Researchers have created a model capable of simulating the complex history of life in South America over thousands of years - an effort to better understand the many complex factors affecting the emergence, distribution and extinction of species on the continent. The model, which incorporates key ecological and evolutionary processes, produced results that closely match the geographical patterns of biodiversity for birds, mammals and plants observed today, a new study reports. While the individual processes responsible for the emergence and distribution of species are generally understood, how each species interacts in concert with others over broad swaths of space and time is complex. The authors suggest that the use of spatially explicit and dynamic models that incorporate a variety of widely understood physical and biological processes has great potential to reveal these processes' elusive underlying interactions. Here, Thiago Rangel et al. present one such model, which combines climate dynamics, evolutionary adaptation, range shifts, fragmentation, speciation, competition and extinction. With it, they simulated the ebb and flow of biodiversity in South America over the last 800,000 years - a period characterized by repeated glacial and interglacial cycles. Unlike other models, Rangel et al.'s simulations rely on the realism of modeled ecological and evolutionary processes, which play out upon modeled continental topography and paleoclimate, to produce shifting spatial and temporal patterns of speciation, persistence and extinction - or, "cradles," "museums," and "graves." Their simulations yielded realistic patterns that bear striking resemblance to contemporary biodiversity on both continental and regional scales. According to the authors, the results suggest the critical role of topography and climate as drivers for species diversification and extinction.
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Science