Interactions among multiple invasive animals

Area of Science:

• Ecology
• Invasive Species Biology
• Conservation Science

Background:

• Increasing rates of species invasions lead to more interactions among invasive species.
• Theories predict invaders can hinder or help each other, with varied impacts on ecosystems.
• Quantitative data on interactions among multiple invasive animals are limited.

Purpose of the Study:

• To quantitatively review interactions among multiple invasive animal species globally.
• To analyze how co-occurring invasive animals affect each other's performance and ecological impacts.
• To compare common interaction types with overall trends and management implications.

Main Methods:

• Global meta-analysis of studies on interactions between multiple invasive animal species.
• Categorization of interactions based on their effects on invader performance.
• Analysis of the combined ecological impacts of multiple invaders (additive vs. non-additive).

Main Results:

• Globally, the average interaction among invasive animals reduces their performance.
• Neutral interactions are the most frequent type observed in individual studies.
• Combined ecological impacts are often additive, but the mean effect is less than predicted (antagonistic).
• Marine invasive animal interactions consistently reduce performance, unlike terrestrial and freshwater interactions.

Conclusions:

• While neutral interactions are most common, the global trend suggests invasive animals negatively impact each other's performance.
• Discrepancies between frequent and mean interaction types indicate case studies may differ from global trends.
• Understanding these interactions is crucial for predicting invasive species dynamics and developing effective management strategies.