Elevational diversity gradient

The first recorded observation of the elevational diversity gradient was by Carl Linnaeus in his treatise On the growth of the habitable Earth.

In this document, Linnaeus based his predictions on flood geology, assuming most of the world was at one point inundated, leaving only the highest elevations available for terrestrial life.

These variables, most notably precipitation and temperature, vary along an elevational gradient, resulting in the distribution of different ecosystems.

Whether this decline is monotonic or if it assumes different shapes based on the taxa or region being studied is still a topic of debate.

This elevational pattern, however, was less consistent for species with small ranges, suggesting that environmental factors may be more clearly accounted for when constraints on domain boundaries are loosened.

In cases where geometric models fail to explain the location of the midpoint or the trend in species richness, other explanations need to be explored.

An example of this can be seen with microbes, which have been shown to exhibit monotonically decreasing diversity when moving from low to high elevations.

[13] Furthermore, under a climatically driven mountain–mass effect, there is a “positive linear trend observed in the elevation of highest diversity with mountain height”.

[3] However increasing temperatures due to climate change have begun to be linked to the spread of chytrid among frogs in the Tropics.

The emerging macroecological experiments along environmental gradients (for example, mountain elevation gradients) are an important tool in ecological research because they allow for the disentangling the effects of individual environmental drivers on biodiversity, the independent effects of which are not easily separated due to their covariance in nature.

[22] A more expansive research program for mountain biogeography may be extremely beneficial for conservation biologists seeking to understand factors driving biodiversity in known hot spots.

[23] Further research and reviews are also needed to address contradictions in the scientific literature and to identify the extent of interactions between current explanations and hypotheses.