3. How behaviour develops

2017 ◽  
Author(s):  
Tristram D. Wyatt
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Natural Selection ◽  
Phenotypic Plasticity ◽  
Mate Choice ◽  
Social Influences ◽  
Future Generations ◽  
Gene Frequencies ◽  
Brain Gene Expression ◽  
Genes And Environment

Behaviours evolve by natural selection. As genes influence how behaviours develop, selection on behaviour will alter gene frequencies in subsequent generations: genes that lead to successful behaviours in foraging, parental care, or mate choice, for example, will be represented in more individuals in future generations. If conditions change, then mutations of the genes that give rise to advantageous behaviours will be favoured by selection. ‘How behaviour develops’ explains that the environment is equally important: both genes and environment are intimately and interactively involved in behaviour development. Behavioural imprinting is also discussed along with co-opting genes, gene regulation, social influences on brain gene expression, phenotypic plasticity, and play.

scholarly journals Gene regulation is commonly selected for high plasticity and low noise

2021 ◽  
Author(s):  
Markéta Vlková ◽  
Olin K Silander
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Natural Selection ◽  
De Novo ◽  
Natural Populations ◽  
Low Noise ◽  
Expression Level ◽  
Direct Selection ◽  
High Plasticity ◽  
Bacterial Gene

Bacteria often respond to dynamically changing environments by regulating gene expression. Despite this regulation being critically important for growth and survival, little is known about how selection shapes gene regulation in natural populations. To better understand the role natural selection plays in shaping bacterial gene regulation, here we compare differences in the regulatory behaviour of naturally segregating promoter variants from Escherichia coli (which have been subject to natural selection) to randomly mutated promoter variants (which have never been exposed to natural selection). We quantify gene expression phenotypes (expression level, plasticity, and noise) for hundreds of promoter variants across multiple environments, and show that segregating promoter variants are enriched for mutations with minimal effects on expression level. In many promoters, we infer that there is strong selection to maintain high levels of plasticity, and direct selection to decrease or increase cell-to-cell variability in expression. Finally, taking an integrated view, we show that across all phenotypes combined, segregating promoter variants are far more phenotypically similar than would be expected given their genetic divergence. This is the consequence of both stabilizing and directional selection acting on individual phenotypes to minimize differences among segregating variants. Taken together, these results expand our knowledge of how gene regulation is affected by natural selection and highlight the power of comparing naturally segregating polymorphisms to de novo random mutations to quantify the action of selection.

scholarly journals Environmental exposures and gene regulation in disease etiology

2008 ◽  
Vol 13 (1) ◽  
pp. 269-281 ◽  
Author(s):  
Thea M. Edwards ◽  
John Peterson Myers
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Environmental Exposures ◽  
Regulatory Mechanisms ◽  
Industrial Chemicals ◽  
Disease Etiology ◽  
Environmental Health Research ◽  
Genes And Environment ◽  
Broad Array ◽  
Gene Regulatory

Health or disease is shaped for all individuals by interactions between their genes and environment. Exactly how the environment changes gene expression and how this can lead to disease are being explored in a fruitful new approach to environmental health research, representative studies of which are reviewed here. We searched Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications. Pharmaceuticals, pesticides, air pollutants, industrial chemicals, heavy metals, hormones, nutrition, and behavior can change gene expression through a broad array of gene regulatory mechanisms. Furthermore, chemically induced changes in gene regulation are associated with serious and complex human diseases, including cancer, diabetes and obesity, infertility, respiratory diseases, allergies, and neurodegenerative disorders such as Parkinson and Alzheimer diseases. The reviewed studies indicate that genetic predisposition for disease is best predicted in the context of environmental exposures. And the genetic mechanisms investigated in these studies offer new avenues for risk assessment research. Finally, we are likely to witness dramatic improvements in human health, and reductions in medical costs, if environmental pollution is decreased.

scholarly journals Expression noise facilitates the evolution of gene regulation

2014 ◽  
Author(s):  
Luise Wolf ◽  
Olin K Silander ◽  
Erik J van Nimwegen
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Natural Selection ◽  
Large Set ◽  
Main Function ◽  
Noise Levels ◽  
E Coli ◽  
Regulatory Interactions ◽  
Expression Noise ◽  
Evolution Of Gene Regulation

In studies of gene regulation, it is often tacitly assumed that the interactions between transcriptional regulators and their target promoters are finely tuned to ensure condition-appropriate gene expression of the targets. However, how natural selection might evolve such precise regulation from an initial state without regulation, is rarely discussed. In addition, the accuracy of gene regulation is affected by noise in gene expression [1]. Expression noise varies greatly across genes [2?5], suggesting that natural selection has affected noise levels, but the role of expression noise in gene regulation is currently poorly understood [6]. Here we present a combination of experimental evidence and theoretical modeling showing that the transmission of expression noise from regulators to their targets can function as a rudimentary form of gene regulation that facilitates the evolution of more finely tuned gene regulation. To assess how natural selection has affected transcriptional noise in E. coli, we evolved a large set of synthetic promoters under carefully controlled selective conditions and found, surprisingly, that native E. coli promoters show no signs of having been selected for minimizing their noise. Instead, a subset of native promoters, which are characterized by high expression plasticity and high numbers of regulatory inputs, show elevated noise levels. A general theoretical model, which recognizes that target genes are not only affected by the condition-dependent activities of their regulators, but also by the regulators? noise, explains these observations. Noise transmission from regulators to their targets is favored by selection whenever regulation is imprecise, and may even constitute the main function of coupling a promoter to a regulator. Our theory provides a novel framework for understanding the evolution of gene regulation, demonstrating that in many situations expression noise is not the mere unwanted side-effect of regulatory interactions, but a beneficial function that is key to the evolvability of regulatory interactions.

Phenotypic plasticity

2018 ◽  
Author(s):  
Karen D. Williams ◽  
Marla B. Sokolowski
Keyword(s):  
Gene Expression ◽  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Behavioral Plasticity ◽  
Behavioral Flexibility ◽  
Insect Behavior ◽  
Behavioral Variability ◽  
Gene By Environment Interactions ◽  
Affect Gene Expression

Why is there so much variation in insect behavior? This chapter will address the sources of behavioral variability, with a particular focus on phenotypic plasticity. Variation in social, nutritional, and seasonal environmental contexts during development and adulthood can give rise to phenotypic plasticity. To delve into mechanism underlying behavioral flexibility in insects, examples of polyphenisms, a type of phenotypic plasticity, will be discussed. Selected examples reveal that environmental change can affect gene expression, which in turn can affect behavioral plasticity. These changes in gene expression together with gene-by-environment interactions are discussed to illuminate our understanding of insect behavioral plasticity.

Interactions Between Natural Selection, Recombination and Gene Density in the Genes of Drosophila

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 595-608 ◽  
Author(s):  
Jody Hey ◽  
Richard M Kliman
Keyword(s):  
Gene Expression ◽  
Natural Selection ◽  
Recombination Rate ◽  
Codon Bias ◽  
Gene Density ◽  
Drosophila Genome ◽  
Functional Variation ◽  
Subtle Effect ◽  
Efficiency Of Selection ◽  
The Impact

AbstractIn Drosophila, as in many organisms, natural selection leads to high levels of codon bias in genes that are highly expressed. Thus codon bias is an indicator of the intensity of one kind of selection that is experienced by genes and can be used to assess the impact of other genomic factors on natural selection. Among 13,000 genes in the Drosophila genome, codon bias has a slight positive, and strongly significant, association with recombination—as expected if recombination allows natural selection to act more efficiently when multiple linked sites segregate functional variation. The same reasoning leads to the expectation that the efficiency of selection, and thus average codon bias, should decline with gene density. However, this prediction is not confirmed. Levels of codon bias and gene expression are highest for those genes in an intermediate range of gene density, a pattern that may be the result of a tradeoff between the advantages for gene expression of close gene spacing and disadvantages arising from regulatory conflicts among tightly packed genes. These factors appear to overlay the more subtle effect of linkage among selected sites that gives rise to the association between recombination rate and codon bias.

scholarly journals Base-Pair Opening Dynamics Study of Fluoride Riboswitch in the Bacillus cereus CrcB Gene

2021 ◽  
Vol 22 (6) ◽  
pp. 3234
Author(s):  
Juhyun Lee ◽  
Si-Eun Sung ◽  
Janghyun Lee ◽  
Jin Young Kang ◽  
Joon-Hwa Lee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Nmr Spectroscopy ◽  
Bacillus Cereus ◽  
Base Pair ◽  
Noncoding Rna ◽  
Hydrogen Exchange ◽  
Magnesium Ion ◽  
Fluoride Ion ◽  
Base Pair Opening

Riboswitches are segments of noncoding RNA that bind with metabolites, resulting in a change in gene expression. To understand the molecular mechanism of gene regulation in a fluoride riboswitch, a base-pair opening dynamics study was performed with and without ligands using the Bacillus cereus fluoride riboswitch. We demonstrate that the structural stability of the fluoride riboswitch is caused by two steps depending on ligands. Upon binding of a magnesium ion, significant changes in a conformation of the riboswitch occur, resulting in the greatest increase in their stability and changes in dynamics by a fluoride ion. Examining hydrogen exchange dynamics through NMR spectroscopy, we reveal that the stabilization of the U45·A37 base-pair due to the binding of the fluoride ion, by changing the dynamics while maintaining the structure, results in transcription regulation. Our results demonstrate that the opening dynamics and stabilities of a fluoride riboswitch in different ion states are essential for the genetic switching mechanism.

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