Ancient Drivers of Adaptations in Plant Traits

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The world has recently seen the worst wildfires in human living memory, including the ongoing siege of California wildfires and 2019-2020 Australian bushfires, which burnt 72,000 square miles. Predictions that global warming will enhance the number of high fire risk days in fire-prone regions highlights the importance of understanding the relationship between plants, climate and fire. Plants that live in fire-prone regions often possess distinctive traits that allow them to thrive following wildfires. However, it remains a major ecological debate if such trait acquisition has actually been driven by fire itself. To understand the drivers of trait acquisition and their continued function in modern ecosystems, we have to look to the past. ADAPT will examine the evolution of the earliest proposed fire-adapted trait, branch shedding in conifers, which emerged in the Permian (280 Mya). To date no research has established the conditions surrounding the origin of this important trait. Therefore, whether this trait emerged as a response to fire or the otherwise changing climate is unknown. ADAPT will test the hypothesis that fire-proneness is a prerequisite for the evolution of fire-adaptive traits, where it will uniquely examine whether a shift in fire-regime post-dates the appearance of branch shedding, suggesting that the trait was the result of multi-agent selection co-opted to improve fitness of some conifers; or prior to the evolution of branch shedding, suggesting that the trait evolved in response to selection by fire and that fire has been a selective force over 100s of millions of years of Earth history. Fire-adapted traits are what continue to ensure survival of plants in Earth’s fire-prone ecosystems. As such, the results of ADAPT are critical if we are to understand the continued functioning of fire-adaptive traits in the changing environmental conditions of the modern world and assess the resilience of Earth’s ecosystems to climate-driven changes in wildfires.