Conquering the World: The Invasion of the Red Swamp Crayfish

One of the biggest threats to biodiversity is the invasion of non-native species, also called invasive alien species. It is crucial for scientists to determine the main introduction routes by which non-native species enter into an ecosystem. We studied the red swamp crayfish (Procambarus clarkii), a freshwater crustacean, and looked at the genetic characteristics of 122 crayfish populations (22 native and 100 introduced) to understand their differences and where they came from. Our results showed a great amount of genetic variability among crayfish populations and that, this crayfish species has invaded different parts of the world via multiple introduction events and pathways, with humans playing a key role in these introductions. It is therefore vitally important to control the likely sources of invasion to avoid further introductions and prevent the rapid expansion of crayfish populations.