Gametic incompatibility and genetic divergence of Pacific and Kumamoto oysters, Crassostrea gigas and C. sikamea

Evolution of Parental Care and Ovulation Behavior in Oysters

“…In addition to Littlewood (1994), a number of molecular studies have provided valuable new insights into oyster evolutionary relationships (Banks et al, 1993(Banks et al, , 1994Anderson and Adlard, 1994;Jozefowicz and Ó Foighil, 1998;Ó Foighil et al, 1998Ó Foighil et al, , 1999Boudry et al, 1998). None of these have sampled all three ostreid subfamilies.…”

Phylogenetic Analysis of Southern Hemisphere Flat Oysters Based on Partial Mitochondrial 16S rDNA Gene Sequences

“…The application of DNA molecular methods to questions of oyster phylogeny (Littlewood, 1994) and systematics (Banks et al, 1993(Banks et al, , 1994Anderson and Adlard, 1994) has provided valuable new insights into oyster evolutionary relationships and has allowed the independent testing of preexisting hypotheses. These studies have involved (as outgroup taxa only) two ostreinid taxa: Ostrea edulis Linné, 1758 in Littlewood (1994) and Ostreola conchaphila (Carpenter, 1857), previously known as Ostrea lurida (Carpenter, 1864), in Banks et al (1993).…”

In search of the Kumamoto oyster Crassostrea sikamea (Amemiya, 1928) based on molecular markers: is the natural resource at stake?

“…With the increased availability of DNA sequences of oysters after the advent of the PCR (polymerase chain reaction) DNA amplification technique, several DNA sequences that nail down the genetic isolation between the two species have been identified. Examples include the large subunit ribosomal RNA mitochondrial gene (16S rRNA gene [3,24]) and mitochondrial cytochrome oxidase I (COI [25,26]), which serve as species-diagnosis DNA markers. In addition to these mitochondrial DNA (mtDNA) markers, diagnostic nuclear DNA markers such as the first internal transcribed spacer (ITS1) of nuclear ribosomal RNA gene family [2,4,25], which can be used to determine the occurrence of Kumamoto/Pacific hybrids [13], are also available.…”

“…5). Of the 260 oysters from Tamana (below ruler), six were Kumamoto oysters and the remaining 254 were Pacific oysters (Sekino M and Kawagishi M, unpublished data, 2008) Numachi [16] was examined in the crossbreeding experiments [3,17].…”

“…1), showing a sympatric distribution with the closely related Pacific oyster (see below). Since the 1990s, or probably after Banks et al [3], the public perception that ''Kumamoto oysters are extremely rare in its native habitat, and possibly on the verge of extinction'' has spread. Several lines of evidence from DNA experiments that may not be impeccable but can iron out this misguided notion have been accumulated; nevertheless, this notion is still sometimes disseminated to the public, probably due to intricate and conflicting information provided by previous studies as well as the very slow progress of field surveys in locating natural Kumamoto oysters due to the difficulty involved in, or rather, the impractical nature of the separation of this species from Pacific oysters unless speciesdiagnosis molecular markers are used.…”