The evolutionary process in talitrid amphipods and salamanders in changing environments, with a discussion of "genetic assimilation" and some other evolutionary concepts

1982 ◽  
Vol 60 (5) ◽  
pp. 733-749 ◽  
Author(s):  
Ryuichi Matsuda
Keyword(s):  
Natural Selection ◽  
Structural Changes ◽  
Evolutionary Process ◽  
Historical Review ◽  
Genetic Assimilation ◽  
Baldwin Effect ◽  
Changing Environments ◽  
Endocrine Mechanism ◽  
Environmental Induction ◽  
The Baldwin Effect

The evolutionary process of talitrid amphipods and salamanders involving neoteny in changing environments consists of the aspect of environmental induction of structural changes as a result of altered activity of the preexisting endocrine mechanism and the aspect of natural selection which results in canalization of development and genetic assimilation of the modified (neotenous) phenotype. The prevalence of genetic assimilation is discussed, along with the cases where traditional neo-Darwinism applies. By taking the fact of environment–hormonal induction of gene regulation and the aspect of natural selection into account, mechanisms of macroevolution, preadaptation, plasticity in morphogenesis, and a mode of speciation are discussed. A historical review is presented concerning the theories (the Baldwin effect and Weismann's theory) related to genetic assimilation and neo-Darwinism.

Landscapes, Learning Costs, and Genetic Assimilation

1996 ◽  
Vol 4 (3) ◽  
pp. 213-234 ◽  
Author(s):  
Giles Mayley
Keyword(s):  
Evolutionary Process ◽  
Small Distance ◽  
Genetic Assimilation ◽  
Phenotypic Traits ◽  
Costs And Benefits ◽  
Baldwin Effect ◽  
Adaptive Processes ◽  
Adaptive Ability ◽  
The Baldwin Effect ◽  
Neighborhood Correlation

The evolution of a population can be guided by phenotypic traits acquired by members of that population during their lifetime. This phenomenon, known as the Baldwin effect, can speed the evolutionary process as traits that are initially acquired become genetically specified in later generations. This paper presents conditions under which this genetic assimilation can take place. As well as the benefits that lifetime adaptation can give a population, there may be a cost to be paid for that adaptive ability. It is the evolutionary trade-off between these costs and benefits that provides the selection pressure for acquired traits to become genetically specified. It is also noted that genotypic space, in which evolution operates, and phenotypic space, in which adaptive processes (such as learning) operate, are, in general, of a different nature. To guarantee that an acquired characteristic can become genetically specified, these spaces must have the property of neighborhood correlation, which means that a small distance between two individuals in phenotypic space implies that there is a small distance between the same two individuals in genotypic space.

scholarly journals Transient Phenomena in Learning and Evolution: Genetic Assimilation and Genetic Redistribution

2005 ◽  
Vol 11 (1-2) ◽  
pp. 177-188 ◽  
Author(s):  
Janet Wiles ◽  
James Watson ◽  
Bradley Tonkes ◽  
Terrence Deacon
Keyword(s):  
Vitamin C ◽  
Environmental Changes ◽  
Initial Conditions ◽  
Universal Grammar ◽  
Fitness Function ◽  
Genetic Assimilation ◽  
Baldwin Effect ◽  
Transient Phenomena ◽  
The Baldwin Effect ◽  
Redistribution Effect

Deacon has recently proposed that complexes of genes can be integrated into functional groups as a result of environmental changes that mask and unmask selection pressures. For example, many animals endogenously synthesize ascorbic acid (vitamin C), but anthropoid primates have only a nonfunctional version of the crucial gene for this pathway. It is hypothesized that the loss of functionality occurred in the evolutionary past when a diet rich in vitamin C masked the effect of the gene, and its loss effectively trapped the animals in a fruit-eating lifestyle. As a result, the complex of abilities that support this lifestyle were evolutionarily bound together, forming a multilocus complex. In this study we use evolutionary computation simulations to explore the thesis that masking and unmasking can transfer dependence from one set of genes to many sets, and thereby integrate the whole complex of genes. We used a framework based on Hinton and Nowlan's 1987 simulation of the Baldwin effect. Additional gene complexes and an environmental parameter were added to their basic model, and the fitness function extended. The simulation clearly demonstrates that the genetic redistribution effect can occur in silico, showing an initial advantage of endogenously synthesized vitamin C, followed by transfer of the fitness contribution to the complex of genes that together allow the acquisition of vitamin C from the environment. As is well known in the modeling community, the Baldwin effect only occurs in simulations when the population of agents is “poised on the brink” of discovering the genetically specified solution. Similarly, the redistribution effect occurs in simulations under specific initial conditions: too little vitamin C in the environment, and its synthesis it is never fully masked; too much vitamin C, and the abilities required to acquire it are not tightly integrated. The Baldwin effect has been hypothesized as a potential mechanism for developing language-specific adaptations like innate universal grammar and other highly modular capacities. We conclude with a discussion of the relevance of genetic assimilation and genetic redistribution to the evolution of language and other cognitive adaptations.

scholarly journals Evolutionary significance of phenotypic accommodation in novel environments: an empirical test of the Baldwin effect

2009 ◽  
Vol 364 (1520) ◽  
pp. 1125-1141 ◽  
Author(s):  
Alexander V Badyaev
Keyword(s):  
Natural Selection ◽  
Empirical Test ◽  
Transient State ◽  
Evolutionary Significance ◽  
Baldwin Effect ◽  
Genetic Determination ◽  
Developmental Variation ◽  
Organic Selection ◽  
Novel Environments ◽  
The Baldwin Effect

When faced with changing environments, organisms rapidly mount physiological and behavioural responses, accommodating new environmental inputs in their functioning. The ubiquity of this process contrasts with our ignorance of its evolutionary significance: whereas within-generation accommodation of novel external inputs has clear fitness consequences, current evolutionary theory cannot easily link functional importance and inheritance of novel accommodations. One hundred and twelve years ago, J. M. Baldwin, H. F. Osborn and C. L. Morgan proposed a process (later termed the Baldwin effect) by which non-heritable developmental accommodation of novel inputs, which makes an organism fit in its current environment, can become internalized in a lineage and affect the course of evolution. The defining features of this process are initial overproduction of random (with respect to fitness) developmental variation, followed by within-generation accommodation of a subset of this variation by developmental or functional systems (‘organic selection’), ensuring the organism's fit and survival. Subsequent natural selection sorts among resultant developmental variants, which, if recurrent and consistently favoured, can be inherited when existing genetic variance includes developmental components of individual modifications or when the ability to accommodate novel inputs is itself heritable. Here, I show that this process is consistent with the origin of novel adaptations during colonization of North America by the house finch. The induction of developmental variation by novel environments of this species's expanding range was followed by homeostatic channelling, phenotypic accommodation and directional cross-generational transfer of a subset of induced developmental outcomes favoured by natural selection. These results emphasize three principal points. First, contemporary novel adaptations result mostly from reorganization of existing structures that shape newly expressed variation, giving natural selection an appearance of a creative force. Second, evolutionary innovations and maintenance of adaptations are different processes. Third, both the Baldwin and parental effects are probably a transient state in an evolutionary cycle connecting initial phenotypic retention of adaptive changes and their eventual genetic determination and, thus, the origin of adaptation and evolutionary change.

Relaxation of Selection, Niche Construction, and the Baldwin Effect in Language Evolution

2010 ◽  
Vol 16 (4) ◽  
pp. 271-287 ◽  
Author(s):  
Hajime Yamauchi ◽  
Takashi Hashimoto
Keyword(s):  
Natural Selection ◽  
Language Learning ◽  
Genetic Predisposition ◽  
Niche Construction ◽  
Language Evolution ◽  
Key Factors ◽  
Baldwin Effect ◽  
Learning Capability ◽  
Linguistic Behavior ◽  
The Baldwin Effect

Deacon has suggested that one of the key factors of language evolution is not characterized by an increase in genetic contribution, often known as the Baldwin effect, but rather by a decrease. This process effectively increases linguistic learning capability by organizing a novel synergy of multiple lower-order functions previously irrelevant to the process of language acquisition. Deacon posits that this transition is not caused by natural selection. Rather, it is due to the relaxation of natural selection. While there are some cases in which relaxation caused by some external factors indeed induces the transition, we do not know what kind of relaxation has worked in language evolution. In this article, a genetic-algorithm-based computer simulation is used to investigate how the niche-constructing aspect of linguistic behavior may trigger the degradation of genetic predisposition related to language learning. The results show that agents initially increase their genetic predisposition for language learning—the Baldwin effect. They create a highly uniform sociolinguistic environment—a linguistic niche construction. This means that later generations constantly receive very similar inputs from adult agents, and subsequently the selective pressure to retain the genetic predisposition is relaxed.

scholarly journals Epigenetic inheritance and evolution: a historian's perspective

2021 ◽  
Vol 376 (1826) ◽  
Author(s):  
Laurent Loison
Keyword(s):  
Historical Context ◽  
Epigenetic Inheritance ◽  
Genetic Assimilation ◽  
Late Nineteenth Century ◽  
Historical Reconstruction ◽  
Theme Issue ◽  
Baldwin Effect ◽  
Genetic Inheritance ◽  
History Of ◽  
The Baldwin Effect

The aim of this article is to put the growing interest in epigenetics in the field of evolutionary theory into a historical context. First, I assess the view that epigenetic inheritance could be seen as vindicating a revival of (neo)Lamarckism. Drawing on Jablonka's and Lamb's considerable output, I identify several differences between modern epigenetics and what Lamarckism was in the history of science. Even if Lamarckism is not back, epigenetic inheritance might be appealing for evolutionary biologists because it could potentiate two neglected mechanisms: the Baldwin effect and genetic assimilation. Second, I go back to the first ideas about the Baldwin effect developed in the late nineteenth century to show that the efficiency of this mechanism was already linked with a form of non-genetic inheritance. The opposition to all forms of non-genetic inheritance that prevailed at the time of the rise of the Modern Synthesis helps to explain why the Baldwin effect was understood as an insignificant mechanism during the second half of the twentieth century. Based on this historical reconstruction, in §4, I examine what modern epigenetics can bring to the picture and under what conditions epigenetic inheritance might be seen as strengthening the causal relationship between adaptability and adaptation. Throughout I support the view that the Baldwin effect and genetic assimilation, even if they are quite close, should not be conflated, and that drawing a line between these concepts is helpful in order to better understand where epigenetic inheritance might endorse a new causal role.This article is part of the theme issue ‘How does epigenetics influence the course of evolution?’

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