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Dan Simberloff Ryan Eldridge

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Presentation on theme: "Dan Simberloff Ryan Eldridge"— Presentation transcript:

1 Dan Simberloff Ryan Eldridge

2 Simberloff vs. Diamond

3 Assembly Rules Diamond (1975) postulates 7 “assembly rules” governing communities based on field observations of bird distributions in the Bismarck Archipelago Attributes certain rules largely to competition

4 Assembly Rules Connor & Simberloff (1979)…don’t agree “At least one of the assembly rules is untestable, three are tautological consequences of definition plus elementary laws of probability, and the remaining three describe situations which would for the most part be found even if species were randomly distributed on islands.” (Connor & Simberloff 1979) “That such an all-encompassing theory should be built on so little evidence invites an examination of the procedures used in its construction.” (1979)

5 Connor & Simberloff (1979)

6 Checkerboards Connor & Simberloff’s (1979) refutation of Diamond (1975) used birds from New Hebrides and West Indies due to unavailability of Diamond’s data Upon release of data (Mayr & Diamond 2001), Collins, Simberloff & Connor (2011) use “binary matrices” to scan “checkerboard” distributions of birds in the Bismarcks to test Diamond’s assertion of competitive exclusion driving the observed patterns

7 Checkerboards Collins, Simberloff & Connor (2011) find greater percentage of species/genera exhibiting checkerboard distribution than expected by chance Result does not refute Diamond’s competitive exclusion hypothesis Paper does not dismiss competition as an important driver of species distributions, but argues insufficient evidence exists to rule out other hypotheses So the debate is ongoing Figure from Collins, Simberloff & Connor 2011

8 Simberloff vs. Diamond cont: SLOSS From MacArthur & Wilson’s Theory of Biogeography (1963), Diamond (1975b) infers that due to the species- area relationship and the importance of habitat connectivity, one large preserve should be preferable to several smaller preserves. Figure from Diamond (1975b)

9 SLOSS Simberloff & Abele (1976) counter: the Theory of Island Biogeography indeed suggests the superiority of a larger preserve over a smaller preserve all else being equal, but all else is generally not equal and the Theory does not differentiate between 1 large preserve and several small preserves whose combined area equals that of the large

10 SLOSS Simberloff & Abele (1976) use species-area equation to demonstrate capacity of a number of small reserves to support a greater number of species than a single large Interestingly, they invoke a competitively- driven checkerboard-like mechanism as a possible force driving greater species richness in several small preserves!

11 Simberloff vs. Diamond step-by-step Step 1: Diamond makes an assertion with broad implications Step 2: Simberloff & colleagues accuse Diamond of jumping to conclusions

12 Daniel S. Simberloff: Brief Life Summary Born 1942 Raised in rural Pennsylvania Demonstrates early passion for nature, collecting insects from age 5 Less able to pursue hobby upon move to NYC at 11

13 Life Summary Attends Harvard as a math major Loses excitement over math career and converts to biology; introduced to E.O. Wilson 4/web_images_oct/awards/eminent_simberloff.jpg

14 Life Summary Taken on by Wilson as a grad student Wilson encourages Simberloff’s application of his math background to ecology Receives PhD in 1969 Holds faculty position at Florida State Currently on faculty at University of Kentucky

15 Accomplishments CV: 13.org/admin/pers onfile/ pdf 13.org/admin/pers onfile/ pdf 300+ papers published citations per paper (Web of Science) 109 Book Reviews

16 Back to papers

17 Simberloff & Wilson 1969 First experimental test of Wilson’s equilibrium Theory of Biogeography D.S. and E.W. fumigate 6 mangrove islands in Florida Keys and observe the returns of arthropod species

18 Simberloff & Wilson 1969 Re-colonization of islands found to conform to Theory All islands return to original species richness—this suggests the presence of equilibrium D.S. and E. W. suggest species richness overshoots equilibrium initially, trends downwards (with oscillations) toward equilibrium due to interspecies interaction (i.e. competition/predation) Existence of equilibrium curves lays foundation for Diamond (1975)

19 Advocacy of Null Models Many ecological studies had introduced empirically-based models attributing their patterns to such forces as competition (“largely as a legacy of Robert MacArthur”, Simberloff 1978) Simberloff argued that these explanations had largely not been tested against pure stochasticity (Simberloff 1978)

20 Null models cont. “Confirmatory evidence per se is not very compelling since one can always find some.” (Simberloff 1983) Simberloff (1983) argues that community ecology is full of theories that have not been well-tested, and that a “falsification procedure” is needed— i.e., a null hypothesis “The full range of forces generating the pattern [should] be recognized so that the search for its causes [are] not […] unduly circumscribed initially.” (Simberloff 1983) Simberloff’s single greatest contribution to community ecology?

21 Simberloff Update Now at University of Tennessee, Simberloff directs the Institute for Biological Invasions His research spanning roughly the 90’s until now has focused on the ecology of invasive species—some of these studies rank among his most-cited papers

22 Simberloff & Stiling (1996) Paper questions popular assumption that modern species introductions as biological control methods are sufficiently safe Mention that most cases have not been studied well enough to say whether introduced species are negatively affecting their new environment Bring up competition with native species, ecosystem effects and other risks associated with species introductions Article cited 360+ times

23 Simberloff 2003 Argues that intensive study of the population biology of invasive organisms is often not necessary, and that the time required to do so can be costly due to continual proliferation of the species Cites numerous examples of invasive species that were eradicated or controlled using very basic knowledge of the organism’s biology Emphasizes that early action is often the most effective way to limit damage caused by exotics

24 Simberloff & Gibbons 2004 “Spontaneous collapse”: when an invasive species’s population abruptly declines without human intervention Parasites and resource shortages have generally been invoked to explain such declines But the causes remain speculation in most cases While a potentially important aspect of invasion ecology, Simberloff & Gibbons do not ascribe great importance to these scenarios in management: spontaneous collapse is not the norm, and the examples contained in the paper comprised a large percentage of those to have been observed

25 References Diamond, J. M Assembly of species communities. Pages in M. L. Cody and J. M. Diamond, editors. Ecology and evolution of communities. Harvard University Press. Cambridge, Massachusetts, USA. Connor, E. F. and Simberloff, D The assembly of species communities: chance or competition? Ecology 60: Mayr, E. and Diamond, J. (2001) The birds of northern Melanesia: speciation, ecology, and biogeography. Oxford University Press, Oxford. Collins, M. D., Simberloff, D., and Connor, E. F Binary matrices and checkerboard distributions of birds in the Bismarck Archipelago. Journal of Biogeography 38: Diamond, J. M. 1975b. The island dilemma: lessons of modern biogeographic studies for the design of nature preserves. Biological Conservation 7: Simberloff D. S. and Abele L. G Island biogeography theory and conservation practice. Science 191: Conservation Scholars: Daniel Simberloff Web. Accessed 23 April Simberloff, D. S CV. Simberloff, D. S. and Wilson, E.O Experimental zoogeography of islands: the colonization of empty islands. Ecology 50: Simberloff, D. S Using island biogeographic distributions to determine if colonization is stochastic. The American Naturalist 112: Simberloff, D Competition theory, hypothesis-testing, and other community ecological buzzwords. The American Naturalist 122: Simberloff, D. and Stiling, P How risky is biological control? Ecology 77: Simberloff, D How much information on population biology is needed to manage introduced species? Conservation Biology 17: Simberloff, D. and Gibbons, L Now you see them, now you don’t!-population crashes of established introduced species. Biological Invasions 6:


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