Understanding Biodiversity: The Phenotype-History-Ecology Nexus

Three interactive components, phenotype, history and ecology underlie species richness patterns. Of these, phenotype is often overlooked. Even between animals of a similar size, energy requirements for maintenance, growth and reproduction can be demonstrated to differ widely. Energy use is budgeted over differing temporal spans, up to and including a lifetime. The lower the energy requirements of an organism the more individuals a given area can support. An upper limit on potential species richness for a given biomass, is probably set by "population viability" factors. A temporal element must also be included in biodiversity models. Low energy availability should not prevent the development of high diversity in ecosystems, if the organisms have evolved energy-' efficient physiological traits. Energy consumption per individual, per unit of time, may be an order of magnitude lower in the deep sea than on a coral reef. An important question to be addressed is "for a given energy input, do some habitats/ecosystems support more taxa than others?". History (time), plays a key role in the formation of species richness, through refuge-invasion cycles. Energy and living space may set ultimate ceilings to biodiversity, but they cannot be responsible for limiting diversity in depauperate habitats. These habitats have been disturbed in some way from their trajectory towards high biodiversity.