Functional and Phylogenetic Structure of Forest Bird Assemblages Along an Afrotropical Elevational Gradient

Area of Science:

• Ecology
• Evolutionary Biology
• Ornithology

Background:

• Tropical mountains are biodiversity hotspots, yet avian diversity in equatorial Africa is poorly understood.
• Elevational gradients are key for studying biodiversity patterns and assembly processes.
• Functional (FD) and phylogenetic diversity (PD) offer insights into community assembly.

Purpose of the Study:

• To examine FD and PD of bird assemblages along a Cameroon elevational gradient.
• To test the roles of abiotic filtering and biotic interactions (competition) in community assembly.
• To assess niche packing versus niche expansion in relation to taxonomic diversity (TD).

Main Methods:

• Analysis of bird occurrence data and morphological/resource-use traits along a ~2300m elevational gradient.
• Application of null models to infer drivers of FD and PD patterns.
• Evaluation of functional space occupied by species in diverse assemblages.

Main Results:

• Functional richness and TD decreased with elevation; functional dissimilarity and PD increased.
• Evidence of niche packing in species-rich lowlands and niche expansion at higher elevations.
• Phylogenetic clustering suggests independent radiations, with partial support for competition influencing assembly.

Conclusions:

• Abiotic filters and lowland competition shape avian diversity but are not the sole drivers.
• Niche packing and expansion contribute to TD patterns along the gradient.
• Findings partially support the guild assembly rule in avian communities.