“You move to an area, and you multiply, and multiply, until every natural resource is consumed. The only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. A virus.” -Agent Smith from The Matrix

Maybe at a time like this you wish you actually paid attention in Genetics class, well, not really. The dragon plague that affected Pern came down to one thing, the genetics within dragons.

The plague was a virus. In our modern world, we already know that viruses have the ability to mutate, so that a virus that caused simple colds can mutate within years to become an illness that causes respiratory failure. Viruses can also show up in small pockets and then rapidly spread across the planet effecting a huge population, which is the case with AIDS/HIV.

A decade before the actual Dragon Plague, there were some signs that some illness was causing the death of dragons. The interesting observation was that these small pockets appeared only in dragonets. One weyr would lose maybe two or three weyrlings a year due to the disease, which was nothing compared to the number of those lost in threadfall. Dragonets are vulnerable to diseases and other health abnormalities. There was no sign that it spread, so the weyrs had no concern for the few lives lost.

No one on Pern really understood the small killer among them. Without the technology of the original colonists, there was only Moreta’s vaccine for the virus spread by the feline and herbs for curing bacterial diseases. Genetics in the 14th pas means if you breed two fast runnerbeasts, you are likely to have a fast runnerbeast and down its bloodline. No one understands what genetics are really made of or how they work. The fact that some genes makes a person immune to a disease would not be understood at all.

It took a decade for the virus to mutate and perfect itself to the point where it could not just affect dragonets, but adult dragons in their prime. At first, High Reaches and Telgar Weyr began to have an increasing number of dragons take ill. The disease was a quiet, but efficent killer as dragons took ill and died within hours to a few days. Having finally perfected its use for a specific host, the disease spread rapidly across the Northern Continent into the Southern Continent. Dragons were dying at an alarming rate. The Weyrs were in panic as dragon numbers declined drastically, resulting in the deaths of hundreds of riders who had either gone between with their beloved or took their own lives. The terror lasted two full turns without the Weyrs knowing how the disease was caused, spread, or cured. Speculation grew over what caused the plague. Some pointed fingers to rebellous groups of the Southern continent, some believed a substance contaminated herdbeasts making them carriers.The dragon plague then suddenly dwindled as the virus consumed all of its resources, before the illness completely disappeared from the planet…or so they thought.

The number of clutches also dropped to a new low. While everyone thought the Plague was over, it lingered in a new way. The surviving dragons were carriers of the disease. As Weyrs began reconstruction, the riders had no clue what was going to unfold as clutches began to hatch…because there was a connection within the parents.

The truth lied in the fact that there was a recessive gene present in some dragons that made them immune. Here’s where genetics comes in. The virus killed all dragons whose genes were homozygous dominant, XX, which was present in the majority of dragons on Pern. Dragons who were homozygous recessive, xx, or heterozygous, Xx, survived the Plague since they both had the recessive gene present. Dragon clutches before the plague had mixed results, with either the dam or sire having an XX, while usually the other parent had Xx. As a result the majority of clutches resulted within XX offspring, who would eventually die of the plague.

After the plague, the dragon population only consisted of dragons with the Xx or xx recessive gene. The majority of the population now consists of heterozygous dragons, aka Xx. There are new combinations and percentages of offspring and genes.

The mating of two xx dragons results in offspring that will all be xx.
The mating of an Xx dragon and an xx dragon results in offspring that will be either Xx or xx.
The mating of two Xx dragons results in offspring that will be Xx, xx AND XX.

All is believed to be fine since so far the other Weyrs are hatching clutches from parents who are xx & xx or Xx & xx. The result of a mating between two Xx dragons has yet to be seen in a clutch. Which is why many believe the plague is over…

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We were approved by the Dragonlady herself in 2000, and we follow her rules and that Pern and The Dragonriders of Pern are copyrighted to her.
All references to worlds and characters based on Anne McCaffrey's fiction are copyright (C)
Anne McCaffrey 1967, 2000, all rights reserved, and used by permission of the author.
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The original founders of Dark Cove Weyr include Cassie and Beth.