Desiccation Tolerance: Phylogeny and Phylogeography

BioQUEST Workshop 2009 Resurrection Plants

 Desiccation tolerant  Survive dehydration  Survive in dormant state for extended time period  Survive rehydration

Xerophyta humilis, from J. Farrant web site (http://www.mcb.uct.ac.za/Staff/JMF/index.htm) Figure 2. Selaginella lepidophylla http://en.wikipedia.org/wiki/ File:Rose_of_Jericho.gif Desiccation Issues

 Membrane integrity  Protein structure  Generation of free radicals

Rascia, N, La Rocca, N. 2005 Critical Reviews in Plant Sciences Solutions

 Repair upon hydration  Prevent damage during dehydration  Production/accumulation of replacement solutes  Inhibition of photosynthesis

http://www.cbs.dtu.dk/staff/dave/roanoke/elodeacell.jpg Evolution of Desiccation Tolerance

From Oliver, et al 2000. Plant Ecology Convergent Evolution Among Vascular Plants

From Oliver, et al 2000. Plant Ecology Desiccation Tolerance in Vascular Plants

 Seeds  Pollen  Spores  Osmotic stress Desertification

 40% of Earth’s surface  38% of population  Low productivity  Lack of water  Depletion of soil  Loss of soil  Delicate system Using Evolutionary Relationships to Identify Genes for Crop Enhancement

 If desiccation sensitive plants have retained genes involved in desiccation tolerance, perhaps expression of those genes can be genetically modified to enhance desiccation tolerance. Expression patterns in dehydratingTortula and Xerophyta

Michael Luth

Xerophyta humilis, from J. Farrant web site (http://www.mcb.uct.ac.za/Staff/JMF/index.htm) ? Methods

Occurrence data for Anastatica hierochuntic: o Downloaded from the Global Biodiversity Information Facility (gbif.org). o Of 127 available occurrence points, only 68 were georeferenced with latitude and longitude information.

Environmental layers: Precipitation and temperature from the IPCC climate dataset

Niche Modeling:

Maximum Entropy (Maxent)

Maxent principle is to estimate the probability distribution such as the spatial distribution of a species.

Maxent uses entropy as the means to generalize specific observations of presence of a species, and does not require absence points Figure 4. Rainfall Volume. Source: GapMinder.org. Results

A representation of the Maxent model for Anastatica hierochuntica can be seen in Figure 5.

Warmer colors show areas with better predicted conditions. White dots show the presence locations used for training.