Parasites, desiderata lists and the paradox of the organism

Parasitology ◽  
1990 ◽  
Vol 100 (S1) ◽  
pp. S63-S73 ◽  
Author(s):  
R. Dawkins
Keyword(s):  
Evolutionary Theory ◽  
Evolutionary Biology ◽  
Gene Pools ◽  
Final Solution ◽  
Evolution Of Sex ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Prime Movers ◽  
Minority View

Eavesdrop morning coffee at any major centre of evolutionary theory today, and you will find ‘parasite’ to be one of the commonest words in the language. Parasites are touted as prime movers in the evolution of sex, promising the final solution to that problem of problems, the puzzle that led G. C. Williams to proclaim in 1975 ‘a kind of crisis’ at hand in evolutionary biology (Hamilton, 1980; Tooby, 1982; Seger & Hamilton, 1988). Parasites seem to offer a plausible justification for the otherwise futile effort females put into choosing among posturing males (Hamilton & Zuk, 1982; but see Read, 1990). Frequency-dependent selection exerted by parasites is, according to one admittedly minority view, largely responsible for the high levels of diversity found in gene pools (Clarke, 1979). One might even extrapolate to a time when the entire metazoan body could come to be seen as a gigantic adaptation against microscopic pathogens.

scholarly journals Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures

2017 ◽  
Vol 114 (31) ◽  
pp. 8325-8329 ◽  
Author(s):  
Mathieu Chouteau ◽  
Violaine Llaurens ◽  
Florence Piron-Prunier ◽  
Mathieu Joron
Keyword(s):  
Evolutionary Biology ◽  
Natural Populations ◽  
Mate Preferences ◽  
Visual Signals ◽  
Wing Pattern ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Conservation Medicine ◽  
Local Diversity ◽  
Adaptive Diversity

Explaining the maintenance of adaptive diversity within populations is a long-standing goal in evolutionary biology, with important implications for conservation, medicine, and agriculture. Adaptation often leads to the fixation of beneficial alleles, and therefore it erodes local diversity so that understanding the coexistence of multiple adaptive phenotypes requires deciphering the ecological mechanisms that determine their respective benefits. Here, we show how antagonistic frequency-dependent selection (FDS), generated by natural and sexual selection acting on the same trait, maintains mimicry polymorphism in the toxic butterfly Heliconius numata. Positive FDS imposed by predators on mimetic signals favors the fixation of the most abundant and best-protected wing-pattern morph, thereby limiting polymorphism. However, by using mate-choice experiments, we reveal disassortative mate preferences of the different wing-pattern morphs. The resulting negative FDS on wing-pattern alleles is consistent with the excess of heterozygote genotypes at the supergene locus controlling wing-pattern variation in natural populations of H. numata. The combined effect of positive and negative FDS on visual signals is sufficient to maintain a diversity of morphs displaying accurate mimicry with other local prey, although some of the forms only provide moderate protection against predators. Our findings help understand how alternative adaptive phenotypes can be maintained within populations and emphasize the need to investigate interactions between selective pressures in other cases of puzzling adaptive polymorphism.

Adaptive Diversification (MPB-48)

2011 ◽  
Author(s):  
Michael Doebeli
Keyword(s):  
Evolutionary Biology ◽  
Biological Diversity ◽  
Adaptive Dynamics ◽  
Theoretical Treatment ◽  
Mathematical Framework ◽  
Evolutionary Branching ◽  
Rare Type ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Adaptive Diversification

Understanding the mechanisms driving biological diversity remains a central problem in ecology and evolutionary biology. Traditional explanations assume that differences in selection pressures lead to different adaptations in geographically separated locations. This book takes a different approach and explores adaptive diversification—diversification rooted in ecological interactions and frequency-dependent selection. In any ecosystem, birth and death rates of individuals are affected by interactions with other individuals. What is an advantageous phenotype therefore depends on the phenotype of other individuals, and it may often be best to be ecologically different from the majority phenotype. Such rare-type advantage is a hallmark of frequency-dependent selection and opens the scope for processes of diversification that require ecological contact rather than geographical isolation. This book investigates adaptive diversification using the mathematical framework of adaptive dynamics. Evolutionary branching is a paradigmatic feature of adaptive dynamics that serves as a basic metaphor for adaptive diversification, and the book explores the scope of evolutionary branching in many different ecological scenarios, including models of coevolution, cooperation, and cultural evolution. It also uses alternative modeling approaches. Stochastic, individual-based models are particularly useful for studying adaptive speciation in sexual populations, and partial differential equation models confirm the pervasiveness of adaptive diversification. Showing that frequency-dependent interactions are an important driver of biological diversity, the book provides a comprehensive theoretical treatment of adaptive diversification.

scholarly journals Negative frequency-dependent selection is frequently confounding

2017 ◽  
Author(s):  
Dustin Brisson
Keyword(s):  
Genetic Diversity ◽  
Evolutionary Biology ◽  
Balancing Selection ◽  
Natural Populations ◽  
Research Progress ◽  
Selective Force ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection ◽  
Peer Community

AbstractThis preprint has been reviewed and recommended by Peer Community in Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100024).The existence of persistent genetic variation within natural populations presents an evolutionary problem as natural selection and genetic drift tend to erode genetic diversity. Models of balancing selection were developed to account for the high and sometimes extreme levels of polymorphism found in many natural populations. Negative frequency-dependent selection may be the most powerful selective force maintaining balanced natural polymorphisms but it is also commonly misinterpreted. The aim of this review is to clarify the processes underlying negative frequency-dependent selection, describe classes of natural polymorphisms that can and cannot result from these processes, and discuss observational and experimental data that can aid in accurately identifying the processes that generated or are maintain diversity in nature. Finally, I consider the importance of accurately describing the processes affecting genetic diversity within populations as it relates to research progress.

Frequency-Dependent Selection at the Payne Inversion in Drosophila melanogaster

Evolution ◽  
1973 ◽  
Vol 27 (4) ◽  
pp. 558 ◽  
Author(s):  
R. Nassar ◽  
H. J. Muhs ◽  
R. D. Cook
Keyword(s):  
Drosophila Melanogaster ◽  
Frequency Dependent ◽  
Frequency Dependent Selection

scholarly journals Evolutionary biology today and the call for an extended synthesis

2017 ◽  
Vol 7 (5) ◽  
pp. 20160145 ◽  
Author(s):  
Douglas J. Futuyma
Keyword(s):  
Natural Selection ◽  
Evolutionary Theory ◽  
Evolutionary Biology ◽  
Epigenetic Inheritance ◽  
Reaction Norm ◽  
Evolutionary Synthesis ◽  
Historical Background ◽  
Extended Evolutionary Synthesis ◽  
Extended Synthesis ◽  
Proximate Causation

Evolutionary theory has been extended almost continually since the evolutionary synthesis (ES), but except for the much greater importance afforded genetic drift, the principal tenets of the ES have been strongly supported. Adaptations are attributable to the sorting of genetic variation by natural selection, which remains the only known cause of increase in fitness. Mutations are not adaptively directed, but as principal authors of the ES recognized, the material (structural) bases of biochemistry and development affect the variety of phenotypic variations that arise by mutation and recombination. Against this historical background, I analyse major propositions in the movement for an ‘extended evolutionary synthesis’. ‘Niche construction' is a new label for a wide variety of well-known phenomena, many of which have been extensively studied, but (as with every topic in evolutionary biology) some aspects may have been understudied. There is no reason to consider it a neglected ‘process’ of evolution. The proposition that phenotypic plasticity may engender new adaptive phenotypes that are later genetically assimilated or accommodated is theoretically plausible; it may be most likely when the new phenotype is not truly novel, but is instead a slight extension of a reaction norm already shaped by natural selection in similar environments. However, evolution in new environments often compensates for maladaptive plastic phenotypic responses. The union of population genetic theory with mechanistic understanding of developmental processes enables more complete understanding by joining ultimate and proximate causation; but the latter does not replace or invalidate the former. Newly discovered molecular phenomena have been easily accommodated in the past by elaborating orthodox evolutionary theory, and it appears that the same holds today for phenomena such as epigenetic inheritance. In several of these areas, empirical evidence is needed to evaluate enthusiastic speculation. Evolutionary theory will continue to be extended, but there is no sign that it requires emendation.

scholarly journals Evolutionary theory of bacterial quorum sensing: when is a signal not a signal?

2007 ◽  
Vol 362 (1483) ◽  
pp. 1241-1249 ◽  
Author(s):  
Stephen P Diggle ◽  
Andy Gardner ◽  
Stuart A West ◽  
Ashleigh S Griffin
Keyword(s):  
Quorum Sensing ◽  
Evolutionary Theory ◽  
Kin Selection ◽  
Evolutionary Biology ◽  
Bacterial Cells ◽  
Evolutionary Perspective ◽  
Population Response ◽  
Future Action ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum

The term quorum sensing (QS) is used to describe the communication between bacterial cells, whereby a coordinated population response is controlled by diffusible molecules produced by individuals. QS has not only been described between cells of the same species (intraspecies), but also between species (interspecies) and between bacteria and higher organisms (inter-kingdom). The fact that QS-based communication appears to be widespread among microbes is strange, considering that explaining both cooperation and communication are two of the greatest problems in evolutionary biology. From an evolutionary perspective, intraspecies signalling can be explained using models such as kin selection, but when communication is described between species, it is more difficult to explain. It is probable that in many cases this involves QS molecules being used as ‘cues’ by other species as a guide to future action or as manipulating molecules whereby one species will ‘coerce’ a response from another. In these cases, the usage of QS molecules cannot be described as signalling. This review seeks to integrate the evolutionary literature on animal signalling with the microbiological literature on QS, and asks whether QS within bacteria is true signalling or whether these molecules are also used as cues or for the coercion of other cells.

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