lunes, 28 de julio de 2008

Historical Biogeography and pattern

The study of Historical Biogeography is divided in two items. The pattern and Procces approaches. The objective of pattern approaches is elucidate the hierarchy (relationships) among areas (biotes, areas of endemism).

Several methodologies has been proposed to identify these relationships. Brooks Parsimony Analysis - BPA - (Brooks, 1981, 1988), Component Analysis (Nelson & Platnick, 1978, 1981), Component Compatibility Analysis - CCA - (Zandee & Roos, 1987), and Paralogy-Free Subtrees - TASS - (Nelson & Ladiges, 1996), among others. However, The efficient of these methods is considered ambiguous in some issues.

The ideal approach in Historical Biogeography (pattern) must be include all available phylogenetic and distributional data. Thus, methods such as Component Analysis (Nelson & Platnick, 1978, 1981) and TASS (Nelson & Ladiges, 1996). The elimination of incongruent data is not desirable because this lost minimizes the realibility of results in the analysis.

The node analysis among area cladograms is also an debate point in Historical Biogeography. The comparison of internal nodes within area cladogram is not necessary. The area cladograms must be compared among them (area cladogram vs. area cladogram). The comparison among internal nodes is not produces relevant information about areas relationships.

Likewise, an optimization criterion is necessary to estimate the best area topology (hierarchy). Other point of debate is the inclusion of events methods in the seek of area relationships. The area topologies is a graphic representation of areas relationships. These topologies are not inferences about the evolutionary process in the areas.