Biology subjects

Mori, T. F.

Publications and source records attributed to Mori, T. F..

5 recordsLinked to original sources

bioRxiv2026

Fixation of a homozygote and dynamical characterization of the Price equation

Price equation and genotype dynamics are two methods for studying the fixation of one allele by natural selection in a diploid population. There are two strict monotonicity conditions that imply the fixation of one allele. The genotype dynamics is called Haldane monotone if the relative frequency of one allele strictly increases along all solutions of the genotype dynamics, so this allele is fixed. In this paper, we show that the genotype dynamics is Haldane monotone if and only if the right-hand side of the Price equation is always strictly positive. The other strict monotonicity condition requires that the relative frequency of a homozygote strictly increase according to the genotype dynamics. For example, in a model where the genotype dynamics is governed by interactions between individuals, the cost-accepting homozygote is fixed by natural selection if the other genotypes always receive a smaller average gain from all interactions than the cost-accepting homozygote. Both monotonicity conditions require that the interaction is not well-mixed in the population. These two conditions are not equivalent. In addition, we give a non-monotonicity condition, which also implies the fixation of a homozygote. The fixation of a homozygote depends on the phenotypic payoff of the interaction, the genotype-phenotype mapping, and the interaction scheme. In a sexual population, the interaction scheme of siblings depends on the mating system, and so do the conditions of fixation of the cost-accepting homozygote. We present examples showing that if we only change the monogamous mating system, assuming panmixing or mating assortativity, then the condition for the fixation of the cooperator homozygote is b > 2c and b > c, respectively.

evolutionary biology↗

bioRxiv2024

Survival cost sharing among altruistic full siblings in Mendelian population

BackgroundWe focus on Haldanes familial selection in monogamous families in a diploid population, where the survival probability of each sibling is determined by altruistic food sharing with its siblings during starvation. An autosomal recessive-dominant or intermediate allele pair uniquely determines the altruistic or selfish behavior, which are coded by homozygotes. We focus on the case when additive cost and benefit functions determine the survival probability of each full sibling. ResultsWe provide conditions for the existence of the altruistic and selfish homozygote. We show that the condition of evolutionary stability of altruism depends on the genotype-phenotype mapping. Furthermore, if the offspring size increases then the condition of evolutionary stability of altruism becomes stricter. Contrary to that, for the evolutionary stability of selfish behavior it is enough if the classical Hamiltons rule does not hold. Moreover, when the classical Hamiltons rule holds and the condition of evolutionarily stability of altruism does not hold, then the selfish and altruistic phenotypes coexist. ConclusionsIn summary, the classical Hamiltons rule is a sufficient condition for the existence of altruism, but it alone does not imply the evolutionary stability of the pure altruistic homozygote population when the altruistic siblings share the cost of altruism.

evolutionary biology↗

bioRxiv2022

Game of full siblings in Mendelian populations

We adapt the concept of evolutionary stability to familial selection when a game theoretic conflicts between siblings determines the survival rate of each sibling in monogamous, exogamous families in a diploid, panmictic population. Similarly to the classical evolutionary game theory, the static condition of evolutionary stability of mixed Nash equilibrium implies the local stability of the genotype dynamics, in spite of that the mating table based genotype dynamics is not a replicator dynamics. We apply our general result to the case where a matrix game determines the survival rate of siblings. In our numerical studies we consider the prisoners dilemma between siblings, when the cooperator and defector behaviour are unequally determined by a recessive-dominant allele pair at an autosomal locus. When the prisoners dilemma game is strict (cf. iterated one) and the cooperator phenotype is recessive resp. dominant, then the cooperator and defector phenotypes are the unique stable phenotypes, respectively. When the prisoners dilemma game is not strict, both phenotypes coexist, independently of the genotype-phenotype mapping. However, the frequencies of the phenotypes are different according to which phenotype is dominant.

evolutionary biology↗

bioRxiv2022

Subsistence of sib altruism in different mating systems and Haldane arithmetic

The moral rule "Risk your life to save your family members" is, at the same time, a biological phenomenon. The prominent population geneticist, J.B.S. Haldane told his friends that he would risk his life to save two drowning brothers, but not one - so the story goes. In biological terms, Haldanes arithmetic claims that sib altruism is evolutionarily rational, whenever by "self-sacrifice" an altruistic gene "rescues", on average, more than one copy of itself in its lineage. Here, we derive conditions for evolutionary stability of sib altruism, using population genetic models for three mating systems (monogamy, promiscuity and polygyny) with linear and non-linear group effect on the siblings survival rate. We show that for all considered selection situations, the condition of evolutionary stability is equivalent to Haldanes arithmetic. The condition for evolutionary stability is formulated in terms of genetic relatedness and the group effect on the survival probability, similarly to the classical Hamiltons rule. We can set up a "scale of mating systems", since in pairwise interactions the chance of evolutionary stability of sib altruism decreases in this order: monogamy, polygyny and promiscuity. Practice of marrying and siblings solidarity are moral rules in a secular world and in various religious traditions. These moral rules are not evolutionarily independent, in the sense that the subsistence of sib altruism is more likely in a monogamous population. HighlightsO_LIHaldanes arithmetic is introduced C_LIO_LIConditions for evolutionary stability of sib altruism are given C_LIO_LIEvolutionary stability is equivalent to Haldanes arithmetic in the studied model C_LIO_LIGeneralized Hamiltons rules are formulated C_LI

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↗