‘Universal thermal performance curve’ means life cannot adapt well to extremes of temperature
That’s according to research published today by Trinity College Dublin zoologists, Professor Andrew Jackson and Dr Nicholas Payne, and colleagues overseas in the top journal, Proceedings of the National Academy of Sciences.
The findings suggest that researchers have overestimated the ability of many species to adapt to global warming. When faced with relentlessly rising temperatures, species do poorly when, in response, they either do nothing, or attempt to increase the optimum temperature at which they perform best.
This suggests that species are not as able to change and adapt to temperature as scientists had thought.
One strategy is to try and increase the optimum temperature they perform well at, by increasing the minimum amount of energy that is made available for chemical reactions to occur.
This does not work well as it comes at the cost of reducing the range of environmental temperatures, above the new optimum, that a life form can deal with before they fail or die.
“They have an evolutionary choice: either stick with their current metabolic system and put up with performing below their maximum, or adapt and shift their optimum upwards at the risk of being more at risk of temperature increases,” Professor Jackson said.
“What follows from our work is that species are more constrained by temperature increase and hence more threatened by increasing temperatures than we previously thought.
“Across thousands of species and almost all groups of life including bacteria, plants, reptiles, fish and insects, the shape of the curve that describes how performance changes with temperature is very similar.”
The TCD scientists discovered a universal thermal performance curve (UTPC) that governs all forms of life.
From a lizard running across a rock, to a shark swimming in the sea, or a bacteria invisible to the naked eye dividing in the soil, all life forms will operate best within a set range of temperatures, above which their performance tails off rapidly.
The existence of this UTPC, the scientists say, “shackles evolution” as no species found to break free of its constraints.
Under the UTPC, the performance of life forms will slowly increase, as temperature increases, until it reaches an optimum, where performance is at its greatest.
Any further temperature increases result in rapidly declining performance, leading to overheating which risks physiological failure, and death.
The scientists analysed the thermal performance of several thousand species from bacteria, to plants, lizards to insects. They found that despite how incredible varied life is, that all forms are ruled by how temperature influences their ability to function, and billions of years of evolution hasn’t managed to overcome that.
“The next step is to use this model as something of a benchmark to see if there are any species or systems we can find that may, subtly, break away from this pattern,” Dr Nicholas Payne, the lead author of the paper, said.
“If we find any, we will be excited to ask why and how they do it, especially given forecasts of how our climate is likely to keep warming in the next decades,” Dr Payne said.