The evolution of animal senescence

1984 ◽  
Vol 62 (9) ◽  
pp. 1661-1667 ◽  
Author(s):  
Michael R. Rose
Keyword(s):  
Natural Selection ◽  
Group Selection ◽  
Antagonistic Pleiotropy ◽  
Physiological Mechanisms ◽  
Beneficial Effects ◽  
Laboratory Populations

Senescence, the endogenous deterioration of health at later ages, can be explained in terms of evolution. Senescence is not due to group selection but to the decline with age in the force of natural selection acting on individuals. This decline allows the spread of alleles with deleterious effects on late health. Such alleles do not appear to have effects confined to later ages. Instead, they are favoured by natural selection because of beneficial effects at early ages, in spite of later deleterious effects due to antagonistic pleiotropy. Manipulation of laboratory populations of Drosophila has shown that senescence can be postponed using selection. There are no absolute, universal, physiological causes of senescence. Laboratory populations with genetically postponed senescence can be used to study proximate physiological mechanisms of senescence in animals.

Evolution of senescence: late survival sacrificed for reproduction

1991 ◽  
Vol 332 (1262) ◽  
pp. 15-24 ◽  
Keyword(s):  
Population Genetics ◽  
Life History ◽  
Natural Selection ◽  
Antagonistic Pleiotropy ◽  
Widespread Occurrence ◽  
Disposable Soma Theory ◽  
Somatic Tissues ◽  
Competing Demands ◽  
Early Effects ◽  
Late Survival

In so far as it is associated with declining fertility and increasing mortality, senescence is directly detrimental to reproductive success. Natural selection should therefore act in the direction of postponing or eliminating senescence from the life history. The widespread occurrence of senescence is explained by observing that (i) the force of natural selection is generally weaker at late ages than at early ages, and (ii) the acquisition of greater longevity usually involves some cost. Two convergent theories are the ‘antagonistic pleiotropy’ theory, based in population genetics, and the ‘disposable soma’ theory, based in physiological ecology. The antagonistic pleiotropy theory proposes that certain alleles that are favoured because of beneficial early effects also have deleterious later effects. The disposable soma theory suggests that because of the competing demands of reproduction less effort is invested in the maintenance of somatic tissues than is necessary for indefinite survival.

scholarly journals Teaching Evolution & the Nature of Science via the History of Debates about the Levels at Which Natural Selection Operates

2013 ◽  
Vol 75 (2) ◽  
pp. 96-100
Author(s):  
William D. Stansfield
Keyword(s):  
Natural Selection ◽  
Nature Of Science ◽  
Group Selection ◽  
Scientific Methodology ◽  
Teaching Evolution ◽  
Evolutionary Mechanism ◽  
Essential Components ◽  
History Of ◽  
New Research ◽  
Scientific Debates

Students should not graduate from high school without understanding that scientific debates are essential components of scientific methodology. This article presents a brief history of ongoing debates regarding the hypothesis that group selection is an evolutionary mechanism, and it serves as an example of the role that debates play in correcting faulty ideas and stimulating new research in the pursuit of extending scientific knowledge.

High-Intensity Intermittent Exercise: Methodological and Physiological Aspects

2013 ◽  
Vol 8 (6) ◽  
pp. 600-610 ◽  
Author(s):  
Gerhard Tschakert ◽  
Peter Hofmann
Keyword(s):  
High Intensity ◽  
Intermittent Exercise ◽  
Physiological Responses ◽  
Maximal Heart Rate ◽  
Lactate Metabolism ◽  
Physiological Mechanisms ◽  
Beneficial Effects ◽  
Training Adaptations

High-intensity intermittent exercise (HIIE) has been applied in competitive sports for more than 100 years. In the last decades, interval studies revealed a multitude of beneficial effects in various subjects despite a large variety of exercise prescriptions. Therefore, one could assume that an accurate prescription of HIIE is not relevant. However, the manipulation of HIIE variables (peak workload and peak-workload duration, mean workload, intensity and duration of recovery, number of intervals) directly affects the acute physiological responses during exercise leading to specific medium- and long-term training adaptations. The diversity of intermittent-exercise regimens applied in different studies may suggest that the acute physiological mechanisms during HIIE forced by particular exercise prescriptions are not clear in detail or not taken into consideration. A standardized and consistent approach to the prescription and classification of HIIE is still missing. An optimal and individual setting of the HIIE variables requires the consideration of the physiological responses elicited by the HIIE regimen. In this regard, particularly the intensities and durations of the peak-workload phases are highly relevant since these variables are primarily responsible for the metabolic processes during HIIE in the working muscle (eg, lactate metabolism). In addition, the way of prescribing exercise intensity also markedly influences acute metabolic and cardiorespiratory responses. Turn-point or threshold models are suggested to be more appropriate and accurate to prescribe HIIE intensity than using percentages of maximal heart rate or maximal oxygen uptake.

Social Behavior and Evolutionary Thought

2015 ◽  
Author(s):  
James A.R. Marshall
Keyword(s):  
Natural Selection ◽  
Mathematical Theory ◽  
Group Selection ◽  
Inclusive Fitness ◽  
Price Equation ◽  
Inclusive Fitness Theory ◽  
Evolutionary Thought ◽  
Multilevel Selection Theory ◽  
The Individual ◽  
Evolutionary Explanations

This book demonstrates the generality of inclusive fitness theory, with particular emphasis on its fundamental evolutionary logic. It presents the basic mathematical theory of natural selection and shows how inclusive fitness theory deals with more complicated social scenarios. Topics include the Price equation, Hamilton's rule, nonadditive interactions, conditional behaviors, heritability, and maximization of inclusive fitness. This chapter provides a brief historical introduction to the problem of apparent design in biology, evolutionary explanations of this, and in particular, evolutionary explanations of individual behaviors that appear designed to benefit not the individual themselves, but other members of their species. It examines how social behaviors can be shaped by natural selection and discusses the problem of providing an evolutionary explanation of self-sacrifice by individuals, altruism in group selection, and multilevel selection theory.

Genier than thou

1996 ◽  
Vol 19 (4) ◽  
pp. 781-782 ◽  
Author(s):  
Mike Waller
Keyword(s):  
Natural Selection ◽  
Group Selection ◽  
Current Approach ◽  
Selection Model ◽  
Behavioural Sciences ◽  
Selection Of

AbstractMany neo-Darwinists treat natural selection of genes and individual organisms as broadly equivalent. This enables Wilson & Sober (W&S) to propose a multilevel group selection model by drawing parallels between individuals and groups. The notion of gene/individual equivalence is a profound misconception. Its elimination negates W&S's current approach but offers the best way forward for both life and behavioural sciences.

Evolutionary Ethics and Biologically Supportable Morality

1998 ◽  
pp. 23-28 ◽  
Author(s):  
Michael Byron
Keyword(s):  
Natural Selection ◽  
Evolutionary Theory ◽  
Group Selection ◽  
Evolutionary Ethics ◽  
Evolution Of Morality

Consider the paradox of altruism: the existence of truly altruistic behaviors is difficult to reconcile with evolutionary theory if natural selection operates only on individuals, since in that case individuals should be unwilling to sacrifice their own fitness for the sake of others. Evolutionists have frequently turned to the hypothesis of group selection to explain the existence of altruism; but group selection cannot explain the evolution of morality, since morality is a one-group phenomenon and group selection is a many-group phenomenon. After spelling out just what the problem is, this paper discusses several ways of solving it.

Genetic analysis of a population of Tribolium. IX. Maximization of population size and the concept of a stochastic equilibrium

Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 571-580 ◽  
Author(s):  
Robert A. Desharnais ◽  
Brian Dennis ◽  
Robert F. Costantino
Keyword(s):  
Natural Selection ◽  
Population Size ◽  
Density Function ◽  
Corn Oil ◽  
Genetic Selection ◽  
Stochastic Theory ◽  
Gamma Density ◽  
Laboratory Populations ◽  
Experimental Treatments ◽  
Stochastic Population Model

Motivated by the genetic hypothesis that natural selection results in the maximization of the equilibrium population size, we quantified this latter equilibrium for laboratory populations of the flour beetle Tribolium castaneum, using the gamma probability density function. Gamma density functions were fitted to adult numbers for each of the experimental treatments that were started with frequencies of the corn oil sensitive (cos) allele in the range 0–1 at intervals of 0.1. The gamma density function adequately described all observed distributions. However, contrary to theory, statistical comparisons of the fitted distribution indicate that the polymorphic populations did not converge to the same identical distribution and that the polymorphic populations are intermediate in population size to the two homozygous groups. The need for a stochastic theory that combines both population size and genetic selection is discussed.Key words: natural selection, Tribolium, gamma distribution, maximum population size, stationary distribution, stochastic differential equation, stochastic population model.

scholarly journals Ecological determinants of life-history evolution

1991 ◽  
Vol 332 (1262) ◽  
pp. 25-30 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Natural Selection ◽  
Competitive Ability ◽  
Life History Evolution ◽  
Experimental System ◽  
Food Utilization ◽  
Physiological Basis ◽  
Laboratory Populations ◽  
Very High

Density-dependent natural selection has been studied, empirically with laboratory populations of Drosophila melanogaster . Populations kept at very high and low population density have become differentiated with respect to important fitness-related traits. There is now some understanding of the behavioural and physiological basis of these differences. These studies have identified larval competitive ability and efficiency of food utilization as traits that are negatively correlated with respect to effects on fitness. Theory that illuminates and motivates additional research with this experimental system has been lacking. Current research has focused on models that incorporate many details of Drosophila ecology in laboratory environments.

scholarly journals Depression in late life: psychiatric-medical comorbidity

1999 ◽  
Vol 1 (2) ◽  
pp. 81-94
Keyword(s):  
Drug Effects ◽  
Late Life ◽  
Metabolic Effects ◽  
Basic Knowledge ◽  
Medical Illness ◽  
Late Life Depression ◽  
Physiological Mechanisms ◽  
Medical Treatments ◽  
Beneficial Effects ◽  
Health Related

The links between late-life depression and the medical comorbidities that are often associated with it can be divided into two paths. The path from medical illness to depression reflects general mechanisms related to stress, disability, and loss, as well as more specific physiological mechanisms, including those related to subclinical cerebrovascular disease, adverse drug effects, and endocrine/metabolic effects. Similarly the path from depression to medical illness includes general mechanisms related to self-neglect, decreased adherence to medical treatments, maladaptive health-related behaviors, and, possibly, more specific physiological mechanisms including those related to altered endocrine and autonomic functions, in the clinical context, these two paths can interact to constitute a vicious cycle. With further research, it should be possible to translate current understanding in these areas into advances in both basic knowledge and treatments that could initiate virtuous cycles with beneficial effects for both menial and physical health.

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