When did a Mediterranean-type climate originate in southwestern Australia?

Lamont, Byron B.; He, Tianhua

doi:10.1016/j.gloplacha.2017.08.004

Cited by 22 publications

(28 citation statements)

References 105 publications

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“…). After rainforests, the Mediterranean biome may be the oldest of Australia's biomes, with recent estimates suggesting the development of a Mediterranean‐type climate from 30 million years ago (Lamont and He ), whereas temperate forests probably did not become widespread until 25 to 15 million years ago (Byrne et al. ), and modern woodland, grassland, savannah, and arid ecosystems until eight to three million years ago (Hill and Creek ; Beerling and Osborne ; Byrne et al.…”

Section: Discussionmentioning

confidence: 99%

Equilibrium and non‐equilibrium phases in the radiation ofHakeaand the drivers of diversity in Mediterranean‐type ecosystems

Skeels

Cardillo

2019

Evolution

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Mediterranean‐type ecosystems (MTEs) contain exceptional plant diversity. Explanations for this diversity are usually classed as either “equilibrium,” with elevated MTE diversity resulting from greater ecological carrying capacities, or “non‐equilibrium,” with MTEs having a greater accumulation of diversity over time than other types of ecosystems. These models have typically been considered as mutually exclusive. Here, we present a trait‐based explanatory framework that incorporates both equilibrium and non‐equilibrium dynamics. Using a large continental Australian plant radiation (Hakea) as a case study, we identify traits associated with niche partitioning in coexisting species (α‐traits) and with environmental filtering (β‐traits), and reconstruct the mode and relative timing of diversification of these traits. Our results point to a radiation with an early non‐equilibrium phase marked by divergence of β‐traits as Hakea diversified exponentially and expanded from the southwest Australian MTE into biomes across the Australian continent. This was followed from seven million years ago by an equilibrium phase, marked by diversification of α‐traits and a slowdown in lineage diversification as MTE‐niches became saturated. These results suggest that processes consistent with both equilibrium and non‐equilibrium models have been important during different stages of the radiation of Hakea, and together they provide a richer explanation of present‐day diversity patterns.

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Section: Discussionmentioning

confidence: 99%

Equilibrium and non‐equilibrium phases in the radiation ofHakeaand the drivers of diversity in Mediterranean‐type ecosystems

Skeels

Cardillo

2019

Evolution

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“…Where possible, we recorded the age when the lineage first became fire‐prone (Lamont & He, ) and under what conditions the trait was lost. In all, 286 sets of data were collated into tables (Lamont & He, , ; Pausas et al, ; see online Table S2). The data were graphed individually for each of the four trait‐types (see below) and also summed into 10 My age classes for further analysis, including comparison with prevailing temperatures and oxygen levels.…”

Section: Methodology and Corroborationmentioning

confidence: 99%

“…Some 40 My later, bark that was at least twice as thick had evolved in pines plus shedding of old branches (deterring flames from running up the tree) as fires intensified and now could (otherwise) reach the crown (D2). Banksia started to retain its dead leaves indefinitely (increasing flammability and possibly having multiple functions in relation to increasing post‐fire fitness; He et al, ) as the climate became more seasonal and fires intensified (Lamont & He, ). In the tropical grasslands of Brazil, numerous genera began invading from the northern rainforests in the late Miocene/Pliocene once they had evolved fire‐resistant stems/rootstocks (Simon et al, ; Pausas et al, ).…”

Section: Methodology and Corroborationmentioning

confidence: 99%

“…There certainly are many fire regimes, climates and habitat types that can accommodate both fire‐response types simultaneously (Groeneveld et al, ; Batllori et al, ; Cowling et al, ), and their co‐existence is common. However, resprouters are most abundant in SW Australia currently (the centre of diversification of Hakea ) and non‐sprouters in the Cape (the centre of diversification of Protea ), and both experience a Mediterranean‐type climate that was probably already present in both regions at this time (Lamont & He, ).…”

Section: Evolution Of Fire‐stimulated Resproutingmentioning

confidence: 99%

“…As the speciation rate dropped sharply through the Pliocene–Quaternary, so too did the innovation rate (to zero for resprouters) with the slack taken up by an increasing stabilisation rate among non‐sprouters. The only obvious explanation for why speciation would have favoured non‐sprouters at a time of huge climatic and substrate upheavals (Lamont & He, ) might be that the greater seed production by non‐sprouters facilitated their dispersal by wind and migration to suitable but increasingly isolated substrates (Merwin et al, ). Fires in the ‘glacials’ would have become increasingly rare and stochastic (the reverse in the ‘interglacials’) when they should have favoured resprouters.…”

Section: Evolution Of Fire‐stimulated Resproutingmentioning

confidence: 99%

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Evolutionary history of fire‐stimulated resprouting, flowering, seed release and germination

Lamont

Yan

2018

Biological Reviews

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Fire has shaped the evolution of many plant traits in fire-prone environments: fire-resistant tissues with heat-insulated meristems, post-fire resprouting or fire-killed but regenerating from stored seeds, fire-stimulated flowering, release of on-plant-stored seeds, and germination of soil-stored seeds. Flowering, seed release and germination fit into three categories of response to intensifying fire: fire not required, weakly fire-adapted or strongly fire-adapted. Resprouting also has three categories but survival is always reduced by increasing fire intensity. We collated 286 records for 20 angiosperm and two gymnosperm families and 50 trait assignments to dated phylogenies. We placed these into three fire-adapted trait types: those associated with the origin of their clade and the onset of fire-proneness [primary diversification, contributing 20% of speciation events over the last 120 million years (My)], those originating much later coincident with a change in the fire regime (secondary diversification, 30%), and those conserved in the daughter lineage as already adapted to the fire regime (stabilisation, 50%). All four fire-response types could be traced to >100 My ago (Mya) with pyrogenic flowering slightly younger because of its dependence on resprouting. There was no evidence that resprouting was always an older trait than either seed storage or non-sprouting throughout this period, with either/both ancestral or derived in different clades and times.Fire-adapted traits evolved slowly in the Cretaceous, 120-65 Mya, and rapidly but fitfully in the Cenozoic, 65-0 Mya, peaking over the last 20 My. The four trait-types climaxed at different times, with the peak in resprouter speciation over the last 5 My attributable to fluctuating growing conditions and increasing savanna grasslands unsuitable for non-sprouters. All experienced a trough in the 40-30-Mya period following a reduction in world temperatures and oxygen levels and expected reduced fire activity. Thick bark and serotiny arose in the Mid-Cretaceous among extant Pinaceae. Heat-stimulated germination of hard seeds is ancestral in the 103-My-old Fabales. Smoke-(karrikin)-stimulated germination of non-hard seeds is even older, and includes the 101-My-old Restionaceae-Anarthriaceae. A smoke/karrikin response is detectable in some fire-free lineages that prove to have a fire-prone ancestry. Among clades that are predominantly fire-prone, absence of fire-related traits is the advanced condition, associated either with increased fire frequency (loss of serotiny and soil storage), or migration to fire-free habitats (loss of thick bark, pyrogenic flowering, serotiny or soil storage). Protea (Africa) and Hakea (Australia) illustrate the importance of stabilisation processes between resprouting/non-sprouting in accounting for speciation events over the last 20 My and highlight the frequent interchange possible between these two traits.Apart from Pinus, most ancestral trait reconstruction relative to fire has been conducted on predominantly Southern Hemisphere cl...

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Ecological interactions shape the evolution of flower color in communities across a temperate biodiversity hotspot

et al. 2021

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Processes driving the divergence of floral traits may be integral to the extraordinary richness of flowering plants and the assembly of diverse plant communities. Several models of pollinator‐mediated floral evolution have been proposed; floral divergence may (i) be directly involved in driving speciation or may occur after speciation driven by (ii) drift or local adaptation in allopatry or (iii) negative interactions between species in sympatry. Here, we generate predictions for patterns of trait divergence and community assembly expected under these three models, and test these predictions in Hakea (Proteaceae), a diverse genus in the Southwest Australian biodiversity hotspot. We quantified functional richness for two key floral traits (pistil length and flower color), as well as phylogenetic distances between species, across ecological communities, and compared these to patterns generated from null models of community assembly. We also estimated the statistical relationship between rates of trait evolution and lineage diversification across the phylogeny. Patterns of community assembly suggest that flower color, but not floral phenology or morphology, or phylogenetic relatedness, is more divergent in communities than expected. Rates of lineage diversification and flower color evolution were negatively correlated across the phylogeny and rates of flower colour evolution were positively related to branching times. These results support a role for diversity‐dependent species interactions driving floral divergence during the Hakea radiation, contributing to the development of the extraordinary species richness of southwest Australia.

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When did a Mediterranean-type climate originate in southwestern Australia?

Cited by 22 publications

References 105 publications

Equilibrium and non‐equilibrium phases in the radiation ofHakeaand the drivers of diversity in Mediterranean‐type ecosystems

Equilibrium and non‐equilibrium phases in the radiation ofHakeaand the drivers of diversity in Mediterranean‐type ecosystems

Evolutionary history of fire‐stimulated resprouting, flowering, seed release and germination

Ecological interactions shape the evolution of flower color in communities across a temperate biodiversity hotspot

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