Testing the Neutral Theory of Molecular Evolution

Abstract
MacDonald and Kreitman (1991) propose a test of the neutral mutationrandom drift (NM-RD) hypothesis, the central claim of the neutral theory of molecular evolution. The test involves generating predictions from the NM-RD hypothesis about patterns of molecular substitutions. Alternative selection hypotheses predict that the data will deviate from the predictions of the NM-RD hypothesis in specifiable ways. To conduct the test Mac- Donald and Kreitman examine the evolutionary dynamics of the alcohol dehydrogenase (Adh) gene in three species of Drosophila. The test compares the number of DNA sequence changes between species and within species. The number of DNA differences is an indicator of the evolutionary rate of the Adh gene. Based on the test they conclude that there is strong evidence for adaptive protein evolution at particular sites in the gene. Understanding the test requires some basic knowledge about molecular terms and the predictions of neutral theory. The two important terms are fixed differences and polymorphisms. These are determined by comparing DNA sequences made up of thousands of individual nucleotide sites. A site that is unchanged within a species but different from a related species counts as a fixed difference. These are mutations that occur in some common ancestor of the lineage such that all descendants inherit the change. A site that differs within a species counts as a polymorphism. Determining the number of fixed differences and polymorphisms requires placing 1 each individual gene sequence onto a phylogenetic tree. A coalescent tree charts the ancestral relationships for a set of individual gene sequences. Sequences sampled from within a species form a within-species tree. The common ancestors of each within-species tree form a between-species tree. A detected difference counts as a polymorphism or a fixed difference depending on where it occurs in the phylogenetic tree (cf. Table 1). The test uses the numbers of polymorphisms and fixed differences as indicators of evolutionary rates..
Keywords No keywords specified (fix it)
Categories (categorize this paper)
Options
 Save to my reading list
Follow the author(s)
My bibliography
Export citation
Find it on Scholar
Edit this record
Mark as duplicate
Revision history Request removal from index
 
Download options
PhilPapers Archive


Upload a copy of this paper     Check publisher's policy on self-archival     Papers currently archived: 12,068
External links
Setup an account with your affiliations in order to access resources via your University's proxy server
Configure custom proxy (use this if your affiliation does not provide a proxy)
Through your library
References found in this work BETA

No references found.

Citations of this work BETA

No citations found.

Similar books and articles
Joel D. Velasco (2008). Species Concepts Should Not Conflict with Evolutionary History, but Often Do. Studies in History and Philosophy of Science Part C 39 (4):407-414.
Peter J. Beurton (1995). How is a Species Kept Together? Biology and Philosophy 10 (2):181-196.
Bradley E. Wilson (1996). Changing Conceptions of Species. Biology and Philosophy 11 (3):405-420.
A. Aaron Snyder (1982). Taxonomy and Theory. PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association 1982:512 - 521.
Ernst Mayr (1996). What is a Species, and What is Not? Philosophy of Science 63 (2):262-277.
Joel D. Velasco (2010). Species, Genes, and the Tree of Life. British Journal for the Philosophy of Science 61 (3):599-619.
Analytics

Monthly downloads

Added to index

2009-01-28

Total downloads

35 ( #53,222 of 1,101,833 )

Recent downloads (6 months)

2 ( #191,891 of 1,101,833 )

How can I increase my downloads?

My notes
Sign in to use this feature


Discussion
Start a new thread
Order:
There  are no threads in this forum
Nothing in this forum yet.