An international investigation in which the Complutense University of Madrid (UCM) and the National Museum of Natural Sciences (MNCN-CSIC) participate has reconstructed a time series of food webs that spans more than 20 million years. The study uses the high-resolution fossil record of mammals from the Iberian Peninsula and reveals long-term trends in predator-prey interactions.
Made up of an interdisciplinary team of ecologists and paleontologists from Brazil, Spain and Sweden, the research analyzed a series of food webs to determine how their restructuring affected extinction among predators. This work, published in Ecology Letters, shows that, beyond the situation of each species, it is important to analyze their interactions when developing conservation strategies.
“This is the longest time series of mammalian food webs analyzed to date, providing us with a deep understanding of the evolutionary processes in predator-prey relationships,” comments João Nascimento, researcher at the Universidade Estadual de Campinas (Brazil) and author main of the study.
Using so-called Network Analysis, the authors characterized the trophic interactions of predator and prey species over the last 20 million years. To do this, they collected information on the body size and diet of mammal species in the Neogene fossil record of the Iberian Peninsula and calculated their possible interactions. “The trophic interaction of species is key to studying the dynamics of ecosystems. To understand our current biodiversity dynamics, it is necessary to study how interaction patterns changed in the past,” explains Mathias Pires, senior author and professor at the Universidade State of Campinas (Brazil).
Soledad Domingo, co-author of the work and professor at the Faculty of Geological Sciences of the UCM, for her part, adds that “the paleontological record of Iberian mammals is one of the most complete and best studied worldwide for this period, which gives us has allowed us to carry out this research and obtain detailed knowledge about how ecosystems evolved over millions of years.”
Proliferation of large herbivores
The researchers found that food webs underwent a gradual simplification, losing interactions and becoming more dispersed towards the present. Starting approximately 15 million years ago, there was a notable decrease in temperature along with an increase in aridity, which favored the arrival and proliferation of large herbivores while reducing the diversity of medium-sized herbivores. These changes in the body mass distribution of herbivore communities decreased the amount of prey available to most predators, driving simplification of the food web.
“Our study shows the intricate relationship between the composition of herbivore communities and the predators that feed on them, where a change in composition seems to be more important than the individual extinction of species,” adds Juan L. Cantalapiedra, co-author and MNCN researcher.
A broader ecological context
The authors found that the longevity of predators was directly related to their risk of extinction, with predators with fewer prey available experiencing greater risk. “This emphasizes the importance of ecological interactions in influencing extinction patterns over evolutionary time. We should consider not only individual species, but also a broader ecological context to develop conservation strategies that preserve predators in our ecosystems,” concludes Fernando Blanco, co-author of the study and researcher at the University of Gothenburg (Sweden).
This study provides a unique perspective on the evolutionary consequences of species interactions and points to the need to preserve diverse prey populations to maintain healthy predator species and stable ecological networks.
Reference
Nascimento et al, “The reorganization of predator–prey networks over 20 million years explains extinction patterns of mammalian carnivores”, Ecology Letters, 2024
