Biology subjects

Szamado, S.

Publications and source records attributed to Szamado, S..

8 recordsLinked to original sources

bioRxiv2018

Attention seeking in a spatially explicit game of mate choice and the evolution of dimorphic ornaments

The evolution of conspicuous signals fascinated biologist ever since Darwin. The Handicap Principle was dominant explanation in the last decades; it proposed that exaggerated and conspicuous signals are costly signals of quality. There are other less popular explanations however, one them is that conspicuous signals function to call the attention of potential receivers. These attention seeking displays need not reveal the quality of the signaller. There are many empirical examples and recently the idea was modelled in terms of a simple action-response game. However, action-response games model an interaction of a pair of signaller and receiver, thus they omit potential competition between signallers, which could be a crucial force behind the evolution of attention-seeking displays. Here I model this competition in a spatially explicit model of mate choice where males can give a continuous signal to call the attention of potential mates. The results show that attention-seeking displays readily evolve to the allowed maximum when the cost of signalling is low. However, dimorphism evolves when the cost of signalling is high. The population consist of two types of males at this dimorphic state: males that do not give a signals and males that give the highest intensity signal possible. The results show that variation in quality is not a necessary requirement for the evolution of dimorphic traits.

evolutionary biology↗

bioRxiv2018

Honest and cheating strategies in a simple model of aggressive communication: the role of spatial correlations

The evolution and maintenance of communication in terms of aggressive interactions is a long-debated issue. Several game theoretical models and individual based computer simulations investigated this problem in terms of a simple game of aggressive communication. So far all of these investigations focused on well mixed population of individuals. However, spatial correlations can emerge in nature where individuals or group of individuals defend resources. The extensive literature on cooperative games show that these spatial correlations can be vital in the maintenance and evolution of cooperative strategies, thus it is reasonable to expect that such correlations could play an important role in the evolution of honest communication as well. Here we investigate a traditional game of aggressive communication in a spatially explicit context. We investigate the role of spatial correlations by comparing results of evolvability in well mixed populations with results from spatially explicit populations. Spatial correlations seem to inhibit the evolution of communication in the spatially explicit version of this game. This result is unexpected, and it requires further investigation to understand.

evolutionary biology↗

bioRxiv2018

Honesty needs no cost: beneficial signals can be honest and evolutionarily stable

How and why animals communicate honestly is a key issue in biology. The role of signal cost is strongly entrenched in the maintenance in honest signalling. The handicap principle claims that honest signals have to be costly at the equilibrium and this cost is a theoretical necessity. The handicap principle further claims that signalling is fundamentally different from any other adaptation because honest signalling would collapse in the absence of cost. Here I investigate this claim in simple action-response game where signals do not have any cost, instead they have benefits. I show that such beneficial signals can be honest and evolutionarily stable. These signals can be beneficial to both high and low-quality signallers independently of the receivers response, yet they can maintain honest signalling just as much as costly signals. Signal cost-at or out of equilibrium-is not a necessary condition of honesty. Benefit functions can maintain honest signalling as long as the marginal cost-loss of benefit-is high enough for potential cheaters.

evolutionary biology↗

bioRxiv2018

The role of equilibrium cost in the evolution of honest signalling: waste or optimal investment?

The relationship between signal cost and honesty is a controversial and unresolved issue. The handicap principle assumes that signals must be costly at equilibrium to be honest, and the greater the cost, the more reliable the signal. However, theoretical models and simulations question the necessity of equilibrium cost for the evolution of honest signalling. Honest signals can evolve without costs, and they can evolve through differential benefits with no need for differential costs. Here we investigate the role of equilibrium signal cost in the evolution of honest signals in both differential benefit and differential cost models using an agent-based simulation. We found that there is an optimal investment paid by honest individual that allows for the highest level of honesty when there is correlation between signal cost paid by low and high-quality individuals. This holds for both differential benefit and differential cost models as long there is a correlation between signal cost paid by low and high quality individuals. However, increasing equilibrium signal cost poses an obstacle and hinders the evolution of honest signalling when there is no correlation between the cost paid by low and high-quality individuals. Last but not least, we found that the potential cost of cheating is a much better predictor of honesty than the equilibrium cost paid by honest signallers.

evolutionary biology↗

bioRxiv2018

Soft song: help thine enemy!

The proximity risk model offers one possible explanation of honest signalling of aggressive intent in biology. This model assumes that the probability of successful attack is a function of the distance between the contestants and that this distance can be correctly estimated. This later assumption may not hold in nature where contestants have to estimate this distance under noisy conditions. Here I investigate with the help of a game theoretical model whether short-range ranging signals can be evolutionarily stable under such conditions. These signals can help the opponent to estimate the correct distance, thus they can promote honest signalling of intentions. Here I show that ranging signals that help the estimation of distance between opponents can be evolutionarily stable. However, such help only benefits those individuals who are able and willing to attack. As a result, ranging signals in themselves are an honest cue of proximity and in turn they are honest cues of aggressive intent. I give an example: \"soft-song\" in birds, and I discuss the predictions of the model.

evolutionary biology↗

bioRxiv2017

Juvenile honest food solicitation and parental investment as a life history strategy: a kin demographic selection model

Parent-offspring communication remains an unresolved challenge for biologist. The difficulty of the challenge comes from the fact that it is a multifaceted problem with connections to life-history evolution, parent-offspring conflict, kin selection and signalling. Previous efforts mainly focused on modelling resource allocation at the expense of the dynamic interaction during a reproductive season. Here we present a two-stage model of begging where the first stage models the interaction between nestlings and parents within a nest and the second stage models the life-history trade-offs. We show in an asexual population that honest begging results in decreased variance of collected food between siblings, which leads to mean number of surviving offspring. Thus, honest begging can be seen as a special bet-hedging against informational uncertainty, which not just decreases the variance of fitness but also increases the arithmetic mean.\n\nAuthor SummaryParent-offspring communication is a fascinating problem that captures the attention of scientist and layman alike. Parent-offspring interaction is the first interaction with non-self in the life of most young birds and mammals. The future life success of such young animals crucially depends on how successful they are in interacting and communicating with their parents. This communication has different functions: it is important for the offspring to solicit food from the parent and it is important for the parent to be informed about the state (hunger level) of the offspring. There is an optimization problem on top of this level: the parent has to decide what part of the available resources should be allocated to the offspring and what part should she keep for herself. Here we show in a probabilistic model that the honest phenotype -where offspring beg only if they are hungry-has a greater growth rate than a selfish type - which begs regardless of its hunger level. This result holds in asexual populations; here honesty serves as a reduction uncertainty for the parents. The improved decision making of the parents -in turn-increases the survival of the offspring as well.

evolutionary biology↗

bioRxiv2017

One problem, too many solutions: How costly is honest signalling of need?

The \"cost of begging\" is a prominent prediction of costly signalling theory, suggesting that offspring begging has to be costly in order to be honest. More specifically, it predicts that there is a single cost function for the offspring (depending on e.g. offspring quality) that maintains honesty and it must be proportional to parents fitness loss. Here we show another interpretation of the cost. We demonstrate that cost, proportional to the fitness gain of the offspring, also results in honest signalling. Since the loss of the parent does not necessarily coincide with the gain of the offspring, it is provable that any linear combination of the two cost functions (one proportional to parents loss, one to offsprings gain) also leads to honest signalling. Our results, applied for a specific model, support the previous general conclusion that signalling games have different cost functions for different equilibria. Consequently, costly signalling theory cannot predict a unique equilibrium cost in signalling games especially in case of parent-offspring conflicts. As an important consequence, any measured equilibrium cost in real cases has to be compared both to the parents fitness loss and to the offsprings fitness gain in order to provide meaningfully interpretation.

evolutionary biology↗

bioRxiv2017

Caring for parents: an evolutionary rationale

The evolutionary roots of human moral behavior are a key precondition to understand human nature. Here we investigate whether a biological version of Fifth Commandment (\"Honor your father and your mother, that your days may be long\"), respected in different variants across cultures, can spread through Darwinian competition. We show by a novel demographic model that a corresponding Fifth Rule (\"During your reproductive period, give away from your resources to your post-fertile parents\") will spread even if the cost of support to post-fertile grandmothers considerably decreases the demographic parameters of fertile parents but radically increases the survival rate of grandchildren. Teaching vital cultural content is likely to have been critical for the value of grandparental service. Selection on such behavior may have produced an innate moral tendency to honor parents even in situations, such as experienced today, when the quantitative conditions would not necessarily favor the maintenance of this trait.

evolutionary biology↗