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Contents:

1 - Introduction: What are signals?; 2 - The theory of costly signalling; 3 - Strategic signals and minimal-cost signals; 4 - Indices of quality; 5 - The evolution of signal form; 6 - Signals during contests; 7 - Signals in primates and other social animals.

Review:

We are used to explaining ecological ideas through the use of physical attributes and conditions. This is excellent in field situations and the vast majority of ecological texts use it as the basis for their work. Plants are the best option here because of ease of observation and obvious changes between locations. This has left animal study as a minority field and yet there is much that can be gained, possibly in situations where plant study is limited. When I first received this text I was wondering how to best present the review for educators given this usual lack of animal study. This coincided with reports of problems with field work (cost, safety etc.) and the inevitable calls for its reduction. The solution would be to turn to other areas of ecology to cover the work. All animals communicate. Communication is used to define a range of parameters including territory (spatial distribution) and breeding (population ecology). Since much of this (as the authors make abundantly clear) is open to debate, it follows that animals signals have much to offer ecological education. Perhaps what we need is to take a different perspective on an issue and see what happens.

Animal signals and their interpretation has been a core part of animal ecology and biology for decades. This text is an attempt to bring together major ideas: not least to address the confusion seen as ecologists use the same terms in different contexts. Chapter one opens with this last idea: what are signals trying to do and how do we describe them. We are introduced to types of signals and their possible meanings. A handy terminology section staightens out the confusion in describing signals (or at least makes it standard for this text!). We are told that signals have a cost. Usually this cost would be the energy in producing the signal but in some cases the cost seems too high. Chapter two tackles the work of, amongst others, the Zavahi's whose still-controversial 'handicap principle' suggests signals are produced at high cost to show fitness (i.e. look at all the energy I can waste in producing this signal etc.). In both these chapters the aim is to look at the evolutionary processes that ensure signals are relaible i.e. there is no advantage to be gained from 'lying'. As with most of the work on signals there is no one single answer and so chapters three and four explore the matter in more depth. Chapter three starts be looking at the handicap principle to see how common it is. Whilst there are a number of obvious cases the authors also argue that 'cheaper' signals can also be effective where both parties agree beforehand on the most likely outcome. In this case, the signal would apprear to be a reinforcement of an agreed situation. Another type of signal is called an index. This is a case where an animal signals in such a way that it cannot be a lie or faked. For example, larger spiders produce a different web vibration than a lighter spider - this cannot be faked and is therefore reliable. However, not all cases are so easy to distinguish as chapter four demonstrates. Not all signals are indices where the greater the signal, the greater the item communicated. This leaves chapter five to consider alternatives to this. Some signals might have evolved to be rituals, others might be a result of bias towards a sensory system of receivers. whilst others may be a case of mimicry (deception ). Chapter six studies signals in conflicts. Although each participant will want their own outrcome, signals may help reduce the lilelihood of an escalating fight. A final chapter looks at communication in primates and humans.

This is not a common ecological topic but the authors have made the complexities of their subject easy enough for the beginner to understand. It is an ideal text for the undergraduate new to the field. Part of the problem is the lack of a basic set of agreed concepts and definitions (signals?!) for workers in the field. This makes it an ideal starting place for ecological discussions where school students can try out different ideas as they try to understand ecology. There's even a caseto be made for this as a way of doing fieldwork. Overall, worth reading for the insights it gives us.