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.