Bernacki, S., J.A. Clevinger, C.K. McMullen, and C.C. Clevinger. 2001. A preliminary phylogenetic study of Alternanthera (Amaranthaceae) in the Galápagos Islands.

Poster Abstract: A study was done to look for genetic variance in different species of Alternanthera that grow in the Galápagos islands off of mainland Ecuador. The objectives were to estimate the number of colonization events of Alternanthera in the islands as well as identify any mainland sister groups to Alternanthera. In this preliminary study eight species of Alternanthera were collected. The leaf material was then ground and DNA was extracted. Two different regions of DNA were amplified by Polymerase Chain Reaction. One region (ITS) consisted of nuclear DNA while the other was a region (trnL-trnF) of chloroplast DNA. The samples were purified and sequenced using an automated sequencer. The sequences were aligned manually with a computer program, Sequencher, and then the data set was analyzed using another program PAUP*. The outgroup used was A. reinickii, a cultivated cosmopolitan species. The phylogenies for both DNA regions were essentially identical. The results revealed a strongly supported clade containing three endemic and one native species. A second strongly supported clade contained two introduced and one purported endemic, A. echinoceophala. If A. echinoceophala is considered to be an endemic then our preliminary data supports the hypothesis of at least two colonization events of Alternanthera to the Galápagos Islands.