Toward resolution of species diversity and distribution in the calcified red algal genera Corallina and Ellisolandia (Corallinales, Rhodophyta)

Abstract

Cryptic species diversity and the misapplication of names have restricted an understanding of species boundaries in the tribe Corallineae of the calcified red algal order Corallinales. Recent DNA sequencing of type material provided a framework facilitating further examination of genera within the tribe. A phylogenetic study of the genera Corallina and Ellisolandia, based on cytochrome c oxidase subunit 1 and ribulose-bisphosphate carboxylase gene sequences, was undertaken using Natural History Museum herbarium collections and contemporary samples to explore species diversity, geographic distributions and the extent to which names have been misapplied. Twenty Corallina clades likely corresponding to species were resolved, of which C. officinalis and C. caespitosa were confirmed, four were clades newly identified during the present study and 14 had been reported by other workers in previous studies. These data indicated considerable genetic diversity within the genus that was not readily apparent on the basis of morphology. The generitype C. officinalis was shown to have a predominantly North Atlantic Ocean, cool-temperate distribution, whereas the global distribution of C. caespitosa is confirmed for the first time, with samples from Asia, Australasia, Europe, Africa and America. Widespread misidentification of Corallina species was documented, as was the need for sequencing of type specimens to correctly apply names and for comparison with historical collections. The phylogeny reported here serves both as a baseline for future phylogenetic positioning of Corallina species and highlights the degree to which species concepts within this genus remain unresolved.

The regulation of coralline algal physiology, an in situ study of <i>Corallina officinalis</i> (Corallinales, Rhodophyta)

“…1b and c). This site is located in the middle of C. officinalis' range across the NE Atlantic, which spans from Iceland to northern Spain (Williamson et al, 2015).…”

“…This study focuses on Corallina officinalis, a species that dominates North Atlantic turfing assemblages (Williamson et al, 2015) and has been the focus of recent studies aiming to understand coralline algal physiology and future fate (Hofmann et al, 2012a, b;Williamson et al, 2014a, b;Williamson et al, 2015;Perkins et al, 2016). Whilst the skeletal mineralogy (Williamson et al, 2014b), photophysiology (Williamson et al, 2014a;Perkins et al, 2016) and phylogenetics of C. officinalis (Williamson et al, 2015) have been examined, information on in situ physiology in relation to key environmental stressors is currently lacking.…”

“…Whilst the skeletal mineralogy (Williamson et al, 2014b), photophysiology (Williamson et al, 2014a;Perkins et al, 2016) and phylogenetics of C. officinalis (Williamson et al, 2015) have been examined, information on in situ physiology in relation to key environmental stressors is currently lacking. We therefore performed the first high-resolution in situ assessment of C. officinalis physiology (production, respiration and calcification) in relation to key environment stressors (irradiance, temperature and carbonate chemistry) over both daytime and night-time tidal emersion periods, across multiple seasons.…”

Photoacclimation and photoregulation strategies of Corallina (Corallinales, Rhodophyta) across the NE Atlantic

“…As such, much recent research has been aimed at gaining a better understanding of Corallina ecophysiology, particularly in the NE Atlantic (e.g. Brodie et al, 2013Brodie et al, , 2016Williamson et al, 2014aWilliamson et al, , 2014bWilliamson et al, , 2015Williamson et al, , 2017Perkins et al, 2016). The aim of this study was to build on the initial work of Williamson et al (2014b) in order to identify the suite of photoacclimation and photoregulation mechanisms that allow Corallina to optimize light use in the variable intertidal environment, thus contributing to their dominance of NE Atlantic rock pools, and to characterize the use of these mechanisms in space and time.…”

“…Photophysiological assessments were performed in situ across a full seasonal cycle in the UK intertidal, and complemented with ex situ techniques under laboratory conditions. Latitudinal comparisons were further performed for C. officinalis across the full extent of the species' range in the NE Atlantic (Iceland-northern Spain, Williamson et al, 2015), and for C. caespitosa in northern Spain.…”