Josefin Stiller

We use molecular markers to study how seadragon populations are structured across the Australian coast. This data will inform conservation actions for these popular fishes. We are particularly interested in understanding what signatures historical processes have left in the genomes of seadragons.  Main collaborators: Greg Rouse, Nerida Wilson

The leafy seadragon is a marine fish, which can only be found in southern Australia. The species is characterized by its remarkable camouflage that mimics kelp blades. Our work on the leafy seadragon investigates population structure and genetic diversity differs across their range in Australia. Image: Greg Rouse

In this study we investigated population structuring and genetic diversity in the leafy seadragon. We found low genetic diversity, particularly in the western part of the range. Our current work is following up on these results with extended sampling in Western Australia and genome-wide genetic markers. Stiller, Wilson, Donnellan & Rouse (2017). The leafy seadragon, a flagship species with low but structured genetic variability. Journal of Heredity 108:152-162 (2017).

The common (or weedy) seadragon is a marine fish that inhabits the southern Australian coast from Sydney, to Tasmania to Perth in Western Australia. Our work on the common seadragon uses genetic data from hundreds of individuals across the range to investigate phylogeographic structuring. We are particularly interested in investigating the effects of historical processes. Image: Greg Rouse

The common seadragon shows pronounced population structure across its range in Australia. Genetic diversity was low in the eastern part of the range in New South Wales and Tasmania. This first genetic assessment of this species, which will have implications in the conservation of the common seadragon. Wilson, Stiller & Rouse (2017). Barriers to gene flow in common seadragons (Syngnathidae: Phyllopteryx taeniolatus). Conservation Genetics 18:53-66.

In the course of our work we described a new species of seadragon, which is only the third known species. Phyllopteryx dewysea sports a crimson color (amongst other morphological differences to the other two species), hence its common name, the ruby seadragon. Click to read the article. Stiller, Wilson & Rouse (2015). A spectacular new species of seadragon (Syngnathidae). Royal Society Open Science 2:140458.

In April 2016, we set out on an expedition to find the ruby seadragon in the wild. Equipped with an underwater robot searching for the (red) needle in the haystack. Click to read about what we have learnt about this enigmatic species and see the videos of the live footage below. Rouse, Stiller & Wilson (2017). First live records of the ruby seadragon (Phyllopteryx dewysea, Syngnathidae). Marine Biodiversity Records 10:2

Seadragons are only a small group of the diversity of syngnathid fishes (seahorses, pipefishes, pipehorses). The ruby seadragon was found to be the closest relative to the common seadragon. Click to read the full story. Stiller, Wilson & Rouse (2015). A spectacular new species of seadragon (Syngnathidae). Royal Society Open Science 2:140458.

This figure shows X-ray images of the skeletons of the leafy, common and ruby seadragon (from top to bottom). Comparing these images helped us identify characteristics of the skeletal system that distinguish the ruby seadragon from its relatives. Click to read the full account and see the videos below for a 3D model of the ruby's skeleton. Stiller, Wilson & Rouse (2015). A spectacular new species of seadragon (Syngnathidae). Royal Society Open Science 2:140458.

The syngnathids comprise about 300 species of seahorses, seadragons, pipehorses and a variety of pipefish lineages. We used genome-wide genetic markers (Ultraconserved Elements) to reconstruct the evolutionary relationships among >350 individuals of syngnathids and their allies. This data will be used to better understand the diversification of this group. Collaborators: Healy Hamilton, Sarah Longo, Greg Rouse, Norah Saarman, Graham Short, Brian Simison, Peter Wainwright

My current work is investigating the evolutionary relationships of birds. As part of the B10K project, our group is using whole genome sequences from over 300 species of birds to understand the phylogenetic relationships of birds. Click to read more about the 10,000 Bird Genome project (B10K) and a review about the bounty of applications in phylogenetics and comparative biology that whole genomes are expected to have.

Check out this study that sequenced the genome of an extinct bird, the Carolina parakeet that went extinct in North America. I contributed the evolutionary placement of this parrot based on ~5000 genetic loci and dated the phylogeny using fossils.