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Phylogeography, a textbook based on a combining of the empirical and conceptual fields of phylogenetic biology and population genetics, is not for everyone. Although anyone seriously interested in the science of biology, and especially evolution, will want a copy for reference, the book is aimed primarily at graduate biology students and biology professionals. Since I don't fall into either category, I must admit, that, at times, the text was slow going and/or difficult to fully comprehend. However, two books that I had previously read were very helpful in bringing me almost up to speed--Patterns in Evolution : The New Molecular View and Systematics and the Origin of Species from the Viewpoint of a Zoologist. The latter is in many ways a precursor to the contents of this book, presented at a time when mtDNA analysis had yet to be created. But now I'm getting ahead of myself.
Phylogeography is a field of study concerned with the principles and processes governing the geographic distributions of genealogical lineages. This includes both intra- and inter-species analysis. Empirical mitochondrial DNA (mtDNA) research got going in the mid- to late 1970s and the 1980s. Phylogeography as a field of study is a natural result of the questions that can be asked and the data accumulated via this "new" research. The "clock" in mtDNA is the primary tool employed in this field and is capable of shedding much light on both micro- and macro-evolution.
Some of the more "popular" topics covered in the text include the African replacement (or "Noah's Ark") vs. multi-regional approach to the geographic origins of humans, our non-relatedness to Neanderthals (i.e., we likely share a common ancestor from more than half a million years ago--not less than a hundred thousand years ago as anti-evolutionists assert), the rapid radiation of African cichlid fish into numerous species, and the "ring species" of California salamanders Ensatina eschscholtzii.
The incredible aspect of these last two items is the differences in their speciation rates. While a sample of the cichlid fish have become 14 species in 9 genera after only a few thousand years of evolution, their mtDNA has only diverged by approximately 1%. On the other hand, the salamanders are still one species, capable of reproducing where the ring meets, even though the subspecies vary in numerous ways both morphologically and at the mtDNA level. In contrast to the fish, the salamander mtDNA varies by up to 13% thanks, in large part, to the five million years of evolution that has occurred within the species. As Avise so aptly states on page 323
The biological world is richly diverse in phylogeographic patterns and speciational modes.By peering back in time through the usage of comparative mtDNA studies and aligning the data obtained with those from other disciplines such as climatology, geography, and paleontology, scientists can not only get a glimpse at the past, they can also see how the future may be shaped through future changes in (say) climate. When conditions change on Earth we see the higher extinction rates and higher rates of speciation. Phylogeography doesn't wax philosophical though. The book emphasizes the epistemology of the field. However, it is through studying the small, the incremental changes, that we can come to understand the whole.
from the publisher:
Phylogeography is a discipline concerned with various relationships between
gene genealogies--phylogenetics--and geography. The word
"phylogeography" was coined in 1987, and since then the scientific literature
has reflected an exploding interest in the topic. Yet, to date, no book-length
treatment of this emerging field has appeared. Phylogeography: The History and
Formation of Species fills that gap.
The study of phylogeography grew out of the observation that mitochondrial DNA lineages in natural populations often display distinct geographic orientations. In recent years, the field has expanded to include assessments of nuclear as well as cytoplasmic genomes and the relationships among gene trees, population demography, and organismal history, often formalized as coalescent theory. Phylogeography has connections to molecular evolutionary genetics, natural history, population biology, paleontology, historical geography, and speciation analysis.
Phylogeography captures the conceptual and empirical richness of the field, and also the sense of genuine innovation that phylogeographic perspectives have brought to evolutionary studies.
This book will be essential reading for graduate students and professionals in evolutionary biology and ecology as well as for anyone interested in the emergence of this new and integrative discipline.
John C. Avise, Professor of Genetics at the University of Georgia, is a member of the National Academy of Sciences, and a Fellow of the American Academy of Arts and Sciences. He is also the author of The Genetic Gods: Evolution and Belief in Human Affairs.
"Avise founded the study of phylogeography, and the field has become an extremely active area in evolutionary biology. While most of the studies are of species of animals, there is a substantial number on humans, and some on plants. I doubt that anyone could have created a book on phylogeography that would be as authoritative and insightful. Avise not only compiles the literature for the reader, he summarizes many of the best studies, and then directs future studies by indicating where the field is shallow, and where the field needs to go. His writing style is easy to read, direct and clear. This is a fine book." --Jeffry B. Mitton, The University of Colorado at Boulder"Phylogeography is a wonderful work and will be a benchmark contribution. The writing style is simple and direct, the content fabulous and the perspective illuminating. It will be a valuable resource for graduate students and other professionals in the field of population genetics, but it should interest all biologists." --Stephen Palumbi, Harvard University
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