Community‐level phylogenetic diversity does not differ between rare and common lineages across tallgrass prairies in the northern Great Plains

• Published in: Ecology and evolution Vol. 12; no. 11; pp. e9453 - n/a
• Main Authors: Herzog, Sarah A., Latvis, Maribeth
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01-11-2022; John Wiley and Sons Inc; Wiley
• Subjects: Biodiversity; Biodiversity Ecology; Biodiversity loss; Botany; Breakpoints; Coexistence; Community; community assembly; conservation; Conservation Ecology; Differentiation; Evolutionary Ecology; grassland; Hypotheses; Mathematical analysis; niche differentiation; Niches; phylogenetic diversity; Phylogenetics; Phylogeny; Plant communities; Prairies; Rare species; Redundancy; Species diversity; Species richness; Wildlife conservation; South Dakota; Great Plains; United States > US; North Dakota; rare species; conservation; niche differentiation; community assembly; grassland; phylogenetic diversity
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.9453

Niche differentiation has served as one explanation for species coexistence, and phylogenetic relatedness provides a means to approximate how ecologically similar species are to each other. To explore the contribution of rare species to community phylogenetic diversity, we sampled 21 plant communities across the Prairie Coteau ecoregion, an area of high conservation concern. We used breakpoint analysis through the iterative addition of less abundant species to the phylogenetic tree for each community to assess the contribution of rare species to community phylogenetic diversity. We also quantify the phylogenetic signal of abundance using Blomberg's K statistic and calculated the phylogenetic similarity between rare and common species using a phylogenetic beta‐diversity metric (Dnn). To estimate the phylogenetic structuring of these prairie communities, we calculated two common metrics that capture evolutionary relatedness at different scales (MPD and MNTD). Additionally, we examine the correlation between Faith's PD, MPD, and MNTD and species richness. We found rare species do not generally contribute higher levels of phylogenetic diversity than common species. Eight communities had significant breakpoints, with only four communities having an increasing trend for the rarest species. The phylogenetic signal for abundance was low but significant in only four communities, and communities had lower phylogenetic diversity than expected from the regional species pool. Finally, the strength of the correlation between species richness and phylogenetic diversity was mixed. Our results indicate niche differentiation does not explain the persistence of rare species in tallgrass prairies, as they were more closely related than expected from random, suggesting high functional redundancy between rare and common species. This is promising for the long‐term resilience of this ecosystem, but only insofar as enough species remain in the system. With ongoing biodiversity loss, it is essential that we understand the role rare species play in their communities.
Niche differentiation theory predicts rare species are maintained in communities through niche differentiation. Using phylogenetic diversity, we find plant communities in tallgrass prairies of the Great Plains are closely related, with rare species being closely related to more common species and other rare species, rejecting this hypothesis.