The evolution of cooperative behaviours has received a large amount of attention in the literature. A recurrent result is that a spatial population structure often aids the evolution of cooperation. One such possible structure is a graph. Members of the population reside on vertices and interact with those connected by edges. The population changes over time via births and deaths and these changes are manifest in changing gene frequencies. I am interested in the change in frequency of a cooperative allele and one way to calculate this is with the inclusive fitness effect. The inclusive fitness effect is the sum of the effects of a behaviour on the members of a population, each effect weighted by a measure of genetic relatedness. In this thesis, I derive inclusive fitness theory in the context of evolutionary graphs. I provide new ways of calculating components of the inclusive fitness effect and high- light remaining challenges posed by graph-structured population models. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2012-10-02 17:55:12.267

W.D. Hamilton has been celebrated as the twentieth-century Darwin. His extension of evolutionary theory to explain social behaviours has been extensively documented. Current accounts, however, have often overlooked the extent to which his early research goals were tied to his desire to see that a better world was created through a scientific understanding of society. In fact, when his interests in humans, and especially his eugenic concerns, have been acknowledged, they have been distanced from his scientific achievements and treated separately. Using new sources to reexamine the development of Hamilton’s most famous idea, the theory of inclusive fitness, we may better understand how his perception of cultural upheaval shaped his reading of social behaviours as evolved characters following universal laws. Understanding this, we may see that however successful Hamilton was, he never realized his original dream, which was to devise a theory that would inform the human world, replacing religious and ideological beliefs. As he sought to solidify his career in the 1970s, he moved away from publicly disclosing his more controversial ideas. This meant that by the time the science of social behaviour inspired heated debates, he was almost always absolved from political critiques. Many assumed that his theory was derived from observations of insects, and his eugenic ideas were forgotten, ignored, or not understood. He was therefore well positioned to become the objective figurehead of a new discipline, sociobiology. This does not mean that his desire to understand society as the result of genetic laws subsided, and by placing inclusive fitness against its social and political background, we might reimagine its trajectory and its impact in new ways. We might also begin to see Hamilton not as an isolated scholar unengaged with society but as an individualist whose extra-scientific beliefs paralleled his scientific theories in meaningful ways.

Consistent leadership of group travel by specific individuals has been documented in many animals. Most species exhibiting this type of leadership have relatively stable group membership. Animals using fission-fusion grouping are not expected to use specific leaders because associations would not be frequent. Certain conditions, however, may allow this type of control over group travel to occur. First, a population would need to be small enough to allow regular associations between individuals. Second, leadership may be useful if the environment where the population in question lives is complex and requires learning to access the resources efficiently. To determine whether fission-fusion species existing under these conditions utilize specific individual leadership, I examined a small residential population of bottlenose dolphins (Tursiops truncatus) in the Lower Florida Keys (LFK) where the benthic habitat is highly complex. My goals were to 1) determine whether specific individuals in this population led group travel more often than expected; 2) determine whether certain factors predicted which animals would lead most often and 3) investigate the benefits of leading to leaders and to followers in a fission-fusion society. Multiple types of data were collected to answer questions posed including dolphin behavior (for leadership analyses), fish sampling (to examine dolphin habitat use under leadership), and dolphin biopsy sampling (for genetic analyses). Results of analyses provided strong evidence for consistent leadership in this population. Leaders were female, most were mothers and on average they had larger measures of centrality within the LFK population. Leaders benefited by leading individuals who were more closely related than expected. Followers benefited from efficient access to profitable habitat. Results build on previous leadership research by expanding our knowledge about the type of species in which specific individuals lead and predictors for what types of individuals may lead. Additionally, results provide the first detailed information about benefits group members obtain by both leading and following.

Notre relation avec nos apparentés forme une grande partie de notre monde social; et la façon dont nous reconnaissons et traitons nos apparentés a donné lieu à une importante somme de recherche. Lorsqu'il s'agit de reconnaître un apparenté direct, la similarité faciale est considérée comme un indice d'apparentement. Dans cette thèse, j'étudie si elle joue un rôle comparable lorsqu'il s'agit de reconnaître un apparentement entre des tiers, en menant deux lignes de recherche: les prédictions de comportement népotistiques et les prédictions de préférences de couple, par des tiers, en présence de stimuli faciaux. La catégorisation devant servir l'action, la similarité faciale doit avoir un effet dépendant du contexte sur ces prédictions, susceptible à des changements de valence et de domaine. En l'absence de contexte, les individus semblent pouvoir détecter la similarité faciale et la mettre en relation avec l'apparentement. Nos deux séries d'expériences offrent une conclusion différente. Quand la valence du contexte change et que nous analysons les prédictions des participants en terme de kin selection, leurs choix ne semblent pas mettre en relation similarité faciale et apparentement. / Our relation to our kin shapes much of our social world. It's no surprise then, that how we recognize and react to our own kin has been a widely investigated topic. In particular, when tackling direct kin recognition, facial similarity has emerged as a putative cue of relatedness. In this thesis, I investigate whether or not the same can be said for third party kin recognition. Split between two lines of research, we explore individuals' predictions of nepotistic and mating behavior} in third party scenarios using facial stimuli. These two domains provide the backbone of our research. Categorization must serve action. So, what would strengthen the notion of a presence of third-party kin recognition in humans? Facial similarity \emph{must have} a context-dependent effect on participants predictions, susceptible to valence changes in scenarios and switches from the prosocial and mate choice domains. This is precisely what we set out to do with our two lines of research. Though our literature review revealed that when context is starved participants seem to be able to detect similarity and seemingly connect it to relatedness. Our nepotism and mating series of experiments, by re-inserting context, offers us a different conclusion altogether. Within scenarios in which valence is modified and our participants analysis is bounded by predictions made by kin selection, their choices do no reflect a connection between similarity and relatedness.

Inclusive fitness theory concerns the study of social traits. Often, individuals differ in their phenotype (e.g. size, weight, nutritional state) independently of their genetic make up, that is, individuals differ in their quality. Individuals can then be classified into different “classes” according to their quality, which enable us to understand social evolution in class-structured populations. This is important because individuals in natural populations often differ in quality, either because of intrinsic factors (e.g. size), or extrinsic factors (e.g. resource availability). My thesis concerns the evolution of social traits in class-structured populations. In chapter 1, I make a brief introduction to my thesis, providing the abstract of each chapter. In chapter 2, I outline a general theory of individual quality, where I show how individual quality impacts social evolution in two fundamental ways. In chapter 3, I show that resource heterogeneity greatly influences the evolution of conditional social behaviour. In chapter 4, I show that temporal group-size heterogeneity promotes the evolution of both conditional helping and harming. In chapter 5, I analyse the effect of individual quality on kin selection. I find that individual quality has an important impact in kin selection, which can lead to extreme forms of social behaviour. In chapter 6, I show that stable environments promote the evolution of negative density-dependent dispersal, while unstable environments promote the evolution of positive density-dependent dispersal. In chapter 7, I show that budding and low local quality promote the evolution of dispersal and cooperation.

<p>This thesis combines behavioral observations of African lions (<i>Panthera leo</i>) with genetic analyses, in an attempt to clarify causes and consequences of lion group living. The numerous complex cooperative behaviors of lions present an excellent opportunity to investigate the evolution and maintenance of group living. This thesis focuses on female group living and male dispersal patterns.</p><p>Lion sociality is found to be more complex than previously thought. Short dispersal distances result in strong kinship ties among prides, creating the potential for kin selection to operate among prides. Simultaneously, some prides contained unrelated females, depriving females in such prides of inclusive fitness benefits from group living. Concurrent with short dispersal distances in both males and females, significant genetic differentiation could be detected over relatively short distances in analyses of males. Extensive behavioral observations showed that territorial behaviors were unaffected by kinship ties to intruders. Instead, favorable odds and several environmental conditions were important factors. Space use analyses showed large overlap among prides. Again, kinship did not affect degree of overlap. </p><p>Conclusively, these results show that the ultimate causes of lion sociality remain elusive, but that kin selection may be less important than generally thought. Lion sociality seems to be explicable mainly in terms of direct fitness benefits, which therefore should be given more attention.</p>

This thesis combines behavioral observations of African lions (Panthera leo) with genetic analyses, in an attempt to clarify causes and consequences of lion group living. The numerous complex cooperative behaviors of lions present an excellent opportunity to investigate the evolution and maintenance of group living. This thesis focuses on female group living and male dispersal patterns. Lion sociality is found to be more complex than previously thought. Short dispersal distances result in strong kinship ties among prides, creating the potential for kin selection to operate among prides. Simultaneously, some prides contained unrelated females, depriving females in such prides of inclusive fitness benefits from group living. Concurrent with short dispersal distances in both males and females, significant genetic differentiation could be detected over relatively short distances in analyses of males. Extensive behavioral observations showed that territorial behaviors were unaffected by kinship ties to intruders. Instead, favorable odds and several environmental conditions were important factors. Space use analyses showed large overlap among prides. Again, kinship did not affect degree of overlap. Conclusively, these results show that the ultimate causes of lion sociality remain elusive, but that kin selection may be less important than generally thought. Lion sociality seems to be explicable mainly in terms of direct fitness benefits, which therefore should be given more attention.

Menopause, the cessation of female reproduction well before death, is a puzzling phenomenon, because evolutionary theory suggests there should be no selection for survival when reproduction has ended. Nevertheless, menopause does exist in a limited number of species, and besides humans it has predominately evolved among toothed whales (Odontoceti). The aim of this thesis is to review both adaptive and non-adaptive theories. Of the latter, the most prominent proposes that menopause is a product of a physiological trade-offs between reproductive benefits early in life and negative late-life reproduction. Among the adaptive theories the grandmother hypothesis is the most acknowledged. This theory is based on inclusive fitness benefits gained from increasing the reproductive success of kin at an advanced age, when prospects of successfully raising additional offspring is reduced. Alternatively, the mother hypothesis suggests that increased investment in already produced offspring at late life explains menopause. There are support for both the care of mothers and grandmothers, but whether this is enough to compensate for repressed reproduction is debated. The reproductive conflict hypothesis provides a complementary explanation, and suggests that inter-generational conflict between either in-laws or kin selects the older female to shift investment into the younger female’s offspring due to asymmetries in how older and younger females are related to one another’s offspring. The evolution of menopause is a complex issue, containing many factors, kinship dynamics among the most important. Theories apply unequally to various species and populations, meaning an integrated approach is necessary for decrypting the evolution of menopause.

I develop social evolution theory to study the evolution of cooperation as follows: (1) Many organisms undergo a dispersal phase prior to breeding; I demonstrate that knowing ones dispersal status aids the evolution of helping (by non-dispersers) and harming (by dispersers). (2) Policing driven by group-benefits may be selected to enforce cooperation in human and animal societies. I extend existing theory to show that policing may be harder to evolve that previously thought, but that it is maintained more readily than it evolves. (3) Archeological and anthropological evidence suggests that warfare was prevalent during our evolution. I show that, contrary to previous suggestions, between-group competition can favour any social behaviour (pro-social or anti-social) so long as it helps the group compete, and that such traits can be altruistic or mutually beneficial. (4) Reproductive leveling is analogous to policing; in the human literature there is doubt as to whether it can evolve. I extend my previous work to consider the coevolution of culturally and genetically inherited traits for reproductive leveling and selfishness. I find that cooperation can evolve between non-kin if they share the same culture. (5) Monogamy is thought to favour the evolution of cooperative breeding. I show that in the simplest case, because of the cost of competition between non-dispersing siblings, the level of promiscuity has little or no effect on the evolution of cooperation. (6) Spatial structure (limited dispersal) is thought to favour the evolution of inter-specific mutualisms as it aligns the partners’ interests. I consider the case of plant-fungi mutualisms and show that spatial structure can disfavour cooperation if it limits the potential fungal partners available to the plant.

Natürliche Selektion bevorzugt effiziente Zusammenarbeit innerhalb von eusozialen Kolonien. Dennoch kann bei polyandrischen Arten die Aufzucht von Königinnen Konflikte auslösen. Es wird vermutet, dass Honigbienen nepotistisch bei der Königinnenaufzucht agieren. Bienen sind in der Lage zwischen verschiedenen verwandten Individuen zu unterscheiden. Die bisher publizierten Daten sind aber widersprüchlich. In meiner Untersuchung zeigte sich, dass standardisiert aufgezogene Larven durch verwandte Arbeitsbienen nicht signifikant bevorzugt werden, aber dass ein höheres Gewicht der Eier, aus denen die Larven geschlüpft sind, ihre Chancen als Königin aufgezogen zu werden signifikant erhöhen. Ein hohes Eigewicht führte außerdem zu einer zwar nicht signifikanten, aber tendenziellen Erhöhung von Fitness Eigenschaften der resultierenden Königinnen. Probleme, Nepotismus eindeutig zu belegen, sind möglicherweise dadurch verursacht, dass die Verwandtschafts-Präferenz bestimmter Individuen nicht in eine Kolonie-Entscheidung überführt werden kann. Ich habe deshalb – mit molekulargenetischen Methoden – die Verwandtschaft der Larven, die als Königinnen aufgezogen werden sollen, mit jener der Pflege-Bienen, die deren Aufzucht initiierten, vergliechen. In fünf Kolonien, deren Königinnen mit jeweils drei Drohnen von drei verschiedenen Herkünften besamt wurden, fand ich keine Präferenz von Arbeitsbienen für ihre nah-verwandten Geschwister. Dafür zeigten sich signifikante Unterschiede bezüglich Präferenz für Larven der drei Drohnen-Herkünfte. Dies kann so interpretiert werden, dass Honigbienen in der Lage sind, zwischen genetischen Varianten zu unterscheiden, aber dass diese Fähigkeit nicht für Nepotismus genutzt wird. In einem natürlichen, durch Mehrfachpaarung genetisch variablen, aber mindestens zu 25 % verwandten Volk, ist eine genetisch oder umwelt- (maternal) induzierte Attraktivität, und nicht der Grad der Verwandtschaft, das zentrale Selektionskriterium in. / Natural selection favours an efficient cooperation within eusocial colonies. However, in polyandrous species, queen rearing may provide some conflict. Worker bees are assumed to play a nepotistic role during the queen-rearing phase by preferring more closely related larvae. Honeybee workers were found to be able to discriminate between different related individuals, but published data are inconsistent. Here in my study I show that larvae reared on a standardized basis were not significantly preferred by related worker bees, but that a higher egg weight – from which the larvae originated – significantly increased the chance to receive a royalty treatment and showed a tendency to correlate positively with fitness traits of the resulting queen. Queen rearing results from a colony decision, and this involves many workers. Consequently any lack of a nepotism which is proved may be due to the fact that relatedness-driven kin preference of individuals cannot be applied to a colony decision. In view of this, using DNA fingerprinting, I also tested the relatedness of larvae to be reared as queens and those nursing worker bees which initiated the queen−rearing process. In five colonies, each inseminated with three drones from three different origins, I did not observe any preference of worker bees for their closely related sib for queen rearing, but I did find significant differences with respect to the preference of worker bees for larvae from the three drone origins. Our data provide evidence that honey bees have the ability to discriminate genetic differences, but they do not use it for nepotism. In a natural, diverse – but always at least 25%-related – framework within a colony, genetically or environmentally driven attractiveness but not relatedness represents the key criteria for selecting larvae for gyne production.