Oral Papers 98

CORE Metadata, citation and similar papers at core.ac.uk Provided by Open Marine Archive Oral Papers 98 Syste´matique & Evolution, Muse´um National hand are thought to be dominated by relatively d’Histoire Naturelle, 57 rue Cuvier, CP 39, 75231 young lineages, having largely diversified in the Paris cedex, France and 2Plymouth Marine Paleocene and Eocene possibly in response to Laboratory, Prospect Place, The Hoe, Plymouth increased herbivory. Data availability, e.g. inade- PL1-3DH, United-Kingdom quate diversity estimates, geographical sampling bias, uncertainty about phylogenetic relationships In brown algae (Phaeophyceae), pyrenoids are and divergence times, as well as methodological reported to occur on the plastids of only a few issues related to historical biogeography, make taxa, where they often prove valuable for systema- that scenarios of macroalgal diversification have tic delineation. Members of the Ectocarpales dis- rarely been tested explicitly. By integrating para- play large, stalked and exserted pyrenoids on their metric models in historical biogeography we test plastids, while the Scytothamnales as well as the the hypothesis that: 1.) independent marine algal genera Asterocladon, Asteronema and Bachelotia flora’s developed along the western and eastern exhibit stellate plastidomes with pyrenoids shores of Australia while it was still part of embedded in the plastidial stroma. Although pre- Gondwana; 2.) the Australian algal flora acted vious molecular studies have initiated the resolu- predominantly as a donor region from which spe- tion of the systematic position of some of the latter cies dispersed in the Cenozoic; 3.) the diversifica- taxa, a significant amount of work remained to be tion of typical tropical families is a relatively recent done, particularly in order to shed light upon rela- phenomenon coinciding with thermal stratification tionships between and within Ectocarpalean of the oceans and increased herbivory. We make families. To reassess phylogenetic relationships of use of global algal phylogenetic datasets (e.g. pyrenoid-bearing taxa among brown algae, a Dictyotales, Bryopsidales) developed over the last seven-locus data set (46000 bp) was generated for decade in our research group and integrate these a species-rich, class-level taxon sampling with a data with species distribution models and diver- particular attention to the order Ectocarpales. gence time estimates to explore the evolution of Within the Ectocarpales, the inter-familial relation- ecological niches. ships have been clarified as well as the position of several enigmatic genus, Bachelotia (included in the Scytothamnales). Our resolved phylogenetic ana- 7A.9 lyses lead to new taxonomic proposals, particularly within the negatively-defined family MACROALGAL CRYPTOGENESIS: WHERE Chordariaceae, which leads to a discussion on the ARE WE? evolution of pyrenoid-bearing plastids et pyrenoid Fre´de´ric Mineur ([email protected]) and architecture within Phaeophyceae. Christine A. Maggs ([email protected]) School of Biological Sciences, Queen’s University of 7A.8 Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Downloaded by [193.191.134.1] at 23:44 22 June 2014 HISTORICAL BIOGEOGRAPHY, Kingdom DIVERSIFICATION AND NICHE SHIFTS OF MARINE MACROALGAE In the light of global change, biological invasions are considered as one of the most important threats Olivier De Clerck ([email protected]), Heroen Verbruggen (heroen.verbruggen@ to biodiversity. Over the 20th century, introduction ugent.be), Lennert Tyberghein (lennert. events have increased exponentially. A higher fre- [email protected]) and Frederik Leliaert quency of vector movements and new transport ([email protected]) pathways are clearly responsible for that trend. Introductions of exotic species of seaweeds have Phycology Research Group, Ghent University, been recorded for two centuries. However, on Krijgslaan 281 S8, 9000 Gent, Belgium global scale, transport pathways have been in place at least since the Age of Discovery (15th cen- It is often hypothesized that many of the modern tury). As a result, many marine species have now a algal families have a Mesozoic origin in cold- and cosmopolitan distribution and are considered as cool-temperate waters of the southern hemisphere cryptogenetic (i.e. neither native nor exotic). rather than tropical regions. Support for a south- Using some macroalgal examples, we show how ern origin of many algal groups comes from the phylogeographic studies can help to resolve these recognition of possible ancestral taxa in the cold- issues, but also the limits of this approach for some and cool-temperate shores of Australia, Tasmania taxa with a long history of transport with a result- and New Zealand. Tropical regions on the other ing strongly influenced global distribution..

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