Affiliation: | 1. Department of Statistics, Stanford University, , Stanford, California, 94305 U.S.A.;2. Department of Statistics, Columbia University, , New York, New York, 10027 U.S.A.;3. Department of Biology, Stanford University, , Stanford, California, 94305 U.S.A.;4. Department of Ecology, Evolution, and Marine Biology, UC Santa Barbara, , Santa Barbara, California, 93106 U.S.A. |