Biomass-dispersal trade-off and the functional meaning of species diversity

Production–diversity patterns lack a single explanation fully integrated in theoretical ecology. An ecological state equation has recently been found for ruderal vegetation. We studied 1649 plots from twenty-nine ecological assemblages and analyzed the relationship between diversity, biomass and dispersal looking for a pattern across these ecosystems. We found that high biomass and low dispersal values were significantly associated with high diversity plots under stationary conditions, and vice versa, involving a biomass-dispersal trade-off that is coherent with well-established ecological principles. Therefore, energy per plot, estimated as one half of the product of mean individual biomass and mean square dispersal multiplied by the number of individuals per plot, only reaches its maximum at intermediate levels of diversity. This explains the well-known humped relationship between production and diversity. We also explore why the rest of the diversity–production patterns can be explained starting from disruptions of this basic pattern. Simultaneously, the product of diversity, biomass and square dispersal is statistically equal to the ecological equivalent of the Boltzmann’s constant included in the ecological state equation that remains valid for all the assemblages explored due to scale variations in the value of the abovementioned constant. Biomass-dispersal trade-off resembles the principle of equipartition of energy from the kinetic theory of gases but in a characteristic way, because the alternative micro-associations of dispersal-biomass in function of species diversity are not randomly distributed as it happens with the combinations of molecular mass and velocity in a mixture of gases. Therefore, this distinctive ecological feature should be assumed as one of the main pro-functional gradients or thermodynamic constraints to avoid chaos and ecological degradation under stationary conditions. Hence, biomass-dispersal tradeoff explains production–diversity patterns and the ecological state equation in simultaneous agreement with conventional ecology and physics.Fundación Canaria Rafael ClavijoDIVERBO

Uncertainty principle in niche assessment: A solution to the dilemma redundancy vs. competitive exclusion, and some analytical consequences

There has been a categorically unresolved crucial question in ecology and evolutionary theory for manydecades; perhaps from the times of Charles Darwin himself: Is it possible, under natural conditions,that two species can perform a commonly shared ecological niche? There are two extreme conventionalresponses that have kept divided the scientific community in this regard for almost forty years: (a) No;that is to say, the well-known competitive exclusion principle (CEP). (b) Yes; that is to say, the well-knownhypothesis of full functional redundancy (HFR). Obviously, the reliability of both responses depends on anunderlying and even more essential requisite: that the ecological niche of a given species can be assessedwith such accuracy as we could want in order to detect the degree in which it is shared between coexistingspecies. This article is the seventh in a continuous series of interconnected recent publications that pro-motes an alternative understanding of ecology and evolutionary biology which is in favor of strong andmutually fruitful analytical links between biology and physics. This article analyzes the statistical behav-ior of ecological niches by taking into account two indicators that are essential to perform the ecologicalniche of all species: species diversity per plot (Hp) and eco-kinetic energy (Ee) as a proxy for trophic energyin a scalar field Hp, Eein which an oscillating performance of ecological niches is deployed. According toour results, in the same measurement in which the accuracy of Hpassessments increases (reduction ofHp’s standard deviation: Hp) the accuracy of Eeassessment decreases (increment of Ee), and vice versa, inagreement with a pattern that is completely equivalent to that of the Heisenberg’s uncertainty principlein quantum mechanics (i.e.: Hp· Ee 1/2heec/2 ; where heec: ecological equivalent of Planck’s con-stant found in previous publications). As a result, the ecological niche is, even in principle in addition toin practice, indeterminable with enough exactness to arrive to a categorical response to the above-statedquestion. This means that CEP and HFR are simultaneously true and false in the same measure, becausethe only feasible option to keep the functional stability of ecosystems is a wave-like combination of bothoptions: when species are pushed to a high degree of coexistence (increase of partition of the gradient) in regard to Hpvalues (a trend in favor of HFR), their degree of coexistence in regard to Eevalues dimin-ishes (decrease of partition of the Eegradient, a trend in favor of CEP), and vice versa. The final sections ofthe article highlight the eco-evolutionary, biogeographical and socio-economic meaning of this result, byoffering plausible alternative explanations to a wide spectrum of phenomena that appear to be only par-tially understood so far, e.g.: the contradictory results about the relationship between body size, speciesdiversity and macroevolutionary rates; the general environmental scenario in favor of macroevolutionaryleaps with a low probability to leave footprints in the fossil record; the unnecessary, although stimu-lant, influence of geographic isolation to promote evolutionary changes; the island rule; and the generalmeaning of the interaction between nature and society