Functional trait evolution in Sphagnum peat mosses and its relationship to niche construction

Abstract

Summary Species in the genus Sphagnum create, maintain, and dominate boreal peatlands through ‘extended phenotypes’ that allow these organisms to engineer peatland ecosystems and thereby impact global biogeochemical cycles. One such phenotype is the production of peat, or incompletely decomposed biomass, that accumulates when rates of growth exceed decomposition. Interspecific variation in peat production is thought to be responsible for the establishment and maintenance of ecological gradients such as the microtopographic hummock‐hollow gradient, along which sympatric species sort within communities. This study investigated the mode and tempo of functional trait evolution across 15 species of Sphagnum using data from the most extensive studies of Sphagnum functional traits to date and phylogenetic comparative methods. We found evidence for phylogenetic conservatism of the niche descriptor height‐above‐water‐table and of traits related to growth, decay and litter quality. However, we failed to detect the influence of phylogeny on interspecific variation in other traits such as shoot density and suggest that environmental context can obscure phylogenetic signal. Trait correlations indicate possible adaptive syndromes that may relate to niche and its construction. This study is the first to formally test the extent to which functional trait variation among Sphagnum species is a result of shared evolutionary history.

Intraspecific differentiation: Implications for niche and distribution modelling

“…The second criterion that could be employed to help deciding whether clade or subclade models should be applied is based on niche overlap analyses and niche similarity tests (Broennimann et al., 2012; Warren et al., 2008), which failed here to demonstrate niche divergence. Instead, evidence for niche conservatism was found in half of the species considered, in line with broad support for this mechanism (Peterson et al., 1999) and emerging evidence for it in bryophytes (Johnson et al., 2015; Piatkowski & Shaw, 2019). In bryophytes, evidence for niche expansion outside of the native range in invasive species is lacking (Mateo et al., 2015), but correlations between genetic and ecological distances, potentially pointing to ecological specialization, have been recurrently reported (Hutsemékers et al., 2010; Magdy et al., 2016; Mikulášková et al., 2015; Pisa et al., 2013; Szövényi et al, 2009).…”

Axenic in vitro cultivation of 19 peat moss (Sphagnum L.) species as a resource for basic biology, biotechnology, and paludiculture

“…Our inability to detect a correlation between subgenus and biomass gain may reflect the situation in the field. Piatkowski & Shaw (2019) did not detect an influence of phylogeny on the majority of traits in their study on 15 Sphagnum species and suggested that the environmental context can obscure the phylogenetic signal. Our novel method creates an artificial but standardized environment for 19 Sphagnum species.…”

Functional diversity and trait composition of vascular plant and Sphagnum moss communities during peatland succession across land uplift regions

“…Then, phylogenetic inference was performed using NGphylogeny.fr (Lemoine et al., 2019). The resulting Sphagnum phylogenetic tree was supported by the high‐resolution tree recently built for Sphagnum mosses and based on 16 loci (Piatkowski & Shaw, 2019).…”

“…When the species are missing from the mega‐tree, V.Phylomaker uses species that are sister to or closely related with some species or genera in the mega‐tree to accurately attached species to their relatives in the phylogenetic tree. As bryophytes are missing from V.Phylomaker, we used gene sequence from the ribosomal non‐coding protein trnL intron and trnL‐F intergenic spacers to build Sphagnum phylogeny (Piatkowski & Shaw, 2019). We selected these loci as they were the only available sequences for all Sphagnum species in our species list in the GeneBank database.…”