The decrease in prey has led to the extinction of predators on the Iberian Peninsula.

An international study involving the Complutense University of Madrid (UCM) and the National Museum of Natural Sciences (MNCN-CSIC) has reconstructed food web time series spanning more than 20 million years. The study uses the high-resolution mammal fossil record from the Iberian Peninsula and reveals long-term trends in predator-prey interactions.

An interdisciplinary team of ecologists and paleontologists from Brazil, Spain and Sweden conducted a study that analyzed a range of food webs to determine how their restructuring affected the extinction of predators. This work, published in the journal Ecology Letters, shows that beyond each species’ situation, it is important to analyze their interactions when developing conservation strategies.

“This is the longest time series of mammalian food webs analyzed to date, which gives us a deep understanding of the evolutionary processes in predator-prey relationships,” comments João Nascimento, a researcher at the University of Campinas (Brazil) and author of the main study of the study.

Using so-called network analysis, the authors characterized trophic interactions between predator and prey species over the past 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. “Trophic interactions between species are key to studying ecosystem dynamics. To understand current biodiversity dynamics, it is necessary to study how interaction patterns changed in the past,” explains Matias Pires, senior author and professor at the University of Campinas. (Brazil).

Soledad Domingo, co-author of the work and professor at the Faculty of Geological Sciences at UCM, for his part adds that “the fossil record of Iberian mammals is one of the most complete and best studied in the world for this period, which allows us to carry out this study and gain detailed knowledge about how ecosystems have evolved over millions of years.”

Distribution of large herbivores

The researchers found that food webs gradually simplified, losing connectivity and becoming increasingly dispersed. Around 15 million years ago, there was a marked decrease in temperature along with an increase in aridity, which facilitated the arrival and spread of large herbivores while reducing the diversity of medium-sized herbivores. These changes in the body mass distribution of herbivore communities have reduced the amount of prey available to most predators, leading to a simplification of the food web.

“Our study shows a complex relationship between the composition of herbivore communities and the predators that feed on them, with changes in composition appearing to be more important than individual species extinctions,” adds Juan L. Cantalapiedra, co-author of MNCN. Researcher.

Wider environmental context

The authors found that the lifespan of predators was directly related to their risk of extinction, with predators with less available prey being at greater risk. “This highlights the importance of ecological interactions influencing extinction patterns over the course of evolution. We must consider not only individual species, but also the broader ecological context to develop conservation strategies that keep predators in our ecosystems,” concludes Fernando Blanco, study co-author and researcher at the University of Gothenburg (Sweden).

This study provides unique insight into the evolutionary consequences of species interactions and highlights the need to maintain diverse prey populations to maintain healthy predator species and stable ecological networks.

Link

Nascimento et al., “Reorganization of predator-prey networks over 20 million years explains extinction patterns of carnivorous mammals,” Ecology Letters, 2024.