An Old Hypothesis on the Dwarf Sloth
When I looked up on some of my old files, I have discovered this old hypothesis of the origin of the pygmy sloth.
The Pygmy Three-toed Sloth (Bradypus pygmaeus) is a small sloth that is native to the Isla Escudo de Veraguas. It is about 40% smaller in body mass than the mainland Three-Toed Sloth (Bradypus variegatus).
My hypothesis of them being there is that they arrived there by drifting vegetation a couple centuries or less ago. With that sloths both have a very low metabolism (they would go the bathroom only once a week) and they are considerably good swimmers, that sort of transportation seems logical.
How they became small is, I believe, to be a combination of food and isolated genetics. The main food source the pygmy sloth eat are red mangrove leaves and they are poor in nutrients than the leaves that their mainland relatives/ancestors eat. Other animals have been known to become smaller due to lack of nutrients, some of them are mustangs. Also, since that they are isolated from the mainland sloths, they become 'victims' of a Founder Effect. With both their isolation and lack of selective pressures from predators (as far as anyone knows) and with the nutrient-poor food, the dwarf trait spreads throughout the isolated population like wildfire.
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| A Pygmy Three-Toed Sloth (Our Endangered World) |
The Pygmy Three-toed Sloth (Bradypus pygmaeus) is a small sloth that is native to the Isla Escudo de Veraguas. It is about 40% smaller in body mass than the mainland Three-Toed Sloth (Bradypus variegatus).
My hypothesis of them being there is that they arrived there by drifting vegetation a couple centuries or less ago. With that sloths both have a very low metabolism (they would go the bathroom only once a week) and they are considerably good swimmers, that sort of transportation seems logical.
How they became small is, I believe, to be a combination of food and isolated genetics. The main food source the pygmy sloth eat are red mangrove leaves and they are poor in nutrients than the leaves that their mainland relatives/ancestors eat. Other animals have been known to become smaller due to lack of nutrients, some of them are mustangs. Also, since that they are isolated from the mainland sloths, they become 'victims' of a Founder Effect. With both their isolation and lack of selective pressures from predators (as far as anyone knows) and with the nutrient-poor food, the dwarf trait spreads throughout the isolated population like wildfire.
That's my hypothesis.
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