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Inducible defences can improve survival in variable environments by allowing individuals to produce defences if they detect predators. These defences are often expressed as inter‐related developmental, morphological, and behavioural changes. However, producing defences can incur costs, which may be expressed immediately and/or during subsequent life stages. In Australia, waterborne cues of potentially cannibalistic conspecific tadpoles induce hatchlings of invasive cane toads to accelerate their developmental rate, thereby reducing their window of vulnerability. However, the mechanisms and costs of such accelerated development are poorly understood, and whether cane toad embryos show cannibal‐induced plasticity in other traits is unknown. Here, we found no evidence of altered time of hatching for embryos exposed to non‐feeding conspecific cannibal tadpole cues. Additionally, hatchling dispersal behaviours were not affected by exposure to these cues. However, developmental acceleration of hatchlings induced by exposure to tadpole cues was accompanied by reduced hatchling growth, indicating a trade‐off between these processes. At the conclusion of the hatchling stage, cannibal‐exposed individuals were smaller and morphologically distinct from control siblings. This size reduction affected performance during the subsequent tadpole stage: smaller cannibal‐exposed individuals were more likely to die, and initial size tended to be positively associated with subsequent tadpole growth and development across treatments (respectively, p =.07 and p =.06). However, even accounting for variation in initial size, there was an additional negative effect of cannibal exposure on tadpole growth and development, demonstrating that the fitness costs associated with developmental acceleration are not entirely attributable to size reductions. [ABSTRACT FROM AUTHOR]

Background and Aims: The leaf economic spectrum (LES) is related to dry mass and nutrient investments towards photosynthetic processes and leaf structures, and to the duration of returns on those investments (leaf lifespan, LL). Phosphorus (P) is a key limiting nutrient for plant growth, yet it is unclear how the allocation of leaf P among different functions is coordinated with the LES. We addressed this question among 12 evergreen woody species co-occurring on P-impoverished soils in south-eastern Australia. Methods: Leaf 'economic' traits, including LL, leaf mass per area (LMA), light-saturated net photosynthetic rate per mass (Amass), dark respiration rate, P concentration ([Ptotal]), nitrogen concentration, and P resorption, were measured for three pioneer and nine non-pioneer species. Leaf P was separated into five functional fractions: orthophosphate P (Pi), metabolite P (PM), nucleic acid P (PN), lipid P (PL), and residual P (PR; phosphorylated proteins and unidentified compounds that contain P). Results: LL was negatively correlated with Amass and positively correlated with LMA, representing the LES. Pioneers occurred towards the short-LL end of the spectrum and exhibited higher [Ptotal] than non-pioneer species, primarily associated with higher concentrations of Pi, PN and PL. There were no significant correlations between leaf P fractions and LL or LMA, while Amass was positively correlated with the concentration of PR. Conclusions: Allocation of leaf P to different fractions varied substantially among species. This variation was partially associated with the LES, which may provide a mechanism underlying co-occurrence of species with different ecological strategies under P limitation. [ABSTRACT FROM AUTHOR]

Adaptations of plants to phosphorus (P) deficiency include reduced investment of leaf P in storage (orthophosphates in vacuoles), nucleic acids and membrane lipids. Yet, it is unclear how these adaptations are associated with plant ecological strategies. Five leaf P fractions (orthophosphate P, P i ; metabolite P, P M ; nucleic acid P, P N ; lipid P, P L ; and residual P, P R ) were analysed alongside leaf economic traits among 35 Australian woody species from three habitats: one a high-P basalt-derived soil and two low-P sandstone-derived soils, one undisturbed and one disturbed by human activities with artificial P inputs. Species at the undisturbed low-P site generally exhibited lower concentrations of total leaf P ([P total ]), primarily associated with lower concentrations of P i , and P N . The relative allocation of P to each fraction varied little among sites, except that higher P L per [P total ] (rP L ) was recorded at the undisturbed low-P site than at the high-P site. This higher rP L , reflecting relative allocation to membranes, was primarily associated with lower concentrations of leaf nitrogen at the undisturbed low-P site than at the high-P site. Associations between leaf P fractions and leaf nitrogen may provide a basis for understanding the variation in plant ecological strategies dependent on soil P availability., (© 2024 The Authors. New Phytologist © 2024 New Phytologist Foundation.)

Prescribed burning is used in Australia as a tool to manage fire risk and protect assets. A key challenge is deciding how to arrange the burns to generate the highest benefits to society. Studies have shown that prescribed burning in the wildland–urban interface (WUI) can reduce the risk of house loss due to wildfires, but the costs and benefits of different arrangements for prescribed burning treatments have rarely been estimated. In this study, we use three different models to explore the costs and benefits of modifying the spatial arrangement of prescribed burns on public land, using the south-west of Western Australia as a case study. We simulate two hypothetical scenarios: landscape treatments and WUI treatments. We evaluate the long-term costs and benefits of each scenario and compare the results from the three models, highlighting the management implications of each model. Results indicate that intensifying prescribed burning treatments in public land in the WUI achieves a greater reduction in damages compared with applying the majority of the treatments in rural areas. However, prescribed burning in the WUI is significantly more expensive and, despite additional benefits gained from this strategy, in most cases it is not the most economically efficient strategy. We explored the cost and benefits of modifying the spatial arrangement of prescribed burns on public land. We found that wildland–urban (WUI) interface treatments are significantly more expensive than landscape treatments and, despite additional benefits gained from WUI treatments, in most cases, it is not the most economically efficient strategy. [ABSTRACT FROM AUTHOR]

Spatial sorting on invasion fronts drives the evolution of dispersive phenotypes, and in doing so can push phenotypes in the opposite direction to natural selection. The invasion of cane toads (Rhinella marina) through tropical Australia has accelerated over recent decades because of the accumulation of dispersal‐enhancing traits at the invasion front, driven by spatial sorting. One such trait is the length of the forelimbs: invasion‐front toads have longer arms (relative to body length) in comparison with populations 10–20 years after invasion. Such a shift likely has fitness consequences: an increase of forearm length would decrease the strength with which a male could cling to a female during amplexus and so render such a male less competitive in competition for mates, compared to short‐armed conspecifics. Our laboratory trials of attachment strength confirmed that males with relatively longer arms were easier to displace, and competition trials show higher duration of amplexus for males with shorter arms. Together with the sharp cline in limb length observed behind the invasion front, these results imply an opposition of selective forces: spatial sorting optimizes dispersal, but as this force wanes behind the invasion front, we see the primacy of natural selection reassert itself. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to test the integrated model of operations strategy as proposed by Schmenner and Swink to explain whether firms trade-off or accumulate capabilities, taking into account their positions relative to their asset and operating frontiers. Design/methodology/approach – The four major airlines based in Australia were studied. The paper is based on longitudinal data obtained from secondary sources. The four operations capabilities cost, quality, delivery and flexibility, and asset and operating frontiers, were all measured with proxy variables. Findings – The study provides some support for the integrated model. Firms do appear to trade-off capabilities when their asset and operating frontiers are close to each other. Firms show signs of accumulation when the asset frontiers are expanding significantly over time. There is indirect evidence that firms could be accumulating capabilities when the gap between the two frontiers is large. Practical implications – The study provides insights into when firms trade-off or accumulate capabilities. A good understanding of asset and operating frontiers is important in this regard. Managers need to better identify, establish and combine their firms' capabilities in response to varying internal and external contingencies. Originality/value – The paper provides an original and detailed empirical validation of Schmenner and Swink's integrated model. In doing so, this study contributes to informing and clarifying the debate in the operations strategy area relating to the circumstances in which firms trade-off and/or accumulate capabilities. [ABSTRACT FROM AUTHOR]

We examine the determinants of corporate cash holdings in Australia and the impact on shareholder wealth of holding excess cash. Our results show that a trade-off model best explains the level of a firm's cash holdings in Australia. We find that 'transitory' excess cash firms earn significantly higher risk-adjusted returns compared to 'persistent' excess cash firms, suggesting that the market penalises firms that hoard cash. The marginal value of cash also declines with larger cash balances, and the longer firms hold on to excess cash. The results are consistent with agency costs associated with persistence in excess cash holdings. [ABSTRACT FROM AUTHOR]

Abstract: The nitrogen-driven trade-off between nitrogen utilisation efficiency (yield per unit nitrogen uptake) and water use efficiency (yield per unit evapotranspiration) is widespread and results from well established, multiple effects of nitrogen availability on the water, carbon and nitrogen economy of crops. Here we used a crop model (APSIM) to simulate the yield, evapotranspiration, soil evaporation and nitrogen uptake of wheat, and analysed yield responses to water, nitrogen and climate using a framework analogous to the rate-duration model of determinate growth. The relationship between modelled grain yield (Y) and evapotranspiration (ET) was fitted to a linear-plateau function to derive three parameters: maximum yield (Y max), the ET break-point when yield reaches its maximum (ET#), and the rate of yield response in the linear phase (ΔY/ΔET). Against this framework, we tested the hypothesis that nitrogen deficit reduces maximum yield by reducing both the rate (ΔY/ΔET) and the range of yield response to evapotranspiration, i.e. ET# − E s, where E s is modelled median soil evaporation. Modelled data reproduced the nitrogen-driven trade-off between nitrogen utilisation efficiency and water use efficiency in a transect from Horsham (36°S) to Emerald (23°S) in eastern Australia. Increasing nitrogen supply from 50 to 250kgNha−1 reduced yield per unit nitrogen uptake from 29 to 12kggrainkg−1 N and increased yield per unit evapotranspiration from 6 to 15kggrainha−1 mm−1 at Emerald. The same increment in nitrogen supply reduced yield per unit nitrogen uptake from 30 to 25kggrainkg−1 N and increased yield per unit evapotranspiration from 6 to 25kggrainha−1 mm−1 at Horsham. Maximum yield ranged from 0.9 to 6.4tha−1. Consistent with our working hypothesis, reductions in maximum yield with nitrogen deficit were associated with both reduction in the rate of yield response to ET and compression of the range of yield response to ET. Against the notion of managing crops to maximise water use efficiency in low rainfall environments, we emphasise the trade-off between water use efficiency and nitrogen utilisation efficiency, particularly under conditions of high nitrogen-to-grain price ratio. The rate-range framework to characterise the relationship between yield and evapotranspiration is useful to capture this trade-off as the parameters were responsive to both nitrogen supply and climatic factors. [Copyright &y& Elsevier]

Trade-offs between the costs and benefits of growth are thought to be mediated by behaviour, whereby rapid growth is associated with greater predation mortality because of increased foraging effort. We tested this hypothesis by collecting young Pomacentrus amboinensis using light traps and settling them onto patch reefs where their behaviour and survivorship were monitored for 24h. One month later, individuals of the same cohort were collected from shallow reefs and released onto patch reefs where their behaviour and survivorship were monitored for 6 days. At settlement young fish suffered high (60% in 24h) mortality that preferentially removed larger, faster-growing individuals. However, we could find no evidence that foraging behaviour contributed to this selective mortality. In contrast, 1 month later the same cohort underwent negative size-selective mortality where the smallest, slower-growing fish were preferentially removed by predators. Larger fish spent more time foraging, were more aggressive, swam greater distances and chased more fish than smaller individuals. Thus, consistent individual differences in behaviour contributed to patterns of mortality, but in a way that involved no apparent trade-off with growth. For P. amboinensis, consistent variation in growth may be maintained by spatial and temporal differences in the selective regime within the reef environment. [Copyright &y& Elsevier]

There is considerable discussion about the relative importance of conserving high quality wilderness areas (i.e. large and intact landscapes) versus conserving areas with high biodiversity values. Places that are needed to achieve one aspect of biodiversity conservation are not necessarily optimal for another which can lead to conflict in assigning conservation priorities. However, both are important for biodiversity conservation, and carry social, economic, and ecological values. Investment in both (a) representation of elements of biodiversity (e.g. species, habitats) and (b) wilderness conservation is not only complementary but important for the long-term persistence of biodiversity. We develop two approaches to identify areas important for the conservation of biodiversity in terms of both wilderness quality and biodiversity representation, using Australia as a case study. We defined intact areas as sub-catchments with at least 70% or more vegetation that has not been subjected to extensive habitat loss and fragmentation as the result of land clearing. The first approach aims to achieve biodiversity representation goals in areas with intact native vegetation. The results of this approach would be extremely expensive to implement as they require a large portion of land. The second approach aims to achieve biodiversity representation goals anywhere across the landscape while placing a strong emphasis on identifying spatially compact intact areas. The results of this approach show the trade-offs between the economic costs of conservation and the size of conservation areas containing intact native vegetation. This manuscript provides a novel framework for identifying cost-effective biodiversity conservation priorities inclusive of wilderness quality. [Copyright &y& Elsevier]

Vertebrates that destroy or disturb habitats used by other animals may influence habitat selection by sympatric taxa. In south-east Australian forests, superb lyrebirds ( Menura novaehollandiae) displace soil, leaf litter and rocks during their daily foraging activities. We investigated whether superb lyrebirds disturb small sandstone rocks that endangered broad-headed snakes Hoplocephalus bungaroides and common small-eyed snakes Cryptophis nigrescens use as diurnal thermoregulatory sites. To estimate the frequency of lyrebird rock disturbance, and to assess whether lyrebirds also attack small snakes, we placed 900 plasticine snake replicas under stones on rock and soil substrates along transects on three sandstone plateaux. Because juvenile snakes must select retreat sites that simultaneously allow them to thermoregulate and minimize predation risk, we quantified the thermal environments underneath stones on rock and soil substrates. During the 6-week experiment, animals disturbed rocks on soil substrates twice as often (16.9%) as rocks lying on rock substrates (8.2%). Disturbed rocks were significantly smaller and lighter than undisturbed rocks on both substrates. Lyrebirds were the major agents of disturbance, and attacked 40% of snake models under disturbed rocks. Rocks on soil substrates conferred the greatest thermal benefits to snakes, but both species of snake avoided these microhabitats in the field. Instead, juvenile snakes selected rocks on rock substrates, and sheltered under stones that were too heavy for superb lyrebirds to disturb. By disturbing rocks over millennia, superb lyrebirds not only have shaped the physical landscape, but also may have exerted strong selection on habitat selection by sympatric snakes. [ABSTRACT FROM AUTHOR]

Summary 1 Many narrowly endemic species are restricted to distinctive edaphic environments. The adaptations that make these species successful in their restricted habitat may incur a cost, and decrease their success in more common habitats. We compared growth, biomass allocation and root morphology of two narrowly endemic Hakea species (Proteaceae) of Mediterranean south-western Australia with those of five more widespread congeners, in a glasshouse study. The rare Hakea species occur in endangered winter-wet shrublands that grow on skeletal (0–20 cm deep) soils overlying massive ironstone rock, whereas their common congeners occur nearby on deeper wetland and non-wetland soils. 2 The ironstone endemics differed consistently from their widespread congeners in some important root characteristics. During early development they allocated relatively more biomass to their roots, and had a higher specific root length due to a lower average root diameter and a lower root mass density. Therefore, when compared at the same plant mass, the ironstone endemics had a considerably greater total root length. 3 The ironstone endemics also favoured root growth in deeper layers of the substrate: they invested up to 64% of their root mass in the bottom 10 cm of 40-cm-deep pots, vs. 35% for common species. Only in the ironstone endemics did the extension of the main root axis continue at the same rate after reaching the bottom of the pot. 4 We suggest that the observed differences are the consequence of evolutionary trade-offs, and represent specializations of the endemic species to increase the chances of getting access to water before the onset of severe summer drought in these habitats. However, while adaptive in a shallow-soil habitat, these traits may reduce success on deeper soils by compromising both below-ground and above-ground competitive abilities. [ABSTRACT FROM AUTHOR]