Environmental filtering mediates desert ant community assembly at two spatial scales

Area of Science:

• Ecology
• Community Ecology
• Evolutionary Ecology

Background:

• Species coexistence and community assembly are fundamental ecological questions.
• Understanding trait-environment relationships is key to predicting ecological changes.
• Desert ecosystems provide unique settings to study community assembly mechanisms.

Purpose of the Study:

• To test if niche-based processes, specifically environmental filtering and limiting similarity, assemble desert ant communities.
• To investigate the influence of environmental stress gradients on functional trait structure and species distributions.
• To determine the interplay between environmental filtering and biotic interactions in structuring ant communities.

Main Methods:

• Population-level morphological trait measurements (body, femur, antennal scape, head lengths) were used to assess functional structure along a dryland stress gradient.
• Species distribution models were developed to quantify large-scale climatic niche overlap.
• Correlation analyses were performed between morphological traits and environmental gradients.

Main Results:

• Ant communities showed significant functional overdispersion regionally, indicating strong competition.
• Functional trait divergence decreased with increasing environmental stress, suggesting stress mediates limiting similarity.
• Lower climatic niche overlap correlated with greater morphological trait dissimilarity, highlighting filtering at distribution scales.

Conclusions:

• Niche-based assembly mechanisms, including environmental and biotic filtering, jointly structure desert ant communities.
• Environmental stress plays a crucial role in mediating limiting similarity and influencing trait divergence.
• Both regional and large-scale distribution patterns are shaped by these interacting assembly processes.