Approaches to detecting hybridization events and genetic introgression under phylogenetic incongruence
aSevertsov Institute of Ecology and Evolution, RAS
Leninsky pr., 33, Moscow, 119071 Russia
*e-mail: k_vakka@yahoo.com
**e-mail: llavrenchenko@gmail.com
Hybridization and consequent exchange of genetic material (introgression) are widespread phenomena in the evolution of plants and animals. Interspecies gene flow can become obvious in phylogenetic analyses of different loci resulting in gene tree discordance. However, other evolutionary processes, such as incomplete lineage sorting, can also result in the phylogenetic incongruence. The rate and evolutionary significance of hybridization and introgression are difficult to evaluate due to the hardship in distinguishing hybridization from incomplete lineage sorting. The review provides a brief characterization of the main processes (hybridization and introgression, incomplete lineage sorting) that are responsible for the phylogenetic incongruence between gene trees. The review also summarizes classical phylogenetic and analytical methods contributing to detection and distinguishing hybridization and introgression from incomplete lineage sorting under comparing a phylogenetic trees inferred from separate genetic markers. The approaches developed not only for detection of introgression patterns in the presence of incomplete lineage sorting, but also for characterizing the revealed introgression (proportion of admixture, direction, time) are examined; the advantages and methodological limitations of each approach are briefly discussed. The methods of phylogenetic networks are also discussed, it is demonstrated that they are an integral tool for reconstructing complex evolutionary histories under reticulate events.
