Slow species turnover drove African megaherbivore decline

A new study in Nature Communications reveals that the decline of Africa's megaherbivores was driven not by faster extinctions but by a failure to generate new species fast enough to replace those lost. Researchers from the MNCN-CSIC, CENIEH, and the University of Alcalá reconstructed 23 million years of evolutionary history using 3,327 fossil records across 396 species Source: ABC.es.

Key findings

• Large species (over one tonne) did not go extinct faster than smaller ones; their extinction rates were actually slightly lower Source: Infobae.
• During peak aridity, small herbivores (under 45 kg) went extinct only 15% faster than giants but produced new species 2.2 times faster, allowing them to maintain diversity Source: ABC.es.
• Megaherbivore speciation rates dropped by about 20% due to aridification, while smaller ungulates saw increased speciation Source: Infobae.

Timeline of aridification

Africa began drying around 7.2 million years ago, altering landscapes and vegetation. Initially, both speciation and extinction rose, but speciation slowed around 3.6 million years ago while extinctions continued, accelerating with the Pleistocene 2.58 million years ago Source: ABC.es.

Implications

Megaherbivores are ecosystem engineers, so their loss affects vegetation and habitats. The study suggests human activity was not the primary cause of their long-term decline, though it may have contributed to recent extinctions Source: Infobae.