The giant northern termite Mastotermes darwiniensis showing the close relationship between termites and other cockroaches.
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Researchers from the University of Sydney have just published a paper on termite evolution in Science which will make depressing reading for any creationists brave enough to attempt it. The study comprehensively refutes several articles of creationist faith.
A common creationist assertion is that loss of genetic information is invariably fatal, so mutations cannot be selected for during evolution. They also insist that evolution, as defined by science, is necessarily a process of increasing complexity, which they then claim would violate the laws of thermodynamics by reducing entropy.
The absurdity of this counter-factual claim is easy to see. Variation between individuals is due to genetic differences, and that variation is only possible if mutations generate novelty. Creationists also conveniently ignore the fact that entropy can decrease locally in open systems. Earth is very much an open system, with a continuous influx of energy from the Sun, so nothing in thermodynamics precludes local increases in order or complexity.
Moreover, the claim is demonstrably false. Many endoparasites, such as parasitic worms, have lost substantial amounts of genetic information as they evolved to rely on their hosts for key functions. Several intestinal worms, for example, have no digestive tract at all, because they absorb nutrients directly from their host’s gut. Evolution does not require an increase or a decrease in complexity as such; it requires only a change in the frequency of alleles in a population over time.
The University of Sydney researchers have now identified another striking example of evolution by gene loss — this time in termites. Their results show a massive loss of genes as termites evolved extreme monogamy and sociality. Paradoxically, a reduction in genetic complexity at the individual level was accompanied by an increase in social complexity at the colony level.
Some of the lost genes are those responsible for producing sperm tails, meaning that termite sperm can no longer swim. This is likely a consequence of strict monogamy within the colony, which removes sperm competition altogether. In species where females mate with multiple males, there is strong selection pressure for highly motile sperm, because the fastest are more likely to fertilise the eggs. In termites, that pressure simply does not exist.
To reach these conclusions, the team — led by Professor Nathan Lo — compared the genomes of ‘domestic’ cockroaches (which share a common ancestor with termites), closely related wood roaches that live in small family groups, and multiple termite species exhibiting different levels of social complexity.
