Temporal Dependence of the Phylogenetic Diversity-Habitat Size Relationship: Evidence from a Closed Fermentation System.

Phylogenetic diversity-habitat size relationship (PDSR), as an extension of the species-area relationship, incorporates evolutionary history to further elucidate the mechanisms shaping biogeographic patterns. However, whether PDSR is temporally unstable during community succession, and the mechanisms underlying such instability, remain poorly understood. In this study, we used a fermentation microbial community as a model and established a closed microcosm system spanning a 10-1000 mL volume gradient. By continuous sampling over 0-60 days and 16S rRNA high-throughput sequencing, we characterized the dynamic changes in PDSR throughout succession. The results showed that PDSR underwent stage-specific shifts during community succession: it was significantly positive in the early stage, weakened or became non-significant in the middle stage, and turned negative or remained non-significant in the late stage. The early positive PDSR was mainly attributable to the greater retention of rare lineages in larger-volume habitats, whereas in the late stage, phylogenetic diversity increased in smaller-volume habitats, suggesting a positive role in the resuscitation of potentially dormant lineages. Phylogenetic beta-diversity analysis further showed that lineage turnover rate increased over time, with significant divergence among samples in the later stage. In addition, pH decreased significantly over succession and, through interactions with time and volume, exerted a marked influence on community phylogenetic structure. This study reveals the temporal dynamism of biodiversity spatial patterns and confirms that PDSR shifts non-steadily across successional stages, providing new insights into the organization of microbial diversity across multiple scales.