The world we live in, with all its living organisms, is similar to the stock market. Growth and variability are encouraged, and DNA is the currency that drives it all. Cloning yourself rapidly (asexual reproduction) is great for growth, but bad for variability. Swapping DNA with someone else (sexual reproduction) is great for variability, but can be time consuming and slow down growth. At some point in their life cycle, all organisms do some form of sexual reproduction. Except…
What’s with all these exceptions to the rule, you ask? There’s literally one in every single post! Living organisms are funny like that and biology is one of those fields of science where there are no hard rules. The minute you attempt to make an umbrella statement, a few “but what abouts” will appear. So yes, most organisms require some sort of sexual reproduction/genetic exchange process in their life cycle. Except the bdelloid rotifers.
Bdelloid rotifers are a class of microscopic animals that have no mechanism in their DNA for meiosis and no males have ever been observed or found. Like the tardigrade, they can dry up (desiccate), fragment their genome, and then rehydrate… without suffering any damage. To increase genetic diversity, rotifers steal DNA from their food and environment: bacteria, fungi, plants, other rotifers. The ability to fragment and rehydrate their DNA gives them a chance to add in all this foreign DNA.
Some people wear dollar sign pendants as a way to show off their status. Others encrust everything with precious gemstones. But these, as we know, are all social constructs. The true currency that perpetuates life is DNA. Our pieces may not be as large or gaudy as a giant gold plate that looks like a $100 bill, but the stories that you can tell about DNA currency are priceless.
