Abstract Detail

Systematics Section/ASPT

Knox, Eric [1].

Cladogenesis and Reticulation in Downingia (Lobeliaceae).

Plants have three genomic compartments with different evolutionary properties. Plastid genomes do not recombine or fuse, and the tempo of point mutations provides excellent markers of phylogenetic relationships. Nuclear genomes recombine in sexually reproducing organisms, and concerted evolution of the nuclear ribosomal RNA cistrons homogenizes mutations. Most plant mitochondrial genomes are maternally inherited and paradoxically have few point mutations despite frequent rearrangements and high levels of non-essential DNA turnover, but mitochondrial genomes can fuse and some lineages have accelerated mutation rates. Downingia comprises 13 annual species that grow in vernal pools that form due to the winter rainfall pattern in California. Downingia has accelerated mutation rates in all three genomes, which capture a rich history of cladogenesis (lineage splitting) and reticulation (lineage fusion). The earliest reticulation event in Downingia occurred 7 million years ago. The plastid genomes traces only one of the two lineages. The nuclear ribosomal cistrons have a blended inheritance of phylogenetic markers from both lineages. The mitochondrial genomes of both lineages fortuitously fused, thereby preserving divergent copies of the mitochondrial genes from each lineage. Although each genomic compartment recorded this ancient reticulation event differently, the synthesis of all three lines of evidence provide a congruent reconstruction of complex evolutionary history.

1 - Indiana University, Department of Biology, 1001 East Tenth Street, Bloomington, IN, 47405, USA

Keywords:
Campanulaceae
Cladogenesis
Downingia
Lobeliaceae
molecular phylogeny
reticulate evolution.

Presentation Type: Oral Paper:Papers for Sections
Session: 60
Location: Salon 2/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 11:00 AM
Number: 60012
Abstract ID:811
Candidate for Awards:None