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ESA 2015 Baltimore, MD
- 2. A metacommunity perspectiveof diversity diversity ~ local processes + regional processes + their interaction
- 3. Metacommunity diversity Modified fromLeibold et al. 2004 EcoLett Species sorting Source-sinkDispersal limitation Identifying the processes that structure metacommunity diversity is challenging, because different processes can lead to similar outcomes dispersal
- 4. Manipulating dispersal ina natural system Species mixer
- 5. ? ? ? ? Diversityresponses to the removal of dispersal limitation Species sorting Localdiversity small large Localdiversity small large Spatial scale of mixing Species-environment relationships small large Spatial scale of mixing Species-environment relationships small large Source-sink ? ? Dispersal limitation Localdiversity small large Spatial scale of mixing Species-environment relationships small large
- 6. Research questions 1. Whichmetacommunity process best explains diversity patterns in natural communities? 2. How does removing dispersal limitation at multiple scales affect metacommunity diversity?
- 7. : McLaughlin serpentine metacommunity▪ water limited ▪ many annual species
- 8. Experimental design: seedvacuuming procedure Vacuuming procedure modified from Coiffait-Gombault et al. 2010 Restor Ecol Environmental parameters were measured concurrent to the community survey % soil moisture
- 9. Experimental design: plotlocations 1 m 5 m 100 m 5 km 10 km Each plot in a block received seed that were mixed from plots at five different spatial scales (the other three plots were control plots) 30 serpentine sites arranged in six clusters of five sites Each site contained a block of eight 0.75 x 0.75 m plots Spatially nested plot arrangement 1 m = essentially natural diversity patterns 10 km = dispersal limitation completely removed
- 10. 1 m 5 m 100m 5 km 10 km 1 m Result 1: Plot-level species richness increased with the spatial scale of seed mixing lmer(species richness ~ treatment + (1|site))
- 11. NS NS Result 2: Communitycomposition shifted with the spatial scale of seed mixing 1 m 5 m 100 m 10 km 5 km
- 12. Example of spatialscaling effects on diversity 1 m 10 km Plantago erecta Hemizonia congesta Microseris douglasii Lepidium nitidium Plantago erecta Hemizonia congesta Microseris douglasii Lepidium nitidium Rigiopappus leptocladus Lasthenia califorica Collinsia sparsiflora Lotus wranglianus What can the effects of removing dispersal limitation reveal about the specific metacommunity class that structures diversity?
- 13. Result 3: Species-environmentassociations increase with the spatial scale of seed mixing 5 km
- 14. 100 m Result 4:Species composition shifts with % soil moisture 0.45 0.35 0.05 0.20 0.20 R2 1 m 5 m 10 km lmer(axis scores ~ % sm *treatment + (1|site)) 5 km
- 15. Community level Species- vs.community-level environmental associations 1 m 5 m 100 m 10 km 5 km 1 m Species level P = 0.011 0% Even in communities with strong environmental determinism, dispersal limitation can still be widespread
- 16. Summary of results Diversityincreases non-linearly with the spatial scale of removed dispersal Species-environment associations increase with the scale of the species pool
- 17. x x The shiftingimportance of metacommunity processes with spatial scale of dispersal removal 1 m 5 m 100 m 5 km 10 km dispersal limitation source-sink species sorting Figure modified from Bell & Lechowicz 1991 JEcol
- 18. x x The shiftingimportance of metacommunity processes with spatial scale of dispersal removal 1 m 5 m 100 m 5 km 10 km dispersal limitation source-sink species sorting suitable Figure modified from Bell & Lechowicz 1991 JEcol
- 19. Acknowledgements The Gilbert Lab TheStrauss lab Susan Harrison Caprice Lee Erica Case Stella Copeland Brian Anacker Webpage: rgermain.wordpress.com Email: rachel.germain@mail.utoronto.ca Paola Arenas Laurren Sergison Kate LeCroy Cathy Koehler
Editor's Notes
- #3 Ecologists are frequently interested in determining the factors that structure species diversity, and very commonly look at local explanations. linking variation in local conditions affects the number and types of species. there is an increasing recognition that local communities are not independent from each other, because they can exchange individuals through dispersal… Community of local communities – or a ‘metacommunity’ – that ultimately determines diversity
- #4 And why this interaction is interesting depending on the relative strengths of species interactions, environmental heterogeneity, and dispersal, lead us into different classes of metacommunity dynamics that have different outcomes for diversity. I am focusing on three of them there that are most relevant for my system, … What we can see is that these 3 are delineated by dispersal, so if there was a way to conceivably remove dispersal, tell them apart
- #5 What we would really need to differentiate these is to manipulate dispersal limitation altogether Theoretically, you could remove dispersal limitation all together …randomizing the species pool. Many theoretical and empirical mesocosm type tests… and it really seems impossible to perform this manipulation in a natural system…but as I ill show you, I did this.
- #6 And so, if we could do this, we could tell which metacommunity paradigm best explains diversity patterns depending on two ways in which species respond to the manipulation…. And so, you don’t need to memorize this, but the point is you can differentiate between them.
- #7 So, using this framework, we can ask two questions: HOW ARE NATURAL COMMUNITIES STRUCTURED, AND HOW DOES MANIPULATION OF DISPERSAL AFFECT DIVERSITY IN TERMS OF METACOMMUNITY PARADIGMS AT MULTIPLE SCALES?
- #8 And so, test these questions in serpentine grasslands in California. This last point is important for the method that I used But most importantly, they are patchy in species and environments, serpentine intermixed with non-serpentine
- #9 And so, I mentioned that a way to…is alter or remove dispersal.
- #10 I am going to show you four main results from this experiment, keep these colours in mind
- #11 Diversity is nearly double
- #12 Clearly, the removal of dispersal limitation at multiple spatial scales affects several components of diversity, but what can this tell us about the ecological mechanisms at play?
- #13 So we have this clear effect pf removing dispersal limitation at multiple scales on several components of diversity, but what can this tell us about the ecological mechanisms at play?
- #14 Not a single species at small scales are associated with environment -rare species have a lower probability of encountering suitable sites at 10 km than 5 km
- #15 Highlights determinism in the community patterns. Slopes are comparable, but more variation
- #16 A side point that is interesting is that
- #17 And so, these two pieces of information allow me to infer two things.
- #18 Using those two pieces of information, we can infer that…. And what I think is happening is that the relative strength of these different metacommunity processes are varying with the scale of seed manipulation. Study is unique because it can tell you what structures a natural community, but also how dispersal rates affect metacommunity outcomes in a real landscape with a real species pool
- #19 Using those two pieces of information, we can infer that…. And what I think is happening is that the relative strength of these different metacommunity processes are varying with the scale of seed manipulation. Study is unique because it can tell you what structures a natural community, but also how dispersal rates affect metacommunity outcomes in a real landscape with a real species pool