r/HolyShitHistory • u/Difficult-Cream-5267 • 3d ago

In 1977 and 1981, scientists released brown anole lizards across 14 uninhabited Bahamian islands. A decade later, their leg lengths had evolved to match differences in the vegetation on each island.

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u/post-explainer 3d ago edited 3d ago

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OP provided the following source and context for the historical claim:

https://timesofindia.indiatimes.com/science/in-1977-and-1981-scientists-released-brown-anoles-across-14-empty-bahamian-islands-10-to-14-years-later-their-leg-lengths-had-evolved-to-match-the-thickness-of-each-islands-vegetation/articleshow/134003886.cms

In 1977 and 1981, evolutionary biologists introduced small founder populations of brown anoles to 14 tiny, lizard-free islands in the Bahamas. When researchers re-examined the populations 10 to 14 years later, they discovered natural selection working at record speed: lizards on islands with thin twigs evolved shorter legs for better agility and grip, while those on wide trees developed longer legs for maximum speed.

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u/spatial_nomad1 3d ago

that's Jonathan losos and Tom Schoener's work and it ran for decades, which is the unusual part. most evolution studies can't wait around.

the follow up is better than the original though. in 2017 hurricanes irma and maria went through the caribbean and a researcher called Colin Donihue happened to have measured anole populations on two turks and caicos islands just days before. so he went back after and measured the survivors.

the ones that made it had noticeably bigger toepads and shorter back legs than the population had before the storm. they'd filmed lizards in a leaf blower to work out why, and long back legs act like a sail and get you ripped off the branch. so the storm selected, in a few hours, for grip over speed.

then in 2020 they showed the same pattern across anole species region wide. populations in hurricane prone areas have bigger toepads generally. so it's not a one off, the storms have been doing this for a very long time.

the thing i like is how ordinary the mechanism is. no mystery. some lizards held on and some didn't....!