Major events in recent human history are factors in the spread of invasive ant species, reveals a new study in Nature Ecology & Evolution. Understanding the traits, dynamics and drivers of successful alien ant invasions could help to stem the spread of other invasive species in the future.
Human trade and travel break down biogeographic barriers, causing changes in the geographical distribution of organisms. As a result, the spread of alien species has become a major threat to biodiversity and ecosystem services worldwide, and rates of new species establishments are predicted to continue to increase. While most research on biological invasions has focused on the progression of individual species throughout the invasion process, it remains largely unknown whether alien species generally follow similar colonization patterns and how such patterns are driven.
Looking at 241 alien ant species known to have been introduced outside their native range, Cleo Bertelsmeier and colleagues found that the ants could be divided into four categories: those with a local, regional, transcontinental, or global distribution, with different dynamics governing the spread of each. The authors then examined the movement of 36 of these species since 1750, finding that these four groups of ant species crossed continents and regions at the same time as two major human waves of migration, globalization, and economic boom. The first wave began in the mid-19th century but declined with World War I and the Wall Street Crash of 1929; the second followed World War II and continued into the 21st century. They also found the most globalized invasive species were likely to be smaller and able to live in a range of habitats, which may explain their success in crossing continents.
By combining details on the distribution patterns of the ants as well as understanding the characteristics that enable the ants to live in different environments, the authors provide valuable insight into the processes driving biological invasions and facilitate the identification of species most likely to become invasive in the future.