Putting the algal tree of life to use
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The increase in resolution and taxon sampling of algal phylogenies resulting from the various algal tree of life projects and other initiatives worldwide opens tremendous opportunity to learn more about the evolution of all aspects of algal biology. Using evolutionary modeling techniques in a phylogenetic context, hypotheses about the evolution of particular traits and their interaction with speciation-extinction dynamics become testable. I will illustrate this with three case studies. First, I will investigate the evolution of the thermal niche of seaweeds, showing how it affects latitudinal diversity patterns. Second, I will test the hypothesis that the evolution of cellular trace element requirements (stoichiometry) is dominated by endosymbiosis events. Third, I will investigate the evolution of morphological traits typically used in species-level systematics, focusing on its implications for the prevalence of cryptic diversity. These case studies show the potential and limitations of the approach, and offer new insights in algal evolution from the very recent to the very ancient, and across the various subdisciplines of algal biology.
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Putting the algal tree of life to use
- 1. Putting the algal tree of life to use Evolutionary dynamics of ecological niches, physiology and species’ diagnostic traits Heroen Verbruggen School of Botany, University of Melbourne
- 2. Algal Diversity • architecture • functional traits • life history • physiology
- 3. Algal Tree of Life • systematics: species delimitation and higher-level relationships • phylogenies in evolutionary enquiry • endosymbiosis events: patchwork of genes → accumulation of genomic features • examples of phylogenetics applied in evolutionary questions
- 4. Talk contents Systematics Thermal Niche Trace Elements
- 5. Thermal niche van den Hoek. 1982. Biol. J. Linn. Soc. 18: 81-144 — Cambridge et al. 1984. Helgol. Meeresunt. 38: 349-363 — Eggert. 2012. In: Wiencke, C., Bischof, K. [Eds.] Seaweed Biology
- 6. Thermal niche Map: T. Schils Species diversity map Codium
- 7. How does the thermal niche evolve? How fast? Which direction? Pulsed or gradual? Effect on biodiversity? Are there covariates?
- 8. Exploration
- 10. Are there covariates? sheltered exposed HalimedaMarcelino et al. 2014. submitted
- 12. Thermal niche & diversification DictyotaTyberghein et al. unpublished
- 13. Thermal niche evolution • thermal niches evolve over geological timescales • microhabitat preferences affect evolvability • diversification relates to SST and its evolvability • results are taxon-specific • scale up to bigger datasets: more species • harder questions: adaptation, interactions, timescales
- 14. Talk contents Systematics Thermal Niche Trace Elements
- 15. Trace element utilization Raven. 1999. Photosynthesis Research 60: 111-149 Thylakoid membrane with photosystems
- 16. Trace element utilization Quigg et al. 2003. Nature 425: 291-294 Hypothesis
- 17. Exploration Cya Eug Cha Stra Din Din Gla Hap Cry Rho Chl time (Ga) 00.511.5 Fe utilization low high
- 18. Hypothesis Model Cya Eug Cha Stra Din Gla Hap Cry Rho Chl Cya Eug Cha Stra Din Din Gla Hap Cry Rho Chl Host phylogeny Plastid phylogeny Parfrey, L.W., Grant, J., et al. 2010. Syst. Biol. 59: 518-533 — Baurain, D., Brinkmann, H., et al. 2010. Mol. Biol. Evol. 27: 1698-1709.
- 19. Results for Fe/P ratio Pulsed Gradual 0 1 0.25 Nuclear Tree 0.40 Plastid Tree Relative rates σ 2ENDO = 73.5 σ 2OTHER = 447.3 Nuclear tree p = 0.09 Relative rates σ 2ENDO = 103.2 σ 2OTHER = 382.9 Plastid tree
- 21. Power analysis
- 22. Trace element utilization • results are inconclusive • support for existing hypotheses is limited • power to detect differential evolution of continuous traits is low • limited effect of increase in taxon sampling • metalloproteomics approaches
- 23. Talk contents Systematics Thermal Niche Trace Elements
- 24. Role of ToL in Systematics Simulation: extrapolate what we know about trait evolution A B C
- 25. Problem: Cryptic Diversity Zuccarello, G.C., West, J.A. 2003. J. Phycol. 39: 948-959. — Photo: J. West How big is the problem?
- 26. Pseudochlorodesmis Verbruggen, H. et al. 2009. J. Phycol. 45: 726-731 — Photo: H. Verbruggen Is it more of a problem in simple organisms?
- 27. Complexity and diagnosability Verbruggen, H. 2014. J. Phycol. 50: 26-31. Simulation: extrapolate what we know about trait evolution 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 0 0 1 0 1 1 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 0 1 1 0 1 1 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 1 0 1 1 1 0 0 1 1 1 1 1 1 1
- 28. Complexity and diagnosability 20 characters theoretical maximum = 1,048,576 10 characters theoretical maximum = 1,024 Verbruggen, H. 2014. J. Phycol. 50: 26-31. • higher complexity more unique morphologies • # unique morphologies << # species in clade total # species #uniquemorphologies
- 29. Habitat selection Verbruggen, H. 2014. J. Phycol. 50: 26-31. A B C D E ➙ 1 ➙ 3 ➙ 5 ➙ 7 ➙ 9
- 30. Habitat selection Verbruggen, H. 2014. J. Phycol. 50: 26-31.
- 31. Plasticity Verbruggen, H. 2014. J. Phycol. 50: 26-31. A B C D E ➙ 1 ➙ 3 ➙ 5 ➙ 7 ➙ 9
- 32. Plasticity Verbruggen, H. 2014. J. Phycol. 50: 26-31.
- 33. Morphological evolution • # unique morphologies << number of species • null hypothesis: cryptic diversity abounds • fundamental inability to distinguish some species (possibly many) morphologically • problem more pronounced in simple organisms • plasticity blurs species boundaries
- 34. Talk contents Systematics Thermal Niche Trace Elements
- 35. Conclusions • test evolutionary hypotheses • insights from parameters • measure uncertainty • simulation to study behavior of methods • simulation to improve expectations • perspectives: genome dynamics, life histories, etc. Verbruggen, Marcelino, Costa (2014) Evolutionary dynamics of algal traits and diversity. Perspectives in Phycology 1: in press [available from www.phycoweb.net]
- 36. Acknowledgements • Collectors • Collaborators • Previous workers