Trophic Interactions of Native and Invasive Mammals in South American Ecosystems

South American ecosystems host a rich mosaic of native mammals – from small insectivores and mid-sized herbivores to apex predators – whose interactions determine energy flow, biodiversity maintenance and ecosystem resilience. In recent decades, the introduction and expansion of non-native mammals, notably European rabbits, wild boar and armadillos, have reshaped these trophic networks. Invasive herbivores can monopolise primary productivity, altering plant communities and reducing resources for native herbivores. Predators such as pumas, foxes and birds of prey may switch to abundant invasive prey, creating novel links that stabilise predator populations but risk apparent competition with native prey. At the same time, strictly carnivorous apex predators sometimes perform unexpected ecosystem services – for example, dispersing seeds of plants consumed by their prey – revealing previously overlooked pathways of energy and nutrient transfer. Restoration efforts in defaunated landscapes aim to rebalance native and invasive biomass, but require accurate estimates of current and target densities. Understanding how invasive mammals interact with native species across trophic levels is vital for management strategies that seek to conserve biodiversity, safeguard ecosystem functioning and mitigate cascading effects of global change.

Research from Nature Portfolio

Cougars, traditionally regarded as obligate carnivores, have been shown to disperse large quantities of viable seeds through secondary ingestion. Predators consuming seed-bearing prey inadvertently contribute to plant regeneration and gene flow across fragmented landscapes. This finding expands the recognised functional role of apex carnivores beyond top-down control, highlighting a non-herbivore-mediated interaction that bridges faunal and floral communities. Such dual functions emphasise the need to integrate trophic and mutualistic processes in models of ecosystem structure.

Trophic Interactions of Native and Invasive Mammals in South American Ecosystems publication trend

The graph below shows the total number of articles in trophic interactions of native and invasive mammals in south american ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Trophic interaction: The feeding relationship between organisms, determining the flow of energy and nutrients through an ecosystem.

Apex predator: A species at the top of the food web with no natural predators, exerting strong top-down control on ecosystem structure.

Apparent competition: An indirect interaction where two prey species share a common predator, resulting in increased predation on one species due to the abundance of the other.

Biomass: The total mass of living organisms in a given area or trophic level, used as a measure of energy storage and resource allocation.

Food web: A complex network of feeding relationships among species in an ecological community, illustrating pathways of energy transfer.

References

1. Setting large- and medium-sized mammal restoration goals in a last mountain Chaco remnant from central Argentina. Ecological Processes (2023).
2. Hypercarnivorous apex predator could provide ecosystem services by dispersing seeds. Scientific Reports (2016).
3. European Rabbit Invasion in a Semi-Arid Ecosystem of Chile: How Relevant Is Its Role in Food Webs?. Life (2023).
4. Diversity and biogeographical patterns in the diet of the culpeo in South America. Ecology and Evolution (2024).