Have you ever wandered through a tropical forest and observed the incredible variety of fruits it contains? From tiny berries to very large, hard-shelled pods, this fruity menu supports a vast array of animals, like bats, birds, monkeys, and more. In exchange for food, these animals disperse the seeds, facilitating forest regeneration. This mutualistic relationship is the engine of tropical forest resilience and diversity. A long-standing question in ecology is whether these intricate ‘who-eats-what’ networks are built by millions of years of coevolution, or whether they are more like a marketplace, where interactions are based on plants and animals characteristics in modern days.
In the new paper ‘Ecological function over evolutionary legacy: the limited role of shared evolutionary history in shaping modern frugivory interactions’, author Lisieux Fuzessy sets out to answer this question.
Our paper is essentially a detective story set in the world of tropical ecology. We wanted to solve the mystery of what determines the structure of frugivory networks—the complex web of connections between fruit-eating animals and the plants they feed on. The main question we sought to answer was: How important is the shared evolutionary history between animals and plants in determining their interactions, compared to their current, observable morphological atributes? In other words, do animals eat certain fruits simply because their ancestors did (a phylogenetic legacy), or because their physical and behavioral atributes are a good match for the fruit’s characteristics today (ecological fitting)?
Our findings were surprising. Using a sophisticated method to compare the family trees of animals and plants (the Procrustes Approach to Cophylogeny, or PACo), we found that the ‘cophylogenetic signal’ was detectable but very weak. This means that while evolutionary history leaves an imprint, it is far from the dominant architect of these networks.
Instead, the main take-home message is that ecological and functional atributes are the real determinants of how vertebrates and plants establish an interaction. The main food item in the vertebrate’s diet, its body size, how well-connected it is in the network, and key fruit traits like color, size, and whether it has a husk were the dominant drivers of who interacts with whom. We found a fascinating asymmetry: animal traits like body size are often evolutionarily conserved (passed down through lineages), but most important fruit traits are evolutionarily labile, meaning they can change rapidly. This suggests plants can quickly adapt their ‘offerings’ to attract dispersers.
The broader impact of this research is significant. It challenges the classic idea of tight, one-to-one coevolution, and instead highlights their flexibility. This is crucial for predicting how these vital ecological networks will respond to global change, like species extinctions or habitat fragmentation. It tells us that conserving biodiversity isn’t just about saving individual species; it’s about protecting the functional roles and the interactions that hold the ecosystem together.
2. About the Research
To build our research, we needed a large amount of data. We built and used the NeoFrugivory database, a compilation of over 10,000 unique interactions between about 758 vertebrate species and 2,375 plant species from across the Neotropics, gathered from hundreds of published studies.
The data collection itself was a lesson in patience and precision. The biggest challenge wasn’t just gathering the data, but curating and standardizing it—ensuring species names were correct, traits were measured consistently, and interactions were reliably documented. We resolved this through manual checks, the use of tools from R programing and by developing a clear framework for classifying interactions.
We analyzed this data through a multi-level framework, looking at the entire network, then zooming in on the most frequent and ecologically important interactions, and finally examining tightly knit subgroups within the network called ‘modules’.
One of the biggest surprises was just how weak the evolutionary signal was, even when we looked at known, textbook examples of specialized partnerships, like bats and pepper plants (Piperaceae) or monkeys and sapote trees (Sapotaceae). We expected these close relationships to show a strong phylogenetic legacy, but they didn’t. This was a clear indicator that even seemingly specialized interactions are likely built more on consistent trait-matching than on an inseparable evolutionary past.
Another surprise was the stark contrast between animal and plant traits. Finding that a monkey’s body size is heavily influenced by its evolutionary history, but the size of the fruit it eats is not, was a powerful illustration of the “asymmetry” we describe.
The natural next step for this research is to move from the macro-scale to the micro-scale. We now need to integrate genomics to look for signs of coevolution at the molecular level and conduct detailed field studies to understand the behavioral choices of individual animals. An interesting next step would be asking, for example, how much of frugivory is innate preference (evolutionary history) versus learned behavior (ecological fitting)? The present study provides the broad framework; now we need to fill in the intricate details.
3. About the Author
I have always been fascinated by the complexity of nature—why certain sMy journey into ecology began with a fascination for the sheer diversity of life, specially in the Brazilian Atlantic Forest. That curiosity never faded. I’m currently a Postdoctoral Researcher at UNESP, São Paulo, Brazil, where I get to spend my days trying to understand the complex rules that govern ecological interactions, mainly frugivory. My current scientific curiosity is focused on the central topic of this paper: the interface between ecology, evolution, and conservation. I am fascinated by how species so often form new interactions based on traits they evolved long ago for a completely different purpose. This concept, known as ‘ecological fitting,’ explains so much about how ecosystems assemble (re-assemble) and persist.
Photo credit: Personal archive.
Outside of research, I recharge by running in nature, practicing yoga, and watching the sunset. There’s no better way to remember why I do this work than by being out in nature itself.
Like many scientists from the Global South, progressing in my career has involved navigating significant barriers, particularly around funding and access to international networks. These hurdles can make research feel like an uphill battle at times, but they also foster incredible resilience and creativity.
If I could give one piece of advice to my younger self, it would be this: Don’t be intimidated by the complexity of life and nature; that’s where the most interesting questions are hidden. Learn the statistical tools, but never lose your sense of wonder for the natural phenomena they are describing. The best science connects a deep curiosity about the world with the rigorous tools needed to understand it.
