Over the past 20 years, molecular biology has revolutionized ecological research. During that time, methods for genetically characterizing individuals, populations and species have become almost routine, and have provided us with a wealth of novel data and fascinating new insights into the ecology and evolution of plants, animals, fungi, algae and bacteria. Molecular markers allow us, among other things, to quantify genetic diversity, track the movements of individuals, measure inbreeding, identify the remains of individuals, characterize new species and retrace historical patterns of dispersal. These applications are of great academic interest and are used frequently to address practical ecological questions such as which endangered populations are most at risk, from inbreeding, and how much hybridization has occurred between genetically modified crops and their wild relatives. Every year it becomes easier and more cost-effective to acquire molecular genetic data and, as a result, laboratories around the world can now regularly accomplish previously unthinkable tasks such as identifying the geographic source of invasive species from only a few samples, or monitoring populations of elusive species such as jaguar or bears based on little more than hair or scat samples.
In later chapters we will take a detailed look at many of the applications of molecular ecology, but before reaching that stage we must first understand just why molecular markers are such a tremendous source of information. The simplest answer to this is that they generate data from the infinitely variable deoxyribonucleic acid (DNA) molecules that can be found in almost all living things. The extraordinarily high levels of genetic variation that can be found in most species, together with some of the methods that allow us to tap into the goldmine of information that is stored within DNA, will therefore provide the focus of this chapter. We will start, however, with a retrospective look at how
Molecular Ecology Joanna Freeland © 2005 John Wiley & Sons, Ltd.
the characterization of proteins from fruitfly populations changed forever our understanding of ecology and evolution.
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