Effect of sampling design on estimation of phylogenetic diversity metrics of fish community

Phylogenetic diversity has been widely used to explore diversity patterns and assess processes governing the species composition in community. The estimates of many metrics depend on high-quality data collected from well-designed sampling surveys. However, knowledge of impacts of sampling design on estimation of phylogenetic diversity metrics remains unclear. This study is aim to evaluate the influence of sampling design on phylogenetic diversity metrics estimation of fish community. Simple random sampling (SRS), systematic sampling (SS) and stratified random sampling (StRS) with different sampling intensities were chosen and mean pairwise distances (MPD), mean nearest taxon distance (MNTD), phylogenetic diversity (PD), phylogenetic species variability (PSV), phylogenetic species evenness (PSE) and phylogenetic species richness (PSR) were selected. SRS and StRS showed similar impact on phylogenetic diversity indices estimation and performed relatively well for collecting data to estimate phylogenetic diversity. The accuracy and precision of the estimation increased with sampling intensity under SRS and StRS except SS. MNTD was the only metric not underestimated in four seasons. Metrics strongly influenced by species richness were underestimated when sampling intensity was insufficient. MPD, PSV and PSE showed an obvious seasonal change, which was due to the seasonal differences in fish species composition. In cases where under-sampling is suspected or logistically unavoidable, phylogenetic diversity metrics that are relatively insensitive to sampling design (e.g., MPD and PSV) should be prioritized, especially for exploring the temporal variation in fish community. This study reveals it is indispensable to evaluate sampling design when estimating phylogenetic diversity metrics, especially those indices susceptible to species richness.