Abstract Detail

Systematics

Morales-Briones, Diego [1], Tank, David [2].

Disentangling the Reticulate Evolutionary History of the Neotropical Plant Radiation of Lachemilla (Rosaceae).

Hybridization has contributed extensively to plant diversity, but it also represents a challenge for phylogenetic reconstruction due the incongruence patterns that produces within and between the nuclear and chloroplast genomes. Additional processes produce similar reticulate patterns, creating the necessity to disentangle them and estimate phylogenetic networks that best represent reticulation. Here we have combine extensive natural history collections with a plurality of phylogenetic methods to elucidate the reticulate evolutionary history of the plant genus Lachemilla. This is a morphologically variable group of ca. 60 species of herbs and shrubs, with a ubiquitous presence in the Neotropical high-altitude grasslands. First, we reconstructed the phylogeny of Lachemilla using single nuclear and plastid sequences and identified four major clades that are in part congruent with morphological classifications. Additionally, widespread patterns of cytonuclear discordance were detected that, in combination with chromosome counts and genome size estimates, provides the first evidence of allopolyploid in Lachemilla. Later, we conducted a phylogenomic analysis of 396 low-copy nuclear genes and complete chloroplasts and found extensive conflict among gene trees and species trees. Moreover, we found that different species trees methods recover alternative topologies among the four main clades of Lachemilla. Species network analyses later revealed that one of these clades is of ancient hybrid origin, and represents the main source of the incongruence among the species trees. Furthermore, we found evidence for a whole genome duplication event shared by Lachemilla and allied genera. Finally, we obtain allelic information for the nuclear ribosomal cistron and several chloroplast regions and found direct evidence of allopolyploid for 30 species. With this work we attempted to clarify the role that hybridization has played in the evolutionary history of Lachemilla, which will facilitate future research in this group and also contributes to broader questions regarding the evolutionary and ecological consequences of polyploidy and hybridization in plants.

1 - University of Minnesota, Plant and Microbial Biology, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA
2 - University Of Idaho, Biological Sciences, 875 Perimeter Dr MS 3051, Moscow, ID, 83844, United States

Keywords:
Cytonuclear discordance
Hybridization
Phylogenomics
Phylogenetic networks
Polyploidy
Rosaceae
Species tree.

Presentation Type: Oral Paper
Session: 19, ASPT Cooley Awards I
Location: 110/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 8:00 AM
Number: 19001
Abstract ID:64
Candidate for Awards:George R. Cooley Award