Aim
The aim of this study is to describe and illustrate with maps the distribution and shape of biotic areas of endemism of fish clades in the western Pacific, including East Asia and Australasia. This study also depicts the allopatric or sympatric distributions of major subclades and makes general statements about the shared history among the areas using information provided by the shape of the distributions, phylogeny, and geology. This study also tests the hypothesis that Australasia is a locus of survival or differentiation for inferred “basal” subclades of global taxa.
Location
Western Pacific.
Taxa
Teleost fishes.
Methods
Clades are mapped to illustrate the shape of their distribution and to infer the shared relationships among distribution, phylogeny, and geology. Phylogenetic hypotheses for groups of taxa are converted into area cladograms which are used to summarize area relationships. This information is compared with that from other clades, ecology, and geology, to make general statements about the biogeographical history of the fish biota.
Results
The distribution of each clade has an identifiable shape. The “basal” subclades of many widespread teleost fish taxa are endemic to the western Pacific, including East Asia and Australasia; hence, this is the inferred location of a principal vicariant event for each clade. The “basal” subclade and its sister clade may be allopatric and represent remnants of general distributional patterns. The distribution of a clade, including its geography and its relationship with a geographical or geological feature, conveys historical information about the clade and the area in which it evolved: its area of endemism. These features repeat in unrelated or distantly related taxa in the biota indicating a shared history.
Main conclusions
The western Pacific including East Asia and Australasia is a locus of survival or differentiation, the site of the principal breaks in the distribution, for an array of teleost clades. It is not their center of origin. Biology and geology should be integrated in biogeographical analyses. Modern distributions reflect remnants of once more widespread distributions. When biogeography acknowledges the connections and correlations between geology and biology, it implements a guiding principle of the work of Alexander von Humboldt.