The Evolution of the South American Fauna

South American Fauna

The continent is home to the largest rainforest in the world, a region of dense tropical vegetation with its own rich biodiversity. The Amazon Basin also contains the world’s biggest wetlands. The Pantanal, for instance, fills and drains in response to rainy seasons, creating vast floodplains where you’ll see jabiru storks, American woodstorks and red and hyacinth macaws. You’ll also find capybaras, giant otters and anteaters among the animals that live here. And on the drier side, the Chaco of Paraguay is home to scrub and thorn forest dominated by the large branching Ipe tree.

Diving into the Rich Tapestry of South American Fauna

Whether or not the basic South American Fauna evolved when it was an island is hard to determine. But the old immigrants certainly occupied a very large and varied continent, which was then allowed to evolve in dynamic equilibrium, undisturbed by genetic interchange with other faunal groups from elsewhere on the globe.

The sigmodontine radiations that occurred later on are also notable. They created diversity hotspots that are largely complementary to the older caviomorph radiations, and they show how topographic complexity contributes to species richness by interrupting and limiting distributions and thus encouraging niche specialization. The central and southern Andes provide the best example, with its zones of elevation that are inhabited by regional faunas and then interrupted and capped by a diversity hotspot of sigmodontine diversity. There are few other places on the planet where this phenomenon is so well exemplified.

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