Abstract Detail

Life without water: evolution and adaptation of xeric plants

Kooyers, Nicholas [1], Blackman, Benjamin [2].

Does drought lead to the evolution of distinct drought resistance strategies? Experimental evidence from an annual monkeyflower.

The evolution of drought resistance occurs through a diverse set of physiological mechanisms that are often classified into distinct strategies including drought escape, drought avoidance, and drought tolerance. While strategies are not necessarily mutually exclusive, different or contrasting physiological or morphological traits are associated with each strategy and the strategy a species employs is often intimately linked to life history and ecology of the species. Despite quantification of these strategies across angiosperms, there are relatively few examples describing how multivariate traits complexes evolve in response to drought events. Here we use annual populations of the common yellow monkeyflower, Erythranthe guttata, as a model to examine evolutionary responses to drought from three perspectives. First, we examine population-level variation in multiple drought-related traits from >50 populations in a common garden experiment. Second, we conduct phenotypic selection analyses in two populations with contrasting water availability and growing seasons dynamics. Finally, we use a resurrection experiment to examine whether and how two populations in low water environments evolved in response to a historic drought in California. Expected tradeoffs between traits associated with drought escape and avoidance were not observed across the range. Instead populations from sites with low water availability exhibited phenotypes consistent with greater drought escape and avoidance strategies. Phenotypic selection analyses indicate the ability to escape drought does tradeoff with both constitutive plant defenses and relative growth rate. However, these tradeoffs were not sufficient to predict phenotypic evolution following severe drought. One post-drought cohort from a thriving population did exhibit higher fitness under dry-down conditions via an unknown phenotypic mechanism while the other post-drought cohort from a declining population had lower relative fitness in all treatments than the pre-drought cohort. Combined, these results highlight both the evolutionary flexibility and constraint associated with the evolution of drought resistance. There is limited evidence for the evolution of distinct drought strategies, rather the evolution of drought resistance must be considered at a whole-plant scale within the broader context of plant functional strategies.

1 - University of Louisiana, Lafayette, Biology, 410 E. St. Mary Blvd., Billeaud Hall, Rm 108, Lafayette, Louisiana, 70503, US
2 - University Of California, Berkeley, Plant And Microbial Biology, 111 Koshland Hall #3102, Berkeley, CA, 94720, United States

Keywords:
drought
life history
phenology
Evolutionary Ecology
Mimulus guttatus
Erythranthe guttata
adaptation.

Presentation Type: Symposium Presentation
Session: SYM7, Life without water: evolution and adaptation of xeric plants
Location: Tucson I/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 1:45 PM
Number: SYM7002
Abstract ID:366
Candidate for Awards:None