ABSTRACT
Life tends to regulate Earth’s system. Diversity is not necessarily correlated with stability if species are thrown together randomly. But natural ecosystems are coevolved and have a ratio of predators, prey, parasites, hosts, symbiotic and commensalal species, and so on, that is close to optimal. In such ecosystems, coevolved diversity promotes stability. Network theory is useful in investigating and testing the ABH. Models from it and empirical evidence support the conclusion that there is a positive correlation between biodiversity on the one hand and stability, connectance, resilience, persistence, productivity, resistance to invasion, and efficient nutrient flow and use of resources in natural ecosystems on the other. Complexity and connectance are positively correlated with stability, resilience, and persistence. These correlations are consistent with the ABH. It is hypothesized here that natural ecosystems evolve toward the maximum possible number and proportion of positive connections between species because this is the most stable state; that is, ecosystems maximize the number of positive interspecific connections.
