<
https://theconversation.com/sloths-are-too-slow-to-adapt-to-climate-change-new-study-240052>
"Sloths are more vulnerable to the rising temperatures associated with climate
change than other mammals, due to their unique physiology.
In a new study, my colleagues and I found that sloths’ ability to adapt to
warming temperatures varies between the cooler, high-altitude and warmer,
low-altitude forests of Costa Rica.
Unlike most mammals, sloths do not actively regulate their body temperature.
Like reptiles, they rely heavily on ambient temperature to do so. This affects
all aspects of their survival, including digestion, metabolism and movement.
Combined with their extremely low-calorie, relatively inflexible leaf-based
diet, these traits mean sloths have much less energy at their disposal than
most other mammals.
As sloth body temperatures become hotter with rising temperatures, their
metabolic rate increases. But those with sharply increasing metabolic rates are
at risk of lower survival rates when temperatures rise, compared with other
sloths.
Together with colleagues, including the founder of UK-based Sloth Conservation
Foundation Rebecca Cliffe, I found that their degree of vulnerability depends
on the altitude of the forests where each sloth originates from.
We calculated the metabolic rates of high- and low-altitude sloths across a
range of temperatures using a method called respirometery. This involves
putting a sloth in a large, closed box (comfortably) to measure how much oxygen
it consumes at each temperature within an allotted time period.
Lowland sloths were able to slow their metabolic rate when temperatures became
too hot. This is an important survival mechanism that may benefit these
populations as climate change continues.
Highland sloths were unable to slow their metabolic rate, which increased with
temperature and became critical above 32°C. Highland sloths are at another
disadvantage – cooler, high-altitude forests tend to be smaller due to the
slower growth rate of trees at higher elevations coupled with habitat loss.
Highland sloths are therefore much less able to migrate and are more restricted
than lowland sloths.
Sloths with higher metabolic rates use more energy, so they need to eat more
food to produce more energy. However, due to their extremely slow rates of food
intake and digestion, sloths take much longer to process food into energy than
other mammals. Essentially, sloths cannot simply eat more food to match their
energy requirements or achieve “energy balance” – the state where calories
consumed equals calories burnt through physical activity.
Combined with inflexible migration options, the restricted metabolism of
highland sloths makes them especially vulnerable to climate change. However,
while lowland sloths appear to have more flexible metabolic responses to
warming temperatures, they won’t be able to escape the effects of climate
change if temperature increases are too extreme, putting their survival at risk
as well.
There is a considerable lack of data on the current status and abundance of
sloths. No comprehensive, long-term population monitoring has been conducted at
a scale that reflects the true challenges sloths face."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
