Related Experiment Video
Updated: Apr 14, 2026

Development of New Methods for Quantifying Fish Density Using Underwater Stereo-video Tools
Published on: November 20, 2017
Contrasting Dispersal Patterns of Co-Occurring Benthic Sister Sea Star Labidiaster Species (Asteroidea:
Nicola Rodewald1,2, Nerida G Wilson3,4,5, Sally C Y Lau1,2
1Centre for Sustainable Tropical Fisheries and Aquaculture James Cook University, College of Science and Engineering Townsville Queensland Australia.
Abstract:
Closely related and co-occurring species offer valuable systems to assess whether dispersal barriers in shared environments are navigated in a consistent manner. Labidiaster radiosus and L. annulatus have been morphologically described as two separate species from southern South America and the Southern Ocean respectively, yet the phylogenetic relationships and boundaries between these species have still not been genetically clarified. Labidiaster annulatus has pelagic larvae; however, the developmental mode for L. radiosus has not been confirmed. This study aimed to employ genetic methods to analyze the phylogeny, distribution, species boundaries, population structure, demographic history and genetic connectivity for L. radiosus and L. annulatus. Two molecular markers were sequenced in this study including a part of the mitochondrial gene cytochrome c oxidase subunit I (COI) and the intron of the nuclear adenosine triphosphate synthetase, beta subunit gene (ATPSβ-intron 7). A sister-species relationship was revealed between L. radiosus and L. annulatus; both species displayed circum-Antarctic distributions, extending their known distributions and were found to co-occur at Heard, Balleny and Scott Islands. Labidiaster radiosus and L. annulatus were estimated to have diverged ~3.56 mya (HPD95: 5.25-2.15). Additionally, L. radiosus was confirmed to have pelagic larvae in the Southern Ocean. Labidiaster radiosus population structure revealed clear subclades north and south of the APF, which diverged ~2.08 mya (HPD95: 3.48-0.58). Analyses for Labidiaster annulatus indicated high genetic connectivity among all locations across the Southern Ocean. Historical dispersal analyses showed high genetic connectivity among Scotia Sea Islands, and the South Sandwich Islands were identified as a possible contemporary sink population. Despite their similarities in life history and circum-Antarctic distribution, L. radiosus and L. annulatus revealed contrasting population structures. This highlights the unpredictable nature of dispersal for Southern Ocean benthic invertebrates when based on life history alone.
More Related Videos
07:43Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop
Published on: July 2, 2018
11:55Streamlined Sampling and Cultivation of the Pelagic Cosmopolitan Larvacean, Oikopleura dioica
Published on: June 16, 2020
Related Concept Videos
Distribution and Dispersion
Formation of Species
Speciation Rates
Fixed Action Patterns
Diversity of Protists III
Genetics of Speciation