Have you ever thought about the optimal temperature for life on Earth? The comfortable temperature for humans is 20°C.When it gets a little warmer, we Work efficiency decreases Because it takes energy to release heat.
We know that many species can survive at much colder or warmer temperatures than humans.But our systematic review Many published studies have found that the temperature ranges of animals, plants, and microorganisms living in air and water overlap at 20°C. Is this a coincidence?
For all species, the relationship with temperature is an asymmetric bell-shaped curve.This means a biological process increases depending on temperaturereaches a maximum value and rapidly decreases when it gets too hot.
Recently, a research group in New Zealand looked at the abundance of marine life. did not peak at the equator, as is commonly assumed. Rather, their numbers have declined, peaking in the subtropics.
follow up the study The results show that the depression has gotten deeper since the last ice age about 20,000 years ago. And with global ocean warming, its depth is accelerating.
When the number of species was plotted against the average annual temperature, a decrease was seen above 20°C. A second coincidence?
biological processes and biodiversity
Research in Tasmania modeled the growth rate. It was also found that 20°C is the temperature at which biological processes in microorganisms and multicellular organisms are most stable.
This “Coakley model” Other research This shows that 20°C is the most stable temperature for biomolecules. Third coincidence?
We worked with colleagues in Canada, Scotland, Germany, Hong Kong, and Taiwan to investigate common patterns of how temperature affects life. Surprisingly, everywhere we look, we find that 20°C is a critical temperature, certainly not just for marine life, but for many measures of biodiversity.
Examples show that various important measures deteriorate when the temperature exceeds approximately 20°C.
- Hypoxia tolerance of marine and freshwater species
- Productivity of pelagic (living in the open ocean) and benthic (living on the sea floor) algae and predation rate of fish on prey
- Global species richness including pelagic fishes, plankton, benthic invertebrates, and fossil molluscs
- and genetic diversity.
In the fossil record, extinctions increased when temperatures exceeded 20°C.
Increased species richness
Globally, coral reef fish and invertebrates have the narrowest temperature range of any species with a geographical distribution centered around 20°C. The same effect is seen in microorganisms.
Most species live at 20°C, although many species have evolved to live in warmer or cooler temperatures. Also, extinctions in the fossil record – sponges, lamp shells, molluscs, sea mats, etc.bryozoan), starfish and sea urchins, worms and crustaceans – were lower at 20°C.
As a species evolves to be able to live at temperatures above or below 20°C, its thermal niche becomes wider. This means that most organisms can survive even at 20°C, even if they live in hotter or colder places.
Coakley’s mathematical model predicts that at 20°C thermal spread should be minimal and biological processes should be most stable and efficient. This should maximize species richness in all areas of life, from bacteria to multicellular plants and animals. Therefore, this model theoretically explains this “20°C effect”.
Predicting the effects of climate change
The fact that the center of life appears to be around 20°C implies fundamental constraints that impair the ability of tropical species to adapt to high temperatures.
As long as species are able to adapt to global warming and shift their range, a 20°C impact would mean a local increase in species richness by an average of 20°C per year. Beyond that, abundance decreases.
This means that many marine species that can adapt to global warming by changing their geographic distribution are unlikely to become extinct due to climate change.
However, as cities, agriculture, and other human infrastructure change the landscape, terrestrial species may not be able to shift their geographic distribution so easily.
The 20℃ effect most easily explains the above phenomenon as follows. Trends in species richness and genetic diversity with temperature. Extinction rates in the fossil record. Biological productivity. Optimal growth rate. and marine predation rates.
Despite the complexity of multicellular species, it is noteworthy that cellular-level thermal efficiency is reflected in other aspects of biodiversity.
The reason why 20°C is so important and energy efficient for cellular processes may be due to the molecular properties of water associated with cells. These characteristics may also be the reason why ~42°C appears to be the absolute limit for most species.
A deeper appreciation of this 20°C impact could provide new insights into how temperature controls ecosystem processes, species richness and distribution, and the evolution of life.
mark john costelloFaculty of Biological Sciences/Professor nord university and ross coakleyAdjunct Senior Researcher in Biostatistics; University of Tasmania
This article is republished from conversation Under Creative Commons License.read Original work.
