Slow and steady wins the race: Spatial and stochastic processes and the failure of suppression gene drives.

Gene drives that skew sex ratios offer a new management tool to suppress or eradicate pest populations. Early models and empirical work suggest that these suppression drives can completely eradicate well-mixed populations, but models that incorporate stochasticity and space (i.e. drift and recolonization events) often result in loss or failure of the drive. We developed a stochastic model to examine these processes in a simple one-dimensional space. This simple space allows us to map the events and outcomes that emerged and examine how properties of the drive's wave of invasion affect outcomes. Our simulations, across a biologically realistic section of parameter space, suggest that drive failure might be a common outcome in spatially explicit, stochastic systems, and that properties of the drive wave appear to mediate outcomes. Surprisingly, the drives that would be considered fittest in an aspatial model were strongly associated with failure in the spatial setting. The fittest drives cause relatively fast moving, and narrow waves that have a high chance of being penetrated by wild-types (WTs) leading to WT recolonization, leading to failure. Our results also show that high rates of dispersal reduce the chance of failure because drive waves get disproportionately wider than WT waves as dispersal rates increase. Overall, wide, slow-moving drive waves were much less prone to failure. Our results point to the complexity inherent in using a genetic system to effect demographic outcomes and speak to a clear need for ecological and evolutionary modelling to inform the drive design process.

Population genomics of a predatory mammal reveals patterns of decline and impacts of exposure to toxic toads.

Mammal declines across northern Australia are one of the major biodiversity loss events occurring globally. There has been no regional assessment of the implications of these species declines for genomic diversity. To address this, we conducted a species-wide assessment of genomic diversity in the northern quoll (Dasyurus hallucatus), an Endangered marsupial carnivore. We used next generation sequencing methods to genotype 10,191 single nucleotide polymorphisms (SNPs) in 352 individuals from across a 3220-km length of the continent, investigating patterns of population genomic structure and diversity, and identifying loci showing signals of putative selection. We found strong heterogeneity in the distribution of genomic diversity across the continent, characterized by (i) biogeographical barriers driving hierarchical population structure through long-term isolation, and (ii) severe reductions in diversity resulting from population declines, exacerbated by the spread of introduced toxic cane toads (Rhinella marina). These results warn of a large ongoing loss of genomic diversity and associated adaptive capacity as mammals decline across northern Australia. Encouragingly, populations of the northern quoll established on toad-free islands by translocations appear to have maintained most of the initial genomic diversity after 16 years. By mapping patterns of genomic diversity within and among populations, and investigating these patterns in the context of population declines, we can provide conservation managers with data critical to informed decision-making. This includes the identification of populations that are candidates for genetic management, the importance of remnant island and insurance/translocated populations for the conservation of genetic diversity, and the characterization of putative evolutionarily significant units.

Effects of learning and adaptation on population viability.

Cultural adaptation is one means by which conservationists may help populations adapt to threats. A learned behavior may protect an individual from a threat, and the behavior can be transmitted horizontally (within generations) and vertically (between generations), rapidly conferring population-level protection. Although possible in theory, it remains unclear whether such manipulations work in a conservation setting; what conditions are required for them to work; and how they might affect the evolutionary process. We examined models in which a population can adapt through both genetic and cultural mechanisms. Our work was motivated by the invasion of highly toxic cane toads (Rhinella marina) across northern Australia and the resultant declines of endangered northern quolls (Dasyurus hallucatus), which attack and are fatally poisoned by the toxic toads. We examined whether a novel management strategy in which wild quolls are trained to avoid toads can reduce extinction probability. We used a simulation model tailored to quoll life history. Within simulations, individuals were trained and a continuous evolving trait determined innate tendency to attack toads. We applied this model in a population viability setting. The strategy reduced extinction probability only when heritability of innate aversion was low (<20%) and when trained mothers trained >70% of their young to avoid toads. When these conditions were met, genetic adaptation was slower, but rapid cultural adaptation kept the population extant while genetic adaptation was completed. To gain insight into the evolutionary dynamics (in which we saw a transitory peak in cultural adaptation over time), we also developed a simple analytical model of evolutionary dynamics. This model showed that the strength of natural selection declined as the cultural transmission rate increased and that adaptation proceeded only when the rate of cultural transmission was below a critical value determined by the relative levels of protection conferred by genetic versus cultural mechanisms. Together, our models showed that cultural adaptation can play a powerful role in preventing extinction, but that rates of cultural transmission need to be high for this to occur.

La adaptación cultural es un medio mediante el cual los conservacionistas pueden ayudar a las poblaciones a adaptarse a las amenazas. Un comportamiento aprendido puede proteger a un individuo de las amenazas y este comportamiento puede transmitirse horizontalmente (dentro de las generaciones) y verticalmente (entre generaciones), lo que otorga rápidamente una protección a nivel poblacional. Aunque esto es posible en teoría, aún no está claro si dichas manipulaciones funcionan dentro de un escenario de conservación; cuáles son las condiciones requeridas para que funcionen las manipulaciones; y cómo pueden afectar el proceso evolutivo. Examinamos modelos en los cuales una población puede adaptarse tanto con mecanismos genéticos como culturales. Nuestro trabajo estuvo motivado por la invasión de sapos altamente tóxicos (Rhinella marina) en todo el norte de Australia y las declinaciones resultantes de cuoles norteños (Dasyurus hallucatus), los cuales atacan y mueren envenenados por los sapos tóxicos. Analizamos si una estrategia de manejo novedoso en la cual los cuoles silvestres son entrenados para evitar a los sapos puede reducir la probabilidad de extinción. Usamos un modelo de simulación diseñado alrededor de la historia de vida de los cuoles. Dentro de las simulaciones, se entrenó a cuoles individuales y una característica en continua evolución determinó la tendencia innata para atacar a los sapos. Aplicamos este modelo en un escenario de viabilidad poblacional. La estrategia redujo la probabilidad de extinción sólo cuando la heredabilidad de la aversión innata fue baja (<20%) y cuando las madres entrenadas entrenaron a más del 70% de sus crías para evitar a los sapos. Cuando ambas condiciones fueron cumplidas, la adaptación genética fue más lenta pero la adaptación cultural rápida mantuvo a la población vigente mientras se completaba la adaptación genética. Para ganar conocimiento sobre las dinámicas evolutivas (en las cuales vimos un pico transitorio en la adaptación cultural a lo largo del tiempo) también desarrollamos un modelo analítico simple de las dinámicas evolutivas. Este modelo mostró que la fuerza de la selección natural declinó conforme incrementó la tasa de transmisión cultural y que la adaptación procedió solamente cuando la tasa de transmisión cultural estuvo por debajo de un valor crítico determinado por los niveles relativos de protección otorgados por los mecanismos genéticos contra los mecanismos evolutivos. En conjunto, nuestros modelos mostraron que la adaptación cultural puede jugar un papel importante en la prevención de la extinción, pero las tasas de transmisión cultural necesitan ser altas para que esto ocurra.

Evolution Transforms Pushed Waves into Pulled Waves.

Understanding the dynamics of biological invasions is crucial for managing numerous phenomena, from invasive species to tumors. While the Allee effect (where individuals in low-density populations suffer lowered fitness) is known to influence both the ecological and the evolutionary dynamics of an invasion, the possibility that an invader's susceptibility to the Allee effect might itself evolve has received little attention. Since invasion fronts are regions of perpetually low population density, selection should be expected to favor vanguard invaders that are resistant to Allee effects. This may not only cause invasions to accelerate over time but, by mitigating the Allee effects experienced by the vanguard, also make the invasion transition from a pushed wave, propelled by dispersal from behind the invasion front, to a pulled wave, driven instead by the invasion vanguard. To examine this possibility, we construct an individual-based model in which a trait that governs resistance to the Allee effect is allowed to evolve during an invasion. We find that vanguard invaders evolve resistance to the Allee effect, causing invasions to accelerate. This results in invasions transforming from pushed waves to pulled waves, an outcome with consequences for invasion speed, population genetic structure, and other emergent behaviors. These findings underscore the importance of accounting for evolution in invasion forecasts and suggest that evolution has the capacity to fundamentally alter invasion dynamics.

Forecasting species range dynamics with process-explicit models: matching methods to applications.

Knowing where species occur is fundamental to many ecological and environmental applications. Species distribution models (SDMs) are typically based on correlations between species occurrence data and environmental predictors, with ecological processes captured only implicitly. However, there is a growing interest in approaches that explicitly model processes such as physiology, dispersal, demography and biotic interactions. These models are believed to offer more robust predictions, particularly when extrapolating to novel conditions. Many process-explicit approaches are now available, but it is not clear how we can best draw on this expanded modelling toolbox to address ecological problems and inform management decisions. Here, we review a range of process-explicit models to determine their strengths and limitations, as well as their current use. Focusing on four common applications of SDMs - regulatory planning, extinction risk, climate refugia and invasive species - we then explore which models best meet management needs. We identify barriers to more widespread and effective use of process-explicit models and outline how these might be overcome. As well as technical and data challenges, there is a pressing need for more thorough evaluation of model predictions to guide investment in method development and ensure the promise of these new approaches is fully realised.

Can pathogens optimize both transmission and dispersal by exploiting sexual dimorphism in their hosts?

Pathogens often rely on their host for dispersal. Yet, maximizing fitness via replication can cause damage to the host and an associated reduction in host movement, incurring a trade-off between transmission and dispersal. Here, we test the idea that pathogens might mitigate this trade-off between reproductive fitness and dispersal by taking advantage of sexual dimorphism in their host, tailoring responses separately to males and females. Using experimental populations of Daphnia magna and its bacterial pathogen Pasteuria ramosa as a test-case, we find evidence that this pathogen can use male hosts as a dispersal vector, and the larger females as high-quality resource patches for optimized production of transmission spores. As sexual dimorphism in dispersal and body size is widespread across the animal kingdom, this differential exploitation of the sexes by a pathogen might be an unappreciated phenomenon, possibly evolved in various systems.

Targeted gene flow and rapid adaptation in an endangered marsupial.

Targeted gene flow is an emerging conservation strategy. It involves translocating individuals with favorable genes to areas where they will have a conservation benefit. The applications for targeted gene flow are wide-ranging but include preadapting native species to the arrival of invasive species. The endangered carnivorous marsupial, the northern quoll (Dasyurus hallucatus), has declined rapidly since the introduction of the cane toad (Rhinella marina), which fatally poisons quolls that attack them. There are, however, a few remaining toad-invaded quoll populations in which the quolls survive because they know not to eat cane toads. It is this toad-smart behavior we hope to promote through targeted gene flow. For targeted gene flow to be feasible, however, toad-smart behavior must have a genetic basis. To assess this, we used a common garden experiment, comparing offspring from toad-exposed and toad-naïve parents raised in identical environments, to determine whether toad-smart behavior is heritable. Offspring from toad-exposed populations were substantially less likely to eat toads than those with toad-naïve parents. Hybrid offspring showed similar responses to quolls with 2 toad-exposed parents, indicating the trait may be dominant. Together, these results suggest a heritable trait and rapid adaptive response in a small number of toad-exposed populations. Although questions remain about outbreeding depression, our results are encouraging for targeted gene flow. It should be possible to introduce toad-smart behavior into soon to be affected quoll populations.

Using connectivity to identify climatic drivers of local adaptation.

Understanding the climatic drivers of local adaptation is vital. Such knowledge is not only of theoretical interest but is critical to inform management actions under climate change, such as assisted translocation and targeted gene flow. Unfortunately, there are a vast number of potential trait-environment combinations, and simple relationships between trait and environment are ambiguous: representing either plastic or evolved variation. Here, we show that by incorporating connectivity as an index of gene flow, we can differentiate trait-environment relationships reflecting genetic variation vs. phenotypic plasticity. In this way, we rapidly shorten the list of trait-environment combinations that are of significance. Our analysis of an existing data set on geographic variation in a tropical lizard shows that we can effectively rank climatic variables by the strength of their role in local adaptation. The promise of our method is a rapid and general approach to identifying the environmental drivers of local adaptation.

Invasion history alters the behavioural consequences of immune system activation in cane toads.

Acute activation of the immune system often initiates a suite of behavioural changes. These "sickness behaviours"-involving lethargy and decreased activity-may be particularly costly on invasion fronts, where evolutionary pressures on dispersal favour individuals that move large distances. We used a combination of field and laboratory studies to compare sickness behaviours of cane toads from populations differing in invasion history. To do this we stimulated immune system activation by injecting lipopolysaccharide (LPS) to mimic bacterial infection. We predicted that LPS would result in less severe sickness behaviour in toads from range-edge populations because they had undergone selection for rapid and sustained dispersal (activities in conflict with lethargy and decreased activity). Contrary to our prediction, LPS injection caused a greater reduction in dispersal-relevant traits in invasion-front individuals than in conspecifics from the range-core. Our data suggest that the rapid invasion of cane toads through tropical Australia has seen an evolutionary shift in the magnitude of sickness behaviour elicited by pathogen infection. The increased sickness behaviour among range-edge toads suggests a shift away from pathogen tolerance (seen in range-core populations) towards resistance to pathogen attack. But as a consequence, when pathogens do become successfully established, toads from invasion-front populations may have less capacity to tolerate their ill-effects.

The perils of paradise: an endangered species conserved on an island loses antipredator behaviours within 13 generations.

When imperilled by a threatening process, the choice is often made to conserve threatened species on offshore islands that typically lack the full suite of mainland predators. While keeping the species extant, this releases the conserved population from predator-driven natural selection. Antipredator traits are no longer maintained by natural selection and may be lost. It is implicitly assumed that such trait loss will happen slowly, but there are few empirical tests. In Australia, northern quolls (Dasyurus hallucatus) were moved onto a predator-free offshore island in 2003 to protect the species from the arrival of invasive cane toads on the mainland. We compared the antipredator behaviours of wild-caught quolls from the predator-rich mainland with those from this predator-free island. We compared the responses of both wild-caught animals and their captive-born offspring, to olfactory cues of two of their major predators (feral cats and dingoes). Wild-caught, mainland quolls recognized and avoided predator scents, as did their captive-born offspring. Island quolls, isolated from these predators for only 13 generations, showed no recognition or aversion to these predators. This study suggests that predator aversion behaviours can be lost very rapidly, and that this may make a population unsuitable for reintroduction to a predator-rich mainland.

The impact of parasites during range expansion of an invasive gecko.

Host-parasite dynamics can play a fundamental role in both the establishment success of invasive species and their impact on native wildlife. The net impact of parasites depends on their capacity to switch effectively between native and invasive hosts. Here we explore host-switching, spatial patterns and simple fitness measures in a slow-expanding invasion: the invasion of Asian house geckos (Hemidactylus frenatus) from urban areas into bushland in Northeast Australia. In bushland close to urban edges, H. frenatus co-occurs with, and at many sites now greatly out-numbers, native geckos. We measured prevalence and intensity of Geckobia mites (introduced with H. frenatus), and Waddycephalus (a native pentastome). We recorded a new invasive mite species, and several new host associations for native mites and geckos, but we found no evidence of mite transmission between native and invasive geckos. In contrast, native Waddycephalus nymphs were commonly present in H. frenatus, demonstrating this parasite's capacity to utilize H. frenatus as a novel host. Prevalence of mites on H. frenatus decreased with distance from the urban edge, suggesting parasite release towards the invasion front; however, we found no evidence that mites affect H. frenatus body condition or lifespan. Waddycephalus was present at low prevalence in bushland sites and, although its presence did not affect host body condition, our data suggest that it may reduce host survival. The high relative density of H. frenatus at our sites, and their capacity to harbour Waddycephalus, suggests that there may be impacts on native geckos and snakes through parasite spillback.

Living on the Edge: Parasite Prevalence Changes Dramatically across a Range Edge in an Invasive Gecko.

Species interactions can determine range limits, and parasitism is the most intimate of such interactions. Intriguingly, the very conditions on range edges likely change host-parasite dynamics in nontrivial ways. Range edges are often associated with clines in host density and with environmental transitions, both of which may affect parasite transmission. On advancing range edges, founder events and fitness/dispersal costs of parasitism may also cause parasites to be lost on range edges. Here we examine the prevalence of three species of parasite across the range edge of an invasive gecko, Hemidactylus frenatus, in northeastern Australia. The gecko's range edge spans the urban-woodland interface at the edge of urban areas. Across this edge, gecko abundance shows a steep decline, being lower in the woodland. Two parasite species (a mite and a pentastome) are coevolved with H. frenatus, and these species become less prevalent as the geckos become less abundant. A third species of parasite (another pentastome) is native to Australia and has no coevolutionary history with H. frenatus. This species became more prevalent as the geckos become less abundant. These dramatic shifts in parasitism (occurring over 3.5 km) confirm that host-parasite dynamics can vary substantially across the range edge of this gecko host.

The genetic backburn: using rapid evolution to halt invasions.

The impact of an invasive species depends upon the extent of area across which it ultimately spreads. A powerful strategy for limiting impact, then, is to limit spread, and this can most easily be achieved by managing or reinforcing natural barriers to spread. Using a simulation model, we show that rapid evolutionary increases in dispersal can render permeable an otherwise effective barrier. On the other hand, we also show that, once the barrier is reached, and if it holds, resultant evolutionary decreases in dispersal rapidly make the barrier more effective. Finally, we sketch a strategy--the genetic backburn--in which low-dispersal individuals from the range core are translocated to the nearside of the barrier ahead of the oncoming invasion. We find that the genetic backburn--by preventing invasion front genotypes reaching the barrier, and hastening the evolutionary decrease in dispersal--can make barriers substantially more effective. In our simulations, the genetic backburn never reduced barrier strength, however, the improvement to barrier strength was negligible when there was substantial long-distance dispersal, or when there was no genetic variation for dispersal distance. The improvement in barrier strength also depended on the trade-off between dispersal and competitive ability, with a stronger trade-off conferring greater power to the genetic backburn.

Targeted gene flow for conservation.

Anthropogenic threats often impose strong selection on affected populations, causing rapid evolutionary responses. Unfortunately, these adaptive responses are rarely harnessed for conservation. We suggest that conservation managers pay close attention to adaptive processes and geographic variation, with an eye to using them for conservation goals. Translocating pre-adapted individuals into recipient populations is currently considered a potentially important management tool in the face of climate change. Targeted gene flow, which involves moving individuals with favorable traits to areas where these traits would have a conservation benefit, could have a much broader application in conservation. Across a species' range there may be long-standing geographic variation in traits or variation may have rapidly developed in response to a threatening process. Targeted gene flow could be used to promote natural resistance to threats to increase species resilience. We suggest that targeted gene flow is a currently underappreciated strategy in conservation that has applications ranging from the management of invasive species and their impacts to controlling the impact and virulence of pathogens.

Do pathogens become more virulent as they spread? Evidence from the amphibian declines in Central America.

The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence is regularly observed, directional shifts in virulence are less commonly observed and are typically associated with decreasing virulence of biological control agents through coevolution. It is increasingly appreciated, however, that spatial effects can lead to evolutionary trajectories that differ from standard expectations. One such possibility is that, as a pathogen spreads through a naive host population, its virulence increases on the invasion front. In Central America, there is compelling evidence for the recent spread of pathogenic Batrachochytrium dendrobatidis (Bd) and for its strong impact on amphibian populations. Here, we re-examine data on Bd prevalence and amphibian population decline across 13 sites from southern Mexico through Central America, and show that, in the initial phases of the Bd invasion, amphibian population decline lagged approximately 9 years behind the arrival of the pathogen, but that this lag diminished markedly over time. In total, our analysis suggests an increase in Bd virulence as it spread southwards, a pattern consistent with rapid evolution of increased virulence on Bd's invading front. The impact of Bd on amphibians might therefore be driven by rapid evolution in addition to more proximate environmental drivers.

Increasing arboreality with altitude: a novel biogeographic dimension.

Biodiversity is spatially organized by climatic gradients across elevation and latitude. But do other gradients exist that might drive biogeographic patterns? Here, we show that rainforest's vertical strata provide climatic gradients much steeper than those offered by elevation and latitude, and biodiversity of arboreal species is organized along this gradient. In Philippine and Singaporean rainforests, we demonstrate that rainforest frogs tend to shift up in the rainforest strata as altitude increases. Moreover, a Philippine-wide dataset of frog distributions shows that frog assemblages become increasingly arboreal at higher elevations. Thus, increased arboreality with elevation at broad biogeographic scales mirrors patterns we observed at local scales. Our proposed 'arboreality hypothesis' suggests that the ability to exploit arboreal habitats confers the potential for larger geographical distributions because species can shift their location in the rainforest strata to compensate for shifts in temperature associated with elevation and latitude. This novel finding may help explain patterns of species richness and abundance wherever vegetation produces a vertical microclimatic gradient. Our results further suggest that global warming will 'flatten' the biodiversity in rainforests by pushing arboreal species towards the cooler and wetter ground. This 'flattening' could potentially have serious impacts on forest functioning and species survival.

Colony-level aggression escalates with the value of food resources.

BACKGROUND: Theory predicts that the level of escalation in animal contests is associated with the value of the contested resource. This fundamental prediction has been empirically confirmed by studies of dyadic contests but has not been tested experimentally in the collective context of group-living animals. Here, we used the Australian meat ant Iridomyrmex purpureus as a model and employed a novel field experimental manipulation of the value of food that removes the potentially confounding effects of nutritional status of the competing individual workers. We draw on insights from the Geometric Framework for nutrition to investigate whether group contests between neighbouring colonies escalate according to the value to the colony of a contested food resource. RESULTS: First, we show that colonies of I. purpureus value protein according to their past nutritional intake, deploying more foragers to collect protein if their previous diet had been supplemented with carbohydrate rather than with protein. Using this insight, we show that colonies contesting more highly valued food escalated the contest, by deploying more workers and engaging in lethal 'grappling' behaviour. CONCLUSION: Our data confirm that a key prediction of contest theory, initially intended for dyadic contests, is similarly applicable to group contests. Specifically, we demonstrate, through a novel experimental procedure, that the contest behaviour of individual workers reflects the nutritional requirements of the colony, rather than that of individual workers.

Evolutionary predictions for a parasite metapopulation: Modelling salmon louse resistance to pest controls in aquaculture.

Pests often evolve resistance to pest controls used in agriculture and aquaculture. The rate of pest adaptation is influenced by the type of control, the selective pressure it imposes, and the gene flow between farms. By understanding how these factors influence evolution at the metapopulation level, pest management strategies that prevent resistance from evolving can be developed. We developed a model for the metapopulation and evolutionary dynamics of the salmon louse (Lepeophtheirus salmonis), which is a major parasite affecting salmon aquaculture. Different management scenarios were simulated across a network of salmon farms covering half of Norway, and their effects on louse epidemiology and evolution were investigated. We compared louse controls that differed in how they were deployed through time (discrete vs. continuous), how they impacted the louse life cycle, and in their overall efficacy. We adjusted the strength of selection imposed by treatments, the dominance effect of the resistant allele, and the geographic location at which resistance originated. Continuously acting strategies (e.g., louse-resistant salmon) were generally more effective than discrete strategies at controlling lice, especially when they increased louse mortality during early developmental stages. However, effective strategies also risked imposing frequent and/or strong selection on lice, thus driving rapid adaptation. Resistant alleles were more likely to be lost through genetic drift when they were recessive, had a low-fitness advantage, or originated in low-farm-density areas. The north-flowing current along the Norwegian coastline dispersed resistant genes from south to north, and limited gene flow in the opposite direction. We demonstrate how evolutionary models can produce quantitative predictions over large spatial and temporal scales and for a range of pest control scenarios. Quantitative outputs can be translated into practical management decisions applied at a regional level to minimise the risk of resistance developing.

Applying genetic technologies to combat infectious diseases in aquaculture.

Disease and parasitism cause major welfare, environmental and economic concerns for global aquaculture. In this review, we examine the status and potential of technologies that exploit genetic variation in host resistance to tackle this problem. We argue that there is an urgent need to improve understanding of the genetic mechanisms involved, leading to the development of tools that can be applied to boost host resistance and reduce the disease burden. We draw on two pressing global disease problems as case studies-sea lice infestations in salmonids and white spot syndrome in shrimp. We review how the latest genetic technologies can be capitalised upon to determine the mechanisms underlying inter- and intra-species variation in pathogen/parasite resistance, and how the derived knowledge could be applied to boost disease resistance using selective breeding, gene editing and/or with targeted feed treatments and vaccines. Gene editing brings novel opportunities, but also implementation and dissemination challenges, and necessitates new protocols to integrate the technology into aquaculture breeding programmes. There is also an ongoing need to minimise risks of disease agents evolving to overcome genetic improvements to host resistance, and insights from epidemiological and evolutionary models of pathogen infestation in wild and cultured host populations are explored. Ethical issues around the different approaches for achieving genetic resistance are discussed. Application of genetic technologies and approaches has potential to improve fundamental knowledge of mechanisms affecting genetic resistance and provide effective pathways for implementation that could lead to more resistant aquaculture stocks, transforming global aquaculture.