Scientists Have Discovered a Universal Rule That Shackles Evolution

Scientists have identified a universal rule that appears to govern how all living things respond to temperature, from bacteria to animals. Performance rises gradually with warming, peaks at an optimal point, and then drops sharply as temperatures climb further. Credit: Stock A hypothetical generalized thermal performance curve (TPC), illustrating how performance traits —such as running speed in lizards —exponentially increase with temperature until reaching a maximum performance at the optimal temperature. Beyond this peak, performance declines sharply as temperature continues to rise, eventually reaching a minimum or collapsing at the critical temperature. Credit: Prof. Nicholas Payne and Prof. Andrew Jackson, Trinity College Dublin Biological performance across the tree of life collapses onto the Universal Thermal Performance Curve (UTPC). Shown are approx. 30,000 performance measurements derived from seven kingdoms, 39 phyla and 2710 experiments. Performance is represented by diverse rates including metabolism, individual growth, foraging intensity, voluntary activity, and population growth. Credit: Prof. Nicholas Payne and Prof. Andrew Jackson, Trinity College Dublin A single thermal performance curve applies across life, from bacteria to animals. Species differ in optimal temperatures, but not in the fundamental shape of their response to heat. Researchers at Trinity College Dublin have identified what they describe as a “universal thermal performance curve” (UTPC) that appears to govern how all species respond to changes in temperature. According to the scientists, this shared pattern effectively “shackles evolution,” since no known organism has escaped the fundamental limits the curve places on how temperature influences biological performance. Temperature affects every form of life, but the UTPC brings together tens of thousands of previously separate curves used to describe performance across different species. The same underlying relationship applies regardless of what is being measured, whether it is a lizard running on a treadmill, a shark swimming in open water, or the rate at which bacterial cells divide, showing that a single rule links temperature and performance across the living world. Why warming helps, then harms Crucially, the new UTPC shows that as all organisms warm: As organisms heat up, their performance rises gradually until it reaches an optimal point (where performance is highest). Once temperatures climb beyond this optimum, performance drops off rapidly. This sharp decline at higher temperatures means that overheating poses serious risks, including physiological breakdown or death. A key implication of the research, recently published in the international journal PNAS , is that species may have less flexibility to adjust to global climate change than previously thought, especially as temperatures continue to rise in most regions. From lizards running on a treadmill, to sharks swimming in the ocean, and cell division rates in bacteria, the universal thermal performance curve applies to all species and dictates how they respond to temperature change. Once things get too hot, performance tails off rapidly. Data collapse, and models converge onto this Universal Thermal Performance Curve (UTPC), which only requires optimal and critical temperatures as parameters. Credit: Prof. Andrew Jackson, Trinity College Dublin Evolution can shift, not escape Andrew Jackson, Professor in Zoology in...

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