The use of taxonomic relationships among species in applied ecological research: Baseline, steps forward and future challenges

Abstract

Taxonomy is more than a mere exercise of nomenclature and classification of biological diversity: it profiles the identity of species by investigating their biological and ecological traits. Taxonomy is intimately related to ecology which, in turn, cannot be a mere exercise in describing ecological patterns, but instead requires deep knowledge of species' biological structures, roles, interactions and functions. Thus, the study of taxonomic and phylogenetic relatedness of species is of paramount importance in ecological research, enabling insights into potential evolutionary patterns and processes, allowing a more comprehensive view of biodiversity, and providing opportunities to improve the assessment and monitoring of ecological changes in time and space. The work of K. Robert ('Bob') Clarke forged new pathways in this direction, providing new ideas and statistical tools to include and exploit taxonomic relationships in applied marine ecological studies and beyond, also inspiring the next generation of ecologists. In this short review, we synthesise the application and development of these tools and concepts in marine biodiversity research over the last three decades and suggest future pathways in this evolving field.

Benthic species patterns in and around the Cape Canyon: A large submarine canyon off the western passive margin of South Africa

“…In terms of depth gradients, the increase of species richness (S) in the 200-400 m depth range agrees with previous local studies (Lange, 2012) that observed highest richness at depths of 300-399 m. Our results, however, contrast with the Duffy et al (2014) submarine canyon observations of species richness steadily increasing with depth between 200-700 m. This may be an artifact of the low number of samples (n < 11) represented in the 501-700 m range, as species richness is dependent on sampling effort (Clarke and Warwick, 1998;1999;Bevilacqua et al, 2021). The average taxonomic distinctiveness index (delta +), on the other hand, showed a fluctuation and opposing trend, whereby the lowest measure was identified at 201-300 m (the second most speciose depth) and the highest at 601-1000 m (least species richness).…”

“…Canyon areas were defined by higher species richness and diversity as compared to non-canyon areas. Even though sampling biases occurred, the use of gamma+ as the basis of testing multivariate responses to predictor variables accounted for this by considering taxonomic relationships of species at all levels (Clarke et al, 2006;Bevilacqua et al, 2021). Nonetheless, high species variability at both the canyon and non-canyon stations was documented in which taxonomic groups discriminating the comparison were present.…”

Functional beta diversity of New Zealand fishes: Characterising morphological turnover along depth and latitude gradients, with derivation of functional bioregions

“…Note that, whereas taxonomic distinctness uses a taxonomic tree to calculate distances among species, it is possible also to perform the calculations using a functional (or other) distance matrix among species instead (see Bevilacqua et al . 2021, this volume ). We performed the TAXDTEST algorithm separately for each depth stratum, using a normalised Euclidean distance matrix based on the 8 functional traits averaged across the dataset at the species level ( n = 144).…”

Introduction: In appreciation of K. Robert Clarke

“…Stanislau Bevilacqua and colleagues then provide a timely overview of approaches that integrate taxonomic information in multivariate ecological studies; by pointing to present and future methods, this contribution is both retrospective and forward‐looking in its scope (Bevilacqua et al . 2021). The next two contributions – one led by Odette Howarth and the other led by Lizzy Myers – deal with precisely the sort of extensions envisaged by the Bevilacqua et al .…”