Rosa Rubicondior: Unintelligent Design - Evolution By Viral Infection

Apple Snail, Pomacea canaliculata

Lingnan University joint research analyses genome of global agricultural pest ‘apple snail’: Ancient viral gene-driven evolution of ‘terrestrial oviposition’ ability - Press Release | Lingnan University

A paper recently published in the journal Advanced Science, by researchers including Assistant Professor Jack Chi-Ho Ip, from Lingnan University, Hong Kong, is deeply problematic for creationists, not only because it describes a process that took place over an immense period of time incompatible with the biblical narrative, but also because it deals with a mechanism for evolution that cannot be waved aside as mere "variation within a kind", or something creationists like to dismiss as "micro-evolution".

Creationists continue to insist that large-scale evolution does not happen, so everything must have been specially created more or less as it is, with only limited variation within the "kind" — a term always left conspicuously undefined, so the goalposts can be moved whenever the evidence becomes inconvenient. This is despite the well-attested mechanisms by which biodiversity arises, including classical Darwinian natural selection acting on inherited variation, and genetic drift, in which chance changes in allele frequencies can lead to a neutral mutation becoming fixed in, or eliminated from, a population gene pool.

There is also the founder effect, where a non-representative sample of a population becomes isolated from the parent population, usually by a physical or ecological barrier. The new population therefore begins with a different allele-frequency profile from the population from which it came. Then there is hybridisation, where hybrid offspring can, in some circumstances, become reproductively isolated from both parent species, forming a new genetically distinct population or species.

And lastly, we have horizontal gene transfer, where an organism acquires genetic material from another biological lineage in its environment. This is especially familiar in bacteria, but it also occurs in animals, often through viruses. Retroviruses are particularly important in this respect because they insert a DNA copy of their genome into that of their host. Over time, the viral sequence may be disabled by mutation, or the host may evolve a defence against it. Either way, the remnant of the virus can become part of the host genome, where it is free to mutate over time. Occasionally, such inherited viral DNA is exapted for a new function, creating useful new genetic information without the slightest need for supernatural assistance. One well-known example is syncytin, derived from ancient retroviral genes, now involved in the formation and function of the mammalian placenta.

Now researchers at Hong Kong's Lingnan University and their collaborators have shown that a viral-derived gene in apple snails is probably involved in their ability to lay eggs out of water — a key adaptation in the evolution of aerial egg-laying and one reason some apple snails have become such successful invasive pests. The gene, associated with the perivitelline fluid surrounding the developing embryo, was probably acquired by the ancestor of the Ampullariidae during the Jurassic. It would be interesting to see a creationist explain how acquiring a gene from an entirely unrelated viral lineage can be described as "variation within a kind". It would also be interesting to see them explain why an intelligent designer would need to borrow viral genetic material to equip a snail to lay eggs above the waterline.

Background^ Apple Snails And The Evolutionary Move Towards Land. Apple snails are freshwater gastropod molluscs belonging to the family Ampullariidae. They are not land snails, but many are partly amphibious, living mainly in water while also possessing adaptations that allow them to exploit the air-water boundary. This makes them useful models for studying one of evolution’s recurring themes: the repeated movement of animals from water towards land.

Unlike many fully aquatic snails, apple snails possess both a gill and a lung-like chamber. This dual respiratory system allows them to obtain oxygen from water and from air, an obvious advantage in warm, stagnant, oxygen-poor freshwater habitats. In some species, such as Pomacea canaliculata, air breathing is especially important and is associated with behaviours such as surfacing, aestivation in mud, and laying eggs above the waterline.

The family has an ancient evolutionary history and a wide tropical and subtropical distribution. Molecular studies indicate a deep split between Old World and New World apple snails, consistent with an origin influenced by the break-up of Gondwana. Old World genera include Pila and Lanistes, while New World genera include Pomacea, Marisa, and related forms. This is not a young group appearing suddenly, but a lineage with a long, branching history spread across continents and shaped by changing environments over immense spans of time.

One of the most striking differences within the family is reproductive. Some apple snails lay their eggs under water, while others, including many Pomacea species, lay conspicuous clutches above the waterline. This move out of the water created new problems for the developing embryos: they had to resist drying, heat, ultraviolet light, terrestrial predators, and microbial attack. Evolution answered not with foresight or design, but by modifying available anatomy, behaviour, proteins, and gene regulation.

The eggs of aerial-laying apple snails are protected by specialised perivitelline fluid, the nutrient-rich material surrounding the embryo. In some species this contains defensive proteins, pigments, calcium-binding proteins, and toxins that help protect the eggs from harsh terrestrial conditions and from being eaten. These biochemical adaptations help explain how an aquatic snail could evolve a reproductive strategy partly displaced onto land.

The new Advanced Science study adds an even more awkward fact for creationists: a key protein involved in this reproductive innovation, PVF1/PV1, appears to have originated from ancient horizontal gene transfer from viruses into the ancestor of the apple-snail family during the Jurassic. In other words, part of the genetic toolkit that helped these snails lay eggs out of water was probably not created specially for snails at all, but was acquired from a viral lineage and later co-opted by evolution.

This is exactly the sort of messy, opportunistic, historically contingent process that evolution predicts. Structures are modified; genes are duplicated, repurposed, borrowed, or rewired; and lineages adapt to new ecological opportunities. It is also exactly the sort of process creationism cannot honestly accommodate because a gene acquired from a virus and later used in snail reproduction cannot sensibly be dismissed as mere "variation within a kind".

The paper in Advanced Science was accompanied by a press release from Lingnan University:

Lingnan University joint research analyses genome of global agricultural pest ‘apple snail’: Ancient viral gene-driven evolution of ‘terrestrial oviposition’ ability
Pomacea canaliculata, commonly known as the apple snail, a pest commonly found in Hong Kong’s wetlands and farmlands, feeds on aquatic plants and deposits its eggs on terrestrial plants or stone bunds. It is listed by the International Union for Conservation of Nature (IUCN) as one of the “100 of the World's Worst Invasive Alien Species”. The Division of Science of Lingnan University and its collaborative research team analysed the genomes of the Pomacea canaliculata and its close relatives, and discovered that despite being aquatic animals, they possess the trait of terrestrial reproduction, and their egg masses also exhibit desiccation resistance, UV screening, and predator deterrence. This capability may originate from an infection by a virus during the Jurassic period, where their ancestors integrated the viral gene to evolve in their own genome, and scholars point out that this could not only provide foundational insight into how land invasion occurred, but also suggest potential avenues for developing inhibitors to eradicate the snail pest from the root. These research findings were recently published in the top international academic journal Advanced Science.
The research team was led by corresponding author Prof Jack Ip Chi-Ho, Assistant Professor (Presidential Early Career Scholar) of the Division of Science (DoS) at Lingnan University, in close collaboration with Prof Jian-Wen Qiu (Hong Kong Baptist University) and Prof Jin Sun (Ocean University of China), together with international malacological experts.

The team pointed out that after the ancient continent split around 128 million years ago, the ancestors of the Pomacea canaliculata living in freshwater environments parted ways and evolved independently across Asia, Africa, and the Americas. Interestingly, a similar land-laying reproductive trait evolved independently in two apple snail lineages that diverged more than 100 million years ago—one in Asia and Africa (Pila) and one in the Americas (Pomacea). The team deduced that the ancestors of the apple snail were infected by a virus before the split as early as 145 million years ago during the Jurassic period. By integrating the viral gene into their own genome, they drove the evolution of the reproductive trait of laying eggs on land, thereby reducing the threat of aquatic predators such as fish to the egg masses.

Using comparative genomics, the team analysed the genome of six apple snail species (from Asia, Africa, and the Americas), and conducted a genome-wide comparison with their close relatives, including the family Viviparidae (river snails) and other molluscs. The results revealed that in the terrestrial egg-laying species of the Old World genus Pila and the New World genus Pomacea, their egg fluid contains over 80 per cent of the protein PV1, which helps enhance their ability to resist desiccation and ultraviolet rays.

Further analysis indicated that within the New World genus Pomacea, including Pomacea canaliculata and Pomacea maculata, there is also a neurotoxic protein called PV2, which provides additional toxic defence to deter predators. Together, these key egg-fluid proteins exhibit unique neurotoxic and physical protective characteristics, which may have helped drive the apple snail to enhance its reproductive capacity—producing red-pink, toxic egg masses resembling miniature grapes that deter terrestrial predators such as birds and insects while allowing the egg masses to maintain water balance in the air, resisting desiccation and ultraviolet rays.

Prof Ip explained that the Pomacea, originally native to the Amazon River basin in South America, was introduced to Asia for food, but because it harbours parasites that can cause severe diseases in humans, it ultimately became an invasive species in freshwater ecosystems worldwide, including Hong Kong. Each apple snail can produce up to 500 eggs in a single week, and eats aquatic plants such as water spinach and watercress, affecting crop growth. Its astonishing reproductive capacity allows it to compete with native freshwater snails for living space, disrupting the ecological balance of wetlands, affecting the habitats of birds and amphibians, and causing severe damage to the environment.

In the past, controlling the snail pest in Hong Kong relied mainly on manual removal of egg masses and the application of chemical pesticides, which yielded limited efficacy. The use of chemical agents could also cause pollution to wetland ecosystems and crops. The Pomacea is not the only aquatic animal to have evolved terrestrial reproductive traits, and this study reveals an important transition in the evolutionary history of animals moving from water to land for reproduction. We found that two apple snail lineages, which evolved independently for over 100 million years, could develop a similar trait of terrestrial oviposition, and this helps the academic community understand the critical evolutionary role played by viral infections in driving environmental adaptation and species evolution. In the future, we hope to conduct an in-depth study on the PV1 protein that protects the snail eggs, in order to develop biological inhibitors targeting this protein to eradicate the snail pest, opening up a new direction to mitigate its ecological destruction.

Assistant Professor Jack Chi-Ho Ip, co-corresponding author
Division of Science
Lingnan University
Hong Kong SAR
China.

[Assistant Professor Jack Chi-Ho Ip] expects to suppress the reproductive capacity of the Pomacea from the root in a way that does not damage the wetland environment and crops, providing a definitive solution for local and international ecological conservation and sustainable agriculture.

Publication:
Y. Zhou, H. Mu, X. Nie, et al.
Two Routes to Land: Genomic Underpinnings of Parallel Aerial Egg Deposition in Aquatic Old-World Pila and New-World Pomacea (Ampullariidae). Advanced Science (2026): e22371. https://doi.org/10.1002/advs.202522371

ABSTRACT
The evolution of aerial oviposition in Old-World Pila and New-World Pomacea apple snails—diverged since the Gondwanan breakup—offers a powerful model for probing genomic adaptations underpinning key evolutionary innovations. We generate a chromosomal-level genome for Pila celebensis and a scaffold-level genome for Pila pesmei, revealing a genus-specific doubling in genome size driven by transposable element expansions. Analyses of macrosynteny and topologically associating domains (TAD) identified lineage-specific chromosomal rearrangements associated with positive selection in gene blocks enriched for environmental sensing, metabolism, and stress response. Breakpoints in aerial egg layers preferentially are localized within TADs, suggesting convergent rewiring of gene regulation. Gene family evolution revealed parallel expansions in cellulases, β-D-xylosidases, and immune genes, alongside convergent positive selection in aquaporins critical for aerial osmoregulation. Perivitelline fluid (PVF) proteomics uncovered the central role of PVF1, likely acquired via ancient horizontal gene transfer (HGT) from viruses in the Ampullariidae ancestor in the Jurassic. Subsequent duplications enabled lineage-specific adaptation; PVF1 in aerial eggs shows parallel increases in hydrophobicity and aromatic residues (notably phenylalanine), enhancing desiccation resistance. Collectively, these convergent genomic mechanisms—structural rearrangement, gene family dynamics, and HGT-driven innovation—underpin the independent evolution of aerial oviposition in Pila and Pomacea, providing a multi-layered blueprint for understanding key ecological transitions.

FIGURE 1
Genome landscape and evolutionary dynamics in Pila. (A) Circos plot of 14 linkage groups (corresponding to “chromosome”) showing marker distributions in 1 Mb sliding windows from outer to inner circle: Illumina sequencing depth, GC content and gene density, with the shell shape of Pila celebensis at the center. (B) Maximum-likelihood phylogenetic tree of 23 molluscs, including cephalopoda, Bivalvia, and polyplacophora as outgroups (left). The tree was calibrated at five nodes (indicated by red dots) using fossils and geological events, revealing divergence times with 100% bootstrap support; dark-purple lines indicate 95% confidence intervals. The circular diagram in the Ampullariidae tree (right) illustrate aerial and aquatic egg laying in Ampullariidae family. (C) Comparison of repetitive elements showing expansion of four transposable element classes (i.e., SINEs, LINEs, LTRs, and DNAs) in the Ampullariidae and Bellamya purificata genomes. Estimated LTR insertion times for Pila celebensis are indicated within a gray dotted border. (D) Schematic of Hox gene clusters in seven Ampullariid species, illustrating Hox-linked chromosomes evolution. Gene names are labeled centrally, with connections indicating scaffolds; line lengths do not represent sequence lengths. The symbol “//” indicates a break between different scaffolds, and transcription direction is indicated by a bullet head. Ancestral linkage groups are denoted as MLG (Mollusca), AvLG (Ampullariidae and Viviparidae), and AmLG (Ampullariidae).

And so, once again, the real world turns out to be nothing like the simplistic creationist caricature of biology. There was no sudden appearance of a fully-formed apple snail, equipped from the outset with everything it needed for life at the water’s edge. Instead, there was a long evolutionary history, extending back into deep time, during which existing structures, behaviours and genes were modified, repurposed and combined in new ways.

The especially awkward detail for creationists is that this adaptation appears to have involved genetic material acquired from a virus. This is not a minor colour variation, a slight change in shell shape, or any of the other trivial changes creationists try to contain within their conveniently undefined “kind”. It is the incorporation and evolutionary repurposing of genetic material from an entirely different biological source, producing a functional contribution to a major reproductive adaptation.

In other words, this is new biological information arising by natural mechanisms, with no designer required and no biblical narrative involved. It is precisely the sort of opportunistic, historically contingent process evolution predicts: genes are copied, altered, transferred, disabled, reactivated, co-opted and repurposed, while natural selection preserves what works well enough in a particular environment.

Creationism, by contrast, has no explanatory mechanism here. It can only deny, redefine, or retreat into word games about “kinds”. But a viral gene pressed into service in the reproductive biology of an aquatic snail laying eggs above the waterline is not something Genesis predicted, not something intelligent design explains, and not something creationists can honestly dismiss as mere variation within a created kind.

As usual, the science reveals a rich, testable and evidence-based history of life, while creationism offers only slogans, special pleading and a refusal to look where the evidence points. The apple snail’s borrowed viral inheritance is yet another reminder that evolution is not a belief system competing with creation mythology; it is the observable, investigable process by which life diversifies, adapts and leaves its history written in its genes.

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