New book Chapter: Towards an Integrative Phylogeography of Invasive Marine Seaweeds, Based on Multiple Lines of Evidence.

In: Seaweed Phylogeography: Adaptation and Evolution of Seaweeds under Environmental Change.

Chapter 7
Towards an Integrative Phylogeography of Invasive Marine Seaweeds, Based on Multiple Lines of Evidence

Marianela Zanolla & Nikos Andreakis

Molecular phylogeography has for decades been a frequently used
approach to delineate novel evolutionarily significant units (ESUs) and to study the dynamics of invasive species. Next-generation sequencing technology (NGS) and the use of environmental DNA (eDNA) have the potential to revolutionize our way of understanding biodiversity and to establish rapid protocols for early-stage detection of invasive species. In seaweeds, however, several years of research on iconic invasive taxa of ambiguous taxonomic status (e.g. Caulerpa, Codium, Asparagopsis) have suggested that an integrative approach, namely the combination of multiple lines of evidence (e.g. phylogeographic, ecological, physiological and predictive modelling), is necessary to accurately resolve the taxonomy and their invasive potential. At present, integrative approaches in these fields are often weak because of incongruences among species delineation, newly discovered ESUs which remain undescribed taxonomically, and because databases containing vouchers of barcoded specimens are incomplete. As relocations of marine biota accelerate and climatic changes offer new potential niches for invasive seaweeds, new, transferable and internationally adopted protocols are necessary for exploring, monitoring and managing marine biodiversity. This is particularly urgent in areas of intense maritime traffic, such as the Mediterranean Sea and the Hawaiian archipelago, in order to achieve sustainable socio-economic development without compromising the local marine resources.

Endemic or introduced? phylogeography of Asparagopsis (Florideophyceae) in Australia reveals multiple introductions and a new mitochondrial lineage

We have just had a new paper accepted in Journal of Phycology that investigates the lineage diversity of the red seaweed genus Asparagopsis in Australia. This study reports a new Asparagopsis taxiformis mitochondrial lineage and demonstrates the presence of three A. taxiformis cryptic lineages along the Australian coastline. Now, together with lineage 4 found in Cocos (Keeling) Islands, and the two A. armata lineages reported from western Australia and Tasmania our work brings up to six the total number of Asparagopsis lineages in Australian waters. 



Anonymous Asparagopsis lineage
growing on coral colony



 

The question is: are they native or introduced?

 If they are introduced, their early detection is critical for determining the feasibility of either eradication or effective containment as control measures and for the establishment of subsequent conservation plans and management actions.

If they are native, the identification of cryptic endemisms is essential, although challenging, for conservation biogeography and biodiversity management strategies.

Exploring the origins of Australian marine endemic diversity

This is an evolutionary understanding of Australia’s marine fauna that can explain the modern bio-geographic patterns and assist vulnerability-risk assessments of fish families to present and future environmental changes. It is interesting that the Australian continent emerges as a reservoir of biodiversity for the indo-Pacific Ocean in geological periods and as a Noah’s Ark’ for biodiversity in modern days. Read the full NERP report here. In the photo a fossil of an extinct ray. The maskrays originated after the collision of the Australian and Eurasian plates and their speciation may have been accelerated by falls in sea level millions of years ago (Image by John Adamek).