Phylogeny as a Proxy for Ecology in Seagrass Amphipods: Which Traits Are Most Conserved?

Abstract

Increasingly, studies of community assembly and ecosystem function combine trait data and phylogenetic relationships to gain novel insight into the ecological and evolutionary constraints on community dynamics. However, the key to interpreting these two types of information is an understanding of the extent to which traits are phylogenetically conserved. In this study, we develop the necessary framework for community phylogenetics approaches in a system of marine crustacean herbivores that play an important role in the ecosystem functioning of seagrass systems worldwide. For 16 species of amphipods and isopods, we (1) reconstructed phylogenetic relationships using COI, 16S, and 18S sequences and Bayesian analyses, (2) measured traits that are potentially important for assembling species between and within habitats, and (3) compared the degree to which each of these traits are evolutionarily conserved. Despite poor phylogenetic resolution for the order Amphipoda as a whole, we resolved almost all of the topology for the species in our system, and used a sampling of ultrametric trees from the posterior distribution to account for remaining uncertainty in topology and branch lengths. We found that traits varied widely in their degree of phylogenetic signal. Body mass, fecundity, and tube building showed very strong phylogenetic signal, and temperature tolerance and feeding traits showed much less. As such, the degree of signal was not predictable based on whether the trait is related to environmental filtering or to resource partitioning. Further, we found that even with strong phylogenetic signal in body size, (which may have large impacts on ecosystem function), the predictive relationship between phylogenetic diversity and ecosystem function is not straightforward. We show that patterns of phylogenetic diversity in communities of seagrass mesograzers could lead to a variety of interpretations and predictions, and that detailed study of trait similarities and differences will be necessary to interpret these patterns.

Predicting consequences of climate change for ecosystem functioning: variation across trophic levels, species and individuals

“…1a), here we found that at least one of those species (P. cowani) may be negatively affected by even the 18°C average temperature on the harbour mudflats where much of the Ulva is found (Fig. However, in our previous measurements of temperature tolerance, we found high correspondence between effects of constant high temperature and tidal-scale temperature variation (Best & Stachowicz, 2013). This experiment did exclude the variation around this mean that would naturally be found in the harbour, and such variation can have important consequences for survival and feeding rates (Sanford, 2002;Clusella-Trullas et al, 2011;Marshall & McQuaid, 2011).…”

“…These mesograzers play a key role in controlling blooms of benthic algae and facilitating the growth of seagrasses, which are key habitat providers in coastal and estuarine systems (Duarte, 2002;Valentine & Duffy, 2006;Best & Stachowicz, 2012;Whalen et al, 2013). However, the species from the outer coast can survive in increased water temperatures (25°C, nearing the maximum temperatures reached at shallow harbour sites at low tide) for longer than several species that are currently found in Bodega Harbor, including both native species and successful exotic colonists (Best & Stachowicz, 2013; data summarized in Fig. and/or seagrasses, and they consume Ulva in feeding trials (Fig.…”

Cryptic species as a window into the paradigm shift of the species concept

“…However, applying this approach to conservation biology (Asmyhr, Linke, Hose, & Nipperess, ) and local community ecology (Elbrecht & Leese, ; Jones, Ghoorah, & Blaxter, ) can be risky. OTUs of unknown vulnerability to different threats lack protection, and their ecological role in local assemblages cannot be inferred from phylogenetic relatedness alone (Best, Caulk, & Stachowicz, ; Best & Stachowicz, , ; Kembel, ).…”

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

“…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). …”