Presentation Detail

SSB Symposium: Ernst Mayr Symposium

Matzke, Nicholas J [1].

Founder-event speciation dramatically improves likelihoods and alters parameter inference in Dispersal-Extinction-Cladogenesis (DEC) analyses.

Probabilistic modeling of geographic range evolution was a major advance in historical biogeography, making biogeographical problems accessible to model-based maximum likelihood (ML) and Bayesian methodologies. The most popular model is Dispersal-Extinction-Cladogenesis (DEC), implemented in the software LAGRANGE (Ree & Smith 2008). Standard DEC is a model with two free parameters specifying the rate of "dispersal" (range expansion) and "extinction" (range contraction). However, while dispersal and extinction rates are free parameters, the cladogenesis model is fixed, such that the geographic range of the ancestral lineage is inherited by the two daughter lineages through a variety of scenarios fixed to have equal probability. This fixed nature of the cladogenesis model means that it has been indiscriminately applied in all DEC analyses, and has not been subjected to any inference or formal model testing. I re-implement DEC in my R package BioGeoBEARS, which exactly reproduces LAGRANGE 2-parameter inferences and likelihoods. However, BioGeoBEARS also allows additional parameters controlling the probability of new cladogenesis models, such as "founder-event speciation", in which one daughter jumps to an area completely outside the ancestral range. The effects are dramatic in several test datasets. For example, for Hawaiian Psychotria, the original test clade for LAGRANGE, addition of founder-event speciation to a geographically unconstrained analysis improves the log-likelihood from -34.5 to -20.9, and the ML inferences for dispersal and extinction rates are moved to zero. The 3-parameter model is 300490 times more probable in terms of relative AIC weight. Thus, careful consideration of cladogenesis models in historical biogeography is recommended.

Related Links:
R package "BioGeoBEARS"

1 - University of California, Berkeley, Integrative Biology, 2851 Buena Vista Way, Berkeley, CA, 94708, United States

Keywords:
biogeography
phylogenetics.

Presentation Type: Symposium Presentation
Session: 212
Location: Ballroom 2/Cliff Lodge
Date: Sunday, June 23rd, 2013
Time: 11:45 AM
Number: 212006
Abstract ID:1242
Candidate for Awards:Ernst Mayr Award