Abstract Detail

Systematics

Abbo, Tito [1], Morrison, Glen R [1], Huang, Yi [2], Buehlman, Angela [3], Parker, V. T. [4], Sanders, Andrew [5], Jolles, Diana [6], Stoughton, Thomas [7], Litt, Amy [8].

Studying introgression and species relationships in a high diversity system is to explore the relationship between introgression and divergence.

Phylogenomics research suggests introgression is a normal element of the early stages of speciation, but its precise role in evolution remains uncertain. Therefore, it is important to look for patterns of introgression in a high diversity system to understand how introgession varies with divergence and whether it promotes or hinders speciation. Arctostaphylos Adans. is the most diverse woody genus in the California Floristic province (CAFP) with c. 105 taxa. Most are found exclusively in California and are of conservation concern. Understanding the species relationships within Arctostaphylos has been historically challenging with both morphological and molecular methods. Taxonomic identification is complicated by relative uniformity of floral characters, high variability among descriptive characters such as pubescence, and limited access to material from rare and remote taxa. A key complication for Arctostaphylos systematics is the preponderance of morphologically intermediate individuals, traditionally interpreted as a result of introgression. This, as well as the presence of putative allotetraploid lineages suggest that reproductive isolation is limited in the genus. Early molecular phylogenetics research using the nuclear ITS region identified an early divergence into two sister clades but failed to resolve terminal taxa. We present preliminary phylogenomic data for 27 Arctostaphylos species (37 taxa including subspecies) with ≳ 3 replicates per taxon using the ddRAD sequencing method. Our SVD-quartets phylogenetic tree shows a high-level of geographic structure with clusters of narrowly distributed, closely related lineages forming clades that correspond to important CAFP physiographic regions. We also present evidence for the polyphyly of the A. glandulosa tetraploid complex. We are also carrying out sample-set wide introgression tests using the D-statistic to explore how introgression varies as species and clades diverge. We are especially interested in the origin of polyploid lineages, and we are investigating whether there is a pattern in the age of lineages that have given rise to allopolyploid taxa. We hypothesize that polyploidization occurs in hybrids of diverged lineages that have begun to form reproductive barriers. This research will help biologists understand the general interplay between introgression, hybridization and speciation.

1 - University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
2 - Riverside, CA, United States
3 - University of California, Riverside, Botany & Plant Sciences, Riverside, CA, 92521
4 - San Diego state university
5 - UC Riverside
6 - Plymouth State University, Biological Sciences, 17 High Street, Msc 48, Plymouth, NH, 03264, United States
7 - 2211 Shenandoah Lane, Glendora, CA, 91741, United States
8 - University Of California Riverside, Botany Dept, 900 University Ave, Riverside, CA, 92521, United States

Keywords:
Arctostaphylos
introgression
phylogeny
systematics
RADseq
phylogenomics.

Presentation Type: Oral Paper
Number: COOLEY003
Abstract ID:799
Candidate for Awards:George R. Cooley Award