Drought-induced trans-generational tradeoff between stress tolerance and defence: consequences for range limits?

• Published in: AoB plants Vol. 5; p. plt038
• Main Authors: Alsdurf, Jacob D., Ripley, Tayler J., Matzner, Steven L., Siemens, David H.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-01-2013
• Series: Editor's choice
• Subjects: chemical defence; drought tolerance; glucosinolate; epigenetic; tradeoff; range limit; Boechera stricta
• ISSN: 2041-2851; 2041-2851
• DOI: 10.1093/aobpla/plt038

In the study of geographic range boundary development, the focus has been on leading rather than on trailing edge dynamics. This is an important caveat as trailing edge dynamics will be critical for an understanding population level persistence. Our study begins to fill this knowledge gap and extends the conceptual framework of the field by focusing on trans-generational environmental effects. We found that while these effects may overcome some constraints on stress tolerance evolution and range expansion, other constraints may be created to limit range.
Abstract
Areas just across species range boundaries are often stressful, but even with ample genetic variation within and among range-margin populations, adaptation towards stress tolerance across range boundaries often does not occur. Adaptive trans-generational plasticity should allow organisms to circumvent these problems for temporary range expansion; however, range boundaries often persist. To investigate this dilemma, we drought stressed a parent generation of Boechera stricta (A.Gray) A. Löve & D. Löve, a perennial wild relative of Arabidopsis, representing genetic variation within and among several low-elevation range margin populations. Boechera stricta is restricted to higher, moister elevations in temperate regions where generalist herbivores are often less common. Previous reports indicate a negative genetic correlation (genetic tradeoff) between chemical defence allocation and abiotic stress tolerance that may prevent the simultaneous evolution of defence and drought tolerance that would be needed for range expansion. In growth chamber experiments, the genetic tradeoff became undetectable among offspring sib-families whose parents had been drought treated, suggesting that the stress-induced trans-generational plasticity may circumvent the genetic tradeoff and thus enable range expansion. However, the trans-generational effects also included a conflict between plastic responses (environmental tradeoff); offspring whose parents were drought treated were more drought tolerant, but had lower levels of glucosinolate toxins that function in defence against generalist herbivores. We suggest that either the genetic or environmental tradeoff between defence allocation and stress tolerance has the potential to contribute to range limit development in upland mustards.