Deep sea scleractinian corals will be particularly vulnerable to the effects of
climate change, facing loss of up to 70% of their habitat as the
Aragonite Saturation Horizon (below which corals are unable to form calcium
carbonate skeletons) rises. Persistence of deep sea scleractinian corals will
therefore rely on the ability of larvae to disperse to, and colonise, suitable
shallow-water habitat. We used DNA sequence data of the internal transcribed
spacer (ITS), the mitochondrial ribosomal subunit (16S) and mitochondrial
control region (MtC) to determine levels of gene flow both within and among
populations of the deep sea coral Desmophyllum dianthus in SE
Australia, New Zealand and Chile to assess the ability of corals to disperse
into different regions and habitats. We found significant genetic subdivision
among the three widely separated geographic regions consistent with isolation
and limited contemporary gene flow. Furthermore, corals from different depth
strata (shallow <600 m, mid 1000–1500 m, deep >1500 m) even on the
same or nearby seamounts were strongly differentiated, indicating limited
vertical larval dispersal. Genetic differentiation with depth is consistent with
the stratification of the Subantarctic Mode Water, Antarctic Intermediate Water,
the Circumpolar Deep and North Pacific Deep Waters in the Southern Ocean, and we
propose that coral larvae will be retained within, and rarely migrate among,
these water masses. The apparent absence of vertical larval dispersal suggests
deep populations of D. dianthus are unlikely to colonise
shallow water as the aragonite saturation horizon rises and deep waters become
uninhabitable. Similarly, assumptions that deep populations will act as refuges
for shallow populations that are impacted by activities such as fishing or
mining are also unlikely to hold true. Clearly future environmental management
strategies must consider both regional and depth-related isolation of deep-sea
coral populations.
Brachiopods are a lineage of invertebrates well known for the breadth and depth of their fossil record. Although the quality of this fossil record attracts the attention of paleontologists, geochemists, and paleoclimatologists, modern day brachiopods are also of interest to evolutionary biologists due to their potential to address a variety of questions ranging from developmental biology to biomineralization. The brachiopod shell is a composite material primarily composed of either calcite or calcium phosphate in close association with proteins and polysaccharides which give these composite structures their material properties. The information content of these biomolecules, sequestered within the shell during its construction, has the potential to inform hypotheses focused on describing how brachiopod shell formation evolved. Here, using high throughput proteomic approaches and next generation sequencing, we have surveyed and characterized the first shell-proteome and shell-forming transcriptome of any brachiopod, the South American Magellania venosa (Rhynchonelliformea: Terebratulida). We find that the seven most abundant proteins present in the shell are unique to M. venosa, but that these proteins display biochemical features found in other metazoan biomineralization proteins. We can also detect some M. venosa proteins that display significant sequence similarity to other metazoan biomineralization proteins, suggesting that some elements of the brachiopod shell-forming proteome are deeply evolutionarily conserved. We also employed a variety of preparation methods to isolate shell proteins and find that in comparison to the shells of other spiralian invertebrates (such as mollusks) the shell ultrastructure of M. venosa may explain the effects these preparation strategies have on our results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.