Evolution and Historical Biogeography of a Song Sparrow Ring in Western North America
The Song Sparrow, Melospiza melodia (Aves: Emberizidae), exhibits a greater degree of geographic variation than does any other North American bird species. Detailed morphological work has demonstrated that a subset of the 25 diagnosable subspecies forms a
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Transferomics: Seeing the Evolutionary Forest Using Phylogenetic Trees John W. Whitaker and David R. Westhead
Abstract Horizontal gene transfer (HGT) is the movement of genetic material between species that would otherwise have isolated heritages. The immediate gain of a gene, or sets of genes, allows traits to be acquired far more rapidly than through Darwinian evolution. The entire set of genes within a species that were acquired through HGT is known as its transferome. Studies of prokaryotes transferomes have revealed that the propensity of a gene to be transferred is related to biological network structure. Recent increases in the number of sequenced eukaryotic genomes have made it possible to carry out analysis of their transferomes, and this has revealed novel insight into eukaryotic evolution. In this chapter, we present a review of some studies that have increased our understanding of transferomes.
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Introduction
Inheritance is the movement of genetic information from one generation to the next. Traditionally information only flows vertically, from parent to offspring, within the same species. This rule of inheritance is so important that it forms the commonly used law upon which a species is defined. That is, for two groups of organisms to be considered the same species, they must be able to reproduce and the resulting offspring must be fertile. During traditional inheritance, new traits can be acquired within a species through the processes of mutation and selection. This has led to the idea of evolution forming a tree, with the last universal common ancestor at the base and modern day species at the leaves. Horizontal gene transfer (HGT) breaks the vertical law of inheritance and allows genes to move between species. The gain of a
J.W. Whitaker and D.R. Westhead Institute of Molecular and Cellular Biology, Garstang Building, University of Leeds, Leeds LS2 9J, UK e-mail: [email protected]; [email protected]
P. Pontarotti (ed.), Evolutionary Biology – Concepts, Molecular and Morphological Evolution, DOI 10.1007/978-3-642-12340-5_6, # Springer-Verlag Berlin Heidelberg 2010
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gene through horizontal transfer can be of great advantage as it allows traits to be acquired far more rapidly than through mutation. The most powerful method of predicting the genes that have been acquired through horizontal transfer is through the construction of phylogenetic trees (Whitaker et al. 2009c). A phylogenetic tree allows the horizontally transferred genes to be identified, because the grouping of species within the tree will differ from that of the accepted taxonomy. The publication of whole genome sequences brings with it the opportunity to carry HGT predictions on a genomic scale. The study of HGT on a genomic level is known as transferomics (Whitaker et al. 2009a) and allows for the comparison of the levels of gene transfer between species. Moreover, it allows gene transfer to be considered in the context of biological systems, such as metabolic netwo
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