High diversity of coralline algae in New Zealand revealed: Knowledge gaps and implications for future research

Abstract

Coralline algae (Corallinophycideae) are calcifying red algae that are foundation species in euphotic marine habitats globally. In recent years, corallines have received increasing attention due to their vulnerability to global climate change, in particular ocean acidification and warming, and because of the range of ecological functions that coralline algae provide, including provisioning habitat, influencing settlement of invertebrate and other algal species, and stabilising reef structures. Many of the ecological roles corallines perform, as well as their responses to stressors, have been demonstrated to be species-specific. In order to understand the roles and responses of coralline algae, it is essential to be able to reliably distinguish individual species, which are frequently morphologically cryptic. The aim of this study was to document the diversity and distribution of coralline algae in the New Zealand region using DNA based phylogenetic methods, and examine this diversity in a broader global context, discussing the implications and direction for future coralline algal research. Using three independent species delimitation methods, a total of 122 species of coralline algae were identified across the New Zealand region with high diversity found both regionally and also when sampling at small local spatial scales. While high diversity identified using molecular methods mirrors recent global discoveries, what distinguishes the results reported here is the large number of taxa (115) that do not resolve with type material from any genus and/or species. The ability to consistently and accurately distinguish species, and the application of authoritative names, are essential to ensure reproducible science in all areas of research into ecologically important yet vulnerable coralline algae taxa.

Bottom Trawling Threatens Future Climate Refugia of Rhodoliths Globally

“…The extensive projected losses may threaten regions of higher conservation value, with rich genetic and species diversity (Bittner et al, 2011;Basso et al, 2015;Gabrielson et al, 2018). Additionally, as rhodolith genetic and species diversity are still greatly underestimated (Twist et al, 2019;Caragnano et al, 2020), putative diversity losses may occur undetected, leading to potentially misperceived assessments of the rhodolith biome diversity and phylogeography, and gene pool conservation status (i.e., shifting genetic baselines; Assis et al, 2014). The exact ramifications of climate change on rhodolith ecosystems are hard to predict, as new insights on their role as bio-engineers and their complex relationships with associated species are only starting to be discovered (Steller et al, 2003;Horta et al, 2016;Gabara et al, 2018;Fredericq et al, 2019;Carvalho et al, 2020).…”

Corallinapetrales and Corallinapetraceae: A new order and family of coralline red algae including Corallinapetra gabrielii comb. nov.

“…2018, Twist et al. 2019). Moreover, techniques have improved for obtaining sequence data from older specimens and are now being applied to type specimens, enabling the resolution of taxonomic problems for some species of coralline algae (Gabrielson et al.…”

“…Abbreviations: BI, Bayesian inference; BP, bootstrap; COI-5P, mitochondrial cytochrome c oxidase subunit I; CN, Herbier, Universit e de Caen, Caen, France; G, Gamma distribution; GTR, General Time Reversible model; I, proportion of invariable sites; ML, maximum likelihood; psbA, plastid-encoded photosystem II reaction center D1 protein gene; TRH, Norwegian University of Science and Technology, Trondheim, Norway Molecular systematics of coralline algae is revolutionizing our understanding of this important and ubiquitous group of benthic marine rhodophytes at all taxonomic ranks. DNA sequence data and phylogenetic analyses have become an essential tool in coralline studies and have led to major insights in the diversity and evolutionary history of this group (e.g., Hind et al 2016, R€ osler et al 2016, Pezzolesi et al 2019, Twist et al 2019). Significant findings based on multi-gene analyses already have resulted in revisions at species level and at higher taxonomic ranks such as circumscription of a new subclass (Corallinophycidae; Le Gall and Saunders 2007) and of new orders (Sporolithales, Le Gall et al 2010;Hapalidiales, Nelson et al 2015).…”

Corallina (Corallinales, Rhodophyta) from Tristan da Cunha and the Falkland Islands: implications for South Atlantic biogeography

“…There are 204 species names and 68 infraspecific names listed for Corallina, of which 28 are currently accepted (Guiry & Guiry, 2020). There has been an increasing drive in recent years to revise the taxonomy of this genus, notably in the northeastern Atlantic (Walker et al, 2009;Brodie et al, 2013;Pardo et al, 2015;Williamson et al, 2015), north-western Atlantic (Hind & Saunders 2013), north-eastern Pacific and New Zealand (Harvey et al, 2005;Broom et al, 2008;Farr et al, 2009;Nelson et al, 2015;Twist et al, 2019). One geographic area where the coralline algae have received little or no attention is the South Atlantic.…”