Metagaming
Metagaming is a phenomenon where a species or lineage is forced to unrealistically survive or die out. Plagues are a common example of metagaming.
Sometimes, metagaming extinction is used to cull species that should not have been approved, such as basal skuniks which were far too large to support their own weight on land without any skeleton. Usually, however, this form of metagaming is done to get rid of perfectly functional lineages that are generally disliked (such as earth clones) or, more rarely, that are considered too popular (such as capiris). The largest, most clear-cut instance of metagamed extinctions occurred in Week 22, where there were a large number of plagues that wiped out entire lineages, as well as dozens of species forced to become extinct by either being made to large to survive the end of the snowball event or by having all of their food made inedible.
Metagaming survival, meanwhile, is usually the result of an extinction event being announced before it occurs. The most clear-cut example of this is Week 15, where dedicated survivors of every popular lineage were made that inexplicably became burrowers or cave dwellers to escape the gamma ray burst. Another example of metagaming survival occurred towards the end of Week 26, where the purge of maladapted polar species was intentionally announced in advance so that the many species affected could be fixed or saved.