Lecture_21

Lecture_21 - Historical Biogeography Fredrik Ronquist...

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Unformatted text preview: Historical Biogeography Fredrik Ronquist November 16, 2005 1 Introduction Historical biogeographers and phylogeographers study very similar problems even though the time scales and spatial scales are typically larger in historical biogeography. Phylogeographers decided early on to ignore much of the existing literature in historical biogeography and the two disciplines still develop largely independently today. Historical biogeography can be divided into two subdisciplines: taxon biogeography and area bio- geography . In the former we are interested in reconstructing the geographic distribution history of a particular group of organisms. Questions we may be interested in answering include: Where did the organisms originate? How did they colonize the areas in which they live today? When did they first come to a particular area? How prone to dispersal is the lineage? In area biogeography, the focus is on general phenomena that affect many groups of organisms. Typical research questions in- clude: How was a particular community assembled? What is the explanation of commonly observed disjunct distributions? What are the most important geographic dispersal barriers that affect or affected the distributions of organisms in a particular region of the world? Are differences in species diversity between two regions best explained by differential speciation or differential extinction? In terms of quantitative methods, historical biogeography is still dominated by parsimony or opti- mization techniques. There is an overwhelming number of approaches that have been discussed in the literature. They can be classified into pattern-based and event-based ; the former approaches are simple numerical recipes whereas the latter identify some biologically interesting events, associate these events with costs, and then find the minimum-cost solutions. In recent years, there has also been a few papers discussing likelihood approaches to problems in historical biogeography, but the development of these methods is still in its infancy. 1 BSC5936-Fall 2005-PB,FR Computational Evolutionary Biology 2 Area models Before discussing the techniques used in taxon and area biogeography, it is useful to describe the different models or scenarios that are used to describe how organism distributions evolve over time. The simplest model is the island model . Geographic areas are represented as islands that remain constant through time (Fig. ?? ). Important processes that shape the distribution of lineages include dispersal between islands and speciation within islands. The use of island models is certainly not restricted to true islands. Many types of geographic situations can be described in terms of islands....
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This note was uploaded on 11/27/2011 for the course BSC 5936 taught by Professor Staff during the Spring '08 term at FSU.

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Lecture_21 - Historical Biogeography Fredrik Ronquist...

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