What term is used to describe the behavioral adaptation where lack of historical pressure sculpts a species' tameness?

Island tameness

The behavioral trait exhibited by the quokka, characterized by unusual trust and lack of wariness toward new species like humans, is specifically termed 'island tameness' in ecological studies. This phenomenon occurs because, in isolated island environments lacking historical pressure from native predators, the selective advantage for heightened fear response diminishes. Over time, the population shifts toward a more relaxed disposition, prioritizing other activities like foraging. When confronted with novel interactions, such as those presented by visiting humans, this tameness becomes maladaptive, highlighting a critical paradox where evolutionary success in one niche leads to profound vulnerability in another.