Genomics reveals abundant speciation in the coral reef building alga Porolithon onkodes (Corallinales, Rhodophyta)

Abstract

An essential suite of coral reef ecosystem engineers is coralline red algae. Among these, the smooth, encrusting Porolithon onkodes has historically been considered the most important and common reef building species worldwide. We assess P. onkodes biodiversity by performing a genomic analysis of the lectotype specimen collected in 1892 from the Tami Islands, Gulf of Huon, east of New Guinea. Comparisons of DNA sequences from the lectotype specimen to those deposited in GenBank and to newly generated sequences from both field-collected and historical specimens demonstrate that at least 20 distinct species are passing under P. onkodes. We hypothesize that there were multiple evolutionary drivers including ecophysiology, hydrodynamic regimes, and biotic interactions as well as historical biogeography, which resulted in this high diversity of smooth, encrusting Porolithon species throughout the tropics. Our results emphasize the need to document the biodiversity, ecophysiology, and habitats of these tropical, reef-building algae in light of climate change and ocean acidification.

Mediterranean Lithophyllum stictiforme (Corallinales, Rhodophyta) is a genetically diverse species complex: implications for species circumscription, biogeography and conservation of coralligenous habitats

“…), which is sometimes striking and has been shown for the tropical reef consolidator Porolithon onkodes representing a complex of at least 20 cryptic species (Gabrielson et al. ). Based on our phylogenetic analyses of specimens with the Lithophyllum stictiforme morphology along with support from GMYC and ABGD species delimitations and geographic distributions, we conclude that numerous distinct species are passing under Lithophyllum stictiforme .…”

“…As a comparison, cryptic species recognized by Gabrielson et al. () in the P. onkodes complex differed by >1%, and divergences of 0.5%–0.8% were used to distinguish species in other genera of Corallinales (Gabrielson et al. , Hind et al.…”

“…Gabrielson et al. () remarked that cryptic species in the Porolithon onkodes complex occupy different habitats, characterized by different wave exposures, irradiances, and biotic interactions. These authors concluded that a number of evolutionary drivers such as eco‐physiology, hydrodynamic regimes, and biotic interactions played a major role in the diversification of this complex.…”

“…, Gabrielson et al. ; western Indian Ocean, Basso et al. ; Subarctic and Boreal Atlantic, Adey et al.…”

Genetic analysis of the Linnaean Ulva lactuca (Ulvales, Chlorophyta) holotype and related type specimens reveals name misapplications, unexpected origins, and new synonymies

“…, Gabrielson et al. ). Finally, we recommend caution when comparing sequences from field‐collected specimens with those in GenBank as a tool for identification, since many of the names applied to GenBank accessions have not been confirmed by sequences from type material.…”