Community Ecology

1. Community Ecology

2. Geography Resources Phylogeny Community Community – collection of species that occur at the same place & time, circumscribed by natural (e.g., serpentine soil), arbitrary, or artificial (e.g., 1-m2 quadrat) boundaries Many prefer a more restrictive definition in which species must interact to be included, e.g., Whittaker (1975) Redrawn from Fauth et al. (1996)

3. Geography Resources Phylogeny Community Taxon – phylogenetically related group of species; a clade E.g., Mammalian Order Rodentia Taxon Redrawn from Fauth et al. (1996)

4. Geography Resources Phylogeny Guild Community Guild – a group of species “without regard for taxonomic position” that “exploit the same class of environmental resources in a similar way” (Root 1967) E.g., granivores Taxon Redrawn from Fauth et al. (1996)

5. Geography Resources Phylogeny Local guild Guild Community Local guild – a group of species that share a common resource and occur in the same community (Root 1967) E.g., Sonoran Desert granivores Taxon Redrawn from Fauth et al. (1996)

6. Geography Resources Phylogeny Local guild Guild Community Assemblage Assemblage – a group of phylogenetically related species within a community Taxon Redrawn from Fauth et al. (1996)

7. Geography Resources Phylogeny Local guild Guild Community Assemblage Assemblage – a group of phylogenetically related species within a community a.k.a. “Taxocene” (Hutchinson 1967) E.g., Sonoran Desert rodents Taxon Redrawn from Fauth et al. (1996)

8. Geography Resources Phylogeny Local guild Guild Community Ensemble Assemblage Ensemble – a phylogenetically bounded group of species that use a similar set of resources within a community E.g., Sonoran Desert granivorous rodents Taxon Redrawn from Fauth et al. (1996)

9. Geography Resources Phylogeny Local guild Guild Community Ensemble Assemblage E.g., granivorous rodents, pond-breeding salamanders… Taxon In this course any collection of two or more species is “fair game” for close scrutiny Redrawn from Fauth et al. (1996)

10. Robert H. MacArthur’s definition of Community “Any set of organisms currently living near each other and about which it is interesting to talk” (MacArthur 1971) Painting by D. Kaspari for M. Kaspari (2008) – anniversary reflection on MacArthur (1958)

11. Community Ecology Some historic landmarks Community Ecology has matured from purely descriptive studies (i.e., description & analysis of patterns) to mechanistic studies (i.e., investigations into processes) that aim to improve our explanatory & predictive abilities In any case, the tradition of good Natural History is not ignored by the best modern practitioners “Though I do not believe that a plant will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders.” (H. D. Thoreau ~1860)

12. Community Ecology Some historic landmarks Charles Darwin (1809 - 1882) Not the first “ecologist,” but clearly recognized the importance of organisms’ interactions(intraspecific, interspecific & with their abiotic environments) for evolution by natural selection Ernst Haeckel (1834 - 1919) coined “oekologie” for the study of Darwin’s multifaceted “struggle for existence” Photo from WikiMedia Commons

13. Community Ecology Some historic landmarks Charles Darwin (1809 - 1882) On biotic interactions: “Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!” (Darwin 1859) Photo from WikiMedia Commons

14. Community Ecology Some historic landmarks Charles Darwin (1809 - 1882) On abiotic processes, e.g., abiotic disturbance: “If turf which has long been mown… be let to grow, the most vigorous plants gradually kill the less vigorous, though fully grown plants; thus out of 20 species growing on a little plot of mown turf (3 feet by 4 feet) nine species perished from the other species being allowed to grow up freely…” (Darwin 1859) Photo from WikiMedia Commons

15. Community Ecology Some historic landmarks Ellen Swallow Richards (1842 - 1911) Chemist who probably “created and taught the first ecology curriculum” in the U.S. and may have introduced the term “ecology” into the English language (from Ernst Haeckel’s “oekologie”) Photo from WikiMedia Commons; for further details see Damschen et al. (2005)

16. Community Ecology Some historic landmarks Stephen Forbes (1844 - 1930) One of the earliest ecologists to examine multiple, cross-trophic level interactions simultaneously within an explicitly evolutionary framework Wondered how in spite of a constant “struggle for existence” some balance is nevertheless maintained in ecosystems (see: The lake as a microcosm, 1887) Photo from http://home.grics.net...

17. Community Ecology Some historic landmarks Henry Cowles (1869 - 1939) A pioneer of “dynamic ecology,” especially on the sand dunes of Lake Michigan Photo of Cowles from http://oz.plymouth.edu... Photo of Lake Michigan sand dune from http://ebeltz.net...

18. Community Ecology Some historic landmarks In the grand traditions of Alexander von Humboldt (1769 - 1859; the “father of biogeography”) &Alfred Russel Wallace (1823 - 1913)… Clinton Hart Merriam (1855 - 1942)also noticed that geographic changes in physical conditions often coincide with changes in biota Merriam devised Empirical Life Zones (similar biotic changes with increased elevation or latitude)

19. Community Ecology Some historic landmarks Leslie Holdridge (1907 - 1999) – devised Theoretical Life Zones (1947) Image from WikiMedia Commons

20. Community Ecology Some historic landmarks Clements vs. Gleason (1920s & 1930s) Frederic Clements (1874 - 1945) – thought succession always reached a predictable climax community; viewed communities metaphorically as “superorganisms” Henry Gleason (1882 - 1975) – proposed the “individualistic concept” of communities; discrete populations whose patterns of distribution and abundance give rise to communities as epiphenomena

21. Community Ecology Some historic landmarks Robert H. Whittaker (1869 - 1939) His gradient analyses helped end the Clements-Gleason debate Photo from WikiMedia Commons; figures from http://ecology.botany.ufl.edu...

22. Community Ecology Some historic landmarks We continue to need good descriptions of patterns, often supported by sound, quantitative techniques E.g., Bray & Curtis (1957) introduced ordination methods to define plant communities in Wisconsin See: The Ordination Web Page (http://ordination.okstate.edu) E.g., the Ecological Society of America, The Nature Conservancy, the U.S. Geological Survey, the U.S. National Park Service & others collaborate to continue to refine the National Vegetation Classification Standard (NVCS)

23. Community Ecology Some historic landmarks Margaret Davis (b. 1931)Her paleo-ecological perspective hashelped increase awareness of historical contingencies Photo of Davis from U. Minnesota; photo of pollen from http://www.gl.rhbnc.ac.uk...

24. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Heralded as milestones in ecology, his studies demonstrated the utility of field experiments for answering ecological questions; empirically assessed multiple hypotheses for intertidal zonation The concept of equifinality was formalized by Ludwig von Bertalanffy (1968; founder of General Systems Theory)– multiple hypotheses or mechanisms can equally explain or generate the same pattern Photo from UCSB

25. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Observations: Balanus balanoides – Larger barnacle, generally found lower in the intertidal Chthamalus stellatus – Smaller barnacle, generally found higher in the intertidal Photo from UCSB

26. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Photo from UCSB

27. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Observations: Balanus balanoides – Larger barnacle, generally found lower in the intertidal Chthamalus stellatus – Smaller barnacle, generally found higher in the intertidal Why might these patterns exist? Photo from UCSB

28. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Hypotheses: Differentialphysiological tolerances to desiccation and submersion Interspecific competition Predation (e.g., Thais lapillus is a predator of Balanus balanoides) Photo from UCSB

29. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Exclusion experiments, results & conclusions: The absence of competitors & predators produced no change in upper level of distributions For Chthamalus, removing Balanus increased downslope survivorship & distribution For Balanus, removing Thais increased downslope survivorship & distribution Photo from UCSB

30. Community Ecology Some historic landmarks Joseph H. Connell (b. 1923) Photo from UCSB; figure from Connell (1961; one of Connell’s 5 Science Citation Classics)

31. Community Ecology Some historic landmarks Robert H. MacArthur (1930 - 1972) More than most of his predecessors, MacArthur demonstrated the utility of simplifying assumptions combined with mathematical rigor for exploring ecological problems Criticisms: oversimplification; over-emphasized competition & equilibria Photo from Wikipedia

32. Community Ecology Some historic landmarks G. Evelyn Hutchinson (1903 - 1991) Conceived of fundamental vs. realized nichespaces or hyper-volumes “Ecologists use the metaphor of the ‘ecological niche’ to express the idea that plant and animal species play certain roles in the ecological community” (Kingsland 2005, pg. 1) Photo from Yale Peabody Archives

33. Community Ecology Some historic landmarks G. Evelyn Hutchinson E.g., Hutchinsonian ratios A ratio of ~ 1.3 in size occurs between pairs of coexisting species, possibly owing to inter- specific competition The idea & disagreement over how to test it helped motivate the development of null models in ecology Figure from Gotelli & Graves (1996, pg. x)

34. Community Ecology Some historic landmarks “Null hypotheses [models] entertain the possibility that nothing has happened…” (Strong 1980) “A null model is a pattern-generating model that is based on randomization of ecological data or random sampling from a known or imagined distribution. The null model is designed with respect to some ecological or evolutionaryprocess of interest. Certain elements of the data are held constant, and others are allowed to vary stochastically to create new assemblage patterns. The randomization is designed to produce a pattern that would be expected in the absence of a particular ecological mechanism…” (Gotelli & Graves 1996)

35. Community Ecology Some historic landmarks Stephen P. Hubbell (b. 1942) Neutral theory… asks how well community-level patterns conform to predictions under the simplifying assumption that all individuals are equal (in terms of probability of recruiting, dying, and replacing themselves through reproduction) “When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this!” (C. Darwin 1859) Photo from UCLA

36. Community Ecology Patterns & Processes Patterns – any observable properties of the natural world, often expressed as variable quantities or distributions (since variation characterizes every level of biological organization) Processes – the causal mechanisms that give rise to the patterns See also Watt (1947) Pattern and process in the plant community – J. Ecology

37. Processes that determine local community composition (most of which produce community structure that wouldn’t be predicted by null models) Redrawn from Morin (1999, pg. 27)

38. Processes that determine local community composition (most of which produce community structure that wouldn’t be predicted by null models) Community A Community B What relative contributions do the various processes make (and have made) towards maintaining (and originally creating) differences between communities A and B? Redrawn from Morin (1999, pg. 27)

39. Processes that determine local community composition (most of which produce community structure that wouldn’t be predicted by null models) From HilleRisLambers et al. (2012, pg. 228)

40. Parallels between Community Ecology & Population Genetics These affect biological variants, i.e., alleles or species Processes Drift Migration Selection Abiotic environment Biotic interactions (e.g., competition, predation, etc.) Speciation … and extinction (owing to drift & selection) Primary patterns(across space & time) Emergent patterns Productivity Species diversity Stability Species composition (identity & traits) Food-web connectance Etc. Species abundances Redrawn from Vellend & Orrock (2010)

41. Parallels between Community Ecology & Population Genetics Global community Drift Selection Speciation Migration Migration Regional community Drift Selection Speciation Local community Migration Migration Drift Selection Speciation Redrawn from Vellend & Orrock (2010)

42. Parallels between Community Ecology & Population Genetics Global community Drift Selection Speciation Migration Migration Regional community Drift Selection Speciation Migration Migration Local community A Local community B Drift Drift Selection Selection Speciation Speciation Redrawn from Vellend & Orrock (2010)

43. Parallels between Community Ecology & Evolutionary Theory Global community “the central narrative of evolutionary theory is that variation originates from random mutation and then natural selection in a local setting acts upon this variation to produce organic diversity” In a parallel fashion the “formational theory of communnity ecology” could be: “local interactions act upon the species arriving at the community’s boundary to produce a diversity of communities” Supply-side ecology Supply-side ecology Local community A Local community B Local interactions Local interactions Roughgarden (2009)

44. + - 0 A B A B A B - - - Antagonism (Predation/Parasitism) Amensalism Competition - + 0 A B A B A B 0 0 0 Neutralism (No interaction) Amensalism Commensalism - + 0 A B A B A B + + + Antagonism (Predation/Parasitism) Mutualism Commensalism Pair-wise species interactions (owing to acquisition or assimilation of resources, etc.) Influence of species A - (negative) 0 (neutral/null) + (positive) - Influence of Species B 0 + Redrawn from Abrahamson (1989); Morin (1999, pg. 21)

45. Pair-wise species interactions Interactions are often asymmetric, even when the sign of the interaction is the same in both directions (e.g., obligate for one organism, but facultative for the other) Species B +/+ _/+ Species A _/_ +/_

46. Laws in Community Ecology In any case, the laws of physics & chemistry apply (e.g., thermodynamics & stoichiometry) Are there “laws” specific to Ecology, and Community Ecology in particular?

47. To separate Ecology and Evolution into separate disciplines is somewhat artificial …just as is completely separating Community Ecology from other related sub-disciplines Nothing in biology makes sense except in the light of evolution (T. Dobzhansky 1973) All organisms interact with other organisms, both conspecific and heterospecific, and their environments; i.e., the evolutionary play takes place within an ecological theater (G. E. Hutchinson 1965) Ecologists and evolutionary biologists must recognize and embrace the complexity of natural ecosystems to understand them, and their components, much as Zen masters recognize and embrace the interconnectedness of the universe (D. P. Barash 1973)