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Nested Subsets

Beginning in the mid-1980s, I examined hierarchical structure in species' distributions and, with collaborator Wirt Atmar, developed concepts and algorithms for exploring nested subsets of species in ecological communities.  Nestedness occurs when the species found in smaller fragments constitute nested or 'proper' subsets of those in progressively richer biotas. 

Nested subsets represent a hierarchical pattern of species composition among islands or fragments

The species found in various kinds of ecological communities often comprise nested subsets of those inhabiting richer ones. This phenonenon, termed nested subsets or nestedness, has biogeographic, ecological, and coevolutionary consequences.  It also has important implications for biological conservation. The following link accesses AICS Research Inc's website, where the software developed by Wirt Atmar and me can be freely downloaded. The software has the proper citation of:

Atmar, W.  & B.D. Patterson. 1995. The nestedness temperature calculator: a visual basic program, including 294 presence-absence matrices. AICS Research, Inc., University Park, NM, and The Field Museum, Chicago. [Please note that this program does not run under later versions of Windows and you will need to find a Windows Xp in order to run that program. An improved algorithm for running the analyses that lacks the visual interface was produced by Strona, G., P. Galli, D. Seves, S. Montano, and S. Fattorini. 2014. Nestedness for Dummies (NeD): A user-friendly web interface for exploratory nestedness analysis. Journal of Statistical Software 59: 1-9.]

Nested subsets of mammal species on Southwestern mountaintops,
as determined with the Nestedness Calculator

I periodically revisit and re-evaluate this paradigm, considering its extensions to other areas of biogeography, ecology, and evolution.  Nested patterns prove to be amazingly common in nature, and scientists now appreciate its significance for studying coevolutionary partnerships, especially mutualisms (plants and their pollinators/seed-dispersers) and host-parasite systems.  A 2009 paper in Ecography (written with Carl Dick and Katha Dittmar) offered a cautionary tale on their application to host-parasite systems. A 2011 paper with Mohammad Abu Baker (in Journal of Arid Environments) examined nestedness of Egyptian rodent assemblages. Nestedness was just one of several community structures examined in a 2012 paper in Global Ecology and Biogeography with the Willig lab at UCONNI am currently working with Argentinian post-doc Daniela Rodriguez and others on a meta-analysis of community structures in desert small mammal ensembles globally.

Publications on Nestedness

Patterson, B.D. & W. Atmar. 1986. Nested subsets and the structure of insular mammalian faunas and archipelagos. Biological Journal of the Linnean Society 28:65-82. download pdf

Patterson, B.D. 1987. The principle of nested subsets and its implications for biological conservation. Conservation Biology 1:323-334. download pdf

Patterson, B.D. 1990. On the temporal development of nested subset patterns of species composition. Oikos 59:330-342. download pdf

Patterson, B.D. & J.H. Brown. 1991. Regionally nested patterns of species composition in granivorous rodent assemblages. Journal of Biogeography 18:395-402. download pdf

Atmar, W. & B.D. Patterson. 1993. The measure of order and disorder in the distribution of species in fragmented habitat. Oecologia 96:373-382. download pdf

Patterson, B.D., V. Pacheco & S. Solari. 1996. Distributions of bats along an elevational gradient in the Andes of south-eastern Peru. Journal of Zoology 240:637-658. download pdf

Wright, D.H., B.D. Patterson, G. Mikkelson, A.H. Cutler & W. Atmar. 1998. A comparative analysis of nested subset patterns of species composition. Oecologia 113:1-20. download pdf

Patterson, B.D., D. Stotz, S. Solari, J. Fitzpatrick & V. Pacheco. 1998. Contrasting patterns of elevational zonation for birds and mammals in the Andes of southeastern Peru. Journal of Biogeography 25:593-607. download pdf

Patterson, B.D. 1999. Contingency and determinism in mammalian biogeography: the role of history. Journal of Mammalogy 80:345-360. download pdf

Patterson, B.D. & W. Atmar. 2000. Analyzing species composition in fragments. Pp. 9-24 in Isolated vertebrate communities in the tropics (G. Rheinwald, ed.). Bonner Zoologische Monographen 46, Bonn, Germany, 400 pp. pdf (970 kb).

Patterson, B.D., C.W. Dick & K. Dittmar. 2009. Nested distributions of bat flies (Diptera: Streblidae) on Neotropical bats: artifact and specificity in host-parasite studies. Ecography 32:481-487. pdf (159 kb)

Abu Baker, M. & B.D. Patterson. 2011. Patterns in the local assembly of Egyptian rodent faunas: co-occurrence and nestedness. Journal of Arid Environments 75:14-19. pdf (504 kb)

Presley, S.J., L.M.Cisneros, B.D. Patterson & M.R. Willig. 2012. Vertebrate meta-community structure along an extensive elevational gradient in the tropics: a comparison of bats, rodents, and birds. Global Ecology and Biogeography 21: 968-976. pdf (950 kb)