The role of evolutionary history in the assembly of plant communities

1. The role of evolutionary history in the assembly of plant communities

2. Current projects • An ecophysiological and evolutionary perspective on functional diversity in the willow genus (Salix) • Jessica Savage (Ph.D. student) • Phylogenetic structure and community assembly of long-term experimental plant communities • Team of talented undergrads • Community age and assembly in a phylogenetic context: Forging links between ecology and evolution in the LTER framework • Software development with Clarence Lehman • Cross-site initiative within the LTER

3. What is a community? • In practice, a community is defined by the organisms and the interactions under investigation at a spatial scale relevant to the questions asked A B

4. What ecological forces influence community assembly? • Dispersal– can a species arrive in the location? • Environmental filtering – can a species tolerate the abiotic environment? • Species interactions – can species compete successfully for resources?

5. Species A B C D E F G H I Traits Communities The role of species traits in community assembly • Environmental filtering operates on species phenotypes or “traits” because these determine the environments they can tolerate Trait similarity within communities is high

6. Species A B C D E F G H I Traits Communities The role of species traits in community assembly • Species Interactions also depend on traits • Species that are too similar cannot coexist Trait similarity within communities is low

7. Evolutionary history influences species traits

8. Phylogenetic overdispersion Phylogenetic clustering What does the phylogenetic structure of a community tell us?

9. Environmental Filtering + Trait evolution Trait similarity in communities Adapted from Cavender-Bares et al Am Nat 2004

10. Adapted from Cavender-Bares et al Am Nat 2004 + Environmental Filtering + Species interactions Trait similarity in communities Trait evolution

11. Forests Mesic Xeric Hydric Grasslands Forests Wetlands In the literature to date: • Several studies have shown that within speciose genera or clades, overdispersion occurs. • When communities are broadly defined to include many taxa, phylogenetic clustering is more likely. • At larger spatial scales with greater environmental heterogeneity, phylogenetic clustering is more likely. Cavender-Bares et al Ecology 2006

12. Willows are a speciose genus well-represented in Minnesota • 13 native willow species occur at Cedar Creek • Good system in which to test for overdispersion

13. Two alternative scenarios • Adaptive radiation into contrasting local habitats led to specialization / character displacement • Labile traits, niche divergence, phylogenetic overdispersion • oaks in Florida, Lizards on Carribean islands • Evolutionary stasis and niche conservatism, led to the maintenance of similar phenotypes among species after vicariance events; species colonized similar habitats following glaciation • Conserved traits, niche conservatism, phylogenetic clustering

14. Jessica Savage

15. An ecophysiological and evolutionary perspective on functional diversity in the genus Salix Objectives: • Determine whether habitat specialization along a soil moisture gradient facilitates the co-occurrence of local willow species. • Determine whether trade-offs influence species habitat preferences. • Determine the phylogenetic structure of willow communities and the extent to which willows show phylogenetic niche conservatism.

16. Salixbebbiana Broad ecological amplitude. Riparian and upland white spruce forests, wet lowland thickets, black spruce treed bogs, prairie margins, dry south-facing slopes, and disturbed areas.

17. S. humilis Restricted to prairie – comparatively dry sites

18. S. pyrifolia • Restricted to bogs –waterlogged conditions

19. S. candida S. bebbiana

20. S. pyrifolia S. pedicellaris S. petiolaris S. discolor

21. Dry-down experiment

22. Willow seeds collected from Cedar Creek • Dry-down experiment to examine differences in drought tolerance • Hydraulic architecture • Gas exchange • Non-photochemical quenching and photoprotective mechanisms • Leaf drop, stem die-back, resprouting

23. Salix phylogeny Lekskinen and Alstrom-Rapaport 1998 New molecular phylogeny: Steve Brunsfeld University of Idaho

24. Phylogenetic structure and community assembly of long-term experimental plant communities Nitrogen Addition Experiment – E001 Old-Field Succession Experiment – E014 Oak-Savanna Burn Experiment – E133

25. Phylogenetic structure and community assembly of long-term experimental plant communities Oak-Savanna Burn Experiment – E133

26. Central Hypotheses • H1: Phylogenetic structure varies with spatial and temporal scale • H2: Environmental perturbation should alter phylogenetic structure • H3: Phylogenetic clustering should increase with increasing environmental heterogeneity

27. Charlie Willis

28. Marta Halina

29. Clarence Lehman Shawn McCarthy Adrienne Keen

30. Phylogeny of Cedar Creek plants Poaceae Asteraceae Eurosid1

31. Species are not randomly assembled Trait-environment correlations provide evidence for environmental filtering Shade Full sun

33. High trait similarity within communities is also evidence for environmental filtering

34. High trait similarity within communities and high trait conservatism cause phylogenetic clustering but scale dependent

35. How does environmental perturbation alter phylogenetic structure? • How does phylogenetic structure change with environmental heterogeneity?

36. Environmental perturbation changes the filtering process Drought

37. Phylogenetic clustering increases with environmental heterogeneity Phylogenetic overdispersion Phylogenetic clustering

38. Community age and assembly in a phylogenetic context: Forging links between ecology and evolution in the LTER framework • Cross-site initiative within the LTER • Collaboration among scientists at Cedar Creek and other LTER sites.

39. Community age and assembly in a phylogenetic context: Forging links between ecology and evolution in the LTER framework • Is phylogenetic structure dependent on • how open or closed communities are? • community diversity? • ecosystem type? • Insights can be gained by comparing communities across sites on a continental scale

40. Software development with Clarence Lehman

42. Within fields – alpha scale communities Values represent rankings of observed data relative to permuted data

43. Phylogenetic clustering is the dominant pattern at larger spatial scales and with greater heterogeneity Across fields – alpha scale communities Across fields – beta scale communities

45. Estimate – intercept • DFIN –use lai meter

46. Increased environmental heterogeneity results in greater phylogenetic clustering Phylogenetic Structure Within field variation for canopy cover (stdev)

47. Factors or forces that influence community assembly • Neutral processes • Environmental filtering • Species interactions • Dispersal