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Abstract Detail


Molecular Ecology and Evolution

Whitelock, C. C. [1], Pratt, R. B. [2], Smith, P. T. [1], Jacobsen, A. L. [3], Tobin, M. F. [3], Traugh, C. A. [1], Nguyen, C. Q. [1], Barrera, S. [1].

Are xylem traits in chaparral species phylogenetically conserved?

The California chaparral region is known for its rich biodiversity and its Mediterranean type climate (MTC) with hot dry summers and cool wet winters. For plant species that dominate the chaparral, surviving the hot dry summers places tremendous demand on the xylem to deliver water safely to evergreen leaves. Previous research on chaparral species has found a strong link between xylem traits and plant fitness. Moreover, studies have documented a broad range in xylem functional and structural diversity among co-occurring chaparral species. In this study, we investigate whether key xylem traits are phylogenetically conserved or, conversely, if closely related species are divergent in xylem traits. To evaluate this, portions of two genes (chloroplast matK and the nuclear 18S, approximately 2500 bp total) were sequenced for each of 32 chaparral shrub species and a phylogeny was estimated using Bayesian methodology. Resistance of xylem to cavitation, xylem hydraulic efficiency, xylem density, stem mechanical strength (Modulus of Rupture; MOR), and xylem carbohydrate storage were analyzed from the same 32 species. To evaluate phylogenetic conservatism, a quantitative convergence index was calculated and compared to a global data set for a subset of traits. The results indicate considerable convergence in some traits, but greater evolutionary convergence in others. The results are discussed in the context of chaparral community assembly.

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1 - California State University Bakersfield, Biology, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
2 - California State University, Bakersfield, Biology, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
3 - California State University, Bakersfield, Department of Biology, 61 Sci, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA

Keywords:
chaparral
biomechanics
evolution
carbohydrate
hydraulic conductivity
cavitation
xylem.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PME002
Abstract ID:679


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