Mites that mate on our faces at night face extinction threat | Zoology

Sliding through the grease and protected by our pores, tiny follicular demodex mites live a secret life inside our skin, only emerging at night to mate on our foreheads, noses and nipples. As successful as these sexual encounters are, their days as independent parasites may be numbered.

The first genome sequencing study of these mites seems to have captured them in the process of transitioning to internal symbionts, totally dependent on us for their existence. Eventually, this process can even lead to their extinction.

Measuring just 0.3mm in length, D follicular they are carried by about 90% of people and are most abundant on the wings of the nose, forehead, ear canal and nipples. They lead harmless lives, feasting on the sebum naturally secreted by the cells in the pores, and are likely present from the beginning of life, having been transferred from our mothers during childbirth or breastfeeding.

“The long association with humans may suggest that they may have simple but important beneficial functions, for example in keeping our facial pores unclogged,” said Dr. the search.

To better understand this relationship, Braig and his colleagues sequenced the genomes of D follicular mites, collected from a person’s nose and forehead using a blackhead remover – with each collection producing around 40 mites.

Their findings, published in Molecular Biology and Evolution, revealed that mites survive with the smallest protein repertoire – the smallest seen in any insect, arachnid or crustacean so far.

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This loss of genes resulted in an extreme reduction in cell numbers in adult mites – a likely first evolutionary step on their journey to adopting a fully symbiotic lifestyle in our tissues.

The more they adapt to us, the more genes they are likely to lose, until eventually they become entirely dependent on us. And with no opportunity to obtain additional genes from less related mites – they do not appear to transfer between adult humans during close physical contact – their isolated existence and the resulting inbreeding may have put the mites on the path to an evolutionary dead end, and potential extinction.

If that happens, it could be bad news for us too. “They are associated with healthy skin, so if we lose them, you could face problems with your skin,” co-author Alejandra Perotti, from the University of Reading, told the BBC.

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