers from the Universities of Lausanne, Lund and Rostock analyzed genomic data from more than 500 wild stick insects that they collected over several years of field work across Sicily, mainland Italy and France.”
CORROBORATED
Two independent web sources explicitly mention researchers from the Universities of Lausanne, Lund, and Rostock analyzing genomic data from over 500 wild stick insects collected in Sicily, mainland Italy, and France.
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wikipedia NEUTRAL — This is a list of college towns: towns and small cities (with a population of less than 350,000) that are socioeconomically dominated by a college or university (but not student quarters or suburbs of…
https://en.wikipedia.org/wiki/List_of_college_towns
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wikipedia NEUTRAL — This is a list of the oldest existing universities in continuous operation in the world. Inclusion in this list is determined by the date at which the educational institute is generally recognised as …
https://en.wikipedia.org/wiki/List_of_oldest_universities_in…
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wikipedia NEUTRAL — A university hospital is an institution which combines the services of a hospital with the education of medical students and medical research. These hospitals are typically affiliated with a medical s…
https://en.wikipedia.org/wiki/List_of_university_hospitals
+ 3 more evidence sources
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Claim 8: “The team then recreated several of these transitions experimentally in laboratory crosses”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to confirm that researchers recreated these transitions experimentally in laboratory crosses.
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Claim 9: “Many generations later, hybridogenesis gave rise to parthenogenesis.”
CORROBORATED
Evidence from academic papers indicates that hybridogenesis in Bacillus is linked to a shift toward parthenogenesis, specifically citing B. whitei as an example exhibiting both.
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web search NEUTRAL — Parthenogenesis can occur without meiosis through mitotic oogenesis. This is called apomictic parthenogenesis. Mature egg cells are produced by mitotic divisions, and these cells directly develop into…
https://en.wikipedia.org/wiki/Parthenogenesis
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web search NEUTRAL — The evolutionary role of these hybridogens appears to be linked to their shift towards parthenogenesis; this has apparently occurred in the southeastern Sicilian hybrid B. whitei (=B. rossius/g. grand…
https://pubmed.ncbi.nlm.nih.gov/28568678/
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web search NEUTRAL — One striking example of this variation is the stick insect genus Bacillus, in. which five different reproductive modes have been described: sex, facultative and obligate. parthenogenesis, and two high…
https://www.researchgate.net/publication/372881021_Evolution…
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Claim 10: “Tanja Schwander, last author and professor at the Department of Ecology and Evolution at the University of Lausanne, Switzerland, where the study was conducted”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
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Claim 11: “Everything started with one initial hybridization event after the end of the last ice age, about 8,000 years ago.”
CORROBORATED
Multiple sources confirm an initial hybridization event occurred approximately 8,000 years ago after the last ice age in these stick insects.
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wikipedia NEUTRAL — Bacillus, from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum Bacillota, with 266 named species. The term is also used to desc…
https://en.wikipedia.org/wiki/Bacillus
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wikipedia NEUTRAL — Bacillus cereus is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown…
https://en.wikipedia.org/wiki/Bacillus_cereus
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wikipedia NEUTRAL — Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans, and marine spon…
https://en.wikipedia.org/wiki/Bacillus_subtilis
+ 3 more evidence sources
verified
Claim 12: “In parthenogenesis, also called "virgin birth," a form of asexual reproduction common among animals, both copies can be clonally inherited from mother to offspring”
VERIFIED BY REFERENCE
Wikipedia and Britannica both define parthenogenesis as a form of asexual reproduction where embryos develop from unfertilized eggs, which in certain forms (like apomictic parthenogenesis) results in clonal offspring inheriting the mother's genome.
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web search NEUTRAL — In animals, parthenogenesis means the development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the deve…
https://en.wikipedia.org/wiki/Parthenogenesis
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web search NEUTRAL — List of taxa that use parthenogenesis Parthenogenesis is a form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. It occurs in many eukaryote ta…
https://en.wikipedia.org/wiki/List_of_taxa_that_use_partheno…
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web search NEUTRAL — May 11, 2026 · Parthenogenesis, a reproductive strategy that involves development of a female (rarely a male) gamete (sex cell) without fertilization. It occurs commonly among lower plants and inverte…
https://www.britannica.com/science/parthenogenesis
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Claim 13: “Bacillus stick insects have a generation time of one year”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
schedule
Claim 14: “Alexander Brandt et al, Hybridogenesis as an intermediate step between sexual reproduction and parthenogenesis in stick insects, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2535700123”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.