Today’s environments outweigh ancient biome area in vertebrate diversity models
Reconstructed biome maps spanning 66 million years put present-day area and energy ahead of historical measures in models of terrestrial vertebrate diversity. The peer-reviewed comparison combined five climate simulations and geological evidence. It found broad agreement about past ecosystem changes, alongside differences that affect how biodiversity’s environmental history can be reconstructed.
Science··Morning
Current conditions lead the diversity comparison
Present-day biome area and energy were better predictors of terrestrial vertebrate richness than historical environmental measures in a peer-reviewed global analysis. Biomes are large regions with characteristic climates and living communities. The comparison covered birds, mammals, reptiles and amphibians. It tested how well today’s diversity follows current ecological conditions against measures accumulated over ancient biome histories, rather than tracing the ancestry of individual species.[1]
Five reconstructions extend across 66 million years
Alexander Skeels and colleagues reconstructed biome maps covering the past 66 million years. They downscaled five simulations of past climates, working at a grid resolution of 0.1 degrees, using temperature and precipitation to classify climates. Four models placed the largest tropical biome area around 40 million years ago, with a mean estimate of 41.8 million square kilometres against 32.7 million today. The fifth followed a different trajectory, reaching its peak in the Oligocene at 33.3 million square kilometres.[1]
Geological comparisons test the reconstructed maps
The maps were checked against indicators from 1,381 geological sites. Mean classification agreement was 71.6 per cent, rising to 81.4 per cent against expert interpretations of paleoclimate evidence. Agreement was stronger for the most recent 25 million years than in the older interval spanning 35–65 million years ago. Among 57 biome–realm combinations, the direction of expansion or contraction matched in 39. Data and code were shared through Zenodo, allowing the alternative reconstructions and analytical choices to be examined.[1]
