Dan Simberloff
Ryan Eldridge
Simberloff vs. Diamond
• 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
Assembly Rules
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.”
Connor & Simberloff (1979)
• 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
• 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
• So the debate is ongoing
Figure from Collins, Simberloff & Connor 2011
Simberloff vs. Diamond cont: SLOSS
• From MacArthur &
Wilson’s Theory of
Biogeography (1963),
Diamond (1975b) infers
that due to the speciesarea relationship and the
importance of habitat
connectivity, one large
preserve should be
preferable to several
smaller preserves.
Figure from Diamond (1975b)
• 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
• 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 competitivelydriven checkerboard-like mechanism as a
possible force driving greater species richness
in several small preserves!
Simberloff vs. Diamond
Step 1: Diamond makes an assertion with broad
Step 2: Simberloff & colleagues accuse Diamond
of jumping to conclusions
Daniel S. Simberloff: Brief Life Summary
• Born 1942
• Raised in rural
• Demonstrates early
passion for nature,
collecting insects
from age 5
• Less able to pursue
hobby upon move to
NYC at 11
Life Summary
• Attends Harvard as a
math major
• Loses excitement over
math career and converts
to biology; introduced to
E.O. Wilson
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 19681997
• Currently on faculty at University of Kentucky
• CV:
• 300+ papers
• 70.38 citations per
paper (Web of
• 109 Book Reviews
Back to papers
Simberloff & Wilson 1969
• First experimental test
of Wilson’s equilibrium
Theory of
• D.S. and E.W. fumigate
6 mangrove islands in
Florida Keys and
observe the returns of
arthropod species
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
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)
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?
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
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
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
• 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
Simberloff & Gibbons 2004
• “Spontaneous collapse”: when an
invasive species’s population
abruptly declines without human
• 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
Diamond, J. M. 1975. Assembly of species communities. Pages 342-444 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. 1979 The assembly of species communities: chance or competition? Ecology
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. 2011. Binary matrices and checkerboard distributions of birds in the
Bismarck Archipelago. Journal of Biogeography 38:2373-2383.
Diamond, J. M. 1975b. The island dilemma: lessons of modern biogeographic studies for the design of nature
preserves. Biological Conservation 7:129-146.
Simberloff D. S. and Abele L. G. 1976. Island biogeography theory and conservation practice. Science 191:285-286.
Conservation Scholars: Daniel Simberloff. 2008. Web. Accessed 23 April 2014.
Simberloff, D. S. 2012. CV.
Simberloff, D. S. and Wilson, E.O. 1969. Experimental zoogeography of islands: the colonization of empty islands.
Ecology 50:278-296.
Simberloff, D. S. 1978. Using island biogeographic distributions to determine if colonization is stochastic. The
American Naturalist 112:713-726.
Simberloff, D. 1983. Competition theory, hypothesis-testing, and other community ecological buzzwords. The
American Naturalist 122:626-635.
Simberloff, D. and Stiling, P. 1996. How risky is biological control? Ecology 77:1965-1974.
Simberloff, D. 2003. How much information on population biology is needed to manage introduced species?
Conservation Biology 17:83-92.
Simberloff, D. and Gibbons, L. 2004. Now you see them, now you don’t!-population crashes of established
introduced species. Biological Invasions 6:161-172.

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