BackgroundThe mitochondrial genome of the Octocorallia has several characteristics atypical for metazoans, including a novel gene suggested to function in DNA repair. This mtMutS gene is favored for octocoral molecular systematics, due to its high information content. Several hypotheses concerning the origins of mtMutS have been proposed, and remain equivocal, although current weight of support is for a horizontal gene transfer from either an epsilonproteobacterium or a large DNA virus. Here we present new and compelling evidence on the evolutionary origin of mtMutS, and provide the very first data on its activity, functional capacity and stability within the octocoral mitochondrial genome.ResultsThe mtMutS gene has the expected conserved amino acids, protein domains and predicted tertiary protein structure. Phylogenetic analysis indicates that mtMutS is not a member of the MSH family and therefore not of eukaryotic origin. MtMutS clusters closely with representatives of the MutS7 lineage; further support for this relationship derives from the sharing of a C-terminal endonuclease domain that confers a self-contained mismatch repair function. Gene expression analyses confirm that mtMutS is actively transcribed in octocorals. Rates of mitochondrial gene evolution in mtMutS-containing octocorals are lower than in their hexacoral sister-group, which lacks the gene, although paradoxically the mtMutS gene itself has higher rates of mutation than other octocoral mitochondrial genes.ConclusionsThe octocoral mtMutS gene is active and codes for a protein with all the necessary components for DNA mismatch repair. A lower rate of mitochondrial evolution, and the presence of a nicking endonuclease domain, both indirectly support a theory of self-sufficient DNA mismatch repair within the octocoral mitochondrion. The ancestral affinity of mtMutS to non-eukaryotic MutS7 provides compelling support for an origin by horizontal gene transfer. The immediate vector of transmission into octocorals can be attributed to either an epsilonproteobacterium in an endosymbiotic association or to a viral infection, although DNA viruses are not currently known to infect both bacteria and eukaryotes, nor mitochondria in particular. In consolidating the first known case of HGT into an animal mitochondrial genome, these findings suggest the need for reconsideration of the means by which metazoan mitochondrial genomes evolve.
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.
Advances in high-throughput sequencing (HTS) are revolutionizing monitoring in marine environments by enabling rapid, accurate and holistic detection of species within complex biological samples. Research institutions worldwide increasingly employ HTS methods for biodiversity assessments. However, variance in laboratory procedures, analytical workflows and bioinformatic pipelines impede the transferability and comparability of results across research groups. An international experiment was conducted to assess the consistency of metabarcoding results derived from identical samples and primer sets using varying laboratory procedures. Homogenized biofouling samples collected from four coastal locations (
Many sessile organisms rely on the transport of one or both types of gametes for reproductive success. While sperm limitation has been reported in some species, high fertilization success has been observed in others including the branching octocoral Pseudopterogorgia elisabethae. In such cases, males may compete for eggs to fertilize and the local dispersion of sperm will be an important component of male success. Individual reproductive success of 91 male P. elisabethae colonies found within a 400 m 2 area on San Salvador Island, Bahamas was examined based on microsatellite analysis of planulae collected from female colonies. Larvae which were brooded on the surface of 4 different females were collected during 2 separate spawning events. Males in the study area were sampled, and parentage was assessed using 5 microsatellite loci and the paternity assignment program CERVUS 3.0. Twenty-five percent of the larvae were assigned sires with ≥80% likelihood and 87% of the planulae could have been sired by males within the study area. The success of males was not related to either distance to the female or to male colony size. On average, successful sperm only travelled 5.2 m and the success of individual males within the 400 m 2 study site was not significantly different from random expectations. Male P. elisabethae may follow spawning strategies that increase the likelihood of siring some planulae, spread success across multiple females and reduce variance in reproductive success.KEY WORDS: Gorgonian coral · Microsatellites · Paternity · Sperm · Dispersal · Male reproductive success Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 367: [153][154][155][156][157][158][159][160][161] 2008 studies have typically been based on paternity analysis of embryos produced in controlled matings involving only a few individuals (Yund & McCartney 1994, Yund 1995. The only study examining paternity in a natural spawning event (Coffroth & Lasker 1998) examined a population of the octocoral Plexaura kuna, in which there were only a few potential sires. Although these studies provide insights into the factors controlling mating patterns, they do not address sperm dispersal and reproductive success in most natural populations in which numerous males are present.The development of highly polymorphic DNA genetic markers such as microsatellites, has increased the possibility of assessing paternity within local populations containing multiple males. For instance, a large number of investigations in plants have used microsatellites to estimate the contribution of pollen dispersal to gene flow, and to assess mating patterns and male reproductive success in natural plant populations (Dow & Ashley 1998, Streiff et al. 1999, Konuma et al. 2000, Lian et al. 2001. In this study, we used microsatellites to assess male reproductive success and sperm dispersal in a population of the branching octocoral Pseudopterogorgia elisabethae.Pseudopterogorgia elisabethae is a gorgoniid alcyonacean wit...
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