Abstract Detail

Recent Topics Posters

Introgression or incomplete lineage sorting? The cause of tree discordance revealed by coalescent simulations.

Sarracenia is a genus of carnivorous plants endemic to North America. The ~10 species in the genus hybridize with one another readily in sympatric populations, and all hybrids are fertile with no obvious intrinsic fitness loss. With frequently observed fertile hybrids in natural populations, the opportunity for interspecific gene flow is high. Phylogenetic analysis of 199 nuclear genes resolved most species relationships within the genus, but a whole chloroplast genome (plastome) phylogeny is strongly discordant with the nuclear species tree. This discordance between the plastome tree and the species tree could be due to introgression of the chloroplast due to frequent hybridization and backcrossing, or it could be due to incomplete lineage sorting. To determine whether the level of discordance between the two trees could be caused by incomplete lineage sorting, 1000 gene trees are simulated under the multispecies coalescent assuming no hybridization. The simulated gene trees are compared to the species tree and plastome tree using an information theoretic generalized tree distance metric. The tree distances between the species tree and the simulated gene trees are consistently significantly lower than the distances between the plastome tree and the simulated trees. Similarly, the distance between the plastome tree and the species tree is significantly greater than the distance between the simulated gene tree set and the species tree. These results indicate that the plastome tree is more discordant with the species tree than would be expected under incomplete lineage sorting alone, implying that introgressive hybridization has happened within the genus multiple times.

1 - University of Georgia, Plant Biology

Keywords:
none specified

Presentation Type: Recent Topics Poster
Number: PRT024
Abstract ID:1429
Candidate for Awards:None