Abstract Detail

Biogeography

Moore, Michael [1], Drake, Ellen [1], Douglas, Norman [2], Flores Olvera, Hilda [3], Ochoterena, Helga [3].

An exception to prove the rule: Do edaphic refugia explain the unusual distribution of Dermatophyllum (Fabaceae)?

Dermatophyllum (Fabaceae) is a well-defined, small genus of southwestern North American shrubs with six currently recognized species that were formerly treated in Sophora. A phylogeny of Dermatophyllum including all taxa and based on ITS and the plastid ndhF/rpl32 and rpl32/trnL spacers will be presented. The genus falls into two well-supported sister lineages, one comprised solely of the relatively widespread and common D. secundiflorum (mescal bean), and the other comprised of all remaining taxa. These remaining five species are small but long-lived shrubs that are morphologically very similar. Likewise, all are allopatric from each other and each is narrowly distributed: two of the species (D. gypsophilum and D. juanhintonianum) are known from single, very small deposits of gypsum in east-central Chihuahua and southern Nuevo Leon, respectively; D. purpusii is only known from a handful of populations on shale in the Sierra de Parras in southern Coahuila; D. guadalupense is only known from the western slope of the Guadalupe Mountains and Brokeoff Mountains in Texas/New Mexico; and D. arizonicum is only known from scattered populations in an arc from southeastern to northwestern Arizona. The occurrence of these highly disjunct taxa, especially those in the Chihuahuan Desert region--which appear to be limited to unusual substrates in many cases--may represent an example of a refugial distribution in which a more widespread progenitor survives today only in lower-competition edaphic environments that it tolerates. Packrat midden, phylogenetic, and ecophysiological evidence in support of this hypothesis will be shown. The likely refuge-mediated distribution of these Dermatophyllum taxa contrasts strongly with the island-like distributions of similarly geographically widespread gypsum endemic plant lineages in the Chihuahuan Desert, which almost certainly result from early, localized specialization to gypsum followed by island-hopping to adjacent gypsum exposures.

Related Links:
Moore Lab--the origin and evolution of gypsum endemic plants

1 - Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH, 44074, USA
2 - University of Florida, Department of Biology, 618A Carr Hall, Gainesville, FL, 32611, USA
3 - Instituto De Biologia, UNAM, Depto Botánica, Apdo.Postal 70-367, Mexico, DF, 04510, Mexico

Keywords:
Biogeography
refugium
edaphic endemism
gypsum
Fabaceae
Dermatophyllum
Chihuahuan Desert
Mexico
Arizona
New Mexico
Texas
shale
packrat midden
phylogeny.

Presentation Type: Oral Paper
Session: 30, Biogeography I
Location: 203/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 2:15 PM
Number: 30004
Abstract ID:115
Candidate for Awards:None