Experimental studies of group selection: what do they tell us about group selection in nature?

The study of group selection has developed along two autonomous lines. One approach, which we refer to as the adaptationist school, seeks to understand the evolution of existing traits by examining plausible mechanisms for their evolution and persistence. The other approach, which we refer to as the genetic school, seeks to examine how currently acting artificial or natural selection changes traits within populations and focuses on current evolutionary change. The levels of selection debate lies mainly within the adaptationist school, whereas the experimental studies of group selection lie within the genetic school. Because of the very different traditions and goals of these two schools, the experimental studies of group selection have not had a major impact on the group selection debate. We review the experimental results of the genetic school in the context of the group selection controversy and address the following questions: Under what conditions is group selection effective? What is the genetic basis of a response to group selection? How common is group selection in nature?     

Sexual selection: Another Darwinian process

Why was sexual selection so important to Darwin? And why was it de-emphasized by almost all of Darwin's followers until the second half of the 20th century? These two questions shed light on the complexity of the scientific tradition named “Darwinism”. Darwin's interest in sexual selection was almost as old as his discovery of the principle of natural selection. From the beginning, sexual selection was just another “natural means of selection”, although different from standard “natural selection” in its mechanism. But it took Darwin 30 years to fully develop his theory, from the early notebooks to the 1871 book The Descent of Man, and Selection in Relation to Sex. Although there is a remarkable continuity in his basic ideas about sexual selection, he emphasized increasingly the idea that sexual selection could oppose the action of natural selection and be non adaptive. In time, he also gave more weight to mate choice (especially female choice), giving explicit arguments in favor of psychological notions such as “choice” and “aesthetic sense”. But he also argued that there was no strict demarcation line between natural and sexual selection, a major difficulty of the theory from the beginning. Female choice was the main reason why Alfred Russel Wallace, the co-discoverer of the principle of natural selection, engaged in a major controversy with Darwin about sexual selection. Wallace was suspicious about sexual selection in general, trying to minimize it by all sorts of arguments. And he denied entirely the existence of female choice, because he thought that it was both unnecessary and an anthropomorphic notion. This had something to do with his spiritualist convictions, but also with his conception of natural selection as a sufficient principle for the evolutionary explanation of all biological phenomena (except for the origin of mind). This is why Wallace proposed to redefine Darwinism in a way that excluded Darwin's principle of sexual selection. The main result of the Darwin–Wallace controversy was that most Darwinian biologists avoided the subject of sexual selection until at least the 1950 s, Ronald Fisher being a major exception. This controversy still deserves attention from modern evolutionary biologists, because the modern approach inherits from both Darwin and Wallace. The modern approach tends to present sexual selection as a special aspect of the theory of natural selection, although it also recognizes the big difficulties resulting from the inevitable interaction between these two natural processes of selection. And contra Wallace, it considers mate choice as a major process that deserves a proper evolutionary treatment. The paper's conclusion explains why sexual selection can be taken as a test case for a proper assessment of “Darwinism” as a scientific tradition. Darwin's and Wallace's attitudes towards sexual selection reveal two different interpretations of the principle of natural selection: Wallace's had an environmentalist conception of natural selection, whereas Darwin was primarily sensitive to the element of competition involved in the intimate mechanism of any natural process of selection. Sexual selection, which can lack adaptive significance, reveals this exemplarily.     

Rupert Riedl and the re-synthesis of evolutionary and developmental biology: body plans and evolvability

This paper reviews the scientific career of Rupert Riedl and his contributions to evolutionary biology. Rupert Riedl, a native of Vienna, Austria, began his career as a marine biologist who made important contributions to the systematics and anatomy of major invertebrate groups, as well as to marine ecology. When he assumed a professorship at the University of North Carolina in 1968, the predominant thinking in evolutionary biology focused on population genetics, to the virtual exclusion of most of the rest of biology. In this atmosphere Riedl developed his "systems theory" of evolution, which emphasizes the role of functional and developmental integration in limiting and enabling adaptive evolution by natural selection. The main objective of this theory is to account for the observed patterns of morphological evolution, such as the conservation of body plans. In contrast to other "alternative" theories of evolution, Riedl never denied the importance of natural selection as the driving force of evolution, but thought it necessary to contextualize natural selection with the organismal boundary conditions of adaptation. In Riedl's view development is the most important factor besides natural selection in shaping the pattern and processes of morphological evolution.     

Historical and ecological controls on phylogenetic diversity in Californian plant communities

An unresolved controversy regarding social behaviors is exemplified when natural selection might lead to behaviors that maximize fitness at the social-group level but are costly at the individual level. Except for the special case of groups of clones, we do not have a general understanding of how and when group-optimal behaviors evolve, especially when the behaviors in question are flexible. To address this question, we develop a general model that integrates behavioral plasticity in social interactions with the action of natural selection in structured populations. We find that group-optimal behaviors can evolve, even without clonal groups, if individuals exhibit appropriate behavioral responses to each other's actions. The evolution of such behavioral responses, in turn, is predicated on the nature of the proximate behavioral mechanisms. We model a particular class of proximate mechanisms, prosocial preferences, and find that such preferences evolve to sustain maximum group benefit under certain levels of relatedness and certain ecological conditions. Thus, our model demonstrates the fundamental interplay between behavioral responses and relatedness in determining the course of social evolution. We also highlight the crucial role of proximate mechanisms such as prosocial preferences in the evolution of behavioral responses and in facilitating evolutionary transitions in individuality.     

The Stagnancy of Family Studies in Modern Academia: Resistances Toward the Integration of Evolutionary Theory

The theory of natural selection has been vital in unifying the biological sciences and their research with a single testable metatheory. Despite a plethora of research supporting natural selection, teaching the theory of evolution remains controversial in high schools and higher education (Wilson et al. 2009; Scott 1997). In this article, we sample the attitudes toward evolution of 170 faculty and graduate and undergraduate students in family studies and human development programs from across the United States to determine whether resistances toward evolution remain and to describe the correlates of these resistances. Results reveal that an individual’s prosocial meliorist attitudes, religious ideation, and his or her reported interest in and knowledge of evolution all uniquely contribute to whether they report evolutionary theory as being applicable to their area of research interests. We discuss the relevance of including evolutionary theory within family studies and human development research programs and make suggestions for how to implement an evolutionary studies program (Wilson et al. 2009).     

Population regulation and the life history studies of LaMont Cole

Transformative changes marked the growth of mid-twentieth century American ecology. This included redirection of the scholarly focus of the discipline, especially on the role evolutionary theory and "levels of selection", and increased visibility of ecologist as public figures in the environmental movement with special knowledge of how natural systems work. Cornell ecologist LaMont Cole is an important figure to examine both of these trends. Like many of his contemporaries, Cole was devoted to a perspective on natural selection operating at levels above the individual. However, because of his influential mathematical treatment of animal demography he has been historically subsumed into a group of scholars that views the events in the life course as adaptations to the maximization of individual fitness--life history theory. Cole's popular writings and lectures, which consumed his later career, extend his scholarly portrayal of natural populations as tending toward stable and homoeostatic equilibrium, with the goal of drawing contrasts with the deviance of rapid human population growth. In both regards, Cole serves as a topical and temporal extension of the well-documented and analyzed ecology of his mentors--Alfred Emerson, Thomas Park, and Warder Allee--in the University of Chicago Zoology Department.     

Darwin's "beloved barnacles": tough lessons in variation

In 1846, burdened by insecurity and self-doubt, and having been convinced that he needed to study some group of organisms closely, Darwin embarked on an eight-year odyssey in the protean and perplexing world of barnacles. At the time, he was searching for evidence in support of his theory of evolution by natural selection. In the course of his long study of barnacles, however, he was not just validating his preexisting theoretical system, but was also modifying his views on such fundamental aspects as the universality of individual variation, which is the focus of this paper. According to this notion, the members of any population of living things are expected to exhibit sufficient differences from one another for natural selection to operate. By emphasizing the theoretical value of the barnacle project, my analysis contributes to the historiographic tradition which highlights the significance of the period between the first comprehensive formulation of the theory of evolution by natural selection in 1844 and its urgent publication in the late 1850s. In the course of these years, Darwin's theory was not just accumulating empirical laurels, but was also expected to adapt to a changing conceptual landscape.     

Alfred Russel Wallace, past and future

The naturalist Alfred Russel Wallace (1823–1913) has for many years been standing in the shadow of his more famed co‐discoverer of the principle of natural selection, Charles Darwin. Despite outward similarities between the two men's formulation of the principle, Wallace had fit his appreciation of natural selection into views on evolution that were quite different from Darwin's. A closer examination of what Wallace had in mind suggests a model of process in which natural selection per se acts as the negative feedback mechanism (actually, a ‘state‐space’) in the relation between population and environment, and environmental engagement as made possible by the resulting selection of traits acts as the positive feedback part of the cycle. Thus, it may be better to contextualize adaptive structures as entropy‐relaying biogeochemical facilitators that only ‘generate a potential for evolution’ than to portray them as the end results of evolution. This systems point of view better lends itself to appreciations of the biogeographical context of evolution than does the tree‐thinking of a more conventional style of speciation‐focused Darwinism, which sometimes confuses process with result.     

Using case-study based modules to promote a better understanding of evolution in an undergraduate anatomy and physiology course

ABSTRACT

The impact of evolutionary processes in understanding human health and disease is an important idea for future health professionals to understand. These students, however, typically receive little to no formal instruction in the role of evolution in not only understanding human health, but its impact on how to treat human diseases. To address this issue, we developed and implemented a case-study based learning module designed with a learning cycle implementation as part of a larger evolution across the curriculum program. The module focused on the evolution of skin color to illustrate that natural selection occurs in humans, and that the process of evolution involves tradeoffs (a balance of costs and benefits). Student understanding of the tradeoffs of natural selection was assessed through a pre- post- test design, with students answering a set of questions before instruction and again after. The modules helped improve student comprehension of natural selection, particularly for lower-performing students who were not biology majors, and for those whom reported less interest in evolution.     

Darwin on woman

In his 1871 book The Descent of Man, Darwin exposed the idea of sexual selection as a major principle of human evolution. His main hypothesis, which was already briefly presented in The Origin of Species, is that there exists, besides “natural selection”, another form of selection, milder in its effect, but no less efficient. This selection is operated by females to mate and reproduce with some partners that are gifted with more qualities than others, and more to their taste. At more evolved stages, sexual selection was exerted by men who became able to choose the women most attractive to their taste. However, Darwin insists, sexual selection in the human species is limited by a certain number of cultural practices. If Darwin's demonstration sometimes carried the prejudices of his times regarding gender differences he was the first who took into account the importance of sexual choices in his view on evolution, and who insisted on the evolutionary role of women at the dawn of humanity. Thus, he opened the space for a rich reflection, which after him was widely developed and discussed in anthropological and gender studies.     

Origins of Life: Chemical and Philosophical Approaches

In this article we address selected important milestones of chemical evolution that led to life. The first such milestone could be achieved by Oparin’s model, which accounts for the early stages of chemical evolution. These occurred at the dawn of development of primitive chemical systems that were pre-RNA. Oparin’s model consists of spontaneous formation of coacervates that encapsulate chemical matter, undergo primitive self-replication, and provide a pathway to a primitive metabolism. We review the experimental updates of his model from our laboratory and discuss types of selection that could have occurred in these primitive systems. Another major milestone in chemical evolution is the transition from abiotic to biotic. This has occurred later, after the RNA world evolved. A controversy of what life is interferes with the efforts to elucidate this transition. Thus, we present various definitions of life, some of which specifically include the requirements and mechanisms for this transition. Self-replication is one of the major requirements for life. In this context we re-examine the question if viruses, which do not have capability to self-replicate, are alive. We draw on philosophy of Hegel, Aristotle, Rescher, Priest, and Fry to guide us in our endeavors. Specifically, we apply Hegel’s law on quantity-to-quality transition to abiotic-to-biotic transition, Aristotle’s philosophy to the definition of life, Priest’s dialetheism to the question if viruses are alive or not, Fry’s philosophy to the beginning of natural selection in chemical evolution, and Rescher’s philosophy to the possible cognitive bias toward simple definitions of life.     

Within- and between-species DNA sequence variation and the 'footprint' of natural selection

Extensive DNA data emerging from genome-sequencing projects have revitalized interest in the mechanisms of molecular evolution. Although the contribution of natural selection at the molecular level has been debated for over 30 years, the relevant data and appropriate statistical methods to address this issue have only begun to emerge. This paper will first present the predominant models of neutral, nearly neutral, and adaptive molecular evolution. Then, a method to identify the role of natural selection in molecular evolution by comparing within- and between-species DNA sequence variation will be presented. Computer simulations show that such methods are powerful for detecting even very weak selection. Examination of DNA variation data within and between Drosophila species suggests that 'silent' sites evolve under a balance between weak selection and genetic drift. Simulated data also show that sequence comparisons are a powerful method to detect adaptive protein evolution, even when selection is weak or affects a small fraction of nucleotide sites. In the Drosophila data examined, positive selection appears to be a predominant force in protein evolution.     

Does Darwinism really contribute to ecology

The author questions Ghilarov's (2003) claim that Darwinism has high explanatory power in ecology. He is agree with S.V. Meyen who believed that beside synthetic theory of evolution (the popular variant on Darwinism) other explanations of evolution are possible. It is emphasized that several processes (e.g., diversification and unification of species at one trophic level, as well as individual and diffusive coadaptations of species of different levels) can contribute to community evolution. Communities cannot be considered as units of natural selection.     

Pluralism in evolutionary controversies: styles and averaging strategies in hierarchical selection theories

Two controversies exist regarding the appropriate characterization of hierarchical and adaptive evolution in natural populations. In biology, there is the Wright–Fisher controversy over the relative roles of random genetic drift, natural selection, population structure, and interdemic selection in adaptive evolution begun by Sewall Wright and Ronald Aylmer Fisher. There is also the Units of Selection debate, spanning both the biological and the philosophical literature and including the impassioned group-selection debate. Why do these two discourses exist separately, and interact relatively little? We postulate that the reason for this schism can be found in the differing focus of each controversy, a deep difference itself determined by distinct general styles of scientific research guiding each discourse. That is, the Wright–Fisher debate focuses on adaptive process, and tends to be instructed by the mathematical modeling style, while the focus of the Units of Selection controversy is adaptive product, and is typically guided by the function style. The differences between the two discourses can be usefully tracked by examining their interpretations of two contested strategies for theorizing hierarchical selection: horizontal and vertical averaging.     

The causes of epistasis

Since Bateson's discovery that genes can suppress the phenotypic effects of other genes, gene interactions-called epistasis-have been the topic of a vast research effort. Systems and developmental biologists study epistasis to understand the genotype-phenotype map, whereas evolutionary biologists recognize the fundamental importance of epistasis for evolution. Depending on its form, epistasis may lead to divergence and speciation, provide evolutionary benefits to sex and affect the robustness and evolvability of organisms. That epistasis can itself be shaped by evolution has only recently been realized. Here, we review the empirical pattern of epistasis, and some of the factors that may affect the form and extent of epistasis. Based on their divergent consequences, we distinguish between interactions with or without mean effect, and those affecting the magnitude of fitness effects or their sign. Empirical work has begun to quantify epistasis in multiple dimensions in the context of metabolic and fitness landscape models. We discuss possible proximate causes (such as protein function and metabolic networks) and ultimate factors (including mutation, recombination, and the importance of natural selection and genetic drift). We conclude that, in general, pleiotropy is an important prerequisite for epistasis, and that epistasis may evolve as an adaptive or intrinsic consequence of changes in genetic robustness and evolvability.     

The ecological genetics of speciation

Ecological interactions and the natural selection they cause play a prominent causal role in biological diversification and speciation. As a discipline, ecological genetics integrates the two components of adaptive evolution (natural selection and genetic variability) to study the mechanisms of evolution. Ecological genetics is a fruitful approach to the study of how reproductive isolation can evolve under natural selection. The essence of this way of thinking and the ways in which it can be used to address persistent open questions in speciation are discussed.     

Selectionism and neutralism in molecular evolution

Charles Darwin proposed that evolution occurs primarily by natural selection, but this view has been controversial from the beginning. Two of the major opposing views have been mutationism and neutralism. Early molecular studies suggested that most amino acid substitutions in proteins are neutral or nearly neutral and the functional change of proteins occurs by a few key amino acid substitutions. This suggestion generated an intense controversy over selectionism and neutralism. This controversy is partially caused by Kimura's definition of neutrality, which was too strict (|2Ns|< or =1). If we define neutral mutations as the mutations that do not change the function of gene products appreciably, many controversies disappear because slightly deleterious and slightly advantageous mutations are engulfed by neutral mutations. The ratio of the rate of nonsynonymous nucleotide substitution to that of synonymous substitution is a useful quantity to study positive Darwinian selection operating at highly variable genetic loci, but it does not necessarily detect adaptively important codons. Previously, multigene families were thought to evolve following the model of concerted evolution, but new evidence indicates that most of them evolve by a birth-and-death process of duplicate genes. It is now clear that most phenotypic characters or genetic systems such as the adaptive immune system in vertebrates are controlled by the interaction of a number of multigene families, which are often evolutionarily related and are subject to birth-and-death evolution. Therefore, it is important to study the mechanisms of gene family interaction for understanding phenotypic evolution. Because gene duplication occurs more or less at random, phenotypic evolution contains some fortuitous elements, though the environmental factors also play an important role. The randomness of phenotypic evolution is qualitatively different from allele frequency changes by random genetic drift. However, there is some similarity between phenotypic and molecular evolution with respect to functional or environmental constraints and evolutionary rate. It appears that mutation (including gene duplication and other DNA changes) is the driving force of evolution at both the genic and the phenotypic levels.     

Darwin's evolutionary philosophy: The laws of change

The philosophical or metaphysical architecture of Darwin's theory of evolution by natural selection is analyzed and diflussed. It is argued that natural selection was for Darwin a paradigmatic case of a natural law of change — an exemplar of what Ghiselin (1969) has called selective retention laws. These selective retention laws lie at the basis of Darwin's revolutionary world view. In this essay special attention is paid to the consequences for Darwin's concept of species of his selective retention laws. Although Darwin himself explicity supported a variety of nominalism, implicit in the theory of natural selection is a solution to the dispute between nominalism and realism. It is argued that, although implicit, this view plays a very important role in Darwin's theory of natural selection as the means for the origin of species. It is in the context of these selective retention laws and their philosophical implications that Darwin's method is appraised in the light of recent criticisms, and the conclusion drawn that he successfully treated some philosophical problems by approaching them through natural history. Following this an outline of natural selection theory is presented in which all these philosophical issues are highlighted.     

Creationist Teaching in School Science: A UK Perspective

The creation/evolution controversy in UK schools made headlines in the national press, on TV, and radio in 2002. Claims were made that creationism was being taught in schools. This article looks at the impact this controversy had on the UK government and how creationism is trying to gain ground in UK state schools by introducing students to Intelligent Design through promotional DVDs. Student attitude surveys eliciting views toward science and religion are examined. Concern is also expressed at how the teaching of evolution through standard textbooks may not deliver a persuasive case for evolutionary theory. The article concludes with a number of implications for researchers, teachers, and schools.

Mendelism: from hybrids and trade to a science

In this paper I explore the historical context in which news of the rediscovery of Mendel's laws was received in England. This exploration leads me to the Cambridge zoologist, William Bateson, to his exploitation of the prestige and support of the Royal Horticultural Society, and to his interaction with certain of the leading horticultural tradesmen prominent in that society. I argue that the policy of the RHS in the 1890s to promote hybridisation rather than plant collecting was of crucial importance in bringing about a productive symbiosis between Bateson and his circle and the horticultural community. I look for parallels between the aims of the horticulturists and the character of the Mendelian programme as it is represented in Bateson's foundational text: Mendel's Principles of Heredity (1909).