The climate plays a decisive role in the distribution and evolution of life on Earth, yet many questions remain about how past climate changes have influenced mammalian diversity on our planet. A study led by researchers from the University of Vigo—Sara Gamboa, Sofía Galván, and Sara Varela—published this week in the journal Global Change Biology offers new insights into this relationship.
As scientists from the Marine Research Centre at the University of Vigo explain: “The Earth’s climate changes, and not all species respond in the same way to these changes. Specialist species, such as polar bears or orangutans, which can only survive in a specific climate, are considered more vulnerable to environmental changes than generalist species, which can thrive in various climates.” However, until now, how different habitats respond to these changes and how they affect mammalian communities over the long term has not been fully explored.
Their study builds on the hypothesis of Dr Elisabeth Vrba, who suggested that regions with extreme temperature and precipitation conditions should host a greater number of specialist species than other regions due to greater historical fragmentation. To test this hypothesis, the University of Vigo researchers used climatic data from the past five million years and advanced statistical analysis techniques, enabling them to assess the relationship between climate fragmentation and mammal distribution across the planet’s major climatic zones, covering all terrestrial mammal species—over 5,000 in total.
The findings of this study suggest that past climates have left an “indelible mark” on the distribution and evolution of species, even more so than the current climate. As Vrba asserted, “The number of specialist species increases with historical fragmentation of regional climates, whereas overall climatic species richness declines.” The relationship between past climate changes and mammalian diversity is approximately 40% stronger than the correlation between the current climate and species richness for specialists, and 77% stronger for generalists. The data show, for instance, that tropical, temperate, and polar regions have been most affected by climatic changes, whereas arid and cold regions have demonstrated greater stability.