Been wondering for a while why so many animals and our old relative the homo Floresiensis grew to be so small on this particular island. Is it to do with natural predators or maybe the food? Anyone have any clue?
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I believe it’s because islands are small with a limited amount of food and resources. The bigger you are the more energy you require. That’s not beneficial when on an island with limited food and energy sources. Over time animals and humans shrink to increase their chances of survival on the island. Sometimes meat eaters will change to plant eaters as well
The are two phenomena that often affect species that get onto islands – island dwarfism and island giantism.
Small species that get onto islands often leave large descendants. If they can arrive early with little competition and / or few predators then there’s an opportunity for them to get much larger. There’s a reason you get giant tortoises on multiple different islands.
Large species though often get smaller. Limited resources for a population of large animals means that selection for smaller individuals who need less food etc. means they tend to shrink.
Occasionally these can come together and you get the amazing phenomena on ancient Malta of giant swans with dwarf elephants (there’s art online of this).
In the case of Flores, this tended to be dwarfism with things like miniature humans, and also today you can see the anoa (dwarf buffalo) but there are also giant extinct storks that lived alongside H. floresiensis.
TLDR limited resources means evolution selects for smaller individuals who can survive on little.
Upping your weight class is normally a response to predation. The larger you get the fewer things are capable of eating you. If you don’t have predators then staying small and energy efficient will likely be selected for.
Galapagos turtles are a bit of an outlier. They don’t have any predators either but larger bodies and long necks let them reach plants that are higher off the ground. Birds and agile small mammals can usually reach all the calories available.
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