Fundamentals of Genetics Chapter 1 Pre-Mendelian Concepts of Heredity Dr
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Theodosius Dobzhansky: a Man for All Seasons
GENERAL ARTICLE Theodosius Dobzhansky: A Man For All Seasons Francisco J Ayala In 1972, Theodosius Dobzhansky addressed the convention of Francisco J Ayala the National Association of Biology Teachers on the theme obtained his Ph D with Theodosius Dobzhansky "Nothing in biology makes sense except in the light of evolu in the 1960s and is tion". The title of that address (published in The American presently the Donald Bren Biology Teacher, Vol. 35, pp. 125-129) might serve as an epigram Professor of Biological of Dobzhansky's worldview and life, although it is limited in Sciences at the University of California, Irvine and a scope, for Dobzhansky believed and propounded that the impli member of President cations of biological evolution reach much beyond biology into Clinton's Committee of philosophy, sociology, and even socio-political issues. The Advisors on Science and place of biological evolution in human thought was, according Technology. He is a member of the U S to Dobzhansky, best expressed in a passage that he often quoted National Academy of from Pierre Teilhard de Chardin: "(Evolution) is a general Sciences and has been postulate to which all theories, all hypotheses, all systems must President and Chairman hence forward bow and which they must satisfy in order to be of the Board of the American Association for thinkable and true. Evolution is a light which illuminates all the Advancement of facts, a trajectory which all lines of thought must follow - this is Science. He has worked what evolution is". extensively on the population ecology and The Modern Synthesis of Evolutionary Theory evolutionary genetics of Drosophila species. -
Darwin's Big Problem and Mendelian Genetics
Introduction to Biological Anthropology: Notes 7 Darwin’s big problem and Mendelian genetics Copyright Bruce Owen 2011 − Darwin’s big problem − We have seen that natural selection works by favoring the most successful variants among the individuals in a population − it only works if individuals vary in ways that affect their survival and reproduction − offspring must be similar to their parents, but not exactly the same − if offspring were identical to their parents, they would be identical to each other, and there would be no “more successful” and “less successful” individuals for natural selection to pick from − so there could be no change in the next generation: no evolution − Darwin had no good explanation for why offspring resemble parents, but also vary − he knew that this was a big gap in his theory − The prevalent idea of inheritance in Darwin’s time was blending inheritance − blending inheritance holds that the characteristics of offspring are mixtures of the characteristics of their parents − the idea was that the material from the two parents that controlled inherited characteristics blended like two colors of paint − this is a reasonable approximation, based on everyday experience − so, every mating should produce offspring that are intermediate between the parents − for example, if a six-foot man mates with a five-foot woman… − then the offspring should all be between five and six feet tall − no offspring are expected to be more extreme than either parent − there are two huge problems with the blending model of inheritance − First, it obviously isn't true − lots of parents have children who are taller, or shorter, than both of the parents − many kids have traits like hair color, eye color, etc. -
Monism and Morphology at the Turn of the Twentieth Century
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by IUScholarWorks From a draft. May differ from the published version, which appeared in Monism: Science, Philosophy, Religion, and the History of a Worldview, ed. Todd Weir, 135–158, New York: Palgrave USA, 2012. Monism and Morphology at the Turn of the Twentieth Century SANDER GLIBOFF Indiana University Abstract. Ernst Haeckel’s monistic worldview and his interpretation of Darwin’s theory of evolution worked together to help him rule out any role for divine providence or any non-material mind, spirit, will, or purpose in the organic world. In his account of 1866, the impersonal, unpredictable, and purposeless external environment was what drove evolutionary change. By around the turn of the twentieth century, however, new theories of evolution, heredity, and embryology were challenging Haeckel’s, but Haeckel no longer responded with his earlier vigor. Younger monistically oriented evolutionary biologists had to take the lead in modernizing and defending the monistic interpretation and the external causes of evolution. Three of these younger biologists are discussed here: Haeckel’s student, the morphologist-turned-theoretician Richard Semon (1859–1918); Ludwig Plate (1862–1937), who took over Haeckel’s chair at the University of Jena and became an influential journal editor and commentator on new research on heredity and evolution; and Paul Kammerer (1880–1926), whose experimental evidence for the modifying power of the environment was hotly debated. Despite their very different social, political, and religious backgrounds, their contrasting research methods and career trajectories, and their disagreements on the precise mechanisms of evolution, these three were united by their adherence to Haeckelian monistic principles. -
On Darwin's and Mendel's Concepts and Methods in Heredity
J Gen Philos Sci (2010) 41:31–58 DOI 10.1007/s10838-010-9122-0 ARTICLE Gemmules and Elements: On Darwin’s and Mendel’s Concepts and Methods in Heredity Ute Deichmann Published online: 10 June 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Inheritance and variation were a major focus of Charles Darwin’s studies. Small inherited variations were at the core of his theory of organic evolution by means of natural selection. He put forward a developmental theory of heredity (pangenesis) based on the assumption of the existence of material hereditary particles. However, unlike his proposition of natural selection as a new mechanism for evolutionary change, Darwin’s highly speculative and contradictory hypotheses on heredity were unfruitful for further research. They attempted to explain many complex biological phenomena at the same time, disregarded the then modern developments in cell theory, and were, moreover, faithful to the widespread conceptions of blending and so-called Lamarckian inheritance. In contrast, Mendel’s approaches, despite the fact that features of his ideas were later not found to be tenable, proved successful as the basis for the development of modern genetics. Mendel took the study of the transmission of traits and its causes (genetics) out of natural history; by reducing complexity to simple particulate models, he transformed it into a scientific field of research. His scientific approach and concept of discrete elements (which later gave rise to the notion of discrete genes) also contributed crucially to the explanation of the existence of stable variations as the basis for natural selection. Keywords Variations Á Discreteness Á Gradualism Á Statistical laws Á Chance Á Blending inheritance Á Soft inheritance Á Pangenesis Á Mendel Á Darwin 1 Introduction The emergence of the science of genetics began as a result of the fruitful application of both the research methods and the concept of discrete ‘‘elements’’ (which later gave rise to the concept of discrete genes) developed by Mendel around 150 years ago. -
The Nature of Inheritance
I THE NATURE OF INHERITANCE The consequences of the blending theory, as drawn by Darwin. Difficulties felt by Darwin. Particulate inheritance. Conservation of the variance. Theories of evolution worked by mutations. Is all inheritance particulate ? Nature and frequency of observed mutations. But at present, after drawing up a rough copy on this subject, my conclusion is that external conditions do extremely little, except in causing mere variability. This mere variability (causing the child not closely to resemble its parent) I look at as very different from the formation of a marked variety or new species. DARWIN, 1856. (Life and Letters, ii, 87.) As Samuel Butler so truly said: 'To me it seems that the "Origin of " Variation ", whatever it is, is the only true Origin of Species 'V w. BATESON, 1909. The consequences of the blending theory THAT Charles Darwin accepted the fusion or blending theory of inheritance, just as all men accept many of the undisputed beliefs of their time, is universally admitted. That his acceptance of this theory had an important influence on his views respecting variation, and consequently on the views developed by himself and others on the possible causes of organic evolution, was not, I think, apparent to himself, nor is it sufficiently appreciated in our own times. In the course of the present chapter I hope to make clear the logical con- sequences of the blending theory, and to show their influence, not only on the development of Darwin's views, but on the change of attitude towards these, and other suppositions, necessitated by the acceptance of the opposite theory of particulate inheritance. -
Goings on in Mendel's Garden
40 Evolutionary Anthropology CROTCHETS & QUIDDITIES Goings on in Mendel’s Garden KENNETH WEISS The honorable monk probably didn’t cheat. But he led us astray in other ways. Gregor Mendel gave us the tools by discussed. But this may have inadver- which to do modern genetics, and we tently led us astray, in ways for which have a century of progress to show for we are paying a price today. The arti- it. We properly credit Mendel and his ficial nature of his experiments lured peas for showing us the particulate us into confusing the inheritance of nature of inheritance, but his work traits with the inheritance of genes. both enabled and disabled evolution- And this in turn has led to an unwar- ary thinking for several decades after ranted phenogenetic (see Note 1) de- its rediscovery. Since the factors he terminism that impairs our under- studied didn’t change over genera- standing of biology. tions, Mendel’s discoveries solved the problem that perplexed Darwin, that BLENDING IN blending inheritance would swamp variation and prevent evolution from Mendel wasn’t trying to explain evo- happening. Yet, for the same reason, lution. He knew of traits that varied Mendel’s work impeded evolutionary continuously in his experimental pea thought because evolution requires species, Pisum sativum, and appeared Figure 1. Mendel. change, and discrete variation was to blend in darwinian fashion from also incompatible with darwinian one generation to the next. But he gradualism. Eventually things were wanted to breed agriculturally valu- worked out, we got our unified theory able strains, so he avoided such traits used pea strains that differed only by (the neodarwinian Synthesis), and it and instead selected strains of pea the single traits he reported for each rested on Mendel’s discoveries. -
'Great Is Darwin and Bergson His Poet': Julian Huxley's Other
This is a repository copy of ‘Great is Darwin and Bergson his poet’: Julian Huxley's other evolutionary synthesis. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/124449/ Version: Accepted Version Article: Herring, E (2018) ‘Great is Darwin and Bergson his poet’: Julian Huxley's other evolutionary synthesis. Annals of Science, 75 (1). pp. 40-54. ISSN 0003-3790 https://doi.org/10.1080/00033790.2017.1407442 (c) 2018 Informa UK Limited, trading as Taylor & Francis Group. This is an Accepted Manuscript of an article published by Taylor & Francis in Annals of Science on 04 Jan 2018, available online: http://www.tandfonline.com/10.1080/00033790.2017.1407442 Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ “Great is Darwin and Bergson his poet”: Julian Huxley’s Other Evolutionary Synthesis. Emily Herring School of Philosophy, Religion and History of Science, University of Leeds, Leeds, United Kingdom Email: [email protected] Address: School of Philosophy, Religion and History of Science, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom Orcid id: orcid.org/0000-0002-8377-6319 1 “Great is Darwin and Bergson his poet”: Julian Huxley’s Other Evolutionary Synthesis. -
Lecture 1 Revised2009
BIOL2007 MENDELIAN GENETICS AND EVOLUTION Part 1 = review historical background/milestones of evolutionary biology. Part 2 = examine a simple model as an illustrative example. Evolutionary biology aims to understand the factors that shape the diversity of life. Evolutionary processes occurring rapidly within populations are called microevolution. Processes occurring on a longer timescale to generate diversity in the fossil record and in the relationships of living species are called macroevolution. Note three striking aspects of evolution: 1) Focus of selection is not survival but reproductive success (see e.g. of sexual cannibalism). 2) Strong selection may produce rapid evolution in large populations (e.g. guppies) 3) Organisms are mosaics of parts with different ages. - for points 1) to 3), see further details/text/pictures on supporting handout - Darwin’s theory of natural selection Observations 1) Variation, in the form of individual differences, exists in every species, 2) All organisms produce more offspring than survive to reproductive age. Conclusions 1) A competition for survival causes the elimination of many individuals, 2) The characteristics of the surviving individuals are passed onto future generations. Darwin’s ‘The Origin of Species’ was a triumph, but it was not without problems. In general, biologists accepted the concept of evolution: species were not fixed in form and were not separately created. However, Darwin lacked a satisfactory explanation of the scientific basis of the concepts of variation and inheritance. In Darwin’s theory, the evolution of characters takes place gradually and each successive stage has to be advantageous for it to be favoured by natural selection. Many biologists argued that this was difficult to imagine for the evolution of an organ such as the wing of a bird. -
Evolution, Development, and the Units of Selection (Epigenesis/Modern Synthesis/Preformation/Somatic Embryogenesis/Weismann's Doctrine) LEO W
Proc. Nat. Acad. Sci. USA Vol. 80, pp. 1387-1391, March 1983 Evolution Evolution, development, and the units of selection (epigenesis/Modern Synthesis/preformation/somatic embryogenesis/Weismann's doctrine) LEO W. Buss Department of Biology and Peabody Museum of Natural History, Yale University, New Haven, Connecticut 06511 Communicated by G, Evelyn Hutchinson, December 17, 1982 ABSTRACT The "Modern Synthesis" forms the foundation of those working with the comparative embryology of vertebrates, current evolutionary theory. It is based on variation among indi- saw strong evidence for Weismann's scheme in the sequestering viduals within populations. Variations within individuals are be- of germ cells during early embryology. Finally, several inves- lieved to hold no phylogenetic significance because such variation tigators studying wound-healing had clearly illustrated that many cannot be transmitted to the germ line (i.e., Weismann's doctrine). somatic cells were, in fact, incapable of regeneration. Weismann's doctrine, however, does not apply to protists, fungi, Support for Weismann's doctrine was by no means universal. or plants and is an entirely unsupported assumption for 19 phyla Botanists were Weismann's earliest critics (5). Debate over the of animals. This fact requires that the Modern Synthesis be reex- issue was central in the development of the continuing rift be- amined and modified. tween botanists and zoologists despite the commonality of their interests (G. E. Hutchinson, personal communication). Al- The Darwinian notion of evolution as a process directed by se- though Weismann's doctrine was the subject of two very critical lection acting upon heritable variation has not been challenged reviews in the 20th century (6, 7), these criticisms fell on deaf seriously since Darwin first articulated it. -
5B. Meiosis, Part 1
Meiosis A REDUCTION DIVISION TO PRODUCE GAMETES WHICH ULTIMATELY MAINTAINS A CONSISTENT CHROMOSOME NUMBER IN THE SPECIES P A R T 1 T H I S WORK IS LICENSED UNDER A C R E A T I V E COMMONS ATTRIBUTION - NONCOMMERCIAL - SHAREALIKE 4.0 INTERNATIONAL LICENSE . Types of Cell Division There are two types of normal cell division – mitosis and meiosis. Both types of cell division take place in eukaryotic organisms. Mitosis is cell division which begins in the zygote (fertilized oocyte) stage and continues in somatic cells during the life of the organism. Meiosis is cell division in the ovaries of the female and testes of the male and involves the maturation of primordial oocytes (eggs) and the formation of sperm cells, respectively. Comparing Meiosis and Mitosis https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/the-reproductive- system-27/meiosis-254/meiosis-and-mitosis-1238-11633/images/fig-ch11-01-06/ http://creativecommons.org/licenses/by-sa/4.0/ No changes were made. Wilhem August Oscar Hertwig (1849-1922) • The first to teach that the chromosome was the physical basis of heredity. • One of his greatest achievements was the discovery of the process of fertilization in sea urchins in which he observed and described cell division in 1876. http://upload.wikimedia.org/wikipedia/commons/6/6b/Oskar_Hertwig.jpg Public Domain Edouard-Joseph- Louis-Marie van Beneden (1846 – 1910) • Described a 2-phase cell division in 1883 in Ascaris megalocephala worm eggs • Showed fertilization was the union of 2 half nuclei – one from the male and one from the female – producing a cell containing the full number of chromosomes for the species http://upload.wikimedia.org/wikipedia/commons/7/79/Edouard_van_Beneden_in_front_of_the_Aquarium_et_mus%C3%A9e_d e_zoologie.jpg © Raimond Spekking / CC BY-SA 3.0 (via Wikimedia Commons) http://creativecommons.org/licenses/by- sa/3.0/deed.en No changes were made. -
Perspectives
Copyright Ó 2009 by the Genetics Society of America DOI: 10.1534/genetics.109.109991 Perspectives Anecdotal, Historical and Critical Commentaries on Genetics Darwin and Genetics Brian Charlesworth1 and Deborah Charlesworth Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh EH9 3JT, United Kingdom ABSTRACT Darwin’s theory of natural selection lacked an adequate account of inheritance, making it logically incomplete. We review the interaction between evolution and genetics, showing how, unlike Mendel, Darwin’s lack of a model of the mechanism of inheritance left him unable to interpret his own data that showed Mendelian ratios, even though he shared with Mendel a more mathematical and probabilistic outlook than most biologists of his time. Darwin’s own ‘‘pangenesis’’ model provided a mechanism for generating ample variability on which selection could act. It involved, however, the inheritance of characters acquired during an organism’s life, which Darwin himself knew could not explain some evolutionary situations. Once the particulate basis of genetics was understood, it was seen to allow variation to be passed intact to new generations, and evolution could then be understood as a process of changes in the frequencies of stable variants. Evolutionary genetics subsequently developed as a central part of biology. Darwinian principles now play a greater role in biology than ever before, which we illustrate with some examples of studies of natural selection that use DNA sequence data and with some recent advances in answering questions first asked by Darwin. The power of Selection, whether exercised by man or brought into play under nature through the struggle for existence and the The key is man’s power of cumulative selection: nature consequent survival of the fittest, absolutely depends on the gives successive variations; man adds them up in certain variability of organic beings. -
The So-Called 'Eclipse of Darwinism'
Descended from Darwin Insights into the History of Evolutionary Studies, 1900–1970 Joe Cain and Michael Ruse, Editors American Philosophical Society Philadelphia • 2009 TRANSACTIONS of the AMERICAN PHILOSOPHICAL SOCIETY Held at Philadelphia For Promoting Useful Knowledge Volume 99, Part 1 Copyright © 2009 by the American Philosophical Society for its Transactions series, Volume 99. All rights reserved. ISBN: 978-1-60618-991-7 US ISSN: 0065-9746 Library of Congress Cataloging-in-Publication Data is available from the Library of Congress. Cain and Ruse. 2009. Descended from Darwin (Philadelphia: American Philosophical Society) Chapter 1 The So-Called Eclipse of Darwinism Mark A. Largent Introduction In discussing the emergence and development of evolutionary biology, historians of biology typically divide the nineteenth and twentieth centuries into four eras. The first, the pre-Darwinian period, came prior to publication of the Origin of Species in 1859, and it includes evolutionary theorizing by figures like Lamarck and Chambers. The second period focused on the reception and reaction to Darwin’s work by the public, religious authorities, and natural scientists. This period lasted from 1859 to about 1880 and is best characterized by works that systematically examine the recep- tion of Darwin’s ideas across different countries (Glick, 1974). Beginning about 1880 and lasting through most of the 1930s is a period widely described as the “eclipse of Darwinism” or the “eclipse of Darwin.”1 Biologists and historians of biology alike have described this period as one during which many theories competed for status. During these years, Darwinian evolutionary theory was supposedly obscured, and ultimately discarded, as speculative and old-fashioned natural history.