PARENT SESSION
Oral Session # 16: Ecological Modeling I.
Presiding: C Ray
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 102.
Lineage diversification under neutral theory: An empirical test.
Lake, Jeffrey*,1, Hubbell, Stephen1, 2, Kress, W. John3, 1 University of Georgia, Athens, GA2 Smithsonian Tropical Research Institute, Balboa, Panama, Panama3 National Museum of Natural History, Washington, DC
ABSTRACT- Classical community ecology theory rarely incorporates considerations over evolutionary time periods or considers predictions about evolutionary divergence of taxa. A new theory of biodiversity and biogeography, however, is unique in that it presents a number of testable hypotheses concerning lineage divergence and persistence (Hubbell 2001). Under this neutral theory, individuals have equal per capita probabilities of birth, death, and dispersal, and speciation is modeled as the probability of a speciation event per individual birth. Because abundant lineages have more births per unit time and are expected to have longer evolutionary lifespans, abundant lineages are expected to produce more daughter lineages than rare lineages simply by chance. Older lineages on average should be more abundant than recently derived ones. The theory, under the point mutation model of speciation, also predicts a fractal relationship between lineage number and time depth within a monophyletic clade. In contrast, other models of speciation, such as random fission speciation or peripheral isolate speciation, do not show a single fractal-scaling region. We explore this and other theoretical predictions of neutral theory and test them using a recently published phylogeny of family Costaceae in combination with extensive range data for the family, gathered from herbarium specimens and collections databases. Using empirical data from Costaceae, we examine the relationships between lineage age and range size, measure species richness in individual clades as a function of clade age, and compare these observations.
Key words: evolution, neutral theory, biogeography, speciation