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Molecular evolution describes how inherited DNA and/or RNA change over evolutionary time, and the consequences of this for proteins and other components of cells and organisms. Molecular evolution is the basis of phylogenetic approaches to describing the tree of life. Molecular evolution overlaps with population genetics, especially on shorter timescales. Topics in molecular evolution include the origins of new genes, the genetic nature of complex traits, the genetic basis of adaptation and speciation, the evolution of development, and patterns and processes underlying genomic changes during evolution.
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.
Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution holds that all species are related and gradually change over generations. In a population, the genetic variations affect the phenotypes of an organism. These changes in the phenotypes will be an advantage to some organisms, which will then be passed on to their offspring. Some examples of evolution in species over many generations are the peppered moth and flightless birds. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics, and paleontology.
In population genetics, directional selection is a type of natural selection in which one extreme phenotype is favored over both the other extreme and moderate phenotypes. This genetic selection causes the allele frequency to shift toward the chosen extreme over time as allele ratios change from generation to generation. The advantageous extreme allele will increase as a consequence of survival and reproduction differences among the different present phenotypes in the population. The allele fluctuations as a result of directional selection can be independent of the dominance of the allele, and in some cases if the allele is recessive, it can eventually become fixed in the population.
Evolvability is defined as the capacity of a system for adaptive evolution. Evolvability is the ability of a population of organisms to not merely generate genetic diversity, but to generate adaptive genetic diversity, and thereby evolve through natural selection.
Exaptation or co-option is a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour.
Evolutionary capacitance is the storage and release of variation, just as electric capacitors store and release charge. Living systems are robust to mutations. This means that living systems accumulate genetic variation without the variation having a phenotypic effect. But when the system is disturbed, robustness breaks down, and the variation has phenotypic effects and is subject to the full force of natural selection. An evolutionary capacitor is a molecular switch mechanism that can "toggle" genetic variation between hidden and revealed states. If some subset of newly revealed variation is adaptive, it becomes fixed by genetic assimilation. After that, the rest of variation, most of which is presumably deleterious, can be switched off, leaving the population with a newly evolved advantageous trait, but no long-term handicap. For evolutionary capacitance to increase evolvability in this way, the switching rate should not be faster than the timescale of genetic assimilation.
Canalisation is a measure of the ability of a population to produce the same phenotype regardless of variability of its environment or genotype. It is a form of evolutionary robustness. The term was coined in 1942 by C. H. Waddington to capture the fact that "developmental reactions, as they occur in organisms submitted to natural selection...are adjusted so as to bring about one definite end-result regardless of minor variations in conditions during the course of the reaction". He used this word rather than robustness to consider that biological systems are not robust in quite the same way as, for example, engineered systems.
Joan Roughgarden is an American ecologist and evolutionary biologist. She has engaged in theory and observation of coevolution and competition in Anolis lizards of the Caribbean, and recruitment limitation in the rocky intertidal zones of California and Oregon. She has more recently become known for her rejection of sexual selection, her theistic evolutionism, and her work on holobiont evolution.
Genetic assimilation is a process described by Conrad H. Waddington by which a phenotype originally produced in response to an environmental condition, such as exposure to a teratogen, later becomes genetically encoded via artificial selection or natural selection. Despite superficial appearances, this does not require the (Lamarckian) inheritance of acquired characters, although epigenetic inheritance could potentially influence the result. Waddington stated that genetic assimilation overcomes the barrier to selection imposed by what he called canalization of developmental pathways; he supposed that the organism's genetics evolved to ensure that development proceeded in a certain way regardless of normal environmental variations.
Orphan genes, ORFans, or taxonomically restricted genes (TRGs) are genes that lack a detectable homologue outside of a given species or lineage. Most genes have known homologues. Two genes are homologous when they share an evolutionary history, and the study of groups of homologous genes allows for an understanding of their evolutionary history and divergence. Common mechanisms that have been uncovered as sources for new genes through studies of homologues include gene duplication, exon shuffling, gene fusion and fission, etc. Studying the origins of a gene becomes more difficult when there is no evident homologue. The discovery that about 10% or more of the genes of the average microbial species is constituted by orphan genes raises questions about the evolutionary origins of different species as well as how to study and uncover the evolutionary origins of orphan genes.
The evolution of biological complexity is one important outcome of the process of evolution. Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.
Gerd B. Müller is an Austrian biologist who is emeritus professor at the University of Vienna where he was the head of the Department of Theoretical Biology in the Center for Organismal Systems Biology. His research interests focus on vertebrate limb development, evolutionary novelties, evo-devo theory, and the Extended Evolutionary Synthesis. He is also concerned with the development of 3D based imaging tools in developmental biology.
Günter P. Wagner is an Austrian-born evolutionary biologist who is Professor of Ecology and Evolutionary biology at Yale University, and head of the Wagner Lab.
Sarah Perin Otto is a theoretical biologist, Canada Research Chair in Theoretical and Experimental Evolution, and is currently a Killam Professor at the University of British Columbia. From 2008-2016, she was the director of the Biodiversity Research Centre at the University of British Columbia. Otto was named a 2011 MacArthur Fellow. In 2015 the American Society of Naturalists gave her the Sewall Wright Award for fundamental contributions to the unification of biology. In 2021, she was awarded the Darwin–Wallace Medal for contributing major advances to the mathematical theory of evolution.
Leticia Avilés is an Ecuadoran evolutionary biologist and ecologist who studies the evolution of social behavior and the evolution of life history traits in metapopulations. Her methods include a combination of theory and empirical work, the latter using social spiders as a model system. Her research on these organisms has addressed questions such as why some spiders live in groups, why do they exhibit highly female-biased sex ratios, and why have they evolved a system where individuals remain in the natal nest to mate from generation to generation.
The following outline is provided as an overview of and topical guide to evolution:
L. Lacey Knowles is an ecologist and evolutionary biologist known for her work with speciation, sexual selection, phylogeography, and evolutionary radiation. As of 2012, she is a professor at the University of Michigan and the curator of insects at the university's museum of zoology. She has been an elected member of the councils for the Society for the Study of Evolution and the Society of Systematic Biology. Knowles received her Ph.D. in Ecology and Evolution from the State University of New York at Stony Brook and had a Postdoctoral Fellowship in the Department of Ecology and Evolutionary Biology at the University of Arizona. Knowles has also served as an associate editor of scientific journals such as Evolution, Molecular Ecology, Systematic Biology, and Heredity. She is the author of Estimating Species Trees: Practical and Theoretical Aspects.
The Extended Evolutionary Synthesis (EES) consists of a set of theoretical concepts argued to be more comprehensive than the earlier modern synthesis of evolutionary biology that took place between 1918 and 1942. The extended evolutionary synthesis was called for in the 1950s by C. H. Waddington, argued for on the basis of punctuated equilibrium by Stephen Jay Gould and Niles Eldredge in the 1980s, and was reconceptualized in 2007 by Massimo Pigliucci and Gerd B. Müller.
De novo gene birth is the process by which new genes evolve from non-coding DNA. De novo genes represent a subset of novel genes, and may be protein-coding or instead act as RNA genes. The processes that govern de novo gene birth are not well understood, although several models exist that describe possible mechanisms by which de novo gene birth may occur.
References
- 1 2 3 4 5 6 7 8 9 "Dr. Joanna Masel". University of Arizona. Retrieved 24 March 2024.
- ↑ "Profile with Joanna Masel". The Rhodes Project. 2013.
- ↑ "Joanna Masel". Google Scholar. Retrieved 22 June 2023.
- ↑ Littin, Shelley (22 October 2013). "UA Biologists Awarded John Templeton Foundation Grants for Research on Genetics, Diversity of Life". University of Arizona.
- ↑ "Joanna Masel. Principal Investigator". University of Arizona. Retrieved 1 October 2017.
- ↑ Masel, Joanna (24 April 2017). "Behind the Paper: De novo gene birth". Nature Ecology and Evolution.
- ↑ Wilson, Benjamin A.; Foy, Scott G.; Neme, Rafik; Masel, Joanna (2017). "Young genes are highly disordered as predicted by the preadaptation hypothesis of de novo gene birth". Nature Ecology & Evolution. 1 (6): 0146–146. doi:10.1038/s41559-017-0146. hdl:10150/627822. PMC 5476217 . PMID 28642936.
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