Island Biogeography — Ecology, Evolution and Conservation

I very much enjoyed this book. It is well laid-out and comprehensive in its coverage of issues in insular biogeography. I particularly liked the way that the author discussed and compared evolutionary versus ecological phenomena. The evolutionary and ecological theories of island biogeography have developed along very di€erent lines, and there has been considerable confusion as to what processes operate under what conditions. The author does an excellent job contrasting these approaches, and evaluating their applicability under di€erent circumstances. I found the book to be both enlightening and thought-provoking, as well as being very easy to read. The only major diculty I had in reading the book was which of the citations re ̄ected the primary literature. For example, instead of citing authors of speci®c chapters, an edited book, Wagner and Funk (1995), is cited repeatedly. Likewise, as a reference to the radiation of the plant genus Cyrtandra, the author uses Otte (1989), a book chapter on Hawaiian crickets! There are numerous instances of this throughout the book, and it made it very dicult to locate the primary literature. Examples are heavily biased towards vertebrates. The author states (p. 46) that `No attempt will be made to cover the insects in a systematic fashion'. That is ®ne. However, with insects providing some of the best insights into potential processes in the evolution of insular biotas, it would seem that they might have been worth including more thoroughly. In particular, although still poorly known, the evolutionary biology of a broad spectrum of Hawaiian arthropods has been the subject of a recent symposium (Liebherr & Polhemus, 1997, and references therein) and review (Roderick & Gillespie, 1998). Likewise, in terms of conservation there is little discussion of the conservation status of native species and impacts of alien arthropods. I would have liked to have seen some reference to the huge problem of the introduction of social hymenoptera in Hawaii (Cole et al., 1992; Gambino et al., 1990). One group of arthropods that is discussed in terms of speciation is the butter ̄ies (pp. 47 and 49). Interestingly, the only radiations of butter ̄ies are in the Bismarcks and the Solomons. Citing Adler and Dudley (1994), the author suggests that a `plausible explanation' for the lack of speciation on other islands may be `a consequence of the constraints of the evolutionary ties with particular host plants required by butter ̄y larvae. This may limit their potential for rapid evolutionary change on islands'. This argument ignores the fact that other host-plant specialists (moths, planthoppers, etc) have radiated extensively even in the most isolated islands (Howarth & Mull, 1992; Asche, 1997; Roderick 1997). More thorough coverage of arthropods would have shown the inconsistency in the Adler and Dudley argument. Plants are also treated rather lightly compared with vertebrates. Little more than a passing mention is given to the large Hawaiian plant radiations, and there is no mention of the recent outstanding work on groups such as the silverswords (Baldwin 1997; Baldwin & Robichaux 1995) and Cyanea (Givnish et al., 1995). The sections on genetics could have been made clearer. For example, in discussing founder e€ects (p. 64) it is stated that `genetic variability can be increased after establishment by mutation and resorting'. There is little evidence for any mutational changes subsequent to a bottleneck (Otto & Whitlock, 1997). It does appear, however, that selection subsequent to a genetic bottleneck has an important e€ect on alleles that are initially rare and that would tend to be lost to stochastic events in populations of constant size (Slatkin 1996). Also, in terms of the minimum viable population size (p. 194), the author states that `an increase in inbreeding in small populations reduces ®tness in animals'. Inbreeding will only occur in previously outbred populations; if populations evolve to small size over evolutionary time (as may be quite common on islands), then deleterious alleles can be `purged' from the population (Templeton & Read, 1984). Such populations may show very little genetic variability, but with little cost from inbreeding, and may be quite adequately adapted to their environment. I should emphasize, however, that these problems are minor in consideration of what this book has achieved, both in its encyclopedic coverage and readability. I know of no other book that o€ers such a solid foundation of information on island biogeography. I see the book as being an essential resource for classroom instruction on island biogeography, in addition to being an indispensable reference for others interested in the topic.