This is a sound principle, though there may be rare exceptions: polyploidy in plants is common, and the symbiosis of micro-organisms that formed the eukaryota is a more exotic example.

• 这是一个合理的原则，但也可能有些罕见的例外：植物出现多倍体很常见，但微生物共生形成真核生物是一个比较奇特的例子。