Geography Reference
In-Depth Information
Williams and Ebach (2004) categorized cladistic biogeographic methods
as either transformational or taxic. The latter, which includes area cladistics,
isnomorethanproximalrelationshipsoftwoareasinrelationtoathird(area
homology). A combination of area homologies forms a general areagram or
general area cladogram, which represents geographic homology consisting
of area clades that share a common history. Williams and Ebach (2004) ar-
gued that the alternatives (e.g., identification of dispersal routes, centers of
origin, or even vicariance events) are themselves artifacts of the transform-
ational perspective.
Algorithm
The algorithm consists of the following steps (Ebach 2003;
Ebach and Humphries 2002):
1. Obtain the taxonomic cladograms of the taxa distributed in the areas ana-
lyzed.
2. Replace the terminal taxa from the taxonomic cladograms with the areas
inhabited by them to obtain taxon-area cladograms.
3. Resolve widespread taxa with the transparent method.
4. Represent the nodes of the taxon-area cladograms in either a component
or a three-item matrix.
5. Analyze the data matrix with a parsimony or compatibility algorithm to ob-
tain the general area cladogram.
Software
3item (Ebach et al. 2005b) and Nelson05 (Cao and Ducasse
2005).
Empirical Applications
Ebach and Edgecombe (2001), Escalante et al.
(2007a), and Humphries and Ebach (2004).
The Hawaiian Archipelago, comprising the islands of Kaua'i, O'ahu, Moloka'i,
Lana'i, East and West Maui, Kaho'olawe, and Hawai'i (
fig. 5.23a
)
, is situated in
the North Pacific Ocean, between latitudes of 19° and 29° N, about 4,000 km from
the nearest continent. Its biota contains a high percentage of endemic species.
Humphries and Ebach (2004) undertook an area cladistics analysis of the Hawaii-
an Islands.
