Cover

pdf iconDownload PDF
 

Title Page, Copyright

pdf iconDownload PDF
 

Contents

pdf iconDownload PDF

pp. v-viii

read more

Preface

pdf iconDownload PDF

pp. ix-x

This book is intended to be a survey of the nature of species, their origin, and their evolutionary importance. The reader is assumed not to have any previous knowledge of the subject; consequently, some parts (notably the genetics of speciation) are presented in a simplified form, ...

read more

I. Introduction

pdf iconDownload PDF

pp. 11-14

The science of biological classification is called taxonomy, and it is the task of the animal taxonomist to describe all the known forms of animals, to sort out their relationships so that they can be classified in as natural a way as possible, and to provide a system of nomenclature, so that each form can be referred to rapidly and accurately. ...

read more

II. Methods of Classification

pdf iconDownload PDF

pp. 15-26

There are many different ways of classifying a set of things. We might arrange them according to whether or not they possess some particular character, and then subdivide the groups so formed by the presence or absence of another character, repeating this procedure until all the things in each of our smallest groups were for our purposes identical. ...

read more

III. Rank

pdf iconDownload PDF

pp. 27-41

If for the moment we confine ourselves to living forms, then it is true to say that classification by the natural system gives us a number of groups, which themselves can be collected into larger groups, and so on upwards until we come to the group of all animals, and downwards until we come to individual animals. ...

read more

IV. Names

pdf iconDownload PDF

pp. 42-47

The first concern of the taxonomist is to distinguish and describe natural groups of animals. When he has done so, he must name his groups. Classifying and naming are two quite separate and distinct activities, which must not be confused. ...

read more

V. The Polytypic Species

pdf iconDownload PDF

pp. 48-72

In the series of obligate taxonomic categories given in the preceding chapter the species is the lowest. If we consider the animals that ordinary European people knew best in Linnaeus's day, they were (as now for many) the larger mammals, some birds, some butterflies, and possibly a few others. ...

read more

V.I The Biological Species

pdf iconDownload PDF

pp. 73-97

The polytypic species, then, has one great disadvantage. The place of geographically completely isolated forms within the hierarchy superspecies-semispecies-species-subspecies cannot be conclusively demonstrated. Two terms introduced by Mayr are useful in discussing their status. ...

read more

VII. Other Sorts of Species

pdf iconDownload PDF

pp. 98-129

The introduction of the biological definition of the species is a considerable advance, not only because it takes full account of geographical variation and of crossability as well as of morphological resemblances, but because it cannot be applied to certain animals. ...

read more

VIII. Geographical Speciation

pdf iconDownload PDF

pp. 130-168

One has only to imagine the consequences of unrestrained hybridization between all living animals to appreciate the extreme importance of the process of speciation. If all specific barriers were suddenly and miraculously removed, the result would be an appalling welter of hybrids with every possible combination of characters. ...

read more

IX. Sympatric Speciation

pdf iconDownload PDF

pp. 169-181

While no one now denies the great importance of geographical speciation, many have felt that there is little evidence for it in certain groups. Darwin wavered considerably in his opinions and many passages in the 'Origin' are ambiguous or can be taken to mean speciation within a single population. ...

read more

Conclusion

pdf iconDownload PDF

pp. 182-183

How nearly right Darwin was can readily be appreciated by considering that of the four meanings of 'species' distinguished at the present day, namely, morphospecies, agamospecies, palaeospecies and biospecies, his words are completely applicable in theory to two and in practice to a third. ...

Suggestions for Further Reading

pdf iconDownload PDF

pp. 184-186

read more

Afterword (1993)

pdf iconDownload PDF

pp. 187-202

When this book appeared in 1954, there were four main areas of relevant debate among zoologists: What is a species? How are the limits of particular species to be defined? Are specific characters selected or neutral? And is speciation geographical (allopatric) or within a population (sympatric)? ...

Index

pdf iconDownload PDF

pp. 203-206

Further Reading

pdf iconDownload PDF