生态型（ecotype）概念可追溯到 Göte Turesson 于 1922 年对瑞典海岸盐灌木的研究：不同海岸带的族群在开花时间与茎长等性状上彼此不同，而介于栖地之间者呈中间值；他透过栽培证明这些差异有遗传基础，并以此提出「ecotype」。Kerstin Johannesson 在 1970 年代也在瑞典群岛观察到海洋蜗牛：壳较厚者留在岸边、壳较薄者偏好受浪拍打岩岸，两者之间则有中间型，这引发她对同一物种内部多型性的疑问。
直到 2000 年代初，随著全基因组定序可用，研究者才得以以分子层级检验生态型。Johannesson、Sean Stankowski 等人的分析显示，从海洋蜗牛、棘鱼、竹节虫到更多类群，都可能在同一物种内保留多套适应性 DNA 序列，使自然选择能依环境变化、甚至在数代内，于不同生态型之间切换。这也意味著一些被视为高度多样的类群，例如 Darwin’s finches，可能其实是同种中的不同生态型。
文中以 1964 年 3 月阿拉斯加湾大地震为例：4 分钟内，部分岛屿被抬升 38 英尺，河川与海洋隔绝，并形成淡水湖；约十年后，科学家在那里发现棘鱼仍然繁盛。原本栖于海水、以骨板抵御掠食者的海洋棘鱼，转而呈现更像淡水亲戚的外观与行为，骨板较少，而且这种变化在数十年间完成，速度快到不可能已形成新物种。
The ecotype idea traces back to Göte Turesson’s 1922 studies of Swedish coastal saltbushes, where plants from different stretches of shoreline showed distinct flowering times and stalk lengths, with intermediate traits in between; garden crosses showed the differences were genetic, leading him to coin “ecotype.” In the 1970s, Kerstin Johannesson saw a similar pattern in marine snails in the Swedish archipelago: thicker-shelled snails stayed on shore, thinner-shelled ones preferred wave-battered rocks, and intermediates occupied the middle ground, prompting her to question whether they were one species with multiple forms.
Only in the early 2000s, when whole-genome sequencing became accessible, could ecotypes be tested at the molecular level. Analyses by Johannesson, Sean Stankowski, and others indicate that species from marine snails and stickleback fish to stick insects can retain multiple adaptive DNA sequence sets, allowing natural selection to shift among ecotypes as environments change, sometimes within just a few generations. This suggests that some apparently diverse groups, including Darwin’s finches, may actually be ecotypes within a single species.
The article uses the March 1964 Gulf of Alaska earthquake as an example: within 4 minutes, parts of the islands were lifted 38 feet, rivers were cut off from the ocean, and freshwater lakes formed. Roughly a decade later, scientists found sticklebacks thriving there. Marine sticklebacks, armed with bony plates against ocean predators, had become more like their freshwater relatives, with fewer plates, and this shift happened within decades—far too fast for a new species to have evolved.