Mexican Conifers

Mexico, with four families, 10 genera, and over 90 species, is a world center of conifer diversity.

Pines

Pinus hartwegii, Nevado de Toluca

With 110-120 species, the genus Pinus (pines) includes more living species than any other genus of conifer, and Mexico has more native pine species than any other country. Pinus is the most ecologically important tree genus in the Northern Hemisphere.

The number of pine species in Mexico is an active area of investigation. Recent treatments have included between 45 and 60 species.  An intermediate number may be more reasonable, somewhere around 50. A list of our currently recognized species can be found here.

Conifer phylogeny

Taxus globosaTaxus globosa, Hidalgo.

The main research interest of our lab group is in the systematics and evolution of conifers, particularly New World members of the pine family (Pinaceae).

We sequence DNA and use the pattern of substitutions between different species (and individuals) to infer species relationships and to reconstruct their evolutionary history. We are also tying these DNA based inferences with the fossil record to estimate the time of diversification of Pinaceae lineages.

Conservation genetics

Guadalupe cypressGuadalupe cypress (photo by Patricia Rosas).

For a century, the viability of the only population of the Guadalupe cypress (Callitropsis guadalupensis), located on Isla Guadalupe, Baja California, was threatened from grazing by introduced goats. The goats were eradicated a few years ago, but in September 2008 a large fire burned much of the forest.

Using chloroplast DNA markers, we have found high genetic diversity in the endangered Guadalupe cypress.  The study was published in PLoS ONE in 2011.

DNA barcodes

An international effort is underway to generate short, standardized DNA sequence reads that will facilitate the identification of species. Two terrestrial plant markers were announced in 2009: short fragments from the coding regions of the chloroplast genes rbcL and matK. We are evaluating the performance of these and other DNA markers in distinguishing species of endangered Mexican plants, including conifers. First results for Pinaceae can be found here.

We are assembling a reference database of DNA barcodes for a few hundred species of conifers, agaves, cacti, and orchids. The sequences are in the Barcode of Life database and should be released by the end of 2011.