Dissertation Research: Taking the Heat: Mechanisms of adaptive differentiation in response to extreme heat events

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

There are many studies examining species' responses to changes in average conditions but few studies examine species responses to extreme events (e.g. heatwaves). Extreme events typically are short events that challenge species beyond their ability to acclimate. In California the heatwave season is expected to increase by up to thirteen weeks, yet it remains unclear whether it will start earlier or end later. These two possibilities will have different effects on plants because sudden heat in the cool, wet spring should affect plants differently than extreme heat at the end of the dry summer, when plants have acclimated to high temperatures but soil water availability is low. Moreover, the responses of species may be different across their ranges because of climatic differences across California, where coastal sites are buffered from high temperatures and their annual climate is more stable than inland sites. If plants found in climatically stable sites are adapted to stable climates, they may be disproportionately harmed by increases in climatic extremes. We will determine if variation in response to heatwaves is greater within a population, between inland and coastal populations, or between distant populations. We will create artificial heatwaves and measure performance and stress in seedlings before and after these events and we will study the effect of naturally occurring heatwaves on adult plants. Heatwaves pose a grave threat to biodiversity. To determine the magnitude of threats, and to provide a strong scientific basis for conservation and management strategies, we must forecast responses to climate change. The proposed research is some of the first to examine the influence of local genetic pools on responses to heatwaves. One proposed human adaptation to climate change is assisted migration. Our data will provide valuable insight into the consequences of moving native seed out of its home climate. This project will directly involve undergraduates from the diverse population at UC Berkeley and the scientific process from this project will be disseminated to the public through the Flat Stanley @ Cal Project which pairs a paper doll sent in by a student with a scientist who writes about the "adventure" online.