Samuelsenhurley4017

We also discuss how subtle effects of dominance can increase the chance of evolutionary rescue in diploids when absolute heterozygote fitness is close to 1. These effects do not arise in standard nonrescue models.Ecosystems are under threat from anthropogenic and natural disturbances, yet little is known about how these disturbances alter mutualistic interactions. Many mutualistic interactions are highly context dependent and dynamic due to "ongoing" partner choice, impeding our understanding of how disturbances might influence mutualistic systems. Previously we showed that in the absence of additional known mechanisms of competitive coexistence, mutualistic fungi can coexist in a system where the plant community associates dynamically with two empirically defined arbuscular mycorrhizal fungal types a cheap kind that provides low nutrient benefits, and an expensive type that provides high nutrient benefits. We built on this framework to ask how disturbances of different types, frequencies, amplitudes, and predictabilities alter ongoing partner choice and thereby influence the coexistence of mutualists. We found that the effects of disturbances depend on the type, amplitude, and predictability of disturbances and, to a lesser extent, on their frequency. Disturbance can disrupt mutualist coexistence by enabling hosts more efficiently to exclude partners that behave as parasites. Disturbance can also promote coexistence by altering the strength and direction of consumer-resource interactions. Predicting the effects of disturbance on the mutualist community therefore requires us to understand better the consumer-resource relationships under various environmental conditions. We show how, through such context-dependent effects, disturbance and ongoing partner choice can together generate relative nonlinearity and investment in future benefit, introducing fluctuation-dependent mechanisms of competitive coexistence. Our findings support a broadening of the conceptual framework regarding disturbances and competition to include fluctuation-dependent mechanisms alongside the spatiotemporal intermediate disturbance hypothesis.Egg trading-whereby simultaneous hermaphrodites exchange each other's eggs for fertilization-constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of nontrading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (cheaters who mate only in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of intermediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions, traders can invade-and resist invasion from-providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites.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.In large clonal populations, several clones generally compete, resulting in complex evolutionary and ecological dynamics experiments show successive selective sweeps of favorable mutations as well as long-term coexistence of multiple clonal strains. The mechanisms underlying either coexistence or fixation of several competing strains have rarely been studied altogether. Conditions for coexistence have mostly been studied by population and community ecology, while rates of invasion and fixation have mostly been studied by population genetics. To provide a global understanding of the complexity of the dynamics observed in large clonal populations, we develop a stochastic model where three clones compete. selleck compound Competitive interactions can be intransitive, and we suppose that strains enter the population via mutations or rare immigrations. We first describe all possible final states of the population, including stable coexistence of two or three strains or the fixation of a single strain. Second, we estimate the invasion and fixation times of a favorable mutant (or immigrant) entering the population in a single copy. We show that invasion and fixation can be slower or faster when considering complex competitive interactions. Third, we explore the parameter space assuming prior distributions of reproduction, death, and competition rates, and we estimate the likelihood of the possible dynamics. We show that when mutations can affect competitive interactions even slightly, stable coexistence is likely. We discuss our results in the context of the evolutionary dynamics of large clonal populations.