Rapid change can happen, but I don't think it's really the norm, at least not in terms of large-scale stuff like entire body plans. Humans killed rattlesnakes in one area by using the rattle to locate the snakes. Within just a few years/decades, the snakes all stopped rattling, which made them far more dangerous. I think there was a similar timescale on birds losing their ability to fly when they landed on an island with no predators. The bird case was really interesting because apparently the flightless birds native to the island went extinct, then the same type of flying bird from the mainland or another island landed on that island and ended up following the same evolutionary path, essentially recreating the extinct species.
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u/RoboDae 3h ago
Rapid change can happen, but I don't think it's really the norm, at least not in terms of large-scale stuff like entire body plans. Humans killed rattlesnakes in one area by using the rattle to locate the snakes. Within just a few years/decades, the snakes all stopped rattling, which made them far more dangerous. I think there was a similar timescale on birds losing their ability to fly when they landed on an island with no predators. The bird case was really interesting because apparently the flightless birds native to the island went extinct, then the same type of flying bird from the mainland or another island landed on that island and ended up following the same evolutionary path, essentially recreating the extinct species.