Ants are a ubiquitous presence on our planet, with over 14,000 species distributed across all continents except Antarctica. It is estimated that more than four quadrillion individual ants are inhabiting the Earth. Despite their remarkable success, the evolutionary journey that led to their global domination remains enigmatic.
A recent study published in Evolution Letters sheds light on this mystery by examining the co-evolution of ants and flowering plants over the past 60 million years. The research team, led by Matthew Nelsen from the Field Museum in Chicago, combined fossil evidence, DNA analysis, and data on modern species’ habitat preferences to understand the evolutionary relationship between ants and plants. Their findings suggest that as flowering plants expanded from forests into new environments, ants followed suit, leading to the diversification of ant species we see today.
Around 140 million years ago, both ants and flowering plants, or angiosperms, originated and began spreading to new habitats. Nelsen and his colleagues sought to understand the connection between the two groups’ evolutionary paths. By analyzing the climates inhabited by 1,400 modern ant species and reconstructing the ant family tree using genetic information and amber-preserved fossils, the researchers could make educated assumptions about prehistoric ants’ lives. This data, combined with similar information on plants, offered valuable insights into the early world of ants.
Approximately 60 million years ago, ants primarily lived in forests and built underground nests. As some plants evolved to release more water vapor, creating a rainforest-like environment, ants began moving their nests into the trees. This shift also coincided with the emergence of new arboreal communities involving frogs, snakes, and epiphytic plants.
As flowering plants expanded into more arid regions, adapting to thrive in drier conditions, the study suggests that ants followed suit. These plants likely offered food incentives for ants, such as elaiosomes, and fleshy appendages on seeds. By consuming these elaiosomes, ants inadvertently helped disperse seeds, benefiting the parent plants.
Understanding the relationship between ants and plants is crucial in the context of the ongoing climate and biodiversity crises. Nelsen emphasizes that plants play a significant role in shaping ecosystems, and changes in plant communities can impact animals and other organisms that rely on them. The study highlights the intricate connections within our environment and underscores the importance of preserving ecosystems and biodiversity for the continued survival of countless species, including our own.
Matthew Nelsen et al, Macroecological diversification of ants is linked to angiosperm evolution, Evolution Letters (2023). DOI: 10.1093/evlett/qrad008