KRAAIJEVELD K & KRAAIJEVELD-SMIT F (2001) DNA as a tool in ornithological research. LIMOSA 74 (2): 57-65.


     With the development of new techniques in molecular genetics, many have become available to the ecologically or behaviourally oriented biologist. This paper explains three of the methods most commonly used in ornithology: phylogenetic and population genetic applications, paternity assessment using microsatellite markers and molecular sex-determination. These methods are illustrated by examples of the results that have been obtained.
     The basic technique responsible for these advances is the polymerase-chain-reaction (PCR). Using PCR. a small part of the genome can be amplified many times, alter which the length or base-pair sequence can be determined. Which part is amplified depends on the primers that are added to the reaction. A recently discovered pair of primers amplifies a gene on the sex chromosomes of virtually all bird species. As the length of this gene varies on the two types of sex chromosomes . the sex of an individual bird can be determined. Length-differences are also used in parentage-assessment. Microsatellites, short repetitive sections of DNA are common in the genomes of most organisms. They can vary considerably in length (i.e. number of repeats), which often leads to a large number of different varieties (alleles) of a specific microsatellite in one population. These are inherited according to simple Mendelian genetics and can therefore be used to match parents to their offspring. The application of this method has led to the discovery that extra-pair paternity is a widespread phenomenon in birds. Other sections of the DNA are less variable than microsatellites and these are useful when comparing different species or even different populations of the same species, depending on their mutability. Parts of the maternally inherited mitochondrial DNA are often used for studies of this kind. The base-pair sequence is determined and compared between different populations. When the estimate of the mutation rate of the particular piece of DNA is known, the length of time for which two population have been isolated from each other can be estimated by counting the number of bases that are different between the two.
      These techniques have led to many interesting insights in the life-history and evolution of birds. Undoubtedly new techniques will become available in the future.

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