The size of an organism determines many of its functions, such as metabolism and even birth and mortality. Furthermore, in a population not all individuals are the same size, but there is a whole gradation from the largest to the smallest individuals. Now, a team of scientists from the Federal Polytechnic School of Lausanne (Switzerland) has found what could bea universal equation that, from the mean size, predicts the complete distribution of measurementsfor each of the living species on the planet.
The researchers made their observations on 14 species of aquatic microorganisms, including both unicellular and multicellular species, evolutionarily widely separated and therefore with few kinship ties. These were species with enormous differences in size, which at the macroscopic levelwould be equivalent to comparing a mouse with an elephant. Despite this, the results revealed that the equation was true for all the organisms studied, even when environmental conditions were varied through changes in temperature or the introduction of competitors into the ecosystem.
Based on their results, which are published in the journalPNAS, scientists claim thatboth the genetic characteristics of a species and environmental factors influencein the size distribution of their populations. On the one hand, the environment determines the average size of the species and, on the other, genetics and physiology are the cause of the variability of the individuals in the population with respect to said average magnitude. The authors of the work suggest that this equation should be fulfilled for all species on the planet and, if this is true, the finding will help to understand new aspects of the population dynamics of large ecosystems.
