Biology subjects

Akcay, E.

Publications and source records attributed to Akcay, E..

At least 19 recordsLinked to original sources

bioRxiv2026

Evolution of the division of labor between two interacting public tasks

Individuals in many species perform several costly tasks whose benefits are shared with neighbors: bacteria secrete distinct public metabolites, plants emit distinct defensive volatiles, and human foragers acquire distinct shared foods. Performing one of these tasks often changes the benefits and costs of the other: a forager who brings in one kind of food provides different nutritional benefits to neighbors than one who brings in several kinds, and the difference depends on what the neighbors bring. Here we ask which divisions of labor evolve when two tasks interact. We model the interaction at both the group and the individual level, and we derive the long-run outcomes of the replicator dynamics as functions of the task payoffs and the interaction parameters. Interactions between tasks produce long-run outcomes that cannot occur when the tasks are independent. In particular, specialists, who perform one task but not the other, can coexist in a stable division of labor only if the tasks interact, and in most cases only if the interaction is more favorable when different individuals perform the two tasks than when one individual performs both. We also show that a specialized division of labor can be bistable with a non-specialized one, and we prove that, when both tasks are identical anti-coordination games, individuals in the specialized population have higher fitness. This bistability produces hysteresis in both the division of labor and fitness as interaction parameters vary. Populations with identical payoffs can therefore evolve to divisions of labor with different mean fitness.

evolutionary biology↗

bioRxiv2026

The effects of group size and assortment on the evolution of division of labor

Stable variation in public-good production can generate biological division of labor. Two key drivers are the size of interacting groups and the degree of assortment (relatedness) among individuals with similar investment levels. Here we extend adaptive-dynamic models of continuous public-goods investment by allowing assortment in group formation. We show that increasing group size typically enlarges the range of benefit and cost curvatures that permit evolutionary branching, whereas assortment tends to shrink this range and prevents branching under complete relatedness. For a broad class of models, branching requires diminishing marginal public benefits and diminishing marginal private costs, with costs decreasing faster than benefits. Finally, we analyze post-branching dynamics for one and two public goods, and find that assortment can stabilize the resulting two-type division of labor. Together, these results show how group size, assortment, and payoff curvature jointly determine when heterogeneity in public-goods production can evolve.

evolutionary biology↗

bioRxiv2025

Coupled dynamics of predator group formation and prey populations

1A diverse array of social carnivores, such as orcas and wolves, also hunt cooperatively, but it is not well understood how prey availability feeds back with the size of social carnivore groups. Cooperative hunting may expand predators access to food by allowing them to hunt prey they could not catch alone, but many predator groups are much larger than the group size that would maximize individual food intake. One promising explanation is that if individuals can freely leave and join groups, then predators behaving adaptively should continue to join a group until the fitness that they achieve in the group is the same as that of being solitary. Here, we investigate the stable group sizes that form in a population of predator groups when predators hunt two types of prey: big prey that is best hunted in groups and small prey that is best hunted alone. In conjunction, we track the dynamics of the distribution of predator group sizes when individuals make decisions about whether to join or leave groups based on their own fitness. We find that if individual predators are able to freely leave groups and pair up with other individuals, starting new groups, then group sizes at equilibrium are much smaller than expected, generally staying at or below the size that maximizes individual fitness. Furthermore, accounting for flexible group sizes leads to ecological conditions that are not predicted if predator group sizes are held constant; in some regions of the parameter space, predators partition resources by forming a bimodal distribution of group sizes, and as a result, create situations where an increase in one prey type helps the other prey population grow. This result has applications to management of carnivore-livestock conflict, implying that increasing populations of wild prey may protect livestock.

ecology↗

bioRxiv2025

Competition, Mutualism, and Host Immune Control in a Cancer Microbiome

The microbiome functions as an ecological community, where diverse microbes engage in metabolically mediated interactions such as mutualism and competition. Host immune response can regulate microbial community richness and abundance, which in turn can shape the prevalence of different ecological interactions within the microbiome. Theory predicts that host immune states shift dominant interaction modes among microbes: inflammation favors competition, while immunosuppression favors mutualism. We test these theoretical predictions using the stomach cancer microbiome data through integrated genomic and metabolic analyses. We observe that tumors with high-richness and high-abundance microbiomes were associated with increased mutualistic interactions, whereas tumors with low-richness and low-abundance microbiomes had fewer mutualistic interactions. Host immune gene expression in the high-richness and abundance group was suggestive of a dysregulated or immunosuppressed tumor microenvironment, whereas in the low-richness and abundance group immune signatures were indicative of intact immune function. Notably, competitive interactions remained relatively consistent between groups, whereas mutualism varied markedly, highlighting its sensitivity to shifts in immune state. Finally, the microbiome and host immune states were linked to patient clinical outcomes, with high-richness and abundance microbiomes associated with poorer survival and elevated expression of immune markers linked to adverse prognosis. These results reveal how host immune control can covary with ecological interactions within the microbiome, and the potential consequences of these interactions for host health.

ecology↗

bioRxiv2025

Evolution of division of labor on two public goods with continuous investments

Species throughout the tree of life have evolved to produce multiple public goods, and they often exhibit division of labor, meaning that subpopulations have different allocations of effort across the goods. Despite a robust theoretical literature on mechanisms that lead to division of labor in specific domains, a general evolutionary game-theoretical analysis remains incomplete. Here we model labor as a continuous quantity and the resulting public goods as functions of labor contributed by all individuals using adaptive dynamics. We derive general conditions for the evolution of division of labor and categorize what forms of division may arise. We show that the adaptive dynamics of division of labor has three potential outcomes that differ in expected payoff and variance in payoff. Our findings indicate that the evolution of division of labor can have a diverse range of possible outcomes, with important consequences for fitness, variance in payoff, and the distribution of effort across the population.

evolutionary biology↗

bioRxiv2023

Pathways to cultural adaptation: the coevolution of cumulative culture and social networks

Humans have adapted to an immense array of ecologies by accumulating culturally transmitted knowledge and skills. Culture accumulates in at least two ways: via more distinct cultural traits, or via improvements of existing cultural trait. A trade-off is expected between these owing to the fact that social learning opportunities are finite and social learning often requires multiple exposures. Furthermore, what kind of culture accumulates depends on, and coevolves with, the social structure of societies. Here we show that the coevolution of social networks for learning and cumulative culture results in two distinct pathways to cultural adaptation: highly connected populations with high proficiency but low cultural trait diversity vs. sparsely connected populations with low proficiency but more cultural trait diversity. Importantly, we show there is a general conflict between group-level payoffs, which is maximised in highly connected groups that attain high proficiency, and individual level selection, which favours disconnection. This conflict emerges from the interaction of social learning with population structure and causes populations to cycle between the two cultural and network states. The same conflict creates a paradox where improving individual innovation rates lowers the payoffs of groups. Finally, we explore how populations navigate these two pathways in heterogeneous and changing environments, and show that high heterogeneity in payoffs and slow rate of environmental change favours high proficiency, while fast rate of environmental change favours more trait diversity. We also find that the proficiency pathway to cultural adaptation is favoured with increased population size, but only in slow changing environments. Our results uncover previously unrecognised trade-offs and tensions in the coevolutionary dynamics of cumulative culture and social structure, with broad implications for human social evolution.

animal behavior and cognition↗

bioRxiv2022

Host control and species interactions jointly determine microbiome community structure

1The host microbiome can be considered an ecological community of microbes present inside a complex and dynamic host environment. The host is under selective pressure to ensure that its microbiome remains beneficial. The host can impose a range of ecological filters including the immune response that can influence the assembly and composition of the microbial community. How the host immune response interacts with the within-microbiome community dynamics to affect the assembly of the microbiome has been largely unexplored. We present here a mathematical framework to elucidate the role of host immune response and its interaction with the balance of ecological interactions types within the microbiome community. We find that highly mutualistic microbial communities characteristic of high community density are most susceptible to changes in immune control and become invasion prone as host immune control strength is increased. Whereas highly competitive communities remain relatively stable in resisting invasion to changing host immune control. Our model reveals that the host immune control can interact in unexpected ways with a microbial community depending on the prevalent ecological interactions types for that community. We stress the need to incorporate the role of host-control mechanisms to better understand microbiome community assembly and stability.

ecology↗

bioRxiv2021

A Synthesis of Game Theory and Quantitative Genetic Models of Social Evolution

Two popular approaches for modeling social evolution, evolutionary game theory and quantitative genetics, ask complementary questions but are rarely integrated. Game theory focuses on evolutionary outcomes, with models solving for evolutionarily stable equilibria, whereas quantitative genetics provides insight into evolutionary processes, with models predicting short-term responses to selection. Here we draw parallels between evolutionary game theory and interacting phenotypes theory, which is a quantitative genetic framework for understanding social evolution. First, we show how any evolutionary game may be translated into two quantitative genetic selection gradients, nonsocial and social selection, which may be used to predict evolutionary change from a single round of the game. We show that synergistic fitness effects may alter predicted selection gradients, causing changes in magnitude and sign as the population mean evolves. Second, we show how evolutionary games involving plastic behavioral responses to partners can be modeled using indirect genetic effects, which describe how trait expression changes in response to genes in the social environment. We demonstrate that repeated social interactions in models of reciprocity generate indirect effects and conversely, that estimates of parameters from indirect genetic effect models may be used to predict the evolution of reciprocity. We argue that a pluralistic view incorporating both theoretical approaches will benefit empiricists and theorists studying social evolution. We advocate the measurement of social selection and indirect genetic effects in natural populations to test the predictions from game theory, and in turn, the use of game theory models to aid in the interpretation of quantitative genetic estimates.

evolutionary biology↗

bioRxiv2021

Host phenology drives the evolution of intermediate parasite virulence

AO_SCPLOWBSTRACTC_SCPLOWThe traditional mechanistic trade-offs resulting in a negative correlation between transmission and virulence are the foundation of nearly all current theory on the evolution of parasite virulence. Several ecological factors have been shown to modulate the optimal virulence strategies predicted from mechanistic trade-off models, but these ecological factors have not yet been shown to be sufficient to explain the intermediate virulence strategies observed in any natural system. The timing of seasonal activity, or phenology, is a common factor that influences the types and impact of many ecological interactions but is difficult to incorporate into virulence evolution studies. We develop a mathematical model of a disease system with seasonal host activity to study the evolutionary consequences of host phenology on the virulence of obligate-killer parasite. Results from this model demonstrated that seasonal host activity is sufficient to drive the evolution of intermediate parasite virulence in some types of natural disease systems, even when a traditional mechanistic trade-off between transmission and virulence is not assumed in the modeling framework. The optimal virulence strategy in these systems can be determined by both the duration of the host activity period as well as the variation in the host emergence timing. Parasites with low virulence strategies are favored in environments with long host activity periods and in environments in which hosts emerge synchronously. The results demonstrate that host phenology can be sufficient to select for intermediate optimal virulence strategies, providing an alternative mechanism to account for virulence evolution in some natural systems.

evolutionary biology↗

bioRxiv2020

The legacy of C4 evolution in the hydraulics of C3 and C4 grasses

The anatomical reorganization required for optimal C4 photosynthesis should also impact plant hydraulics. Most C4 plants possess large bundle-sheath cells and high vein density, which should also lead to higher leaf hydraulic conductance (Kleaf) and capacitance. Paradoxically, the C4 pathway reduces water demand and increases water-use-efficiency, creating a potential mis-match between supply capacity and demand in C4 plant water relations. We use phylogenetic analyses, physiological measurements, and models to examine the reorganization of hydraulics in closely-related C4 and C3 grasses. Evolutionarily young C4 lineages have higher Kleaf, capacitance, turgor-loss-point, and lower stomatal conductance than their C3 relatives. In contrast, species from older C4 lineages show decreased Kleaf and capacitance, indicating that over time, C4 plants have evolved to optimize hydraulic investments while maintaining C4 anatomical requirements. The initial "over-plumbing" of C4 plants disrupts the positive correlation between maximal assimilation rate and Kleaf, decoupling a key relationship between hydraulics and photosynthesis generally observed in vascular plants.

ecology↗

bioRxiv2020

Optimal reorganization of photosynthesis after the evolution of C4

C3 and C4 are major functional types in terrestrial biosphere models, with photosynthesis traits as important input parameters. The evolution of C4 required reorganizations of Calvin-Benson-cycle and coordination of C4-cycle enzymes, resulting in divergences of physiological traits between C3 and C4. In addition, photosynthesis further optimized after the evolution of C4 causing diversification within C4 lineages due to different evolutionary histories. We combined optimality modeling, physiological measurements and phylogenetic analysis to examine how various aspects of C4 photosynthetic machinery were reorganized and coordinated within C4 lineages and as compared to closely-related C3 in grasses. Optimality models and measurements indicated a higher maximal electron transport to maximal Rubisco carboxylation ratio (Jmax/Vcmax) in C4 than C3, consistent with the optimal prediction to maximize photosynthesis. The coordination between Calvin-Benson and C4 cycles (Vpmax/Vcmax), however, is in line with the optimal modeling results under 200 ppm, as opposed to current CO2. Such inconsistencies can be explained by a slowly declining assimilation rate beyond optimal Vpmax/Vcmax. Although rapid coordination occurred early in C4 evolution, C4 is still under optimizing processes and photosynthetic measures have continued to increase across time. Lastly, better understandings of Jmax/Vcmax, Vpmax/Vcmax and fluorescence-based-electron-transport proffer enhanced approaches to parameterize terrestrial biosphere models.

ecology↗

bioRxiv2020

Evolution of symbiont transmission in conditional mutualisms in spatially and temporally variable environments

Symbiotic relationships affect the fitness and organismal function of virtually all organisms. In many cases, the fitness effects of symbiosis may be beneficial or harmful depending on the environment. The hosts of such symbionts are favored to acquire them only when the symbiont is beneficial. However, it is not clear whether such selection favors vertical or horizontal transmission, both, or neither. To address this question, we model the evolution of transmission mode in a conditional mutualism experiencing spatial and temporal environmental variation. We find that when symbionts affect host lifespan, but not fecundity, horizontal transmission can contain them to beneficial environments. Vertical transmission can produce symbiont containment when the environmental state is synchronized across locations. We also find an emergent trade-off between horizontal and vertical transmission, suggesting that physiological constraints are not required for the evolution of limits on the total amount of transmission.

evolutionary biology↗

bioRxiv2020

Rank-dependent social inheritance determines social network structure in a wild mammal population

The structure of animal social networks influences survival and reproductive success, as well as pathogen and information transmission. However, the general mechanisms determining social structure remain unclear. Using data on 73,767 social interactions among wild spotted hyenas over 27 years, we show that a process of social inheritance determines how offspring relationships are formed and maintained. The relationships of offspring with other hyenas are similar to those of their mothers over up to six years, and the degree of similarity increases with maternal social rank. The strength of mother-offspring relationship affects social inheritance and is positively correlated with offspring longevity. These results confirm the hypothesis that social inheritance of relationships can structure animal social networks and be subject to adaptive tradeoffs.

animal behavior and cognition↗

bioRxiv2020

Evolution of contribution timing in public goods games

Life history strategies are a crucial aspect of life, which are complicated in group-living species, where payoffs additionally depend on others behaviours. Previous theoretical models of public good games have generally focused on the amounts individuals contribute to the public good. Yet a much less studied strategic aspect of public good games, the timing of contributions, can also have dramatic consequences for individual and collective performance. Here, we develop game theoretical models to explore how the timing of contributions evolves. We show how contributing rapidly is not necessarily optimal, since delayers can act as "cheats," avoiding contributing while reaping the benefits of the public good. However, delaying too long can put the delayers at a disadvantage as they can miss out on the benefits. These effects lead to bistability in a single group, and spatial diversity among multiple interacting groups.

evolutionary biology↗

bioRxiv2019

The role of host phenology for parasite transmission

Phenology is a fundamental determinant of species distributions, abundances, and interactions. In host-parasite interactions, host phenology can affect parasite fitness due to the temporal constraints it imposes on host contact rates. However, it remains unclear how parasite transmission is shaped by the wide range of phenological patterns observed in nature. We develop a mathematical model of the Lyme disease system to study the consequences of differential tick developmental-stage phenology for the transmission of B. burgdorferi. Incorporating seasonal tick activity can increase B. burgdorferi fitness compared to continuous tick activity but can also prevent transmission completely. B. burgdorferi fitness is greatest when the activity period of the infectious nymphal stage slightly precedes the larval activity period. Surprisingly, B. burgdorferi is eradicated if the larval activity period begins long after the end of nymphal activity due to a feedback with mouse population dynamics. These results highlight the importance of phenology, a common driver of species interactions, for the fitness of a parasite.

ecology↗

bioRxiv2019

Internalizing cooperative norms in group-structured populations

Social norms play a crucial role in human behavior, especially in maintaining cooperation within human social groups. Social norms might be self-enforcing or be enforced by the threat of punishment. In many cases, however, social norms are internalized and individuals have intrinsic motivations to observe norms. Here, we present a model for how intrinsic preferences to adhere to cooperative norms can evolve with and without external enforcement of compliance. Using the methodology of preference evolution, we model how cooperative norms coevolve with the intrinsic motivations to follow them. We model intrinsic motivations as being provided by guilt, a kind of internal \"punishment\" that individuals feel for falling short of cooperative norms, and show that the shape of this internal punishment function plays a crucial role in determining whether and how much internalization can evolve. We find that internal punishment functions that eventually level off with the deviation from the norm can support internalization without external punishment. In contrast, internal punishment functions that keep escalating with the deviation from the norm require external punishment, but yield stronger norms and more cooperation when external punishment is present. By showing how different preference mechanisms can enhance or limit norms that stabilize cooperation, these results provide insights into how our species might have evolved the norm psychology that helps us maintain such complex social and cultural institutions.

evolutionary biology↗

bioRxiv2019

The balance of interaction types determines the assembly and stability of ecological communities

What determines the assembly and stability of complex communities is a central question in ecology. Past work has suggested that mutualistic interactions are inherently destabilizing. However, this conclusion relies on assuming that benefits from mutualisms never stop increasing. Furthermore, almost all theoretical work focuses on the internal (asymptotic) stability of communities assembled all-at-once. Here, we present a model with saturating benefits from mutualisms and sequentially assembled communities. We show that such communities are internally stable for any level of diversity and any combination of species interaction types. External stability, or resistance to invasion, is thus an important but overlooked measure of stability. We demonstrate that the balance of different interaction types governs community dynamics. Mutualisms may increase external stability and diversity of communities as well as species persistence, depending on how benefits saturate. Ecological selection increases the prevalence of mutualisms, and limits on biodiversity emerge from species interactions. Our results help resolve longstanding debates on the stability, saturation, and diversity of communities.

ecology↗

bioRxiv2018

Evolutionary games with environmental feedbacks

Strategic interactions form the basis for evolutionary game theory and often occur in dynamic environments. The various strategies employed in a population may alter the quality or state of the environment, which may in turn feedback to change the incentive structure of strategic interactions. This type of feedback is common in social-ecological systems, evolutionary-ecological systems, and even psychological-economic systems - where the state of the environment alters the dynamics of competing types, and vice versa. Here we develop a framework of \"eco-evolutionary game theory\" that permits the study of joint strategic and environmental dynamics, with feedbacks. We consider environments governed either by a renewable resource (e.g. common-pool harvesting) or a decaying resource (e.g. pollution byproducts). We show that the dynamics of strategies and the environment depend, crucially, on the incentives for individuals to lead or follow behavioral changes, and on the relative speed of environmental versus strategic change. Our analysis unites dynamical phenomena that occur in settings as diverse as human decision-making, plant nutrient acquisition, and resource harvesting. We discuss the implication of our results for fields ranging from ecology to economics.

evolutionary biology↗