Phylogenetic dispersion and diversity in regional assemblages of seed plants in China

Abstract

Species assemble into communities through ecological and evolutionary processes. Phylogenetic niche conservatism—the tendency of species to retain ancestral ecological distributions—is thought to influence which species from a regional species pool can persist in a particular environment. We analyzed data for seed plants in China to test hypotheses about the distribution of species within regional floras. Of 16 environmental variables, actual evapotranspiration, minimum temperature of the coldest month, and annual precipitation most strongly influenced regional species richness, phylogenetic dispersion, and phylogenetic diversity for both gymnosperms (cone-bearing plants) and angiosperms (flowering plants). For most evolutionary clades at, and above, the family level, the relationships between metrics of phylogenetic dispersion (i.e., average phylogenetic distance among species), or phylogenetic diversity, and the 3 environmental variables were consistent with the tropical niche conservatism hypothesis, which predicts closer phylogenetic relatedness and reduced phylogenetic diversity with increasing environmental stress. The slopes of the relationships between phylogenetic relatedness and the 3 environmental drivers identified in this analysis were steeper for primarily tropical clades, implying greater niche conservatism, than for primarily temperate clades. These observations suggest that the distributions of seed plants across large-scale environmental gradients in China are constrained by conserved adaptations to the physical environment, i.e., phylogenetic niche conservatism.

Macro‐scale variation and environmental predictors of flowering and fruiting phenology in the Chinese angiosperm flora

“…Augspurger & Salk, 2017). Our results thus provide empirical support for claims that climatic constraints on reproductive phenology are a major determinant for the range size of individual species (reviewed in Chuine, 2010), which in turn underlie large-scale gradients in species richness ( Figure S1), phylogenetic diversity (Du et al, 2015;Qian et al, 2013) and community assembly (Qian et al, 2019;Qiao et al, 2015). The effective use of the longer growing season at lower latitudes, illustrated by high within-grid variance in both flowering and fruiting, is consistent with several theories suggesting the greater plant species richness in the tropics is due to a larger niche space (Stevens, 1989) and/or narrower niche partitioning (Chu et al, 2018), the latter being favoured by lower phylogenetic constraints (Du et al, 2015;Qian et al, 2013).…”

Geographic patterns and environmental correlates of taxonomic and phylogenetic beta diversity for large‐scale angiosperm assemblages in China

“…We used the following R packages for computing β‐diversity metrics and conducting permutation‐based statistic analyses: betapart (Baselga and Orme 2012), vegan (Dixon 2003), ecodist (Goslee and Urban 2007), picante (Kembel et al 2010) and PhyloMeasures (Tsirogiannis and Sandel 2016). For correlation analyses, we considered a correlation (Spearman's rank correlation coefficient, r s ) to be strong for |r s | > 0.66, moderate for 0.66 ≥ |r s | > 0.33 and weak for |r s | ≤ 0.33 (Qian et al 2019). For regression analyses, we normalized both dependent and independent variables (mean = 0 and standard deviation = 1).…”

“…Indeed, if species have tracked their ancestral climatic niches, we would expect to observe predominantly the spatial turnover of closely related species rather than distantly related species (Graham et al 2009, Qian et al 2013). Then, we can expect decreasing phylogenetic turnover towards cold temperatures at higher latitudes (Qian et al 2019). Assemblages in regions with more stressful climates (colder and drier) should be composed of more closely related species (i.e.…”

“…Assemblages in regions with more stressful climates (colder and drier) should be composed of more closely related species (i.e. phylogenetically clustered, see Qian et al 2019, Mienna et al 2020 for example) because most tropical clades failed to disperse into extratropical regions, lacking adaptations to survive winter temperatures below freezing (Ricklefs 2006). Consequently, the turnover component of PBD should contribute less to overall PBD in cold environments (i.e.…”

Community and structural constraints on the complexity of eastern North American forests

“…We (Helmus, Bland, Williams, & Ives, 2007). To characterize phylogenetic species diversity measures, we created a phylogeny of species in each plot using the V.PhyloMaker R package (Qian et al, 2019;Qian & Jin, 2016). We then used the picante R package (Kembel et al, 2010) to calculate phylogenetic species diversity measures from each plot-level phylogeny.…”