Spatio-temporal climate change contributes to latitudinal diversity gradients

Area of Science:

• Biodiversity research
• Ecology
• Evolutionary biology

Background:

• The latitudinal diversity gradient (LDG), a pattern of increasing species richness towards the Equator, is a fundamental concept in ecology.
• Despite over a century of recognition, the underlying mechanisms generating the LDG remain a subject of intense scientific debate.

Purpose of the Study:

• To investigate whether spatio-temporal climatic changes can generate large-scale biodiversity patterns.
• To test the role of speciation, extinction, and dispersal in the formation of the LDG, excluding adaptive niche evolution and biotic interactions.

Main Methods:

• Utilized computer simulations to model biodiversity patterns.
• Speciation was simulated via range disjunctions, and extinction occurred when species lacked suitable habitats.
• Focused on the interplay of fixed species' niches with dynamic climate across landscapes.

Main Results:

• Simulations successfully generated LDGs that closely mirror empirical data for three major vertebrate groups.
• Higher speciation rates at low latitudes, primarily driven by precipitation variability, were key to generating the gradient.
• Temperature variation played a lesser role compared to precipitation in driving tropical speciation.

Conclusions:

• Spatio-temporal climatic fluctuations, especially in precipitation, are significant drivers of the latitudinal diversity gradient.
• Geographical range disjunctions caused by climate shifts historically promoted allopatric speciation, contributing to LDGs.
• Global biodiversity patterns can arise from climate-niche interactions without necessitating niche evolution or biotic interactions.