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Tuatara: Volume 22, Issue 2, June 1976


page 115


Ecological Genetics

Many people have collected moths and butterflies and pinned them in neat rows but it remained for E. B. Ford to carry the process a major step further. Beginning with an interest in Lepidoptera, he saw the evolutionary implications of studying their patterns of variability, unravelling their genetics and then relating these laboratory pursuits to extensive field surveys and analyses. In this way ‘ecological genetics’, which was conceived in 1928, came into being with the publication of Ford's first edition in 1964.

The fourth edition is considerably extended by the addition of up-to-date material, especially in the fields of mimicry and melanism, but it adds no new chapter headings. It does not aim to be a comprehensive review, rather ‘to develop the principles of the subject with enough instances to illustrate them but no more’.

The book is not entirely woven around the Lepidoptera although they are certainly the main material from which Ford draws his examples. Two species in particular that he and his colleagues have brought from near obscurity into the vocabulary of modern geneticists, ecologists and evolutionists are Maniola jurtina, the meadow brown butterfly and Panaxia dominula, the scarlet tiger moth. The first forms the basis for a detailed consideration of the effects of natural selection on the numbers of spots on its hindwings, the result of a long series of studies done in parts of Great Britain and the Scilly Isles. These studies are used to illustrate how small isolated populations can respond to different selective forces and that these forces are often extremely powerful in nature. This theme is developed into an argument for the sympatric evolution of distinctive races. New evidence from acrylamide gel electrophoresis is introduced in this edition.

Genetic polymorphism and the formation of super-genes leads to a discussion of the genetics of Panaxia at a marsh at Cothill, Berkshire —- ‘no natural population of animals has been so fully quantified as that of the scarlet tiger moth’. Snails, primroses and recent work on cyanogenic polymorphism in clovers broaden the examples to other organisms.

Mimicry and melanism occupy a major section of the book which ends with a chapter on isolation and adaptation. Some recent work by the Hon. Miriam Rothschild and others on the chemistry of toxic substances in aposematic insects is briefly referred to in this edition as is the important work of J. van Z and L. P. Brower on vertebrate predation, but the evolution of mimicry is largely from the geneticists' page 116 point of view. The chapter on melanism draws on the recent review by H. B. Kettlewell, ‘The evolution of melanism’ (1973), and includes E. R. Creed's work on the two-spot ladybird, quoted as an instance of industrial melanism in a warningly coloured insect, a view that has been challenged since the publication of Ford's book.

‘Ecological Genetics’ was written for research workers and honours students. It is a difficult subject, supported by complex examples, and is undeniably heavy going. On balance the genetics is dominant, the ecology recessive, so that it is even more difficult for the student of ecology than for the student of genetics. However, there is no denying the fascination of the topic which has sent the book to four editions and which opens up great possibilities for study in New Zealand. The fourth edition is a valuable, up-to-date reference work for serious students of populations and evolution but too expensive in New Zealand to achieve wide bookshelf popularity.


Biomechanics is the application of engineering principles to the study of animals and plants. This little book adds to the sort of material available in standard biology texts by drawing attention to a number of situations where an understanding of mechanics sheds some light on a biological process.

The fields covered in this interdisciplinary outline include biological materials and how they are exploited in life, animal locomotion, human mechanics, plant mechanics and cell mechanics. One notable omission is the area of acustical biology. The text is clear and devotes space to the often ingenious methods that research workers have used to take their measurements. Thus there is a discussion on how oxygen consumption in a flying budgerigar has been measured, and another on the problem of finding the sap pressure in twigs of a redwood tree 82 m above the ground.

The author aims to show where the subject stands at present and to point to some unsolved problems. It introduces many of the current workers in the field and provides a useful list of references with each chapter.

The student of biology interested in how things work will find a summary of mechanical explanations in this book and a guide to further reading.