Metabolism and body size in the third millenium or is the three-quarters coefficient universal? One of the most interesting event in biology of the end of 20th century was the formulation of metabolic theory of biology, based on the theoretical foundation of scaling of metabolism and body size characterized by the exponent of 3/4. Several recent studies show that (1) the three-quarter scaling is not universal, intraspecific scaling coefficient varying between 2/3 and 1, (2) the relationship between body body size and metabolic rate is not an exact power-law but is lightly curvilinear in log-log space, and (3) the scaling coefficient in bacteria is close to 2, and in protists close to 1, indicating major evolutionary transition in metabolic scaling associated with the origin of eukaryotic cell and multicellularity.
Why species are rather scarce then abundant. The distribution of species abundances has been traditionally considered to by lognormal, generated by some random multiplicate process, comprising for instance unequal random division of resources among species. However, we have shown hat the lognormal distribution cannot universally apply across spatial scales. Moreover, the observed shape of the distribution at particular spatial scale can be attributed to the process of splicing from the distribution occurring at smaller scales, given that there is spatial turnover in species composition between neighbouring plots, and that species abundances are spatially autocorrelated. The distribution of species population sizes thus results from the fact that landscape is heterogenous and there are limits of population dispersal.