Pacific Plate Biogeography, with Special Reference to Shorefishes

Pacific Plate Biogeography,
with Special Reference
to Shorefishes
The Pacific Plate (Figures 1,2) is the largest of
all the earth's lithospheric plates and occupies
most of the area that has been referred to as the
Pacific Basin (Figures 3, 4). Although the Pacific
Basin has been the subject of numerous biogeographic
studies, there are only two studies (Springer,
1981a; Rotondo et al., 1981) that have alluded
to the Pacific Plate as a separate biogeographic
unit. I will not recount the Pacific Basin
literature here, but refer the reader to two studies
that together summarize the subject admirably.
Van Balgooy (1971) gave a comprehensive and
scholarly rendering of the general literature on
Pacific Basin biogeography in his analysis of Pacific
plant distributions. The main deficiencies of
van Balgooy's treatise are the absence of reference
to the importance of plate tectonics (a subject
probably too new for him to have incorporated)
and the use of a solely phenetic approach to
relationships. Zoogeographers seem to be unaware
of van Balgooy's work, which merits wider
attention than it has received. Kay (1980), who
did not cite van Balgooy, published an excellent
essay on the development of ideas concerning
Pacific Basin biogeography and included a brief
discussion of the importance of plate tectonic
Victor G. Springer, Department of Vertebrate Zoology, National
Museum of Natural History, Washington, D.C. 20560.
Victor G. Springer
Introduction
1
effects for the distribution of Pacific Basin organisms.
My study is concerned primarily with the distributions
of the shorefishes of the Indo-Pacific as
these distributions relate to the Pacific Plate. I
propose to demonstrate that the Pacific Plate
defines a biogeographic region of major significance,
and I will hypothesize the biological and
geological factors that produced the region. I
believe that study of the Pacific Plate provides
new insights into the patterns of organismal distributions
in the Indo-Pacific, both aquatic and
terrestrial. From this it follows that many of the
constraints to dispersal ordinarily invoked to explain
only the distributions of endemic terrestrial
and freshwater organisms are equally important
in explaining the distributions of endemic, shallow-dwelling
marine organisms.
The day I began to write this introduction, I
received a new issue of American Scientist that
included an article on chance dispersal by
Carlquist (1981). In that article (p. 415) was the
following statement, "Those who investigate organisms
capable of long-distance dispersal have
not adopted the methods of vicariance biogeography."
If this is true, my study is an exception;
many shorefishes appear to be so capable. The
land masses of the Pacific Plate are islands (Figure
2), many of which are highly isolated, and I will