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

Biographical Sketch Robert H. MacArthur April 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. MacArthur April 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 ( ) Professor at Princeton University ( )

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

MacArthur Publication Characteristics Use of simple analytical models to generate and test hypotheses

MacArthur Publication Characteristics Circumvented traditional peer review process Proceedings of the National Academy of Science Princeton Monograph Series Journal of Theoretical Population Biology

MacArthur Publication Characteristics “Weak” tests of hypotheses Observational, not experimental Theory of Island Biogeography – Not tested experimentally until 1969 Warbler paper (1958)

MacArthur Publication Characteristics Many published mistakes MacArthur and Levins’ limiting similarity paper (1967) Warbler paper (1958):

Limited use of citations MacArthur Publication Characteristics 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)

On Optimal Use of a Patchy Environment (MacArthur and Pianka 1966) N = number of items in diet T N = Time per food item T N S = Search time per food item T N 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?

On Optimal Use of a Patchy Environment (MacArthur and Pianka 1966) Search vs. Pursuit (Uniform prey item abundance) Search vs. Pursuit (Non-uniform prey item abundance)

On Optimal Use of a Patchy Environment (MacArthur and Pianka 1966) Hunting time vs. travelling time In a patchy environment Patches ordered by prey density (Number of patches utilized)

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

Population Ecology of Some Warblers of Northeastern Coniferous Forests

Five congeneric species of warblers found together without obvious interspecific differences How do they coexist?

Population Ecology of Some Warblers of Northeastern Coniferous Forests 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

Population Ecology of Some Warblers of Northeastern Coniferous Forests Data – Local censuses Staggered population changes – Museum and diet records – Field observation 27 to 90 minutes of continuous observation – Wintering grounds observation

Population Ecology of Some Warblers of Northeastern Coniferous Forests 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)

Population Ecology of Some Warblers of Northeastern Coniferous Forests 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 Population Ecology of Some Warblers of Northeastern Coniferous Forests 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

MacArthur’s Legacy 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

MacArthur’s Legacy 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)

References Fretwell, S.D. The impact of Robert MacArthur on Ecology. Annu. Rev. Ecol. Syst : Kaspari, M Knowing your warblers: thoughts on the 50 th anniversary of MacArthur (1958). Bulletin of the Ecological Society of America. MacArthur, R. H Population ecology of some warblers of Northeastern coniferous forests. Ecology 39: MacArthur, R.H. and E.R. Pianka On optimal use of a patchy environment. The American Naturalist 100(916): MacArthur, R.H. and E.O. Wilson The theory of island biogeography. Princeton University Press. 205 pp. Martin, T.E Nest predation and nest sites: new perspectives on old patterns. Bioscience 43(8): Pianka, E. R. and H. S. Horn Ecology's Legacy from Robert MacArthur. Chapter 11 (pp ) in K. Cuddington and B. Biesner, eds. "Ecological Paradigms Lost: Theory Change." Academic Press. Wilson, E.O. and G.E. Hutchinson Robert Helmer MacArthur. Biographical Memoirs 58:

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