FIRESCAPE GENOMICS: predicting plant responses to changing fire regimes
The role of fire in historical plant evolution is well understood but there is little knowledge of how species will adapt to the unprecedented changes in fire regimes which are occurring globally.
There is ample evidence that invasive plant species can rapidly adapt to new environments but no studies have yet examined rapid evolution of fire-adaptive traits (e.g. fire-stimulated germination) in invasive species. This is surprising considering that invasive species can alter fire regimes when they change fuel properties and when fire promotes their establishment and growth. The result is a positive ecological feedback, whereby the invasion process accelerates and fire frequency and/or intensity increases, sometimes beyond the level where native vegetation can recover. But do adaptive changes contribute to these feedbacks?
We are investigating if adaptation in invasive species can reinforce changes in fire regimes by increasing the persistence of fire-tolerant or fire-promoting lineages.
Results should help us understand how plant species will adapt to the increases in fire frequency that are occurring around the world with climate change. It should also help us understand if rapid evolution contributes to the fire-vegetation feedback that often occurs with plant invasion.
plant species have been introduced into Australia where fire frequency exceeds
levels found in their native range (i.e. 3 vs > 6 wildfires in the past 100
years). This presents a unique opportunity to predict how ecosystems will
respond to increases in fire frequency that are occurring in Europe under
climate change. We are
capitalising on this opportunity to investigate the phenotypic and genomic basis
underlying adaptation to changing fire regimes in two European plant species: Scotch Broom (Cytisus scoparius (L.) Link, Fabaceae) and St John’s wort (Hypericum perforatum L., Clusiaceae).
Study overview and predicted responses
(A) Distribution of the target species and proposed sampling regions in Europe. (B) Sites already sampled across fire frequency gradients in Australia. (C) The germination response to experimentally induced fire-cues (heat and smoke) is expected to be greater in the invasive (I) than the native (N) range, reflecting adaptation to greater fire frequency. A stronger response is expected in Hypericum perforatum than Cytisus scoparius as it is not common in fire-prone regions of its native range and is thus not pre-adapted to fire. (D) Genomic variation, shown as Principal Coordinates, is expected to be related to origin and fire history, with potential for invasive populations to form genotypes not seen in their native range