Rosa Rubicondior: Refuting Creationism - Observed Evolution of Plants on A Volcanic Island

Nishinoshima Island

Scientists trace origins of now extinct plant population from volcanically active Nishinoshima | EurekAlert!

Scientisst have a remarkable way to verify one of the fundamental principles of evolutionary biology - the 'founder effect' and how it contributes to allopatric speciation - a process that is hotly disputed by creationists who dogmatically refuse to accept any evidence for evolutionary diversification.

The great thing about science is that its theories can be tested and verified. Even better, they are frequently shown to be correct through evidence. This is in stark contrast to faith as a means of determining truth. Faith is not based on evidence, so it cannot be independently verified; in logical terms, it is unfalsifiable.

That doesn’t mean it can’t be falsified, but rather that there are no tests which, if failed, would demonstrate it false. Take, for example, the creationist claim that “God did it.” How could such a claim ever be tested? With no objective evidence beyond subjective feelings, anecdotes, or alleged personal experiences, there is nothing to examine. And if such a claim were challenged, it could always be shielded with further untestable assertions: “God is untestable,” “God is beyond science,” and so on.

By contrast, evolutionary biology offers theories that are not only testable but also repeatedly confirmed. One such theory is the founder effect. This occurs when a new habitat is colonised by only a small sample of a parent population. Two important factors follow:

The new sample is unlikely to perfectly represent the genetic diversity of the parent population, so it will begin with a different allele profile.
For the new colony to succeed, the founding individuals must already be somewhat pre-adapted to the environment. Those less well-suited are eliminated, while those better adapted survive and reproduce. Over successive generations, this natural selection creates a population increasingly fit for its new environment. The result is a wave of adaptation and divergence from the parent stock — the essence of allopatric speciation.

The natural “laboratory” for studying this process exists in the form of Nishinoshima, a remote Japanese island subject to frequent volcanic eruptions. Each eruption wipes the island clean of vegetation, effectively resetting the ecosystem and creating opportunities for colonisation by founder populations from elsewhere.

By careful genetic analysis of the, now extinct, Nishinoshima population of Portulaca oleracea, the team were able to show that the parent population was on nearby Chichijima, another volcanic island, however, the Nishinoshima population differed markedly from the parent population, and were derived from a very small founder population. In addition, there was evidence of genetic drift, which is much more significant in a small population than in a larger one - exactly as the Theory of Evolution predicts. Genetic drift is the process where, by chance alone, a neutral allele can increase or decrease in the population. The smaller the population the more quickly an allele can progress to fixation in the population or be eliminated. (for more detail on this, see the Introduction to my book, Twenty Reasons To Reject Creationism: Understanding Evolution (ISBN 13: ISBN-13 : 979-8306548166).

Now, researchers from Tokyo Metropolitan University have reported the results of this natural experiment, and they align precisely with what evolutionary theory predicts.

Nishinoshima — Background Facts.

Location:

Part of the Volcano Islands (Ōgasawara archipelago), Japan.
~940–1,000 km south/southeast of Tokyo.
~130 km west of Chichijima, the nearest inhabited island.

Volcano type / morphology:

Summit of a large submarine volcano with several satellite cones.
Historically a very small island, enlarged repeatedly by eruptions.

Eruption history:

Major eruption in 1973–74 expanded the island.
Strong eruptive activity from 2013–15, again in 2017–18, and 2019–20.
Renewed eruption phase began in October 2022 and is ongoing.

Size & growth:

As of 2020–2023, island area ~4.1 km², more than 2 km across.
Elevation around 200 m above sea level.
Older land repeatedly buried under new lava flows.

Ecology / biota:

Eruptions destroy vegetation, resetting the ecosystem.
Recolonisation occurs via wind-blown seeds, seabirds, and insects.
Bird guano provides nutrients for soil formation.
Several seabird species breed there, including brown boobies and crested terns.

Scientific importance:

Offers a rare natural “laboratory” to study:

How ecosystems recolonise after total destruction.
The founder effect and genetic drift in plants.
Island biogeography unfolding in real time.

Access / human use:

Uninhabited.
Access difficult and restricted, usually limited to scientists.
Conditions hazardous due to ongoing volcanic activity.

They have published their findings in Plant Systematics and Evolution and summarised them in a news release via EurekAlert!

Scientists trace origins of now extinct plant population from volcanically active Nishinoshima
Snapshot of early ecosystem development reveals genetic quirks
Tokyo, Japan – Scientists from Tokyo Metropolitan University have determined the genetic lineage of a now extinct plant population from Nishinoshima, a volcanic island whose frequent eruptions periodically “reset” the vegetation. While they traced the lineage to a nearby island, they discovered distinct genetic quirks due to the rarity of seeds making it there, including a “founder’s effect”. Their findings offer a rare glimpse into the very earliest stages of ecosystem development in an isolated environment.

Nishinoshima, a part of the Ogasawara Island chain, lies approximately 1000 kilometers south of mainland Tokyo. It is home to regular volcanic activity; a recent series of major eruptions in 2013 destroyed nearly all its vegetation. As devastating as this is for plant life, these periodic “resets” and the sheer remoteness of the island afford scientists a rare glimpse into the early development of ecosystems, as newly arrived genetic material struggles to create a foothold.

A team led by Professor Koji Takayama of Tokyo Metropolitan University, formerly affiliated with Kyoto University, has been investigating samples of common purslane, Portulaca oleracea, recovered from the island in 2019, just before an eruption destroyed virtually all flora on the island. While the species itself is found across temperate and tropical climates worldwide, the population on Nishinoshima is now considered extinct. Genetic analysis was carried out on these rare samples, one of 254 individual samples taken from a total of 51 separate populations sampled from all over Japan and Guam.

Through careful comparison, the team began to uncover where the population in Nishinoshima came from, and where they lay in the “family tree” (phylogenetic tree) of the species Portulaca oleracea. They looked at both chloroplast DNA and a genome-wide survey of nuclear DNA, assigning families based on genetic similarities. It was found that they were most closely related to populations found in nearby Chichijima, another volcanic island. However, it also became clear that individuals from Nishinoshima had distinct genetic traits. Importantly, they seemed to derive from very few individuals, leading to a strong skew in subsequent genetic divergence. This is known as a founder’s effect.

Seeds of common purslane are flat, oblate, and less than a millimeter in size, making it easy for them to disperse via wind, birds, and ocean currents. The team’s analysis, however, showed that opportunities for the plant to survive on the island must have been very limited; the founder’s effect observed in the genetic makeup of the samples was very strong. They also found evidence for genetic drift, where isolated events such as typhoons and volcanic eruptions, not natural selection, are responsible for changes in genetics.

The team’s work is a first glimpse into the phylogenetics of a now extinct population. The unique environment of the islands gives scientists a glimpse into the nascent stages of genetic evolution in isolated island environments, from how populations are established via the transport of seeds, to how they survive and thrive. This may also lead to insights into how plant populations are reestablished in the aftermath of natural disasters.

Publication:
Noda, H., Nakano, T., Kawakami, K. et al.
Origin of populations of Portulaca oleracea on Nishinoshima, an active volcanic oceanic island.
Plant Syst Evol 311, 26 (2025). https://doi.org/10.1007/s00606-025-01957-y

Abstract
Nishinoshima Island, located in the Ogasawara Islands of southern Japan, underwent major volcanic eruptions in 2013, which destroyed nearly all its vegetation. Understanding the origin and characteristics of the plant populations on Nishinoshima provides valuable insights into early stages of island ecosystem development. In this study, we analysed Portulaca oleracea samples collected from Nishinoshima in 2019, before subsequent eruptions eradicated the island’s populations. Phylogenetic and population genetic analyses of plastome sequences and genome-wide single-nucleotide polymorphisms (SNPs) were performed to compare Nishinoshima samples with those from Japan and Guam. The plastome phylogeny identified five distinct lineages across Japan and Guam, two of which were present in the Ogasawara Islands (Chichijima and Hahajima Islands), with one shared between Nishinoshima and Chichijima. Genome-wide SNP analysis revealed two major genetic groups in Japan: one in the northern and another in the southern regions, including the Ogasawara Islands. The Nishinoshima populations belonged to the southern group but exhibited unique genetic characteristics, as shown by network and STRUCTURE analyses. These characteristics are likely due to limited seed dispersal, a founder effect, and genetic bottlenecks resulting from natural disturbance such as volcanic eruptions and typhoons. These findings suggest that P. oleracea on Nishinoshima is genetically close to Chichijima populations but has accumulated distinct mutations. This study provides the first genetic evidence of plant origins on Nishinoshima and contributes to understanding the dynamics of ecosystem development on newly formed oceanic islands.

Introduction
Oceanic islands provide ideal systems for understanding vegetation dynamics and ecological processes over geological timescales (Stuessy et al. 2022; Whittaker et al. 1989, 2023). Newly formed oceanic islands, such as Krakatoa in Indonesia and Surtsey in Iceland, are particularly valuable for studying the early stages of island ecosystem development (Magnússon et al. 2014, 2022.1; Magnússon and Magnússon 2000; Tagawa et al. 1985). Studies on these islands have shown that most colonising plants originate from nearby continental regions or neighbouring islands with wind, birds, and ocean currents facilitating seed or propagule dispersal. However, opportunities to observe island formation and subsequent ecosystem development are rare and stochastic, underscoring the need for further research in these systems to better understand the processes driving colonisation, succession, and long-term ecosystem stability.

Nishinoshima, located at 27.2° N and 140.9° E, is an oceanic island located approximately 130 km west of the neighbouring island, Chichijima in the Ogasawara Islands south of the Japanese archipelago (Fig. 1). The island was first recorded by the Spanish ship Rosario in 1702 and given its namesake, Rosario Island, until it was renamed (Aoki and Osaka 1974; Center for Research and Promotion of Japanese Islands 2004). Nishinoshima is estimated to have formed through volcanic activity about 10 million years ago (Aoki and Osaka 1974). Since its formation, the island has frequently been impacted by large-scale disturbances, including volcanic activity and typhoons. During the Meiji period (1868–1912), workers were sent multiple times to the island collect guano (Aoki and Osaka 1974). Then in 1953, a fishing boat registered in Shizuoka Prefecture reported volcanic smoke rising from the island, signalling ongoing volcanic activity (Center for Research and Promotion of Japanese Islands 2019).

Fig. 1

Photographs, sampling location, and geographical genetic structure of Portulaca oleracea. Clades recognised in the plastome phylogeny are shown. The acronyms of the samples are listed in Table 1. Photo a A distant view of Nishinoshima Island in 2019; b a population of P. oleracea on Nishinoshima; c P. oleracea on Nishinoshima.

Nishinoshima underwent considerable change following a volcanic eruption on the island in 1973. By 1974, a newly formed landmass merged with the older island from the accumulation of sand and sediment (Nakano 2013). Before the eruption, Nishinoshima was originally a small landmass of about 0.07 km2, but by 2024, the combined island had expanded to approximately 3 km².

The first botanical survey of Nishinoshima conducted in 1969 recorded only three species: Eleusine indica (L.) Gaertn. (Poaceae), Echinochloa crus-galli (L.) P. Beauv. (Poaceae), and Portulaca oleracea L. (Portulacaceae) (Asami et al. 1970). A subsequent survey in 1983 identified Ipomoea pes-caprae (L.) R. Br. (Convolvulaceae), and by 2004, Vitex rotundifolia L. f. (Lamiaceae) and Tetragonia tetragonioides (Pall.) Kuntze (Aizoaceae) (Abe 2006; Ohsawa and Kurata 1983). Since 2013, subsequent large-scale volcanic eruptions have covered about 95% of the island with lava (Ono et al. 2015). By 2018, when volcanic activity had subsided, a follow-up survey in 2019 found that only E. indica, E. crus-galli, and P. oleracea survived in the remaining 5% of the uncovered land (Kamijo et al. 2020). However, further volcanic eruptions in 2020 covered this remaining area with lava. As of 2024, no plant life has been confirmed on the island (Kawakami et al. 2022.2).

Due to these recent eruptions and the complete reset of its vegetation, Nishinoshima provides a unique opportunity to study the processes of colonisation and succession in island systems, much like Krakatoa and Surtsey. However, Nishinoshima presents a distinct case due to its extreme isolation, located nearly 100 km from the nearest island. As a result, only three species have successfully established on the island over the past 40 years (1973–2013), reflecting a much slower rate of species colonisation compared to Krakatoa (Whittaker et al. 1989). Such extreme isolation makes Nishinoshima an ideal study site of oceanic island ecosystem development. Investigating the origin and characteristics of plant populations before eruptions provides valuable information on subsequent regeneration processes of natural vegetations and the initial stage of island ecosystem formation.

Portulaca oleracea is a cosmopolitan annual herb found across temperate and tropical regions worldwide (Akiyama 2006.1; Kokubugata 2017). Although the exact mode of seed dispersal for P. oleracea remains unclear, its seeds are nearly flat and oblate with a diameter of less than 1 mm, suggesting high-dispersal capacity by wind, birds, or ocean currents. The plant has high salt tolerance and drought resistance (Alam et al. 2014.1; Yazici et al. 2007), making it well adapted to coastal environments. In addition, germination temperature exceeds 20 °C (Noguchi et al. 1975), allowing for multiple generations per year especially in warm climates. While two varieties are globally recognised (POWO), a recent study by Ocampo (2012) identified seven subspecies. One of the two varieties, P. oleracea var. oleracea commonly found in open fields and along roadsides in Japan (Akiyama 2006.1).

In this study, we aimed to investigate the origin and diversification of P. oleracea populations that once grew on Nishinoshima through phylogenetic and population genetic approaches. We analysed P. oleracea samples collected from Nishinoshima in 2019 prior to complete disappearance of the species due to volcanic eruptions on the island, in addition to other samples collected from sites throughout Japan and Guam, another remote oceanic island located more than 1500 km south of the Ogasawara Islands. To explore the origin of pre-eruption P. oleracea populations on Nishinoshima, we addressed three key questions: (1) What is the genetic diversity of the populations on Nishinoshima? (2) Which populations are mostly closely related to those on Nishinoshima? (3) Is there evidence for genetic differentiation among P. oleracea populations in Japan and Guam? By answering these questions, we discuss plant colonisation and vegetation succession during the early stages of ecosystem development on oceanic islands. These findings provide critical insights into the mechanisms of plant dispersal and establishment in isolated environments, informing strategies for biodiversity conservation and restoration in fragile island ecosystems.

Noda, H., Nakano, T., Kawakami, K. et al.
Origin of populations of Portulaca oleracea on Nishinoshima, an active volcanic oceanic island.
Plant Syst Evol 311, 26 (2025). https://doi.org/10.1007/s00606-025-01957-y

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

What this study shows, once again, is the strength of science as a way of understanding reality. Evolutionary theory makes testable predictions — in this case, that populations established by the founder effect will diverge genetically and ecologically from their parent populations. Researchers can then look for evidence, and if the results had not matched the predictions, the theory would have been called into question.

This is what makes science powerful: it is always open to correction. A scientific theory stands or falls on the evidence, and can be abandoned or revised if it fails the tests. That willingness to be falsified is not a weakness but a profound strength, because it ensures that scientific knowledge grows closer to the truth with each test.

Faith, by contrast, offers no such mechanism. A claim based on faith cannot be tested against the evidence, and therefore cannot be disproved — which means it can never be properly verified either. It is unfalsifiable by design, insulated from scrutiny, and therefore ultimately sterile as a means of gaining knowledge.

In the case of Nishinoshima, we have a vivid demonstration of how science works: a clear hypothesis, an observable natural experiment, and a set of results that align with the predictions. Faith could never deliver such understanding, because it cannot be tested and it cannot fail.

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