Evolutionary potential and adaptation of Banksia attenuata (Proteaceae) to climate and fire regime in southwestern Australia, a global biodiversity hotspot

Abstract

Substantial climate changes are evident across Australia, with declining rainfall and rising temperature in conjunction with frequent fires. Considerable species loss and range contractions have been predicted; however, our understanding of how genetic variation may promote adaptation in response to climate change remains uncertain. Here we characterized candidate genes associated with rainfall gradients, temperatures, and fire intervals through environmental association analysis. We found that overall population adaptive genetic variation was significantly affected by shortened fire intervals, whereas declining rainfall and rising temperature did not have a detectable influence. Candidate SNPs associated with rainfall and high temperature were diverse, whereas SNPs associated with specific fire intervals were mainly fixed in one allele. Gene annotation further revealed four genes with functions in stress tolerance, the regulation of stomatal opening and closure, energy use, and morphogenesis with adaptation to climate and fire intervals. B. attenuata may tolerate further changes in rainfall and temperature through evolutionary adaptations based on their adaptive genetic variation. However, the capacity to survive future climate change may be compromised by changes in the fire regime.

A molecular phylogeny of the genus Diplusodon (Lythraceae), endemic to the campos rupestres and cerrados of South America

“…An example of this is the fire regime adaptation of Banksia attenuata R.Br. (Proteaceae) in southwestern Australia, where candidate SNPs associated with rainfall and high temperature were diverse, whereas SNPs associated with specific fire intervals were mainly found in one allele (He & al., 2016). Multiple, independent dispersals from campo rupestre to cerrado has occurred in several distinct lineages, adding support to the notion that isolation by more severe fire regimes is readily overcome in Diplusodon.…”

Environmental drivers and genomic architecture of trait differentiation in fire‐adaptedBanksia attenuataecotypes

“…At the mesic end of the rainfall gradient, fires are far less likely to reach the canopy (Cowling and Lamont ; Lamont et al ), and over the past 70 years (at least) tree‐crown‐reaching fires have occurred at an estimated 60–140‐year intervals (He et al ). This allows continuous growth of the main trunk, with trees recovering from fire through resprouting from the trunk and main branches rather than the base.…”

“…Fire has played a major role in shaping functional trait evolution in fire‐prone regions, globally (Keeley et al ; He and Lamont ), including southwestern Australia (SWA), for at least 80 million years (He et al , ; Lamont and He 2016). Following severe crown damage by fire, resprouting occurs through new shoot growth from surviving buds or meristems that are located aerially, basally or underground (Clarke et al ).…”

Phenotypic variation and differentiated gene expression of Australian plants in response to declining rainfall

“…First, there must be genetic variation within the population that allows a physiologically beneficial response to low water availability. A study on adaptive genetic variation in response to rainfall and temperature in B. attenuata (usually co-occurring with species studied here) indicated that even populations occurring in wet habitats have genetic variation favouring survival under dry conditions [47]. However, directional selection could deplete population genetic variation, which limits the species' adaptive potential for other stresses that require different suites of genes and regulation networks.…”