Progress 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 the 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 researchers from Brazil, Australia and the University of Porto's Biodiversity and Genetic Resources Research Center (CIBIO) have described in the prestigious scientific journal PNAS (Proceedings of the National Academies of Sciences, USA)a new approach in which they use models to explain how interactions with other species (known as biotic interactions) determine a species' distribution patterns.

The team applied the models to the cururu toad(Rinella marina), a species native to South and Central America. It was introduced to Australia in 1935 with the aim of controlling sugar cane pests and therefore became known as the sugar cane toad. In Australia, the cururu frog 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 a drier climate and extreme temperatures. Curiously, in South America there are areas with a similar climate, but the frog does not occupy them. According to the model developed by the researchers, this territorial limitation is due to the presence of a similar frog species, with which the cururu frog hybridizes, thus establishing a biotic interaction that limits its expansion into neighbouring 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 received funding from the FCT, is applicable to any species or environment and can make a significant contribution to the development of species management and conservation strategies. These could include 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 strengthened with the official opening of a TwinLab. It will be CIBIO's second "twin lab"; the first was established with Lubango in Angola.