Outline:

1.  Definition of niche: response functions vs. resource utilization functions

         A. Grinnell: emphasis on a species’ "place" (more than just locational)

         B. Elton: emphasis on a species’ role

         C. Hutchinson: emphasis on resources used by species

                     i. n-dimensional hypervolume

                     ii. fundamental vs. realized niches

                     iii. ecological release

2. So how can species coexist?  Answer: niche partitioning

         A. Limiting similarity

         B. Character displacement

                     i. the Hutchinsonian 1.3 size ratio

3. Niche vs. guild vs. functional group

niche =

According to Chase and Leibold (2003), the term niche was first used in the ecological sense by Johnson (1910): “One expects the different species in a region to occupy different niches in the environment” (referring to various ladybug species). However, this was (and is) an obscure work, so it is more usually attributed to Joseph Grinnell (1917). Despite Johnson’s chronological precedence, Grinnell is widely considered the person who established niche in the ecological lexicon. He used the term to denote a species’ "place" in the environment (i.e., set of abiotic conditions that meet a species’ life-history requirements)

         Difference between niche and habitat – Odum’s “address vs. profession” analogy

Charles Elton (1927) emphasized the biotic role of a species in the environment

Do empty niches exist?

G. Evelyn Hutchinson (1957)

"n-dimensional hypervolume" -

What does n stand for in the n-dimensional hypervolume?

1. fundamental (pre-interactive) niche - potential niche

2. realized (post-interactive) niche - actual niche

Example from Orians and Willson (1964) involving Red-winged Blackbirds (Agelaius phoeniceus) and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus)

         “Ecological release” – mongoose example

Ecological niches can thus be defined in terms of:
-response functions: how species are distributed on environmental gradients with respect to limitation and optimal performance (a physiological view, prevalent among plant ecologists), i.e., a species’ response to the environment (Whose ideas follow this?)
-resource utilization functions: how species use resources (Whose ideas follow this?)

So if a niche can only be occupied by one species, but if resources are limited such that competitors must share niche space, how similar in terms of niche can two species be and still coexist?  The competitive exclusion principle states that coexistence hinges on niche differentiation (a.k.a. niche partitioning).

Consider the words of Gause (1934), when discussing the competitive exclusion principle: "...as a result of competition two species hardly ever occupy similar niches, but displace each other in such a manner that each takes possess of certain kinds of food and modes of life in which it has an advantage over its competitor."  This is niche partitioning. 

But since most organisms are rare and secretive, how do we observe this? We usually do so only indirectly, via morphology (Ricklefs and Travis 1980):

limiting similarity

Hutchinsonian size ratio

Character displacement

Robert MacArthur (1958) examined niche overlap in a group of five sympatric warbler species (Bay-breasted, Myrtle, Blackburnian, Cape May, and Black-throated Green) in New Hampshire that were the same size and ate the same arthropod species in the same tree!: if they were so similar, how could they coexist?
- found that the birds partitioned the niche space physically

Similar but distinct terms:

Guild -

Functional group -

More recently:

- Pulliam (2000) showed how sometimes a realized niche could in fact be larger than the fundamental niche! (in situations where species occur in sink habitats)

         He also emphasized that dispersal limitation could result in many locations that have the necessary environmental conditions to support a species, yet remain unoccupied.

- Chase and Leibold (2003) sought to unify the niche concepts, integrating the Eltonian and Hutchinsonian niches in a common framework to define a niche as, “The joint description of the environmental conditions that allow a species to satisfy its minimum requirements so that the birth rate of a local population is equal to or greater than its death rate along with the set of per capita effects of that species on these environmental conditions.”

Because the niche concept examines coexistence, it is of fundamental importance to CE. But it has also been the source of much frustration and controversy due to differences in definitions (place vs. role vs. hypervolume), and a backlash against it occurred in the late 1970s-80s due to the lack of null niche models (part of the more general null model revolution in ecology as a whole at that time). And because of its inherent association with competition (which started to be criticized as the overriding factor driving community composition in the 1970s-80s), the niche concept likewise has been criticized. (For more info about the history of the niche concept, I recommend Gaffney 1975 and Chase & Leibold 2003.) The complexity of the niche concept has spurred reviews (e.g. Schoener 1989), calls for redefinition (Whittaker et al. 1973, Hurlbert 1981), and even calls for dismissal of the concept altogether (Hubbell 2001). An alternative approach will be the focus of our next lecture.

References:

NOTE: the Proceedings of the National Academy of Sciences vol. 106 suppl. 2 (2009) has a special colloquium devoted to the niche concept.

Abrams, P.A. 1983. The theory of limiting similarity. Annual Review of Ecology and Systematics 14:359-376.

Barabás, G., R.D. Andrea, and A.M. Ostling. 2013. Species packing in nonsmooth competition models. Theoretical Ecology 6:1-19.

Bruno, J.F., J.J. Stachowicz, and M.D. Bertness. 2003. Inclusion of facilitation into ecology theory. Trends in Ecology and. Evolution 18119-125.

Chase, J.M., and M.A. Leibold.  2003.  Ecological Niches: Linking Classical and Contemporary Approaches.  Univ. Chicago Press, Chicago, IL.

Elton, C.S. 1927. Animal Ecology. Sidgwick and Jackson, London, UK.

Gaffney, B.M. 1975. Roots of the niche concept. Am. Nat. 109:490.

Grinnell, J. 1917. The niche-relationships of the California Thrasher. Auk 34:427-433.

Hawkins, C.P., and J.P. MacMahon. 1989. Guilds: the multiple meanings of a concept. Annual Review of Entomology 34:423-451.

Hubbell, S.P. 2001. The Unified Neutral Theory of Species Abundance and Diversity. Princeton University Press, Princeton, NJ.

Hurlbert, S.H. 1981. A gentle depilation of the niche: Dicean resource sets in hyperspace. Evol. Theory 5:177-184.

Hutchinson, G.E. 1957. Concluding remarks. Cold Spring Harbor Symposium on Quantitative Biology 22:415-427.

Jaksíc, F.M. 1981. Abuse and misuse of the term "guild" in ecological studies. Oikos 37:397-400.

Johnson, R.H. 1910. Determinate Evolution in the Color Pattern of the Lady-Beetles. Publication No. 122 of the Carnegie Institute of Washington, Washington, D.C.

MacArthur, R.H. 1958. Population ecology of some warblers of northeastern coniferous forests. Ecology 39:599-619.

MacArthur, R.H. 1972. Geographical Ecology: Patterns in the Distribution of Species. Harper and Row, New York, NY.

MacArthur, R.H., and R. Levins. 1967. The limiting similarity, convergence, and divergence of coexisting species. American Naturalist 101: 377-385.

MacMahon, J.A., D.J. Schimpf, D.C. Andersen, K.G. Smith, and R.L. Bayn, Jr. 1981. An organism-centered approach to some community and ecosystem concepts. J. Theoret. Biol. 88:287-307.

Meszéna, G., M. Gyllenberg, L. Pásztor, and J.A.J. Metz. 2006. Competitive exclusion and limiting similarity: A unified theory. Theoretical Population Biology 69:68-87.

Mittelbach, G.G., and B.J. McGill. 2019. Community Ecology, 2nd ed. Oxford University Press, Oxford.

Orians, G.H., and M.F. Willson. 1964. Interspecific territories of birds. Ecology 45:736-745.

Pulliam, R.H. 2000. On the relationship between niche and distribution. Ecology Letters 3:349-361.

Ricklefs, R.E., and J. Travis. 1980. A morphological approach to the study of avian community organization. Auk 97:321-328.

Root, R.B. 1967. The niche exploitation pattern of the blue-gray gnatcatcher. Ecol. Monogr. 37:317-350.

Schoener, T.W. 1989. The ecological niche. Pp. 79-113 in: Ecological Concepts (J.M. Cherrett, ed.). Blackwell, Oxford.

Simberloff, D., and T. Dayan. 1991. The guild concept and the structure of ecological communities. Ann. Rev. Ecol. Syst. 22:115-143.

Terborgh, J., and S. Robinson. 1986. Guilds and their utility in ecology. Pp. 65-90 in: Community Ecology: Patterns and Processes (J. Kikkawa and D.J. Anderson, eds.). Blackwell Scientific Publications, Oxford, UK.

Whittaker, R.H., S.A. Levin, and R.B. Root. 1973. Niche, habitat, and ecotope. Am. Nat. 107:321-338.

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