Tagged: Dioon


Dioon

Diversification of Dioon in the Mexican transition zone

The Mexican transition zone originated from the overlap of the Nearctic and the Neotropical biotas. By analysing the genetic variation within the cycad genus Dioon, a relict Neotropical group, Gutiérrez-Ortega et al. test the association betweenthe diversification of Dioon with the biogeographic provinciality of the Mexican transition zone. The variation of two chloroplast DNA fragments and genome-wide single nucleotide polymorphisms reveals four Dioon lineages that are geographically structured. The reconstruction of the expansion of Dioon suggests that Dioon migrated along the mountain chains of Mexico. While dispersing towards their current distribution, each geographic region provided disparate ecological conditions that facilitated...

Continue reading Diversification of Dioon in the Mexican transition zone


Volcano

Plants and Pinatubo, Prestahnukur, Popocatépetl…

Plants are generally sessile organisms that, unlike their puny animal ‘cousins’, can’t get up and run away if the environment is not to their liking. Botanicals by-and-large put up and shut up. Accordingly, that fundamental fact of their existence has led them to adapt to a remarkable array of abiotic factors, e.g. temperature, drought, high light levels, low light levels, excess UV, salinity, fire, heavy metals, herbivory, etc. Yet, however long and imaginative that list may be, what are the chances that you would have included volcanoes (ruptures on the Earth’s crust “that allow hot lava, volcanic ash, and gases...

Continue reading Plants and Pinatubo, Prestahnukur, Popocatépetl…

A stable phylogeny for the cycads

A stable phylogeny for the cycads

The cycads (order Cycadales) are an ancient order of gymnosperms comprising ten genera and 331 species found in all tropical regions of the earth. Using sequences of five single copy nuclear genes, Salas-Leiva et al. resolve a well-supported phylogeny for the group that is consistent across several methods of analysis. The phylogenetic tree robustly supports a close relationship between the South African monotypic genus Stangeria and the American genera Zamia and Microcycas. Biogeographic analysis suggests that massive extinction events eliminated broader distributions for the ancestors of extant cycads, whose radiation dates to no more than 12 million years ago.

Continue reading A stable phylogeny for the cycads