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The evolution of asexual organisms in laboratory microcosms is constrained by the lack of genetic exchange and by isolation from the rest of the world. When these constraints are relaxed, the rate of adaptation and how it is acquired may change. The first section in this chapter is called Horizontal transmission and details gene transfer agents; gene cassettes; and conjugative plasmids. The second section is entitled Sex and it explains all about dominance; sorting in asexual diploid populations; sorting in sexual diplonts; heterozygotes; recombination; the limits to adaptation; purifying selection in sexual populations: mutation clearance; synthetic lethal mutations; mean fitness under purifying selection; directional selection in sexual populations: mutation assembly; directional selection in sexual populations: mutation liberation; the effect of recombination in phage; the effect of sex in microbes; the effect of recombination in Drosophila; and finally sex and the response to selection. The third section is about dispersal and informs on population structure; subdivided asexual populations; subdivided sexual diploid populations; the shifting balance.

This chapter assesses the biogeography of chestnut-backed chickadees using microsatellite analysis, providing alternative scenarios for the glacial refugia and dispersal patterns that could explain the present distribution of distinct, genetic populations. This chapter also considers the potential for hybridization within the brown-capped chickadees to contribute to differentiation among disjunct populations within the chestnut-backed chickadees of northwestern Canada and Alaska. The factors influencing contemporary patterns of population structure in chestnut-backed chickadees are considered, including historical range expansion and geographic distribution, while potential barriers to dispersal are discussed. The patterns found in this western North American species are compared to those of other North American and Eurasian Parids. The population structure of chestnut-backed chickadees, and that of other Parids, appears to be complex and influenced by a variety of factors, most notably postglacial colonization and distribution. Many of the factors limiting dispersal in chestnut-backed chickadees seem to be common in other Parids. These include isolation of peripheral populations, and limited dispersal over large water barriers or other areas of unsuitable habitat.

This chapter focuses on Allee effects in relation to genetics and evolution. These topics intersect in four different ways. First, genetics creates its own set of Allee effect mechanisms (e.g., via inbreeding depression). Second, there may be genetic differences among members of a population in their susceptibility to ecological Allee effects. Third, Allee effects are considered in the light of evolution — have populations evolved mechanisms to avoid Allee effects, and if so, how is it possible to find anything other than the ‘ghosts of Allee effects past’ in modern populations? Finally, Allee effects themselves may act as a selection pressure, and members of populations subject to Allee effects may thus evolve different characteristics as compared with those bounded only by negative density dependence. The chapter considers all these four issues in turn.

This chapter examines the influence of biological lags on consumer–resource dynamics, with particular emphasis on how consumer–resource cycles, or the lack thereof, interact with population level dynamical phenomena. It first considers discrete consumer–resource interactions before discussing the dynamics of stage-structured consumer–resource interactions. It then explains how stage structure promotes the possibility of alternative stable states and changes consumer–resource interaction strength. It also shows how a change in population structure affects food web interactions and/or the strengths of food webs. Finally, it reviews empirical results that show how stage structure and food web interaction influence ecological stability. The chapter argues that weak and inherently stable consumer–resource interactions can mute a potentially unstable population level phenomenon, and that a dynamically decoupled stable stage class can strongly stabilize other stages and the consumer–resource interaction.

This chapter outlines the theory of inbreeding including a brief account on the theory of population subdivision and gene flow. This is of relevance to conservation issues because habitat loss and fragmentation induces elevated levels of population structure in endangered species through reduced migration between remaining habitat fragments. Population structure is a major cause of inbreeding. The relationship between genetic diversity and fitness is discussed, covering the issues of inbreeding depression and heterosis.

This chapter considers a simple and general model of natural selection: replicator dynamics. Many animal traits and behaviors are social, in that they affect the reproductive success not just of the animal performing the behavior, but also conspecifics. Mathematical theories based on classical natural selection, which acts on direct reproduction by individuals, are able to explain the evolution of traits that are for personal advantage. However, this leaves the problem of providing an evolutionary explanation of traits and social behaviors that appear to be personally costly to the bearer, in reproductive terms, while having effects on conspecifics such as increasing their direct reproduction. This chapter uses the replicator dynamics to illustrate the action of natural selection on social behavior, including nonadditive interactions. It considers the additive and nonadditive donation game, and other social interactions, along with public goods games, threshold public goods games, and interactions in structured populations.

This concluding chapter summarizes the lessons learned from this book's study. This book has analyzed the experiences of immigrants and their children in Europe and North America in the contemporary period, putting heavy emphasis on institutional factors shaping their successes as well as continued difficulties. Yet a consideration of potential remedies calls attention to the fact that the problems that have been discussed are not inevitable or unchangeable. In the years ahead, a wide range of social, economic, and political changes are likely to have positive effects on integration pathways, including: the transformation of population structures; educational and occupational gains made by many children and grandchildren of immigrants who may also live near, work with, and sometimes form families with longer-established natives; and growing political representation of immigrant minorities. Government policies as well as strategies and political struggles by those of immigrant origin themselves also have the potential to ameliorate or reduce difficulties they currently face.

This chapter examines what happens in nonadditive interactions when such interactions take place between relatives, and how Hamilton's rule can be extended in two different ways to accommodate such nonadditivity. It first considers the selective pressures on nonadditive behaviors directed towards relatives by making use of the replicator dynamics to capture interactions within structured populations, so that on average, interactions within the population occur between relatives. It then describes two extensions to Hamilton's rule to deal with nonadditive interactions. One approach takes deviations from additivity and accounts for them all in a single synergistic coefficient. The other approach applies partial regression to keep a version of Hamilton's rule with only three parameters, in which costs and benefits vary according to the frequency of social individuals in a population. The chapter also explains the use of the Price equation to study nonadditive social interactions between relatives.

This book has examined the genesis, the logic, and the generality of social evolution theory. In particular, it has presented evolutionary explanations of the many social behaviors we observe in the natural world by showing that William D. Hamilton's inclusive fitness theory provides the necessary generalization of classical Darwin–Wallace–Fisher fitness. This concluding chapter discusses the limitations of the analyses presented in this book and assesses the empirical support for inclusive fitness theory, focusing on microbial altruism, help in cooperative breeders, reproductive restraint in eusocial species, and the evolution of eusociality and cooperative breeding. It also considers more advanced topics in social evolution theory, including sex allocation, genetic kin recognition, spite, and the evolution of organismality. Finally, it reviews theoretical approaches to studying social evolution other than replicator dynamics and the Price equation, such as population genetics, class-structured populations, and maximization approaches.

This chapter assesses how migration patterns can be detected in bioarchaeological and paleoanthropological contexts. Using quantitative genetic models and simulation methods, it demonstrates that past migration has a small or undetectable biological effect when population or migrant numbers are small, migration is a single event, and/or genetic drift has a long time to operate. The examples stress the need for clearly defined testable models of how population characteristics behave under various migration scenarios. The chapter argues that model-bound analyses of prehistoric population structure best evaluate competing ideas about past migration because they explain biological variation in terms of clear, mathematically defined processes without traditional hypothesis-testing frameworks and ad hoc explanations.

Inbreeding and its consequences are the main subject of Chapter 3, beginning with the concepts of identity by descent versus identity by state, the inbreeding coefficient F, genotype frequencies with inbreeding, and calculation of the inbreeding coefficient from pedigrees. Inbreeding and heterosis are discussed along with the effects of inbreeding in humans and other organisms, regular systems of mating (selfing and partial selfing, sib mating), and the utility of recombinant inbred lines. The chapter emphasizes the intimate connection between inbreeding and hierarchical population structure as measured by the F-statistics.

Ecological theory about dynamics of interacting species constitutes the basis for our understanding of the functioning of ecological communities and ecosystems and their responses to changing environmental conditions, natural disturbances, and human impacts. The mathematical foundation of this theory emphasizes changes in species abundances only, ignoring those aspects that make biological organisms unique, in particular within-population variation due to individual development during life history and individual energetics. In contrast, structured population models do take these aspects into account and hence explicitly link individual life history to population dynamics. In this chapter, I review the different types of structured population models and which purposes they are especially suited for. I will subsequently focus on physiologically structured population models (PSPMs), which are especially suited to model the interactions within and between populations. I will review the key ecological insights that have been derived using PSPMs and show how and why predictions by PSPMs often contrast with the basic rules-of-thumb that make up classical theory based on unstructured models. Finally, I will discuss the experimental and empirical evidence for the counter-intuitive predictions by PSPMs, emphasizing that PSPMs allow for testing at both the individual and population level and hence for a tight link between theory and data.

This chapter explores the modeling of multilevel selection (MLS) – and the related concepts of group selection and kin selection – using variance partitioning methods, using the Price equation to elucidate basic issues within MLS theory. An expansion of this theory, based on contextual analysis and direct fitness, is used to show that kin selection and MLS selection have the same mathematical roots, although they are not identical. Kin selection theory is oriented towards identifying the optimal group and individual level traits that maximize the fitness of an organism, while MLS theory is oriented towards identifying the rate of evolution of the group and individual level traits in a specified situation. Because of these differences, kin selection and group selection can be considered as complementary approaches. The chapter also addresses why heritable variation at one level often bears little relation to heritable variation at other levels. It is shown that interactions among units (e.g., individuals) cannot contribute to a response to selection at that level, but can contribute to response to selection at a higher level (e.g., the population). Thus, the response to selection at one level can be qualitatively different than the response to selection at other levels.

This chapter highlights the conservation in addressing the prospects for long-term survival of giant pandas. It is stated that if natural and social environmental conditions in the larger area of giant-panda distribution do not vary greatly, the population in the Qinling Mountains may be able to sustain itself continuously. The giant pandas of the Qinling Mountains have the potential for continued survival. The reproductive potential, population structure, and genetic diversity of the species are characteristics favoring its continued survival. Complementing the genetic data presented, a workshop report reviews the current status of genetic work on both captive and wild populations. Six items of resolutions and recommendation are regarded as the highest priorities for future activity in global genetic analysis of giant pandas.

This chapter discusses projections for educational progress in the next 30 years, up to 2040. Using the estimates on school enrollment and population structure, this chapter constructs projections of educational attainment for the population, disaggregated by gender and age group, for 146 countries from 2015 to 2040 at five-year intervals. The projections show that educational attainment will improve continuously and rapidly over the next 30 years. This trend features significant expansion of tertiary education in advanced and developing countries. The level of educational attainment for the youth population in developing countries is projected to increase at a faster rate than that in advanced countries, thereby narrowing the gap between advanced and developing countries substantially by 2040. Furthermore, gender equality in educational attainment is expected to be almost accomplished.

In group-structured populations in which some other assumptions are satisfied, kin and group selectionist methods provide formally equivalent conditions for change. However, this only shows an equivalence between two statistical methodologies, and this is compatible with there being a real, causal distinction between kin and group selection processes. This chapter pursues a Hamilton-inspired, population-centred approach to drawing that distinction, on which the differences between kin and group selection are differences of degree in the structural properties of populations. The relevant properties are K, the overall degree to which genealogical kin interact differentially, and G, the overall degree to which the population contains stable, internally integrated, and externally isolated social groups. A spatial metaphor (‘K-G space’) provides a useful framework for thinking about these differences.

Evolution is the change in heritable traits of populations over successive generations. At the molecular level this translates into changes in their genetic composition. A general theoretical investigation of how different demographic and evolutionary processes affect genetic variation within and between populations provides us with tools to reconstruct evolutionary history. This is the fundamental purpose of population genetics. This chapter investigates the relationship between allele and genotype frequencies in a hypothetical population that is not subjected to any evolutionary forces—i.e. the Hardy–Weinberg model. Then, one by one, demographic and evolutionary factors such as non-random mating, genetic drift, selection, mutation, and gene flow are introduced to investigate in what ways they affect allele and/or genotype frequencies. The chapter further introduces F-statistics and goodness of fit tests to investigate statistical deviations from expectations.

This chapter considers the migration patterns of bats and its connection with social and population structure. It highlights two phyllostomids, Leptonycterisyerbabuenae and Glossophagasoricina, and looks into how their food habits affect their migratory patterns and social structure. It discusses how sex difference in bats plays a role in migration, and compares their long-distance migratory navigation methods with birds. It examines the social behaviors of bats and describes their consequences across geographical scales, from social structure and the relationships between individual bats to large-scale population structures. It also investigates how historical events affect the population structure of bats.