Brad Nelson BIOL 7083 Community Ecology Robert H. MacArthur: Life, Work, and Legacy

Brad NelsonBIOL 7083

Community Ecology

Robert H. MacArthur:Life, Work, and Legacy

Biographical Sketch

Robert H. MacArthurApril 2, 1930 – November 1, 1972

Personal Background• Born in Toronto, Ontario• Youngest son of John Wood

MacArthur (geneticist)• Married Elizabeth

Whittemore (1952)• Had four children• Died of renal cancer at the

age of 42

Biographical Sketch

Robert H. MacArthurApril 2, 1930 – November 1, 1972

Academic Background• Undergraduate degree

from Marlboro College, 1951• M.S. in Mathematics

from Brown University, 1953• Ph.D. from Yale University, 1958

(under G. Evelyn Hutchinson)• Postdoc at Oxford University• Professor at University of

Pennsylvania (1958-1965)• Professor at Princeton

University (1965-1972)

MacArthur Publications

Pianka and Horn (2005)

MacArthur Publications

Pianka and Horn (2005)

MacArthur Publication Characteristics

• Hypothetico-Deductive (H-D) method

• Most ecological studies at the time were descriptive


• Use of simple analytical models to generate and test hypotheses


• Circumvented traditional peer review process

• Proceedings of the National Academy of Science

• Princeton Monograph Series

• Journal of Theoretical Population Biology


• “Weak” tests of hypotheses

• Observational, not experimental

• Theory of Island Biogeography– Not tested

experimentally until 1969

• Warbler paper (1958)


• Many published mistakes

• MacArthur and Levins’ limiting similarity paper (1967)

• Warbler paper (1958):

• Limited use of citations


MacArthur and Pianka 1966

Selected Publications

The Theory of Island Biogeography

• About 4,150 citations since 2000 (Google Scholar)

On Optimal Use of a Patchy Environment (MacArthur and Pianka 1966)

• Search time vs. pursuit time• Considers effects of patchy environment• Landmark paper in optimal foraging theory

and behavioral ecology• About 110 citations since 2000 (Google

Scholar)


• N = number of items in diet

• TN = Time per food item

• TNS = Search time per

food item• TN

P = Pursuit time per food item

• Food types ranked from most efficient to least (calories/time)

• What is the optimal number of items to include in the diet?


Search vs. Pursuit (Uniform prey item abundance)

Search vs. Pursuit (Non-uniform prey item abundance)


Hunting time vs. travelling timeIn a patchy environment

Patches ordered by prey density

(Number of patches utilized)


Population Ecology of Some Warblersof Northeastern Coniferous Forests


• Five congeneric species of warblers found together without obvious interspecific differences

• How do they coexist?


• MacArthur notes: “…differences … are neither always necessary nor always sufficient to prevent competition and permit coexistence”

• He then documents species differences and concludes that they permit coexistence


• Data– Local censuses• Staggered population changes

– Museum and diet records– Field observation• 27 to 90 minutes of continuous

observation

– Wintering grounds observation


• Warbler coexistence attributed to differences in foraging zone (MacArthur 1958)

• If competition limits diversity (limiting similarity), more species should exist in more complex habitats because more types of foraging sites are available, reducing competition (MacArthur 1958, 1972)


• Evidence of competition and food limitation indirect or absent

Martin 1993:

• Alternative: “Potential-prey-site hypothesis”

• Bird species nest preferentially in different foliage• Predators should search

foliage where abundant species nest

• Preferential nest predation allows persistence of rare species


Martin 1993

MacArthur’s Legacy

• Added open-mindedness to the list of traits desirable in a scientist (along with empiricism and skepticism) (Fretwell 1975)

• Popularized H-D method in ecology– In roughly 5% of Ecology papers before MacArthur

and 50% by 1975 (Fretwell)• Optimal foraging and island biogeography

theory continue to be fruitful avenues of research


• Many ecologists tried to adapt the style of his warbler paper, typically with less success (Fretwell 1975, Kaspari 2008)

• Differences between species continued to be used as explanation for coexistence despite the lack of quantitative testing


• Does MacArthur’s research style have a place in community ecology today?

• Still common in biogeography (Esselstein?), where patterns can be observed, but laboratory and field experiments are not often possible

“To spread, a scientific meme should be correct. But it has to be infectious.”

--Kaspari (2008)

ReferencesFretwell, S.D. The impact of Robert MacArthur on Ecology. Annu. Rev. Ecol. Syst.

1975.6: 1-13.Kaspari, M. 2008. Knowing your warblers: thoughts on the 50th anniversary of

MacArthur (1958). Bulletin of the Ecological Society of America.MacArthur, R. H. 1958. Population ecology of some warblers of Northeastern

coniferous forests. Ecology 39: 599-619.MacArthur, R.H. and E.R. Pianka. 1966. On optimal use of a patchy environment.

The American Naturalist 100(916): 603-609.MacArthur, R.H. and E.O. Wilson. 1967. The theory of island biogeography.

Princeton University Press. 205 pp.Martin, T.E. 1993. Nest predation and nest sites: new perspectives on old

patterns. Bioscience 43(8): 523-532.Pianka, E. R. and H. S. Horn. 2005. Ecology's Legacy from Robert MacArthur.

Chapter 11 (pp. 213-232) in K. Cuddington and B. Biesner, eds. "Ecological Paradigms Lost: Theory Change." Academic Press.

Wilson, E.O. and G.E. Hutchinson. 1989. Robert Helmer MacArthur. Biographical Memoirs 58: 318-327.

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Brad Nelson BIOL 7083 Community Ecology Robert H. MacArthur: Life, Work, and Legacy