How do invasive species outcompete native species for food and living space?

Invasive species often possess a competitive advantage over indigenous organisms, allowing them to thrive in new environments, particularly when natural predators are absent. They outcompete native species for essential resources—such as food, water, and living space—through several mechanisms:1

• Resource Depletion: Some invasive species are highly efficient at consuming shared resources. For example, Asian carp can consume up to 40 percent of their body weight daily, effectively pushing aside native fish to dominate the food supply. Similarly, zebra mussels remove large quantities of algae from aquatic ecosystems, depriving other organisms of a primary food source.2
• Physical Displacement and Overgrowth: Invasive plants often create dense monocultures or thickets that physically crowd out native vegetation. Species like the common buckthorn and kudzu block essential sunlight, preventing native plants from accessing the energy they need to survive.32
• Predatory Pressure: Invasive predators can be so adept at capturing prey that they cause local population declines or even the extinction of native species, which further disrupts the balance of the ecosystem.13

Over time, these pressures can force the localized extinction of native species, leading to a significant reduction in biodiversity.1