Table 1 Mechanisms underlying relationships between energy and species richness based on two recent theoretical treatments^12,20.

Time for speciation

Longer time periods provide more opportunity for speciation.

Diversification rate

Increased energy produces faster speciation or slower extinction rates.

Niche breadth

Higher energy results in greater abundance of preferred resources, a switch away from non-preferred ones, reduction in niche overlap, lower competition, and thus greater richness.

Niche position

Higher energy increases the abundance of rare resources and niche position resource specialists, leading to higher richness.

More trophic levels

Increased energy enables additional trophic levels to occur that are occupied by new consumer species so increasing richness.

Consumer pressure

As a consequence of other mechanisms, consumers are more abundant or diverse, so reducing prey populations and promoting co-existence, resulting in higher richness.

Sampling

Higher energy results in greater numbers of individuals, and random selection from a regional species pool with larger numbers of individuals results in an increased number of novel species in a focal assemblage.

Increased population size/more individuals

Higher energy areas support more individuals, leading to lower extinction rates, and thus greater numbers of species.

Dynamic equilibrium

Increased energy enables faster recovery rates from disturbance, reducing the time during which small population size-associated stochastic extinction is likely to occur, hence elevating richness.

Range limitation

As solar energy increases, climatic conditions are within the physiological tolerance range of more species.