Effectiveness of Biological Surrogates for Predicting Patterns of Marine Biodiversity: A Global Meta-Analysis

Abstract

The use of biological surrogates as proxies for biodiversity patterns is gaining popularity, particularly in marine systems where field surveys can be expensive and species richness high. Yet, uncertainty regarding their applicability remains because of inconsistency of definitions, a lack of standard methods for estimating effectiveness, and variable spatial scales considered. We present a Bayesian meta-analysis of the effectiveness of biological surrogates in marine ecosystems. Surrogate effectiveness was defined both as the proportion of surrogacy tests where predictions based on surrogates were better than random (i.e., low probability of making a Type I error; P) and as the predictability of targets using surrogates (R 2). A total of 264 published surrogacy tests combined with prior probabilities elicited from eight international experts demonstrated that the habitat, spatial scale, type of surrogate and statistical method used all influenced surrogate effectiveness, at least according to either P or R 2. The type of surrogate used (higher-taxa, cross-taxa or subset taxa) was the best predictor of P, with the higher-taxa surrogates outperforming all others. The marine habitat was the best predictor of R 2, with particularly low predictability in tropical reefs. Surrogate effectiveness was greatest for higher-taxa surrogates at a <10-km spatial scale, in low-complexity marine habitats such as soft bottoms, and using multivariate-based methods. Comparisons with terrestrial studies in terms of the methods used to study surrogates revealed that marine applications still ignore some problems with several widely used statistical approaches to surrogacy. Our study provides a benchmark for the reliable use of biological surrogates in marine ecosystems, and highlights directions for future development of biological surrogates in predicting biodiversity.

Global meta-analysis reveals low consistency of biodiversity congruence relationships

“…marine environments, whereas others have reported results entirely opposite to ours (namely, lowest congruence at extremes of spatial scale) 8,30 . However, these differences are clearly attributable to methodological considerations: Mellin et al 31 use 4100 km 2 as their highest category of spatial extent, six orders of magnitude lower than our maximum recorded values, whereas Wolters et al 30 use analysis of grain size rather than spatial extent. These are independent metrics that-as we and others have shown-have differing effects on observed patterns of biodiversity 35,50 .…”

“…It also suggests a need for caution when synthesizing research on processes that vary across spatial scales. For instance, Mellin et al 31 report linearly decreasing congruence with increasing spatial scale in Full coefficient estimates and their degree of statistical significance are given in Table 2. marine environments, whereas others have reported results entirely opposite to ours (namely, lowest congruence at extremes of spatial scale) 8,30 .…”

“…Although these developments have been valuable, they present a challenge to those attempting to synthesize global knowledge on cross-taxon congruence because of the array of different methods that have been applied in the literature 28,29 . Therefore, despite the publication of a number of valuable reviews of the congruence literature 15,28,[30][31][32][33][34] , one important theme has yet to be addressed; namely, the observation that congruence is often highly variable when measured in different locations or at different times 29,35,36 . A key property of biodiversity surrogates and indicators is that they should be able to be applied with confidence in novel contexts 37 , and so this lack of consistency has the potential to undermine the usefulness of biodiversity surrogates in ecology and conservation 38 .…”

Assemblages and habitat preferences of soft bottom Antarctic Amphipoda: Admiralty Bay case study

“…Terlizzi et al (2009) also found that replacing species by genera or families do not cause much information loss in case of betadiversity of mollusks in four marine localities in Norway, Italy, New Zealand and the Arctic. There were, however, some publications which showed that the results obtained from surrogates do not always reflect the ones got from more detailed analyses and can also depend on the statistical method used (Mellin et al 2011). The results of the presently studied material showed that the use of higher taxonomic level (genera and particularly families) does not allow for the recognition similar assemblages in nondisturbed areas as were found on the basis of species study (Figs.…”

Surrogate taxa and fossils as reliable proxies of spatial biodiversity patterns in marine benthic communities

“…Whereas previous studies have provided critical insights into spatial structuring of ecosystems, it remains unclear whether heterogeneities manifested within single taxonomic groups reflect b-diversity of communities [14]. Yet the use of a single taxon, or biological surrogate, to estimate biodiversity is becoming increasingly important in marine conservation because of the costs of marine biodiversity surveys, undescribed species, and challenging species identifications [15][16][17]. Although empirical assessments of 'entire communities' are not feasible, it is viable to collect multi-taxic data (multiple phyla) to evaluate the effectiveness of surrogate taxa (e.g.…”