Though it isn’t certain, many of the world’s organisms seem to shrink due to global warming. A new study provides more insight. New research from Queen Mary, University of London has explored the phenomenon known as the “temperature-size rule”. This affects almost all cold-blooded organisms. The “temperature-size rule” describes how different individuals of the same species reach a smaller adult size when they are reared at warmer temperatures.

Until now, however, scientists have not fully been able to understand exactly how these changes in size take place.

Dr Andrew Hirst and his team from Queen Mary’s School of Biological and Chemical Sciences explore this fascinating shrinking effect in more deatils, as well as determine how it actually happens in their study featured in the journal The American Naturalist.

The study was funded by the Natural Environment Research Council. To test their theories, the team used data based on marine planktonic copepods. These tiny crustaceans are the main animal plankton that reside in the world’s oceans. They are also the important grazers of small plankton, as well as a necessary food source for larger fish, as well as birds and marine mammals.

More than forty years of total research has been put toward studying how the effect of differing temperatures affect these organisms. The team’s results show that growth rate (which is basically how quickly that the mass on their bodies is accumulated), and development rate (how fast the individual passes through the different life stages) are consistently decoupled in a range of pieces. Development is more of a factor when related to temperature than growth is.

Through the research, the team found that the growth and development increase at different rates as the temperature grows warmer. The problem with this is that when the warmer temperatures are reached, the species grows faster… but their development rate is even quicker. This means that they end up achieving a smaller adult size as the cycle continues.

The research team also found that by decoupling these rates, it could have important consequences for the individual species and the ecosystems that they reside in.

These interesting findings suggest that the rates that are fundamental to all organisms may not alter properly as the world becomes warmer. These rates include mortality, reproduction, and feeding, and if they fall out of sync, there many be consequences for the various species.

In truth, the team’s recent findings do disagree with previous discoveries that many macro-ecologists have found in the fast. They explain that, instead, these smaller sizes are associated with the “temperature-size rule” previously noted.

Hirst and his crew from Queen Mary’s School of Biological and Chemical Sciences hope that these findings and their ongoing work will help those who are researching the potential impact of climate change on the natural world.


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