scholarly journals Evolution of adaptive phenotypic variation patterns by direct selection for evolvability

2010 ◽  
Vol 278 (1713) ◽  
pp. 1903-1912 ◽  
Author(s):  
Mihaela Pavlicev ◽  
James M. Cheverud ◽  
Günter P. Wagner
Keyword(s):  
Natural Selection ◽  
Phenotypic Variation ◽  
Genetic Model ◽  
Gene Interaction ◽  
Directional Selection ◽  
Direct Selection ◽  
Phenotypic Traits ◽  
Heritable Variation ◽  
Darwinian Theory ◽  
Theory Of Evolution

A basic assumption of the Darwinian theory of evolution is that heritable variation arises randomly. In this context, randomness means that mutations arise irrespective of the current adaptive needs imposed by the environment. It is broadly accepted, however, that phenotypic variation is not uniformly distributed among phenotypic traits, some traits tend to covary, while others vary independently, and again others barely vary at all. Furthermore, it is well established that patterns of trait variation differ among species. Specifically, traits that serve different functions tend to be less correlated, as for instance forelimbs and hind limbs in bats and humans, compared with the limbs of quadrupedal mammals. Recently, a novel class of genetic elements has been identified in mouse gene-mapping studies that modify correlations among quantitative traits. These loci are called relationship loci, or relationship Quantitative Trait Loci (rQTL), and affect trait correlations by changing the expression of the existing genetic variation through gene interaction. Here, we present a population genetic model of how natural selection acts on rQTL. Contrary to the usual neo-Darwinian theory, in this model, new heritable phenotypic variation is produced along the selected dimension in response to directional selection. The results predict that selection on rQTL leads to higher correlations among traits that are simultaneously under directional selection. On the other hand, traits that are not simultaneously under directional selection are predicted to evolve lower correlations. These results and the previously demonstrated existence of rQTL variation, show a mechanism by which natural selection can directly enhance the evolvability of complex organisms along lines of adaptive change.

Sociobiology

2018 ◽  
Author(s):  
Alex Rosenberg
Keyword(s):  
Natural Selection ◽  
Social Institutions ◽  
Human Behaviour ◽  
Behavioural Science ◽  
Social Scientists ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Mendelian Genetics ◽  
The Individual ◽  
Mental Testing

Following Darwin, biologists and social scientists have periodically been drawn to the theory of natural selection as the source of explanatory insights about human behaviour and social institutions. The combination of Mendelian genetics and Darwinian theory, which did so much to substantiate the theory of evolution in the life sciences, however, has made recurrent adoption of a biological approach to the social sciences controversial. Excesses and errors in social Darwinism, eugenics and mental testing have repeatedly exposed evolutionary approaches in the human sciences to criticism. Sociobiology is the version of Darwinism in social and behavioural science that became prominent in the last quarter of the twentieth century. Philosophical problems of sociobiology include challenges to the explanatory relevance of Darwinian theory for human behaviour and social institutions, controversies about whether natural selection operates at levels of organization above or below the individual, questions about the meaning of the nature–nurture distinction, and disputes about Darwinism’s implications for moral philosophy.

“Data for the Problem of Evolution in Man. V. On the Correlation between Duration of Life and the Number of Offspring”

1901 ◽  
Vol 35 (6) ◽  
pp. 458-479
Author(s):  
M. Beeton ◽  
G. U. Yule ◽  
Karl Pearson
Keyword(s):  
Natural Selection ◽  
Breeding Season ◽  
The Other ◽  
Similar Statement ◽  
Men And Women ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Biennial Plants ◽  
Long Life ◽  
Breeding Seasons

According to the Darwinian theory of evolution the members of a community less fitted to their environment are removed by death. But this process of natural selection would not permanently modify a race, if the members thus removed were able before death to propagate their species in average numbers. It then becomes an important question to ascertain how far duration of life is related to fertility. In the case of many insects death can interfere only with their single chance of offspring; they live or not for their one breeding season only. A similar statement holds good with regard to annual and biennial plants. In such cases there might still be a correlation between duration of life and fertility, but it would be of the indirect character, which we actually find in the case of men and women living beyond sixty years of age—a long life means better physique and better physique increased fertility. On the other hand, there is a direct correlation of fertility and duration of life in the case of those animals which generally survive a number of breeding seasons, and it is this correlation which we had at first in view when investigating the influence of duration of life on fertility in man. The discovery of the indirect factor in the correlation referred to above was therefore a point of much interest. For it seems to show that the physique fittest to survive is really the physique which is in itself (and independently of the duration of life) most fecund.

scholarly journals Data for the problem of evolution in man. V. On the correlation between duration of life and the number of offspring

1901 ◽  
Vol 67 (435-441) ◽  
pp. 159-179 ◽  
Keyword(s):  
Natural Selection ◽  
Breeding Season ◽  
Similar Statement ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Biennial Plants

According to the Darwinian theory of evolution the members of a community less fitted^ to their environment are removed by death. But this process of natural selection would not permanently modify a race, if the members thus removed were able before death to propagate their species in average numbers. It then becomes an important question to ascertain how far duration of life is related to fertility. In the case of many insects death can interfere only with their single chance of offspring they live or not for their one breeding season only. A similar statement holds good with regard to annual and biennial plants.

An Approach to the Theory of Natural Selection

Philosophy ◽  
1969 ◽  
Vol 44 (170) ◽  
pp. 271-290 ◽  
Author(s):  
A. D. Barker
Keyword(s):  
Natural Selection ◽  
Point Of View ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Positive Argument

In this paper I want to examine a view of the Darwinian theory of evolution which was put forward fairly recently by A. R. Manser. His approach is of interest not only in itself, but also because it may be expanded to raise some fundamental questions about the nature of the science of biology in general. I shall not consider these further implications here, but shall concentrate on an examination of his thesis in the context in which it is raised. My paper falls into two sections. In the first I shall state Manser's thesis and some of the arguments with which he supports it, and shall try to show how a series of objections raised by A. G. N. Flew and K. Connolly may be answered. In the second I shall offer on my own account a positive argument to provide a possible basis for his point of view, with the aim of indicating why the theory should be of the kind he suggests, and what form the study of evolution must take.

Introduction

1988 ◽  
Author(s):  
Keith Stewart Thomson
Keyword(s):  
Natural Selection ◽  
Phenotypic Variation ◽  
Charles Darwin ◽  
Dynamic Properties ◽  
Theory Of Evolution ◽  
Genetic Level ◽  
The Individual ◽  
Scientific Subject ◽  
Neutral Mutations ◽  
As If

All of science is fundamentally about cause. It is about explanations of the reasons things are the way they are and the mechanisms that produce them. It is now commonplace to observe that Charles Darwin brought evolution and all of organismal biology into line as a truly scientific subject by discussing evolutionary phenomena in terms of cause, and thus in the same testable, quantifiable frame of reference that applies to other science. Darwin's theory of natural selection as a causal agency for evolutionary change was only the beginning of our problems, not the end. For more than a hundred years, we have sought to find all the layers and intersecting lines of causality that produce natural selection as well as to discover other mechanisms for change that are nonselective in nature—genetic drift or neutral mutations, for example. Natural selection is basically a mechanism that involves two components: the introduction of variants into a system and the subsequent sorting of these variants (Vrba and Eldredge, 1984) so that, over generations, there is a differential contribution of these variants to higher levels such as populations and species. Up to the present time, most attention of evolutionists has concentrated upon two aspects of the problem: the genetic basis of phenotypic variation and the dynamic properties of populations containing the individual variants. The present book is concerned with the mechanisms affecting the expression of variation among individual phenotypes. It has been a surprisingly neglected subject. The New Synthetic theory of evolution and its later modifications have largely been pursued as if the intrinsic mechanisms by which variation is caused among individual organismal phenotypes are less important to the processes of evolution than the extrinsic mechanisms of sorting. If only by default, variation introduced at the level of the individual phenotypes is commonly treated as if it were a simple mapping of variation at the genetic level, or at least were only a very simple function of that. It has seemed not only necessary but sufficient to study genetics in order to understand phenotypic variation.

scholarly journals Fluctuating selection across years and phenotypic variation in food-deceptive orchids

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3704 ◽  
Author(s):  
Giovanni Scopece ◽  
Nicolas Juillet ◽  
Christian Lexer ◽  
Salvatore Cozzolino
Keyword(s):  
Phenotypic Variation ◽  
Phenotypic Variability ◽  
Directional Selection ◽  
Phenotypic Traits ◽  
Fluctuating Selection ◽  
Deceptive Pollination ◽  
Selection Gradients ◽  
Insect Interactions ◽  
Pollination Strategy ◽  
Selection Differentials

Nectarless flowers that deceive pollinators offer an opportunity to study asymmetric plant-insect interactions. Orchids are a widely used model for studying these interactions because they encompass several thousand species adopting deceptive pollination systems. High levels of intra-specific phenotypic variation have been reported in deceptive orchids, suggesting a reduced consistency of pollinator-mediated selection on their floral traits. Nevertheless, several studies report on widespread directional selection mediated by pollinators even in these deceptive orchids. In this study we test the hypothesis that the observed selection can fluctuate across years in strength and direction thus likely contributing to the phenotypic variability of this orchid group. We performed a three-year study estimating selection differentials and selection gradients for nine phenotypic traits involved in insect attraction in two Mediterranean orchid species, namely Orchis mascula and O. pauciflora, both relying on a well-described food-deceptive pollination strategy. We found weak directional selection and marginally significant selection gradients in the two investigated species with significant intra-specific differences in selection differentials across years. Our data do not link this variation with a specific environmental cause, but our results suggest that pollinator-mediated selection in food-deceptive orchids can change in strength and in direction over time. In perennial plants, such as orchids, different selection differentials in the same populations in different flowering seasons can contribute to the maintenance of phenotypic variation often reported in deceptive orchids.

Comment on "Epigenetics and the renaissance of heresy"

Genome ◽  
2003 ◽  
Vol 46 (6) ◽  
pp. 968-972 ◽  
Author(s):  
Rama S Singh
Keyword(s):  
Evolutionary Biology ◽  
Allelic Variation ◽  
Epigenetic Inheritance ◽  
Mendelian Inheritance ◽  
Heritable Variation ◽  
Darwinian Theory ◽  
Phenotypic Differences ◽  
Theory Of Evolution ◽  
Lamarckian Inheritance ◽  
History Of

Lamarckian inheritance (i.e., inheritance of acquired character) and Richard Golschmidt's concept of "systemic mutations" and their role in macroevolution have been two of the most controversial topics in the history of evolutionary biology. The concept of Lamarckian inheritance was put to rest first by Weismann's germplasm theory and experiment and later by the discovery of Mendelian inheritance. Goldschmidt's theory of macroevolution by systemic mutations was put to rest by the discovery of DNA's structure and subsequent demonstration showing allelic variation as the basis for genetic and phenotypic differences observed among organisms. Some authors are using recent demonstrations of epigenetic inheritance in higher organisms to support Lamarckian inheritance and Golschmidt's theory of macroevolution by systemic mutations. In this paper, I show that the recent discoveries related to mutations, such as the so called "directed" mutations in bacteria, and epigenetic inheritance in higher organisms are basically an extension of the notion of "mutation" and thus of the concept of "heritable variation" required for evolution. While the new discoveries of the laws of developmental transformations are enriching our knowledge of the intricate relationship between genotype and phenotype, the findings of epigenetic inheritance do not challenge the basic tenets of the neo-Darwinian theory of evolution, as other than producing new variation no new processes of evolutionary change have been added to the ones we already know — mutation, migration, selection, and drift.Key words: neo-Darwinian theory of evolution, epigenetics, Lamarckian inheritance, systemic mutations, speciation, macroevolution.

Darwinian Evolutionary Theory

2018 ◽  
Author(s):  
Michael Ruse
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Middle Class ◽  
Evolutionary Theory ◽  
Scientific Community ◽  
Homo Sapiens ◽  
Origin Of Species ◽  
Theory Of Evolution ◽  
Descent Of Man

Charles Robert Darwin, the English naturalist, published On the Origin of Species in 1859 and the follow-up work The Descent of Man in 1871. In these works, he argued for his theory of evolution through natural selection, applying it to all organisms, living and dead, including our own species, Homo sapiens. Although controversial from the start, Darwin’s thinking was deeply embedded in the culture of his day, that of a middle-class Englishman. Evolution as such was an immediate success in scientific circles, but although the mechanism of selection had supporters in the scientific community (especially among those working with fast-breeding organisms), its real success was in the popular domain. Natural selection, and particularly the side mechanism of sexual selection, were known to all and popular themes in fiction and elsewhere.

scholarly journals Contributions of source population and incubation temperature to phenotypic variation of hatchling Chinese skinks

2020 ◽  
Author(s):  
Hong-Liang Lu ◽  
Yan-Fu Qu ◽  
Hong Li ◽  
Xiang Ji
Keyword(s):  
Body Mass ◽  
Phenotypic Variation ◽  
Incubation Temperature ◽  
Tail Length ◽  
Population Variation ◽  
Phenotypic Traits ◽  
Source Population ◽  
Relative Importance ◽  
The Difference ◽  
Hatchling Size

Abstract Phenotypic plasticity and local adaptation are viewed as the main factors that result in between-population variation in phenotypic traits, but contributions of these factors to phenotypic variation vary between traits and between species and have only been explored in a few species of reptiles. Here, we incubated eggs of the Chinese skink (Plestiodon chinensis) from 7 geographically separated populations in Southeast China at 3 constant temperatures (24, 28, and 32 °C) to evaluate the combined effects of clutch origin, source population, and incubation temperature on hatchling traits. The relative importance of these factors varied between traits. Nearly all examined hatchling traits, including body mass, snout–vent length (SVL), tail length, head size, limb length, tympanum diameter, and locomotor speed, varied among populations and were affected by incubation temperature. Measures for hatchling size (body mass and SVL) varied considerably among clutches. Source population explained much of the variation in hatchling body mass, whereas incubation temperature explained much of the variation in other examined traits. Our results indicate that between-population variation in hatchling traits of P. chinensis likely reflects the difference in natural incubation conditions and genetic divergence.

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