Survival of the fittest theses

The principle of competitive exclusion states that two species will never occupy exactly the same niche. This is because differences between them will result in one species being marginally better at exploiting the niche, ultimately driving the other species to extinction. In spite of this there are many introductory texts to animal behaviour containing much the same material and contesting the same limited niche. Academia, like nature, endlessly throws up new minor variations. These coexist briefly but in the long run the majority fall by the wayside while a fit few propagate and evolve.

Here are two hopefuls. Both have similar core material but, mindful of competitive exclusion, Roland Siiter with his Introduction to Animal Behavior specifically targets psychology students. As such, he presumes less biological knowledge than does P. J. B. Slater in Essentials of Animal Behaviour , giving, for example, a general primer to evolution and genes, while Slater jumps into behaviour genetics and the comparative method.

The clearest difference is that Siiter concentrates on phenomena and Slater on principles. A glance through the contents reveals Siiter's list of behavioural domains (foraging, mating, parenting and so on), while Slater's is organised with respect to the origins of behaviour (motivation, development, function and so on). This differing perspective is reflected throughout: for example, both authors devote space to animal communication but Siiter is concerned with the sensory channels in which communication is received and its behavioural consequences, while Slater goes beyond this to discuss communication in the context of "selfish gene" manipulation and the question of meaning in animal signals.

An indicator of Siiter's targeting of psychology students is the inclusion of extensive chapters on primate behaviour and evolutionary psychology. These are rather gratuitous: the material is better treated elsewhere by primatologists themselves. But insofar as psychology lecture series often have these subjects bolted onto them at the end, Siiter's apparently overcast net might make for a useful text.

Ultimately, the quality of a student's work probably depends more on the student than on any of the various credible introductory textbooks. Still, a great deal of effort is expended by teachers in the life sciences to get students to see the wood for the trees and extract the principle from the phenomenon. If two students of equal ability, working from these two books, were to present me with an essay, the student of Slater would probably get a better mark. Quite apart from the level of the material, Slater's book surpasses Siiter's in one regard germane to the student essay - it gets the job done in fewer pages.

Thomas Sambrook is a teaching fellow in psychology, University of Stirling.