1. Origins & Maintenance of Diversity A Hierarchy of Processes

2. Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993)

3. Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993) Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level

4. Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993) Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level

5. Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993) Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level

6. Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993) Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level

7. Origins & Maintenance of Diversity A Hierarchy of Processes Figure 30.2 from Ricklefs & Schluter (1993) Processes operate on a variety of temporal & spatial scales to influence diversity The levels are nested Unique (chance) events may occur at any level

8. Regional diversity Local diversity Species production Habitat selection Competitive exclusion Biotal interchange Stochastic extinction Mass extinction Predatory exclusion A major challenge confronting advances to a research program that investigates this multi-scale set of processes is the reconstruction of historical events So, community ecologists have added phylogenetic & biogeographic analyses (e.g., phylogeography) to their toolkits… Origins & Maintenance of Diversity A Hierarchy of Processes Redrawn from figure 30.1, Ricklefs & Schluter (1993)

9. Origins & Maintenance of Diversity Phylogenetic Perspectives

10. Losos (1996) “If species adapted rapidly and without constraint, and if any lineage could occur in any community, then we would expect differences in community structure to be indicative of environmental differences. Because lineages differ in their evolutionary potential and are geographically restricted, however, comparisons of community structure must take account of communities’ histories… “…differences in the structure of communities may result as much from the differences in the lineages that occur in different communities as from differences in environmental conditions” “Phylogenetic information about the constituent lineages in a community can allow lineage effects to be factored out, thus allowing an assessment of environmental determinants of community structure” Origins & Maintenance of Diversity Phylogenetic Perspectives

11. Ricklefs & Schluter (1993) An example from passerine birds compared between Panama and Illinois: Why do different areas vary in species richness of particular clades? “The approximately twofold difference in average age of the taxa matches the twofold difference in diversity, although age and diversity are not well correlated among individual clades.” Origins & Maintenance of Diversity Phylogenetic Perspectives Table 30.2 from Ricklefs & Schluter (1993)

12. Losos (1990, 1996) An example from Anolis lizards inhabiting Caribbean islands: Where & under what community conditions did patterns of niche-use originate? Origins & Maintenance of Diversity Phylogenetic Perspectives

13. 27 islands of the Lesser Antilles contain either one or two species of Anolis lizards; on 9 of the 10 two-species islands, the species differ considerably in size (one large & one small), whereas on 16 of 17 one-species islands, the species are intermediate in size Origins & Maintenance of Diversity Phylogenetic Perspectives Figure from Losos (1996)

14. Hypotheses: (1) “Size adjustment (character displacement): Species of similar size colonize an island & evolve in opposite directions in situ to minimize resource competition” Origins & Maintenance of Diversity Phylogenetic Perspectives From Losos (1990)

15. Large 2 Large 2 Large 2 Small 2 Small 2 Small 2 Int. 1 Int. 1 Int. 1 Int. 1 (Int. 1) Size adjustment (Int. 1) Increase in size Decrease in size Switch to 2-species island Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1990)

16. Hypotheses: (1) “Size adjustment (character displacement): Species of similar size colonize an island & evolve in opposite directions in situ to minimize resource competition” (2) “Size assortment: Competitive exclusion or other processes prevent similar-sized species from colonizing the same island; only species that are already dissimilar in size can successfully colonize and coexist” Origins & Maintenance of Diversity Phylogenetic Perspectives From Losos (1990)

17. Large 2 Large 2 Large 2 Small 2 Small 2 Small 2 Int. 1 Int. 1 Int. 1 Int. 1 (Large 1) (Int. 1) (Small 1) (Int. 1) Size assortment (Int. 1) Increase in size Decrease in size Switch to 2-species island Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1990)

18. Large 2 Large 2 Large 2 Small 2 Small 2 Small 2 Int. 1 Int. 1 Int. 1 Int. 1 (Large 2) (Int. 1) (Small 2) (Int. 1) Size assortment & size adjustment (Int. 1) Increase in size Decrease in size Switch to 2-species island Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1990)

19. Large 2 Large 2 Int. 2 Small 2 Small 1 Small 1 Int. 1 Int. 2 Small 1 Int. 1 (Large 2) (Int. 2) (Int. 1) (Small 1) (Int. 1) No evidence for size assortment or size adjustment (Int. 1) Increase in size Decrease in size Switch to 2-species island Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1990)

20. “In the northern Lesser Antilles, large & small size appear to have evolved simultaneously when two lineages came into sympatry… exactly the prediction of a hypothesis of character displacement…” Dominica Origins & Maintenance of Diversity Phylogenetic Perspectives Figure from Losos (1996); quote from Losos (1990)

21. “By contrast, in the southern Lesser Antilles, evolutionary change in body size appears to have been unrelated to whether a species occurred in sympatry with congeners… Consequently, the existence of size patterns must have resulted from a process of ecological sorting in which only dissimilar- sized species can successfully colonize and coexist on the same island…” Martinique Dominica Origins & Maintenance of Diversity Phylogenetic Perspectives Figure from Losos (1996); quote from Losos (1990)

22. “Thus, the relative importance of co-evolutionary processes in determining community structure differs between the northern and southern Lesser Antilles, a result that is only apparent when these lizards are studied in a historical [phylogenetic] context” St. Maarten St. Eustatius Martinique Dominica Origins & Maintenance of Diversity Phylogenetic Perspectives Figure from Losos (1996); quote from Losos (1990)

23. McPeek (1995) An example from damselflies inhabiting freshwater lakes: Where and under what community conditions did patterns of niche-use originate? Origins & Maintenance of Diversity Phylogenetic Perspectives

24. E. boreale E. hageni E. geminatum E. aspersum E. traviatum E. antennatum E. signatum E. vesperum +2.0 0.0 -0.5 +1.5 -0.3 0.0 +0.1 0.0 +0.9 +0.4 0.0 Numbers represent the amount of evolutionary change in limb length between ancestor & descendant, as deduced using parsimony methods for reconstruction of ancestral character states Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1996), based on McPeek (1995)

25. E. boreale E. hageni E. geminatum E. aspersum E. traviatum E. antennatum E. signatum E. vesperum +2.0 0.0 -0.5 +1.5 -0.3 0.0 +0.1 0.0 +0.9 +0.4 0.0 The common ancestor inhabited lakes occupied by fish, where its best strategy to avoid predation was to hide Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1996), based on McPeek (1995)

26. E. boreale E. hageni E. geminatum E. aspersum E. traviatum E. antennatum E. signatum E. vesperum +2.0 0.0 -0.5 +1.5 -0.3 0.0 +0.1 0.0 +0.9 +0.4 0.0 Bars represent transitions to fishless lakes, where a damselfly’s best strategy to avoid predation by dragonflies is to swim or run away Origins & Maintenance of Diversity Phylogenetic Perspectives Redrawn from Losos (1996), based on McPeek (1995)

27. Cadle & Greene (1993) An example from Neotropical snake assemblages: For areas that differ in the species richness of particular clades, do contrasting characteristics of those clades contribute to emergent community-level properties? Origins & Maintenance of Diversity Phylogenetic Perspectives

28. Cadle & Greene (1993) Observations: Three main lineages of Neotropical snakes within the family Colubridae “Goo-eaters” Origins & Maintenance of Diversity Phylogenetic Perspectives

29. Cadle & Greene (1993) Observations: Three main lineages of Neotropical snakes within the family Colubridae The xenodontine lineages originated & diversified relatively isolated from one another, even though the current distributions overlap substantially Colubrines radiated relatively recently worldwide Principal zones of radiation Origins & Maintenance of Diversity Phylogenetic Perspectives

30. Cadle & Greene (1993) Observations: Three main lineages of Neotropical snakes within the family Colubridae The xenodontine lineages originated & diversified relatively isolated from one another, even though the current distributions overlap substantially The lineages differ in mean body size, diet, and etc. Origins & Maintenance of Diversity Phylogenetic Perspectives

31. Cadle & Greene (1993) An example from Neotropical snake assemblages: For areas that differ in the species richness of particular clades, do contrasting characteristics of those clades contribute to emergent community-level properties? Observation: Sites in Central & South America differ in body size distribution, diet & etc. of their snakes, but those differences are largely due to differences in the dominant clades occupying those sites Conclusion: The overall size distribution, diet & etc. of a community bears a direct relationship to the clade composition (i.e., history matters) Origins & Maintenance of Diversity Phylogenetic Perspectives

32. Cadle & Greene (1993) An example from Neotropical snake assemblages: For areas that differ in the species richness of particular clades, do contrasting characteristics of those clades contribute to emergent community-level properties? Suggested a reinterpretation of patterns from Brazilian caatinga… In contrast to Vitt and Vangilder (1983), “we do not need to ‘explain’ the absence of invertebrate-eating snakes [in the caatinga community] in terms of present-day ecological factors if historical events resulted in the absence of appropriate lineages from the community” Origins & Maintenance of Diversity Phylogenetic Perspectives

33. 2. Species that colonized a community but did not lead to ecological shifts in residents (new associations of lineages, but ancestral ecologies were maintained) Losos (1996), after Brooks & McLennan (1991, 1993) “Four components contributing to community structure”: 1. Species that interact in the same way that their ancestors did in other communities 3. Species that arose in situ and evolved different ecological requirements 4. Species that colonized a community and interacted with species already present, leading to ecological shifts in the colonizer, the resident, or both Origins & Maintenance of Diversity Phylogenetic Perspectives

34. Webb et al. (2002) “The differences among species that co-occur in an ecological community are the result of modifications to a common ancestor that the species all ultimately share” Phylogenetic relationships provide “a new dimension of information… with which to make sense of these differences among species” Differences among species are due to divergence (either in sympatry or allopatry), which may have occurred recently due to changes in the focal species, or in the distant past due to changes in the ancestors of the focal species Similarities among species are either due to shared ancestry, or convergence (either in sympatry or allopatry) Origins & Maintenance of Diversity Phylogenetic Perspectives

35. Webb et al. (2002) Origins & Maintenance of Diversity Phylogenetic Perspectives

36. Webb (2000) An example from rainforest trees: Is the distribution of species among habitats (or samples) in a community nonrandom with respect to phylogeny? “The demonstration of nonrandom spatial association of species with habitats is a necessary but not sufficient criterion in demonstrating that habitat partitioning is important in enabling many species to coexist…” “However, to be able to show that co-occurring species in different habitats are more ecologically similar than expected by chance would support the case that species are partitioning habitat according to their autecology” “On the other hand, if species in local communities were less ecologically similar than expected by chance, this would suggest that negative neighborhood interactions [e.g., competition] were causing increased mortality among ecologically similar species…” Origins & Maintenance of Diversity Phylogenetic Perspectives

37. Webb (2000) Specific question: Are the tree species in 0.16-ha plots more or less related than expected if such communities were formed from a random sampling of available species in the larger area (150 ha)? “…because of the conservatism of many species traits in the evolution of a lineage, we expect, in general, a positive relationship between a measure of the phylogenetic relatedness of two species and a measure of their overall life- history and ecological similarity…” Origins & Maintenance of Diversity Phylogenetic Perspectives

38. Webb (2000) What about character displacement? “Under certain circumstances, where new niches are encountered (e.g., on islands) or where competition with an ecologically similar species is strong and predictable, particular ecological traits of an organism may change adaptively over time… leading to a breakdown of the correlation between phylogenetic relatedness and ecological similarity for some traits… However, even in these organisms we would still expect that a measure of ‘overall’ ecological similarity, taking many traits into account, would be correlated with phylogenetic relatedness” Origins & Maintenance of Diversity Phylogenetic Perspectives

39. Webb (2000) Data: 28 tree plots of 40 x 40 m (0.16 ha) scattered throughout 150 ha of lowland tropical forest, Indonesia How to efficiently estimate relatedness? Origins & Maintenance of Diversity Phylogenetic Perspectives

40. Webb (2000) Data: 28 tree plots of 40 x 40 m (0.16 ha) scattered throughout 150 ha of lowland tropical forest, Indonesia How to efficiently estimate relatedness? Created “supertrees” from published phylogenies and then counted nodes separating terminal taxa Origins & Maintenance of Diversity Phylogenetic Perspectives

41. ABCDEF Phylogeny Community 1: A, B, C, DCommunity 2: A, B, E, F A B C D A B C 1 2 3 4 4 2 Nodal distances: A B E F A B E 1 5 1 5 5 5 Greatest possible mean pairwise nodal distance for a community of 4 taxa (given this phylogeny) = 3.66 nodes (for A, B, E, F) Mean pairwise nodal dist. = (1+2+4+2+4+3)/6 = 2.66 Mean pairwise nodal dist. = (1+5+5+5+5+1)/6 = 3.66 Net Relatedness Index = 1 - (2.66/3.66) = 0.273 Net Relatedness Index = 1 - (3.66/3.66) = 0.0 From Webb (2000)

42. ABCDEF Phylogeny Community 1: A, B, C, DCommunity 2: A, B, E, F A B C D A B C 1 2 3 4 4 2 Nodal distances: A B E F A B E 1 5 1 5 5 5 Nearest Taxa Index = 1 - (1.75/2.0) = 0.125 Mean nearest nodal dist. = (1+1+1+1)/4 = 1.0 Greatest possible mean nearest nodal distance for a community of 4 taxa (given this phylogeny) = 2.00 nodes (for A, C, D, F) Mean nearest nodal dist. = (1+1+2+3)/4 = 1.75 Nearest Taxa Index = 1 - (1.0/2.0) = 0.5 From Webb (2000)

43. Methods: Webb (2000) created 1000 sets of plots with randomized species membership, following two simple rules: (1) each species occurred in the same total number of plots as observed; (2) each plot contained the same total number of species as observed Randomized plots represent expected distributions of species if membership in plots occurs at random with respect to the overall species pool of 324 observed species throughout the 150-ha area Compared the observed Net Relatedness Index (NRI) and the observed Nearest Taxa Index (NTI) to the appropriate distributions of expected values Results: The mean NRI did not differ significantly from the expectation of the null hypothesis, but the mean NTI was significantly greater than expected Origins & Maintenance of Diversity Phylogenetic Perspectives

44. Conclusion: Overall, species in the 0.16-ha plots were more likely to be found with species separated by fewer nodes than expected by chance (e.g., congeners) We can therefore reject the null hypothesis that species are assembled into local communities at random; there is evidence that species occur with closely related species more than we expect by chance Origins & Maintenance of Diversity Phylogenetic Perspectives