ARS | Publication request: PHYLOGEOGRAPHY, HAPLOTYPE TREES, AND INVASIVE PLANT SPECIES

Submitted to: Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2003
Publication Date: April 1, 2003
Citation: SCHAAL, B., CAICEDO, A., GASKIN, J.F. PHYLOGEOGRAPHY, HAPLOTYPE TREES, AND INVASIVE PLANT SPECIES. J. HEREDITY. 2003. V. 94(3). P. 197-204.

Technical Abstract: The distribution of genetic variants in plant populations is stronglyaffected by both current patterns of microevolutionary forces, such as geneflow or selection, and by the phylogenetic history of populations andspecies. Understanding the interplay of shared history and currentevolutionary events is particularly confounding in plants due to thereticulating nature of gene exchange between diverging lineages. Certaingene sequences provide historically ordered neutral molecular variation thatcan be converted to gene genealogies which trace the evolutionaryrelationships among haplotypes (alleles). Gene genealogies can be used tounderstand the evolution of specific DNA sequences and relate sequencevariation to plant phenotype. For example, in a study of the RPS2 gene inArabidopsis thaliana, resistant phenotypes clustered in one portion of thegene tree. The field of phylogeography examines the distribution of allelegenealogies in an explicit geographical context and, when coupled with anested clade analysis, can provide insight into historical processes such asrange expansion, gene flow, and genetic drift. A phylogeographical approachoffers insight into practical issues as well. Here we show how haplotypetrees can address the origins of invasive plants, one of the greatest globalthreats to biodiversity. A study of the geographical diversity ofhaplotypes in invasive Phragmites populations in the United States indicatesthat invasiveness is due to the colonization and spread of distinctgenotypes from Europe (Saltonstall, 2002). Likewise, a phylogeographicalanalysis of Tamarix populations indicates that hybridization events betweenformerly isolated species of Eurasia have produced the most common genotypeof the second worst invasive plant species in the US.