OK, so a new volcanic island arises in the middle of the ocean; plants get washed there as seeds, birds and insects fly there, but the lizards? - I have trouble finding the ‘raft of vegetation’ explanation wholly satisfactory; do lizards really get washed so far out to sea on naturally formed rafts? - has this ever been observed? (observed a long way from land that is)
But surely they couldn’t swim those distances, so maybe it’s true, or is there another explanation? (did they hitch a ride on something else, maybe something alive?)
The swallows carry them there, along with the coconuts.
Here is a site which addresses the colonization of the Canary Islands by three species of Gallotia lizard (rafting is presumed, based on the proximity to the African mainland).
Check the November 27, 1998 entry here which mentions that such sea-going reptiles have been observed (it links to a real-audio thingy which I can’t access here at work, so I’m not sure what the whole story is. But it would at least appear at the surface that rafting reptiles have been observed).
I’ve never heard of direct observation of the “raft of vegetation” hypothesis. On the other hand, I have difficulty thinking of plausible alternatives.
It would be likely that these things happen infrequently, for example, the Hawaiian Islands lack native freshwater fish, amphibians, reptiles, and mammals (except for one bat), even ants didn’t make it to the Hawaiian Islands before people brought them.
Plants and animals can also be intentionally introduced to islands by migrating humans. When the Polynesians came here to Hawaii, they brought over many species of plants and animals. They had to, as they relied on plant and animal products for their survival. Centuries later, the Europeans brought their own variety of wildlife as well, for similar reasons.
Then there’s the the stuff that sneaks aboard or gets smuggled over. Lizards and rodents and insects probably got dragged along for the ride while hiding out in the food and supplies. They also could have been kept as pets by the sailors. Plant seeds could have come over stuck to the clothes of the missionaries.
You can pretty much kiss the natural state of a place goodbye once human traffic to and from there picks up.
