Phylogenetic Structure of Floridian Plant Communities Depends on Taxonomic and Spatial Scale

Abstract

Abstract. Consideration of the scale at which communities are defined both taxonomically and spatially can reconcile apparently contradictory results on the extent to which plants show phylogenetic niche conservatism. In plant communities in north central Florida, we collected species abundances in 55 0.1-ha plots in several state parks. When communities were defined narrowly to include a single phylogenetic lineage, such as Quercus, Pinus, or Ilex, neighbors tended to be less related than expected (phylogenetic overdispersion) or there was no pattern. If the same communities were defined more broadly, such as when all seed plants were included, neighbors tended to be more related than expected (phylogenetic clustering). These results provide evidence that species interactions among close relatives influence community structure, but they also show that niche conservatism is increasingly evident as communities are defined to include greater phylogenetic diversity. We also found that, as the spatial scale is increased to encompass greater environmental heterogeneity, niche conservatism emerges as the dominant pattern. We then examined patterns of trait evolution in relation to trait similarity within communities for 11 functional traits for a single phylogenetic lineage (Quercus) and for all woody plants. Among the oaks, convergent evolution of traits important for environmental filtering contributes to the observed pattern of phylogenetic overdispersion. At the broader taxonomic scale, traits tend to be conserved, giving rise to phylogenetic clustering. The shift from overdispersion to clustering can be explained by the increasing conservatism of traits at broader phylogenetic scales.

Examining variation in the leaf mass per area of dominant species across two contrasting tropical gradients in light of community assembly

“…2008) or across strong edaphic or climatic gradients (Cavender‐Bares et al. 2006; Fine and Kembel 2011). In Peru, the distinct seasonal and diurnal cycles of cloud immersion at the Andes/Amazon transition (Halladay et al.…”

Evaluating community–environment relationships along fine to broad taxonomic resolutions reveals evolutionary forces underlying community assembly

“…In addition, we calculated the phylogeny-based UniFrac metric (Lozupone and Knight, 2005) as a standard to contrast our multi-level taxonomy-based composition analyses, as this metric has recently gained popularity in microbial community analyses and believed to be more informative than taxonomy-based estimates (Lozupone and Knight, 2005;Swenson, 2014). Moreover, given the potential scale dependency (Levin, 1992;Cavender-Bares et al, 2006Swenson et al, 2006Swenson et al, , 2007 in community-environment relationships, we considered case studies covering sampling sites from either global or local scales (Table 1) and which may provide insight into the scale dependency of microbial community assembly. Previous studies on plant communities (focused on within-community phylogenetic structure) have identified concerns about spatiotemporal and taxonomic scales on the detected pattern.…”

“…Previous studies on plant communities (focused on within-community phylogenetic structure) have identified concerns about spatiotemporal and taxonomic scales on the detected pattern. For example, the signal of phylogenetic clustering (that is, taxa within a given community contain lower mean phylogenetic distances than expected from random; as evidence for habitat filtering) has been found to be relatively evident when considering samples from a larger geographic region and/or a broader span of taxonomy (Cavender-Bares et al, 2006Swenson et al, 2006Swenson et al, , 2007. In this study, rather than detecting the within-community structure, we concentrated our analyses on the inter-community pattern (that is, how taxonomic compositions differ across sites in response to environmental factors) to assess whether changing taxonomic resolution affects the explained variance of community-environment relationships (Figure 1).…”

Genetic distance predicts trait differentiation at the subpopulation but not the individual level in eelgrass, Zostera marina

“…However, the magnitude of genetic differentiation at the site level did predict site‐level trait differentiation, although our sample size was relatively small (five sites). Thus, the correlation between genetic relatedness and trait differentiation among eelgrass genotypes appears to be scale dependent, just as has been found for correlations between phylogenetic distance and trait distance among species (Cavender‐Bares, Keen & Miles, 2006; Peay, Belisle & Fukami, 2011). …”

“…However, the underlying assumption that phylogenetic diversity serves as a proxy for trait differentiation is not always supported; in some cases, phylogenetic diversity influences ecosystem structure and functioning even when phylogenetic distance is not correlated with trait differences (Flynn et al., 2011; Tan, Pu, Ryberg & Jiang, 2012). Furthermore, not all traits relevant to the outcome of interactions are evolutionarily conserved (Best, Caulk & Stachowicz, 2013; Best & Stachowicz, 2013; Cavender‐Bares, Ackerly, Baum & Bazzaz, 2004; Cavender‐Bares, Keen & Miles, 2006; Moles et al., 2005; Silvertown, Dodd, Gowing, Lawson & McConway, 2006) and phylogenetic distance does not always influence ecological processes in the expected direction (Burns & Strauss, 2011; Cadotte, Davies & Peres‐Neto, 2017; Godoy, Kraft & Levine, 2014; Narwani, Alexandrou, Oakley, Carroll & Cardinale, 2013). …”