Tectonics, geomorphology and biodiversity.

Abstract

The global distribution of biodiversity broadly follows latitude and climate with regions of high species richness in the tropics and environments rich in energy, water and other factors conducive to life. However, superimposed on the correlation with climate is a correspondence between biodiversity and physical geography. High biodiversity is also associated with mountain systems. The inference is that topographic relief generates ecological heterogeneity through the creation of complex topography, landforms and the interaction of that topography with climate, creating temperature and rainfall gradients, geographic barriers and habitat patchiness. All of these factors create new niches for species, driving formation of new species and thus biodiversity. Mountain ranges are the product of tectonic activity where mantle convection and tectonic plate motion have deformed the surface of the Earth, uplifting crustal rock and creating rugged topography and high relief. Tectonics creates topography, but surface processes, such as mineral weathering, physical erosion by wind, water and ice, as well as sediment transport and deposition, modify that topography. The result is the complex patchwork of landscapes of the Earth's surface whose description is at the core of the field of geomorphology. There is a vast complexity to the processes within tectonics, geomorphology, ecology and evolutionary biology, and the links between the physical and biological processes are only beginning to be understood. To complicate matters, these processes are time dependent, coupled and include multiple feedbacks. Mountain ranges rise and fall. Ocean basins open and close. Moving plates and active faults displace terrains or entire continents across climatic gradients or relative to each other. Rivers and valleys may connect regions, but rivers can be redirected, providing new connections bringing species into a common competitive arena, or closing connections, leaving populations isolated and free to evolve without competitive constraints. Biodiversity emerges from this continual interplay of tectonics, geomorphology, and ecology, with Earth's surface persistently creating and erasing opportunities for life to diversify.