Heredity, Development and Evolution Christine Birkett B.Sc., Certificate in Education, A. Inst. Bioi; formerly Biology department, Weymouth Grammar School, Lecturer, Stoke-on-Trent Cauldon College of Further Education M MACMILLAN To John © C. Birkett 1979 All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this publication may be reproduced, copied or transmitted save with written permission or in accordance with the provisions of the Copyright Act 1956 (as amended), or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 33-4 Alfred Place, London WC1E 7DP. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. First published 1979 Reprinted 1982, 1983, 1984, 1985, 1986, 1989 Published by MACMILLAN EDUCATION LTD Houndmills, Basingstoke, Hampshire RG21 2XS and London Companies and representatives throughout the world ISBN 978-0-333-24192-9 ISBN 978-1-349-03985-2 (eBook) DOI 10.1007/978-1-349-03985-2 Contents Preface v Acknowledgements VI Evolution 2 Mendelian inheritance I8 3 Chromosomes 33 4 Gene structure and mutations 50 5 Gene action 64 6 Genes in populations So 7 Genetic changes in populations go 8 Reproduction 106 9 Development I30 IO Growth and regeneration I 55 I I The progression of life I66 I2 Human evolution I8I I3 Genetic engineering I94 Suggestions for further reading I97 Index I99 FOUNDATIONS OF BIOLOGY General editor L. M. J. Kramer A major advanced biology course for schools and colleges Books in the series are: The diversity of life The cell concept Heredity, development and evolution Metabolism, movement and control Man and the ecosystem Preface Foundations of biology aims to provide a complete pre-university course in biological science. Accordingly, the work is covered in a few handy volumes, not in a single bulky one or numerous monographs. The questions at the ends of the chapters are to test the comprehension of the material covered in the chapters and their contents are not necessarily similar to those set in biological examinations which often require knowledge in several branches of biology if they are to be answered properly. Suggestions are provided for further reading. The course consists of five books written by experienced teachers with special knowledge of biological science, who believe through their experience that fresh approaches to teaching biology are desirable at pre-university level. The books in the series are: The diversity of life The cell concept Heredity, development and evolution Metabolism, movement and control Man and the ecosystem. Biologists will realise the difficulty of sub-dividing the course into a number of books and opinions will undoubtedly differ on how it should best be done. One difficulty is that a number of topics are based upon knowledge of others, so that if each book is to be helpful some overlap must occur with others in the series. In fact, the necessity for overlap has proved to be relatively small and where it occurs the treatment of topics is consistent from one book to another. It is wise to remember that no branch of science is more 'fundamental' than any other, so no suggestion has been made that the books need to be studied in a given order. Teachers will be free to use them in any sequence or combination which suits their own courses. All the authors concerned with the series have felt keenly the inadequacy of purely descriptive biology in giving insight into the basis of science today. It has been necessary therefore for them to introduce some mathematics, physics and organic chemistry to which biology is so closely related. The names of chemical compounds are accompanied by their new names under the IUPAC rules and in The cell concept there is an introduction to the new uses which seem difficult at first but which are in fact logical and easy to follow once the principles have been grasped. L. M. J. KRAMER General Editor Acknowledgements The author would like to thank Dr J. T. Williams of the Food and Agriculture Organization of the UNO for providing material used in chapter 6. The author and publishers wish to thank the following who have kindly given permission for the use of the copyright material:- Artemis Press Limited for an illustration from Understanding the Earth edited by I. G. Grass, P.J. Smith and R. L. C. Wilson. Associated Book Publishers Limited and Professor E. B. Ford for an amalgamation of figures taken from Mendelism and Evolution 7/E, published by Methuen and Company Limited and Ecological Genetics, published by Chapman and Hall Limited; and drawings based on a photograph (Plate 1) from Ecological Genetics. The Associated Examining Board (for the General Certificate ofEducation) for questions from Advanced Level Biology Paper 2 & 3, June 1975, and Paper 3, November I97S· Cambridge University Press for a table from Basic Biology Course, Book 9 by M.A. Tribe, I. Fallan, M. R. Grout, and R. K. Snook, University of Sussex. Wm. Collins Sons & Co. Limited for figures from Pollination of Flowers by Proctor and Yeo, in the New Naturalist Series. W. H. Freeman and Company for illustrations from 'Symbiosis and Evolution' by Lynn Margulis in Scientific American, August 1971 and 'Prenatal Diagnosis of Genetic Disease' by T. Friedmann in Scientific American, November 1971. Heinemann Educational Books Limited for a figure from Plant Growth by M. Black andj. Edelman in Foundations'![ Biology. Longman Group Limited for a table from Nuffield Advanced Biology (1970) Organisms and Populations, A Laboratory Guide. Macmillan Publishing Co. Inc., for figures from Genetics by Monroe W. Strickberger, copyright© 1968, 1976, Monroe W. Strickberger. W. B. Saunders Company and Professor B. I. Balinsky for a figure from Introduction to Embryology© 1965, W. B. Saunders Company, Philadelphia. Professor J .J. Murray,Jnr., for a figure from Genetic Diversity and Natural Selection (based on a paper by Dr Littlejohn in Evolution, 1965, Volume 19). The author and publishers wish to acknowledge the following photograph sources: Heather Angel p. 137. Barnabys Pictures Library p. 63 bottom left. Gene Cox p. 135· Patrick Echlin, Botany School, Cambridge p. 112. John Innes Institute p. 161. Dr Kettlewell, Department of Zoology, Oxford p. 92. Dr G. F. Leedale p. 63 top and bottom right. Dr M. C. F. Proctor pp. 114, 115. C.James Webb pp. 94, 133. Zoological Society of London p. 182. Taken from the publication Looking at Chromosomes, McLeish & Snoad p. 35· Taken from the publication-Webster-Introduction to Fungi-Cambridge University Press p. 49· The publishers have made every effort to trace copyright holders, but if they have inadvertently overlooked any they will be pleased to make the necessary arrangements at the first opportunity. Evolution 1 One of the most striking facts emerging from a study of natural history is the variety of life; another, paradoxically, is its underlying unity. While there are about two million kinds of organisms (living creatures) alive today, each of them can be grouped with others which it resembles. Each of the three-quarters of a million insects, for example, has a body divided into a head, three-part thorax and abdomen. Almost every backboned animal, or vertebrate, has an internal rigid skeleton with four limbs. There are, moreover, different degrees of similarity and difference between living things, which suggests that organisms are variations on a few basic 'themes'. Within each theme are other groups with more characteristics in common, and sub-groups within these yet more similar; thus all beetles resemble one another more closely than do all insects, and all ladybird beetles are more alike still. This hierarchy of variation has stimulated men of all times to classify living forms: we have evidence that the ancient Greeks did so. Indeed, the Greek naturalist and philosopher, Aristotle (384-322 B.c.), aware that variations on a theme are seldom generated independently and separately, put forward the view that there was a gradual change in living forms from plants to animals to man. This was the first recorded hypothesis that organic evolution had occurred, that is that living organisms are descended from earlier, different ones. There is an alternative viewpoint to that expressed by the idea of organic evolution. It is possible that each kind of organism alive today was created separately and has not altered since its creation; that there is no relationship by descent between living forms. This hypothesis is called 'Special Creation'. By the eighteenth and nineteenth centuries, the idea that each species (a group of organisms which does not breed with any other group under natural conditions) had been specially created was much more widely accepted than the view that each had evolved. The Bible, after all, declared that each living thing was 'brought forth after his kind' and the usual interpretation of the statement was a literal one: that a 'kind' or species was unchangeable. In 1 794, a British physician and naturalist, Erasmus Darwin, published a great work called ,(oonomia, in which he proposed that all animals had arisen from one simple living creature by becoming better adapted to their environ ment each generation. At about the same time, a French professor of zoology, Jean-Baptiste Lamarck, suggested a mechanism by which such changes might come about. Lamarck believed that animals and plants respond to their environments by becoming better adapted to them. Bears in cold places grow thicker fur, for example, and plants in shady places develop longer stems and so EVOLUTION reach the light. Once such a small 'improvement' is acquired, Lamarck maintained that it would be inherited by its possessor's offspring. In the offspring, the changing character would become even more pronounced under the en vironmental influence, until much later descendants were quite different from the original form. This theory, known as 'Lamarckism' or 'the inheritance of acquired characteristics' was a first bold attempt to suggest a mechanism by which organic evolution could occur, adapting living creatures more and more perfectly to their surroundings. Lamarckism is not borne out by experiment, however. There is no evidence that changes brought about during the course of an organism's life are inherited by its offspring: indeed all evidence is to the contrary. A blacksmith's son will not have particularly powerful arms unless he subjects them to the same muscular effort as did his father. Despite failing to describe a plausible mechanism for evolution, Lamarck was successful in drawing attention to the fact of evolution at a time when the majority believed species to be unchanged and unchanging. CHARLES DARWIN The man destined to make the greatest, lasting impact on evolutionary theory, Charles Darwin, grandson of Erasmus, was born in I8og. After abandoning a medical career at Edinburgh, Darwin spent three years at Cambridge studying theology. He worked sufficiently hard to obtain a pass degree, but his main interests lay in geology and botany. The professors of these two subjects, Adam Sedgwick andj. S. Henslow, must have recognised Darwin's potential, for they encouraged him in the ways of science. After graduating, his heart not in the Church, Darwin heard from Henslow that Captain Fitzroy was looking for a naturalist to accompany a world survey using his ship, H.M.S. Beagle. Darwin was appointed to the post and set sail on 27 December I831. The voyage of the 'Beagle' The Beagle was at sea for five years, during which time Darwin avidly collected and studied plant, animal and rock specimens. His reading material included volume I ofLyell's Principles ofG eology. Lyell understood that the rocks found on the earth arose by slow changes in the earth's surface, and that the forces producing such changes still operated. Lyell's principle that 'the present is the key to the past' appealed to Darwin. Aided by Lyell's book, Darwin concluded that certain coastal fossil-bearing rocks, towering high above the water, had once formed part of the sea-bed. In the rich South American fossil-beds, Darwin discovered.many species of extinct animals and he noted a similarity between the fossilised and living armadillos, tapirs and anteaters. This observation of resemblance in fundamen tal design but not in detail between fossil and living creatures was crucial to Darwin's later theories. 2 HEREDITY, DEVELOPMENT AND EVOLUTION The Galapagos Islands In 1835, the Beagle spent five weeks in the Gal<ipagos Islands, an archipelago in the Pacific Ocean. Darwin was impressed by the differences between the living creatures and those on the nearest mainland of Ecuador, 950 kilometres (6oo miles) to the east. Marine lizards, peculiar to the Galapagos were common, and each major island had a race of giant tortoise distinct from that of every other island. The birds of the archipelago were remarkable. Of twenty-six kinds which Darwin captured, twenty-five were endemic (peculiar) to the islands. They included thirteen species of finch, fundamentally alike in body-form and plumage, but differing in numerous respects, notably in beak size and shape. Darwin wrote' ... one might really fancy that from an original paucity ofbirds in this archipelago, one species had been taken and modified for different ends.' He was suggesting that these birds had all evolved from modifications of one ancestor yet, at the time of writing, he had not completely shed the belief of the times that species were immutable or unchangeable (Figure 1). insects in wood insects insects nectar from cacti seeds leaves Figure 1 Some of the thirteen types of Galapagos finch showing adaptations to different diets In October 1836, the Beagle returned to Falmouth and Darwin turned his attention to sorting his notebooks and his vast collection. Evolution by natural selection After nine months occupied with writing journals and articles about his voyage, Darwin began an essay called 'The Transmutation of Species'. Within fifteen months he had formulated a theory of how new species were formed by modification (or 'transmutation') of older types and not by Special Creation. Darwin was aware that sexual reproduction (involving two parents) gives rise to much more variable offspring than does asexual reproduction (involving only one parent). Moreover, much of this variation is inheritable. By itself, Darwin EVOLUTION 3