The dazixia butterfly (Sasakia charonda formosana) that is listed as an endangered species reproduces only once a year. On top of this, the species has a very limited range. "To drive them to extinction," writes Yang Ping-shih in a report, "We needn't catch all of them; their population groups just have to get small enough so that inbreeding results in the gradual weakening of the species."
被列入台灣瀕臨絕種名單的「大紫蛺蝶」，每一年只繁衍一代，加上分佈範圍侷限，在楊平世的報告中就指出「我們甚至不用將其捕捉殆盡，只要低於最小族群量，便會因近親交配所造成的遺傳組成劣化，而踏上滅絕的不歸路。」