Biography:

Van Savage received his BS degree in physics with a minor in mathematics from Rhodes College in Memphis, TN where he graduated Phi Beta Kappa. He did his graduate work in theoretical physics at Washington University in St. Louis under advisors Carl Bender and Claude Bernard where he received a PhD for his thesis, Analytical and numerical techniques for studying PT-symmetric but non-Hermitian Hamiltonians. During graduate school, Savage was awarded a six-month NSF fellowship for research at the Santa Fe Institute. While there, Savage began his biological research by studying allometric relationshipshow biological rates and times, such as metabolic rate and lifespan, depend on body size and body temperature across species. Savage returned as a postdoctoral fellow to the Santa Fe Institute and Los Alamos National Laboratory where he was advised by Geoffrey West and James Brown. During this time, he continued his studies of biological scaling and focused on models for the structure and dynamics of vascular systems as shaped by evolutionary forces. Next, Savage moved to Harvard University as a systems biology postdoctoral fellow and then to Harvard Medical School as an Instructor. Savage used this time to combine allometric relationships, vascular system models, and evolutionary principles in order to address a wide range of questions that pertain to sleep, cell size, tumor growth, population growth and mortality, and speciation-extinction dynamics. In January 2009, Savage began an appointment as an Assistant Professor in the Department of Biomathematics at the UCLA Medical Center.

Abstract:

Modeling speciation-extinction dynamics to better understand biodiversity levels

Predicting the time scales for speciation and extinction is a litmus test for any theory of evolution and a lynchpin in arguments that high levels of biodiversity could have evolved over the time spans observed in the fossil record. The neutral theory of biodiversity (NBT), as formulated by Hubbell, successfully predicts several characteristics of biodiversity and links ecology to evolution. However, its predictions for the time scales of speciation and extinction are off by orders of magnitude (≤800 Myr). Moreover, its assumption that mutational and phenotypic changes are neutral has created much controversy. Here, we present a theory that incorporates aspects of NBT but is more consistent with biological knowledge. First, our theory allows new species to arise with more than one individual, as opposed to NBT and the point mutation model. Consequently, our theory can describe real speciation events in which new species often arise with a very large number of individuals (~106 individuals for germinate shrimp). Second, we allow time scales to be affected by environmental stochasticity, not just demographic stochasticity. Therefore, we allow for niche differences and obtain predictions for long times during which selective pressures may average out. We have both contemporary and fossil data for Foraminifera that give empirical estimates of contemporary levels of biodiversity and average time scales of speciation and extinction events over the past 30 Myr. Our new model yields predictions for speciation-andextinction time scales and species-abundance distributions that are consistent with this unique data set for Foraminifera.