Evolutionary genetics and environmental stress

TREE vol. 6, no. 9, September

1991

mation here is accurate and up to date, and cannot be found elsewhere. An extensive section of background information discusses the avifauna and the unique features that set it apart from other regions of the world. This is integrated with information on the natural habitats of the island and their importance for different bird communities and species, the particular threats currently faced by the latter and the significant role that Madagascar’s protected-areas system plays in their preservation. This detailed emphasis on conservation reflects recent work in this field3,6,7, and is found in few other field guides, This guide accurately reflects the current state of knowledge of

Madagascar’s birds and will draw much-needed attention to them. Its detailed and user-friendly approach will be of real benefit to birdwatchers and scientists of all levels of experience in the region. I hope that a less expensive, paperback version in French or Malagasy will also appear.

Michael 1.Evans

3 Collar, N.J. and Stuart, S.N. (1985) Threatened Birds of Africa and Related islands: The ICBP/IUCN Red Data Book

(Part 1,3rd edn), International Council for Bird Preservation and International Union for Conservation of Nature and Natural Resources 4 Dee, T.J. (1986) The Endemic Birds of Madagascar, International Council for Bird Preservation 5 Collar, N.J. and Stuart, S.N. (1988) Key Forests

Montrose,Llanddeiniol,Llanrhystud, DyfedSY235AN, UK References 1 Green, G.M. and Sussman, R.W. (1990) Science

248,2

12-2

15

for

Threatened

Birds

in Africa,

International Council for Bird Preservation 6 Jenkins, M.D., ed. (1987) Madagascar: An Environmental Profile, International Union for Conservation of Nature and Natural Resources 7 Nicoll, M.E. and Langrand, 0. (1989)

2 Milon, P., Petter, J-J. and Randrianasolo, G. (1973) Faune de Madagascar: 35. Oiseaux, ORSTOM and CNRS

for Nature

environmental stimuli and there will be no consequences due to natural selection. Both acclimation and acclimatization are homeostatic phenomena, but each must have genetically set limits to the rate, range and stability of the physiological response. ‘Phenotypic plasticity’ is an environmental response in the phenotype that does not necessarily involve the action of differentgenotypes. Yet, the capacity of an individual genotype to produce a range of phenotypes, for example in development, must vary, and therefore so will the evolutionary consequences of phenotypic plasticity. The ability of an organism to conserve the phenotype in the face of environmental change, or to conserve the genotype by only a phenotypic response to the environment, are important adaptive homeostatic mechanisms. Each depends on a functional connection between gene action, physiological processes and evolutionary change. When environmental change issufficiently large, homeostatic mechanisms are no longer an effective response. The consequences can range from a change in the capacity of an individual to respond to additional environmental insult to a decrease in ‘productivity’, a decrease in darwinian fitness or even death. Except for the last one, each of these potential consequences of environmental change has been offered by various authors as a definition of stress. In Evolutionary Genetics and Environmental Stress, Hoffmann and Parsons define stress as ‘an environmental factor that causes a change in a biological system which is potentially injurious’. Whatever definition

we use, there are great volumes of evidence to demonstrate the effects on physiological performance of physical environmental factors such as temperature, humidity, pollutants and so forth. This book summarizes available information on the genetic consequences of environmental stress-the genetic changes in populations that occur at the extreme end of the stress gradient at the limits of resistance, when homeostatic mechanisms no longer function adequately. The main objective of the book is ‘to examine those genetic aspects of responses to environmental stress that may be generally applicable to a range of organisms’. The authors do a very admirable job in achieving this goal throughout a series of chapters that define stress, describe genetic variation in the stress response, measure the effects of stress on genetic variation and review resistance to stress. The authors emphasize the genetic basis of population and individual levels of physiological variation and cover topics from stress-induced proteins to metaboliccontrol theory, and a lot of traditional Drosophila literature in between. There are some weaknesses in the book. Too many sections review a concept, but are then unable to connect the concept closely to the main theme of the book, as with fluctuating asymmetry, or the cost of phenotypic plasticity. There are perhaps more weaknesses in the science than in the writing; there are many topics where the functional mechanism that connects the actions of specific genes to particular phenotypic traits is simply unknown. This is not atypical of traditional quantitative genetics; the

Madagascar: et des Aires

Revue de la Conservation Protbgbes, World Wide

Fund

- Insult, Injuryand Evolution Evolutionary Genetics and Environmental Stress by Ary A. Hoffmann and Peter A. Parsons, Oxford University Press, 1991. E35.00 hbk (ix + 284 pages) ISBN 0 19 857732 X Characterizing the responseof organisms to external environmental stimuli has traditionally been the purview of ecological and comparative physiologists. Evolutionary biologists study the ‘genetic response’ to such stimuli, which is the change in genetic composition over time, i.e. the action of natural selection. Physiological or metabolic responses of an organism within a generation havegenerally held no interestforthe evolutionist, unless individually different responses could be attributed to different genotypes. It is also true that physiologists, dealing as they do with highly variable and responsive characteristics of organisms, have traditionally shown little concern for the potentially important effects of individual genotype on the magnitude and range of variation in physiological traits. Fortunately, both of these traditions are changing. Physiological and evolutionary processes have been studied in isolation from one another. However, to the degree that they are not wholly and mutually exclusive (and I believe they virtually never are), a more powerful understanding of the biological process is achieved in their combination. Homeostatic mechanisms, whatever these may be in detail, preserve a phenotype both within and between generations; an organism can in some sense ignore

305

TREE vol. 6, no. 9, September

genetic architecture of most quantitative traits is unknown. This is as true for most physiological variation as it is for morphological and developmental phenotypes. Establishing the functional connections between genes and phenotypes will continue to be a major challenge to evolutionary biologists. This will not be easy, especially at a time when

the field is dominated by a focus on questions at the DNA level. There will be a time, however, when the study of phenotypic consequences of DNA sequence variation will come to dominate evolutionary biology, because this knowledge is essential to our understanding of evolutionary processes, especially natural selection. For those wishing to take this exciting

1991

and challenging approach, EvoluConary Genetics and Environmental Stress is an excellent starting point.

Richard K. Koehn

Center for Biotechnology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA

DNAFingerprinting DNA Fingerprinting: An Introduction by Lorne T. Kirby, Macmillan/ Srockton Press (Breakthrough in Molecular Biology Series), 1990. f24.95 pbk (xvi + 365 pages) ISBN 0333540247 Evolutionary and conservation biologists are now abuzz with excitement over a class of techniques emerging in molecular genetics that promises to expose the genetics of natural populations with unprecedented resolution. But this same development is equally heralded in other fields; because of its enormous potential in application to human forensic and criminal law, it is changing the face of modern jurisprudence. This book explains how DNA fingerprinting works from the perspective of its application to thorny human issues and seems aimed at an audience of strange bedfellows: lawyers and scientists. While providing some science literacy to the legal community and structuring a standardized approach for scientists, Kirby presents an interesting historical document that will also be of some use to those with different perspectives. DNA fingerprinting has already provided important results in application to studies of mating systems’, parental investment2 and cooperative behavior3. Because of the extremely high rates of appearance of new-length alleles (roughly two orders of magnitude greater than nuclear mutation rates?, differences should accumulate in isolated populations at a rate detectable over ecological time. The tantalizing prospect of using this technique to gauge population differentiation is becoming a reality5G6. Interest is high in developing single-locus probes to apply to issues of close kinship, as well as population structure. In the former application, single-locus probes allow rapid screening of whole neighborhoods for potential parents, which can then be identified by multilocus or multiple single-locus hybridization. In the latter, single-locus

probes make possible the calculation aspects are slightly outdated, as of allele frequencies appropriate for Kirby attempts to introduce a techuse in standard population-genetics nology that is changing as fast as he models. can write. Lorne Kirby has written a good inNevertheless, the technical basics troduction to the basic technology are here, and having this book in of DNA fingerprinting. For anyone hand will save a novice weeks that coming to this technique without a would otherwise be spent thrashing strong lab background, the refresher through primary literature and textchapter on basic genetic principles is books to accumulate both the latest helpful, and the step-by-step aptechniques and fundamental prinproach to majortechnical procedures ciples. Those who use DNA finger(almost half the book) is well planned. printing will undoubtedly find themThe efficient variations on basic DNAselves back in the primary literature extraction procedures that have been and visiting working labs to absorb developed for nonhumans (rememsubtle tricks, but this book will have ber, all vertebrates but mammals done its job. However, the market is have conveniently nucleated erythrostill open for a full treatment of the cytes) are not given. Because Kirby’s application of these techniques to interest is human forensics, he issues in evolutionary and conserfocuses on the single-locus probes vation biology. favored in North America for that application. Much of the book is Patricia P. Rabenold devoted to legal measures of qualDept of Biological Sciences, Purdue University, W. ity assurance, case histories and Lafayette, IN 47907, USA creation of a standardized human database. However, the lengthy discussions of case documentation References should not be entirely foreign to biol1 Gibbs, H.L. et al. (1990) Science 250, ogists studying patterns of related1394-l 397 M.W. ness among perhaps hundreds of 2 Burke, T., Davies, N.B., Bruford, and Hatchwell, B.J. (1989) Nature 338, individuals, although the cost esti249-251 mate presented is much higher than 3 Rabenold, P.P., Rabenold, K.N., Piper, that experienced in ba’&c academic W.H.. Havdock. J. and Zack. S.W. (1990) labs. Nature 348,53&540 Geneticists will be disappointed in 4 Jeffreys, A.J., Royle, N.J., Wilson, V. the lack of current thinking about re- and Wong, Z. (1988) Nature 332, 278-281 peat elements and the perspective 5 Gilbert, D.A.. Lehman. N.. O’Brien. S.J. provided by new work on sequence and Wayne, R..K. (1990) ‘Nature 344, 764-766 variation within loci7. Discussion of 6 Rabenold, P.P., Rabenold, K.N., Piper, the implications of conservation of W.H. and Minchella, D.J. Anim. Behav. sequences for fundamental genetic (in press) processes across taxa is missing. 7 Jeffreys. A.J., Neumann, R. and Behavioral ecologists will be disWilson, V. (1990) Cell 60, 473-485 appointed by the absence of both population-level applications and statistical approaches to the use of multilocus probes and anything other than straightforward parentage or identity assessments for single-locus probes. The lack of detail on development of species-specific PCR-derived single locus data is perhaps forgivable because a companion book in this series covers PCR technology in depth. It was inevitable that some