Let's face facts. It's not always worth the effort to have sex. Many animals find the whole process of mating so difficult that they decide to reproduce asexually instead.
Evolution is not as appealing as it sounds. However, sex sacrifices can have a devastating effect on a population. Either a species of eukaryotics will have to swap chromosomes or face the possibility of extinction.
This is the rule. However, the beetle mite Opiella nova (Oppiella nuova) has a different opinion.
A team of European researchers compared its genome to that of O. subpectinata its sexually active cousin and discovered that the micrometer-sized arthropod lived a quiet life for millions of years.
These tiny mites, like us, have a copy of every chromosome in their genome. This makes them a diploid organism.
Mix-and-matching chromosomes can give a population more options for genetic combinations. This means that when disaster strikes, be it a heat change, a plague or the introduction of a predator, there will be some people who will be able to cope.
All the bells and whistles are gone, and you have sex. Unfortunately, all those bells, whistles (searching for mates, competing against them, producing all that fertile sperm), can make it difficult to maximize genetic diversity.
Other ways to preserve a certain amount of variation are available that don't depend on sexual reproduction. These mutations can cause different types of mutations (or alleles) to form, creating a unique signature among asexual genes.
This mutation pattern, also known as the Meselson Effect, was named after Matthew Meselson, a Harvard geneticist. It could theoretically be used to identify diploid organisms as bona fide, long term asexual species.
The problem is that there has not been enough evidence to support this conclusion. It has been shown that some ancient linesages of species believed to be asexual were only recently converted, which is quite scandalous considering they may have had a few licentious attempts over the centuries.
Researchers needed a clear signal that there was variation in the genes of an animal thought to have given up sex many, many years ago and never looked back.
This brings us back to O. Nova, a little mite that has sublineages that split off between 6-16 million years ago. It suggests that it's an ancient species.
It is also a species that has been shown to be asexual. This makes it an excellent specimen for studying the Meselson effect.
It was difficult to imagine an animal capable of forming a conga line within a millimeter.
Jens Bast, a reproductive biologist at the University of Lausanne in Switzerland, says that these mites are just one-fifth of millimeters in size and can be difficult to identify.
It took specialized computer programs to decode the genomes. But it was worth it.
Bast says, "Our results clearly demonstrate that O.nova reproduces exclusively sexually."
These beetle mites may still offer a few surprises when it comes to understanding evolution without sex.
However, this is not to say that asexual reproduction doesn't have its difficulties. The beetle mite seems to be an exception to a fairly consistent biology rule.
However, it is possible to survive without sex by finding an animal that has survived without sex for millions of years.
This research was published by PNAS.
