ZOOGEOGRAPHIC DISTRIBUTIONS OF THE SIBLING SPECIES MYTILUS-GALLOPROVINCIALIS AND M-TROSSULUS (BIVALVIA, MYTILIDAE) AND THEIR HYBRIDS IN THENORTH PACIFIC
Th. Suchanek et al., ZOOGEOGRAPHIC DISTRIBUTIONS OF THE SIBLING SPECIES MYTILUS-GALLOPROVINCIALIS AND M-TROSSULUS (BIVALVIA, MYTILIDAE) AND THEIR HYBRIDS IN THENORTH PACIFIC, The Biological bulletin, 193(2), 1997, pp. 187-194
Diagnostic length differences in a PCR amplified fragment of the gene
for byssal adhesive protein were used to study the zoogeographic distr
ibution of Mytilus galloprovincialis and M. trossulus along the west c
oast of North America and in Japan. The distributions of M. galloprovi
ncialis and M. trossulus are patchy, although an overall geographic pa
ttern emerges. M. galloprovincialis was the only species found on eith
er Kyushu or Honshu, and it was the most abundant mussel from Tomales
Bay to San Diego, California. M. trossulus was the only bay mussel fou
nd on Hokkaido and in Alaska, and it was by far the most abundant muss
el along the coasts of Washington and Oregon. Mytilus galloprovinciali
s and M. trossulus are sympatric and hybridize near Whidbey Island, Wa
shington, in San Francisco Bay, and in San Diego Bay. A second diagnos
tic anonymous nuclear PCR marker was used to examine the extent of hyb
ridization at Palo Alto, California. At this site, genotypes appeared
to be a mixture of M. galloprovincialis, F-1 hybrids between M. gallop
rovincialis and M. trossulus, and backcrosses between the F-1's and M.
galloprovincialis. The discontinuity between the zoogeographic distri
butions of these two species at about 40 degrees-41 degrees N latitude
in both the eastern and western Pacific suggests that temperature is
a factor in determining their present distribution and limiting their
dispersal to other regions.