Santa Fe Institute

About: Santa Fe Institute is a nonprofit organization based out in Santa Fe, New Mexico, United States. It is known for research contribution in the topics: Population & Complex network. The organization has 558 authors who have published 4558 publications receiving 396015 citations. The organization is also known as: SFI.

Landscapes and their correlation functions

Abstract: Fitness landscapes are an important concept in molecular evolution. Many important examples of landscapes in physics and combinatorial optimization, which are widely used as model landscapes in simulations of molecular evolution and adaptation, are “elementary”, i.e., they are (up to an additive constant) eigenfunctions of a graph Laplacian. It is shown that elementary landscapes are characterized by their correlation functions. The correlation functions are in turn uniquely determined by the geometry of the underlying configuration space and the nearest neighbor correlation of the elementary landscape. Two types of correlation functions are investigated here: the correlation of a time series sampled along a random walk on the landscape and the correlation function with respect to a partition of the set of all vertex pairs.

The biogeography and filtering of woody plant functional diversity in North and South America

Abstract: Aim In recent years evidence has accumulated that plant species are differentially sorted from regional assemblages into local assemblages along local-scale environmental gradients on the basis of their function and abiotic filtering. The favourability hypothesis in biogeography proposes that in climatically difficult regions abiotic filtering should produce a regional assemblage that is less functionally diverse than that expected given the species richness and the global pool of traits. Thus it seems likely that differential filtering of plant traits along local-scale gradients may scale up to explain the distribution, diversity and filtering of plant traits in regional-scale assemblages across continents. The present work aims to address this prediction.

Response to forum commentary on “toward a metabolic theory of ecology”

Abstract: Ecology, Vol. 85, No. 7MacArthur, R. H. 1968. The theory of the niche. Pages 159–176 in R. C. Lewontin, editor. Population biology and evo-lution. Syracuse University Press, Syracuse, New York, USA.West, G. B., J. H. Brown, and B. J. Enquist. 1997. A generalmodel for the origin of allometric scaling laws in biology.Science 276:122–126.West, G. B., J. H. Brown, and B. J. Enquist. 1999. The fourthdimension of life: fractal geometry and allometric scalingof organisms. Science 284:1677–1679.West, G. B., J. H. Brown, and B. J. Enquist. 2001. Ageneral model for ontogenetic growth. Nature413:628–631.

The Evolution of Strong Reciprocity: Cooperation in Heterogeneous Populations

Abstract: How do human groups maintain a high level of cooperation despite a low level of genetic relatedness among group members? We suggest that many humans have a predisposition to punish those who violate group-beneficial norms, even when this imposes a fitness cost on the punisher. Such altruistic punishment is widely observed to sustain high levels of cooperation in behavioral experiments and in natural settings. We offer a model of cooperation and punishment that we call strong reciprocity: where members of a group benefit from mutual adherence to a social norm, strong reciprocators obey the norm and punish its violators, even though as a result they receive lower payoffs than other group members, such as selfish agents who violate the norm and do not punish, and pure cooperators who adhere to the norm but free-ride by never punishing. Our agent-based simulations show that, under assumptions approximating likely human environments over the 100,000 years prior to the domestication of animals and plants, the proliferation of strong reciprocators when initially rare is highly likely, and that substantial frequencies of all three behavioral types can be sustained in a population. As a result, high levels of cooperation are sustained. Our results do not require that group members be related or that group extinctions occur.