Abstract Detail

Systematics

Freyman, William A. [1], Höhna, Sebastian [2], Baldwin, Bruce G. [1].

Phylogenetic models of chromosome number evolution and chromosomal speciation.

Chromosomal changes play a fundamental role in evolution. Dysploid gains and losses in chromosome number, as well as polyploidization events, may drive reproductive isolation and lineage diversification. The recent development of probabilistic models of chromosome number evolution in the groundbreaking work by Mayrose et al. (2010) have enabled the inference of ancestral chromosome numbers over molecular phylogenies and generated new interest in studying the role of chromosome changes in evolution. However, these models assume all changes occur anagenetically (along branches), and do not model events that are specifically cladogenetic and may be expected if chromosomal changes result in reproductive isolation. Here we present a new class of models of chromosome number evolution that incorporate both anagenetic and cladogenetic change. These models allow us to determine the mode of chromosome number evolution; is chromosome evolution occurring primarily within lineages, primarily at lineage splitting, or in clade-specific combinations of both? Furthermore, we can estimate the location and timing of chromosomal speciation events over the phylogeny. We test our model’s accuracy with simulations and re-examine chromosomal evolution in Aristolochia, Carex section Ovales, Helianthus, Mimulus sensu lato, and Primula section Aleuritia.

1 - University of California Berkeley, Jepson Herbarium and Department of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, CA, 94720-2465, USA
2 - University of California Berkeley, Department of Statistics, 367 Evans Hall, Berkeley, CA, 94720-2465, USA

Keywords:
chromosome evolution
phylogenetic comparative methods
polyploidy
ancestral state reconstruction
character evolution.

Presentation Type: Oral Paper
Session: 21, Cooley Awards I
Location: 201/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 9:15 AM
Number: 21006
Abstract ID:311
Candidate for Awards:George R. Cooley Award