Abstract Detail

Ecophysiology

Feder, Zoë [1], Muller, Clare [2], Drenovsky, Rebecca [2], Moore, Michael [1].

Infrared spectroscopy reveals a striking pattern of foliar gypsum accumulation among Chihuahuan Desert gypsophiles.

The Chihuahuan Desert Region is home to a particularly diverse assemblage of gypsum endemic plants. Ongoing work in the Moore Lab has provided much insight into the origin and evolution of gypsum endemic lineages, revealing that gypsum endemism has evolved independently many times, often within ancestrally tolerant lineages. However, little is known of the ecophysiology of Chihuahuan Desert gypsum endemics. In contrast, many ecological studies in Spain have been conducted on plants growing on gypsum, and these studies demonstrate that such plants appear to employ a variety of ecological mechanisms to survive on gypsum. For example, gypsum endemics in Spain that are geographically widespread have been shown to accumulate gypsum itself in their leaves as a probable mechanism for sequestering the very high levels of calcium and sulfur that characterize gypsum soils, whereas narrowly distributed gypsum endemics and plants that grow on and off of gypsum (gypsovags) do not accumulate gypsum. To test whether Chihuahuan Desert gypsum endemics follow the same patterns of gypsum accumulation, we sampled leaf tissue of 23 species from southeastern New Mexico and west Texas (including 15 gypsum endemics, comprising a mix of geographically widespread and narrowly distributed taxa, and 8 non-endemics). To help control for phylogeny in our analyses, this sampling included 5 pairs of congeneric species or species in closely related genera, where one member of each pair was an endemic and the other a non-endemic. For all samples, we used Fourier transform infrared spectroscopy to generate infrared spectra, which permits the qualitative detection of gypsum. Analyses revealed that almost all geographically widespread gypsum endemic lineages [e.g., Acleisanthes and Anulocaulis (Nyctaginaceae), Sartwellia (Asteraceae), and Tiquilia (Boraginaceae)] accumulated gypsum in their leaves, with the notable possible exception of Nerisyrenia (Brassicaceae). In contrast, narrowly distributed gypsum lineages and non-endemics lacked obvious gypsum accumulation. This overall pattern is remarkably similar to that found in Spain by Palacio and colleagues, including the lack of gypsum accumulation in mustards. The ability to accumulate gypsum may have been an important preadaptation that facilitated the transition to gypsum endemism in some lineages, and it also may have been further enhanced by selection in the widely distributed gypsum endemic clades of the Chihuahuan Desert. In any case, the patterns of foliar gypsum accumulation that we observed suggest that gypsum accumulation has been an important factor in the evolution of Chihuahuan Desert gypsum endemics, and may be an important global phenomenon on gypsum.

Related Links:
The Origin and Evolution of Gypsum Endemic Plants

1 - Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH, 44074, USA
2 - John Carroll University, Department of Biology, 1 John Carroll Blvd, University Heights, OH, 44118, USA

Keywords:
gypsum
infrared spectroscopy
Chihuahuan Desert
edaphic endemism
Brassicaceae.

Presentation Type: Oral Paper
Session: 3, Ecophysiology
Location: 104/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 11:30 AM
Number: 3014
Abstract ID:151
Candidate for Awards:None