Phylogenetic overdispersion in Floridian oak communities

Area of Science:

• Ecology
• Evolutionary Biology
• Botany

Background:

• Environmental filtering and competitive exclusion shape species co-occurrence.
• Understanding mechanisms of plant diversity maintenance is crucial for community ecology.
• Oak (Quercus) species present a model system for studying coexistence in forest communities.

Purpose of the Study:

• To explain the coexistence of 17 oak species in North Central Florida forest communities.
• To investigate the relationship between phylogenetic relatedness, co-occurrence, niche overlap, and trait similarity in oaks.
• To determine the evolutionary processes driving oak diversity patterns.

Main Methods:

• Examined correlations between phylogenetic relatedness and co-occurrence of oak species.
• Assessed niche overlap across environmental gradients for different oak clades.
• Analyzed ecophysiological and life-history trait similarity among co-occurring oak species.

Main Results:

• Oak species communities are phylogenetically overdispersed; co-occurring species are more distantly related than random expectation.
• Oaks within the same clade exhibit less niche overlap than expected, promoting inclusion of different clades (red vs. white/live oaks).
• Habitat specialization traits show evolutionary convergence, leading to phylogenetic overdispersion.

Conclusions:

• Phylogenetic overdispersion, driven by convergent evolution of specialization traits, facilitates the coexistence of distantly related oak species.
• Conserved traits may permit the coexistence of congeners with different evolutionary histories.
• This study provides a framework for understanding how high oak diversity is maintained in North Central Florida ecosystems.