Advances in predicting the occupation of areas colonized by invasive species

In order to predict the territory occupied by a species, as well as the changes that may occur as a result of climate change or the appearance of an invasive species, it is crucial to understand the factors that determine the extent of that territory. The pattern of occupation of a geographical area by a species depends on physiological factors of the species itself, physical barriers, and interactions with other species. Distinguishing between these factors is not always easy, making biodiversity management and conservation difficult.

A team of Brazilian, Australian, and CIBIO (Center for Research in Biodiversity and Genetic Resources) researchers from the University of Porto describe in the prestigious scientific journal PNAS (Proceedings of the National Academies of Sciences, USA)a new approach in which, through models, they are able to explain how interactions with other species (known as biotic interactions) determine the distribution patterns of a species.

The team applied the models to the cane toad (Rinella marina), a species native to South and Central America. It was introduced to Australia in 1935 to control pests in sugar cane plantations, hence its name. In Australia, the cane toad has expanded its territory: today it occupies more than 1.2 million square kilometers and is, paradoxically, considered a pest.

The team of researchers discovered that in Australia, the cururu toad has expanded its territory, occupying areas with drier climates and extreme temperatures. Interestingly, there are areas in South America with identical climates, yet the toad does not occupy them. According to the model developed by the researchers, this territorial limitation is due to the presence of a similar species of frog, with which the cururu frog hybridizes, thus establishing a biotic interaction that limits its expansion into neighboring territories. This similar species does not exist in Australia, so the cururu frog is free to occupy the so-called fundamental niche.

The new approach described in this study, which was funded by FCT, is applicable to any species or environment and can contribute significantly to the development of species management and conservation strategies. These may involve identifying biological agents to control invasive species or effectively predicting the ability of native species to adapt to climate change.

CIBIO has a long-standing collaboration with the Federal University of Belém do Pará in Brazil, which will be reinforced with the official opening of a TwinLab. This will be CIBIO's second "twin lab"; the first was established with Lubango, in Angola.