![Figure. I [Box 1]. Evolutionary scenarios of change in a trait state (continuous lines can be interpreted as representing a period in which fire acted as an evolutionary pressure and dashed lines a period with a different selective environment).](/figures/figure-i-box-1-evolutionary-scenarios-of-change-in-a-trait-f6nxplxv.webp)
![Figure 2. Model of factors selecting for serotiny and costs and benefits of serotiny (modified from figure in [2]). Low soil fertility is hypothesized to select for larger seeds with higher nutrient stores to enhance seedling survival. Predation pressure is heightened due to the lower nutrient stores in most plant tissues in the community and this selects for canopy seed storage.](/figures/figure-2-model-of-factors-selecting-for-serotiny-and-costs-3sxsj75i.webp)
Q2. What is the main reason why low fertility soils are so important?
low fertility soils select for traits such as small sclerophyll leaves and provide well-drained substrates, both of which increase the likelihood of fires.
Q3. What are some traits that could enhance flammability?
In crown fire ecosystems traits that could enhance flammability include small leaves, volatile compounds, and retention of dead leaves and branches to name just a few.
Q4. Why do the MTC regions have species that restrict seedling recruitment to a postfire pulse?
Four of the five MTC regions have species that restrict seedling recruitment to a postfire pulse and the reason why is because fires are a predictable ecosystem process and by removing the dense shrub canopy fires provide superior resources for recruitment of some species.
Q5. What is the argument that if drought were a more likely driving force than fire?
The authors argue that if drought were a stronger driving force than fire it would more likely select for a bet-hedging strategy in which seed dispersal was spread out over multiple years, rather than dump all seeds immediately after fire when there is a significant probability it could be a dry year.
Q6. What is the main reason why plants persist in a multi-variable environment?
plants persist in a multi-variate environment stressed by not just soil fertility but climate and potentially fire, not to mention biotic interactions.
Q7. What is the main reason why serotiny is tied to crown fire regimes?
Serotiny is tied to crown fire regimes and in the absence of fire there is relatively little successful recruitment, making it clearly of adaptive value in these systems.
Q8. What is the common explanation for the germination of MTC species?
In most MTC ecosystems there are species with dormant seed banks that only germinate in the first growing season after fire, and can be shown experimentally to only germinate in response to smoke or charred wood extracts.
Q9. Why do they conclude that serotiny evolved in response to fire?
Bradshaw et al. [1] conclude that because serotiny is concentrated in the two southern hemisphere MTC regions characterized by low soil fertility, that it arose in response to soil infertility.
Q10. What is the primary factor driving the evolution of plant traits in these shrublands?
That paper argues that this ancientassociation with infertile soils is the primary factor driving the evolution of plant traits in these shrublands.
Q11. What is the mechanism of how species store seeds in the shrub canopy?
The proximal mechanism of how species do this varies with the region; in two of the MTC regions, dormant seeds are stored in the soil and serotiny is rare and in two other regions many dominant shrubs store seeds in serotinous fruits in the shrub canopy.
Q12. What is the recent discovery of a butanolide compound in smoke?
The relatively recent discovery of a butanolide compound (karrikinolide) in smoke that will trigger germination of a vast array of species, many that lack any ecological connection with fire, has raised questions about the selective role of fire in MTC ecosystems [1].