mixed messages aboJt phylogenetic racy, robustness and confidence.
accu-
The other theme is more unexpected. More than half the papers in this book ex-
Oxford University Press, 1996. S39.50 hbk, f19.95 pbk (xi + 349 pages) KBN 0 19 854985 7 hylogenetlcs
has come of age in system-
atics. Except for a few nagging issues, systematists have reached a consensus on the power of phylogeny as an organizing principle for comparative biology. The extent of its broader hole it] evolutionary biolo&y has still to be decided, however. in view of the re cent publication
of critiques
of phylogenetic
press a concern for data on absolute ages and durations of lilzeages. Although thrs is not so surprising in Benton’s paper on age and clade rank in the fossil record. or in Smith et uL’s paper on rates of evolution in postPaleozoic echinoids, divergence time is an issue in many of the other works as weii. They are important in the reconstruction of population demographic history (l&e et ol; Moritz), epidemic traneimission modes (Holmes et (I!.), the synchronicity of hostparasite cospeciation (Page ~kn
perspectives in ecological’ and paleontological studies?, A’cJr~r1Lses/or &a! P/~$g4cJ.s arrives at an interesting time. It may servr as
molecuIar genrtically
a focal point in what appears to be an emerging d&ate about the necessity and utilitv of
but exciting because the level of interest ex]~rc~sacd in ihis v~~I111n~~ ?n,l) jJI’#Kld? <:,I 1111.
phylogenetic methods outside of systema&. At first glance, this collection of 20 papers
petus to improve statistical estimation of divergence times. As a whole this book provides a fasci-
looks iike a primer on ‘applied’ rather than ‘basic’ phyiogenetics. In other words, nearly all the papers start from the assumption that a tree has already
been obtained
by some
the most diverse collection of phylogenetic applications ever assembled in one place. Some method.
As such, this volume comprises
of the subjects covered are not quite as ‘new’ as the tit!e of the book suggests (e.g. several papers discuss evolutionary rates. a cornerstone of evolutionary biology and one of the first evolutionary problems that was en,. riched by phylogenetic anal&s’), but the majority of papers cover areas that havra emerged recently.
Some 01 the most exciting
examples include molecular epidemiology, phylogenetic population demography, and the reconstruction of the evolutionary history of corn~~~fl~ty structure. An added value is that several contributions are substantive mini-reviews of now burgeoning literatures in the areas of macroevolution
(Purvisj,
host-
parasite cospeciation (Page and i lafner), conservation biology (Moritz), and the comparative
method Two themes
(Martins and Hansen). occur rapeatectly ia these
clocks remain elusive or phylalocati7ctl wheia present at all I:
nating. if somewhat schizophrenic, perspective on the relationship between phylogeny and evolutionary applications. In many of its papers a phylogeny is just an intermediate step in estimating some parameter of a model, such as rate of gene flow (Barton and Wilson). Despite the earnest intonations of the authors of these papers toward phylugenetic history, in truth the trees are naerely statistical !Msance parameters - black boxes that are a necessary step fiG Sti!?litbiPl): somethin!; that rau be rmdoastood with ot without ‘trer thirmkirmg’.Fu!~rla~llental!~, tht,rdb is no more reason for the users of these mrtl:ods to untierstand the details 01 trees or thGr reconstn ction than there is for the users c,f multivariate statistical methods to unclerstand matrix inversion by Gauss-Jordan elimination. On the other hand, other papers showcase what a phylogeny can convey best, statements about relationships of particular taxa. In Sharp cjt d‘s paper on host :iwilch. ing and the directionality of CWSS-specks transmission of HIV viruses, for exam:b!e, most of the conclusions are contingent on
papers. The first is the effect of phylojenelic error on tree-based inferences. The most extensive discussion of this is in Otto (‘I rrl ‘s
phylogeuetic statements about particular virus taxa associated with particular I-ac~4t
paper on character sampling in complete mitoc’hondrial genomes (;I condensed vf’r-
~~~.oIutiona~.ylrypoth~s~s,
sion of their important recent paper on the same subject) and Crandall and Tempk%on’s
those involving possibly unique features or ljovfEties associated with particular clades.
paper on po~~~~at~~~ngeneaiogies. In other papers. the theme is expressed wicaflPlly rather thau concretely. However this is less
Bjkewise, &osos’ conclusions
the fault of the contributors,
CliKk involved.
are not in the tree-making
most of whom or tree-testing
business, than it is the fault of the phylogenetics community. which continues to send
taxa. Purvis discusses ‘case specific‘ macroby which he mums
about size di-
vergence and character displncPnMJnt in Ant,1;~ lizards arc contingent on the particular Thus, it is somewhat
ironic that the edi-
tors of this book are critical of the notion that evolution’s unique events (its ‘contingencies’)