Ants and flowering plants share a long, intertwined history that shapes today’s ecosystems
Ants evolved to follow specific plant signals, a pattern researchers at the Fields Museum describe as a driving thread in the long coevolution with flowering flora. The two groups trace their roots to roughly 140 million years ago, and through vast stretches of time they have spread to nearly every corner of the globe. Scientists currently estimate around 14,000 ant species, with trillions of individual ants inhabiting every major ecosystem. This remarkable diversity highlights a shared narrative with flowering plants that spans continents and ages.
To investigate whether the evolutionary paths of ants and flowering plants intersected, Matthew Nelsen and colleagues studied the climates inhabited by a broad sample of 1,400 modern ant species. They combined temperature and rainfall data with a reconstructed ant family tree built from genetic information and fossil timelines. This approach allowed them to infer how ant lifestyles—nesting preferences, foraging habits, and habitat choices—are deeply rooted in ancestral lineages, often mirroring the ecological pressures faced by those ancestors. [Attribution: Fields Museum study]
The findings indicate that about 60 million years ago many ant species lived predominantly within forest interiors and built underground nests, shaping a life focused on soil, leaf litter, and subterranean networks. Over time, climate shifts and changing vegetation altered forest structure. Higher humidity and denser canopies gave way to drier, more open conditions. In these evolving environments, certain trees released cues and resources that attracted ants, opening new ecological niches. Some lineages climbed moisture gradients into trees, increasing vertical habitat complexity and linking arboreal and ground-dwelling niches in a dynamic dance of adaptation.
As these ecological transitions unfolded, flowering plants adjusted their strategies for drier climates. In response, some species developed traits that promote ant interactions, including elaiosomes—nutritious, fleshy appendages attached to seeds. These structures lure ants to harvest the elaiosomes and, in the process, transport the seeds, effectively using ants as seed dispersers. When ants gather seeds to eat the elaiosomes, they unintentionally relocate plant propagules, aiding plant spread across varied landscapes and supporting the resilience of plant communities. [Attribution: Fields Museum study]
Experts emphasize that this producer–consumer relationship, with plants offering rewards and ants assisting seed dispersal, helps shape entire ecosystems. The mutual benefits extend beyond seed survival, influencing plant genetic diversity, forest structure, and the flow of nutrients through soil and leaf litter layers. Such interactions show how plant life not only feeds insects but also creates living conditions that sustain a wide range of species, including other insects, fungi, and microorganisms. The study underscores the significant role plants play in the broader ecological web and highlights the interconnectedness that sustains biodiversity across terrestrial habitats. [Attribution: Fields Museum study]