Morphological analysis of a deep-sea whelk Buccinum tsubai in the Sea of Japan

Abstract

Morphometrical analyses were performed on Buccinum tsubai , a deep-sea gastropod found in the Sea of Japan, and morphological differences were examined between the gender and among the four local subpopulations of Hokkaido, Yamagata-Toyama, the Yamato Bank, and San'in which are distinguished by mitochondrial DNA sequence analysis. As a result, sexual dimorphism of B. tsubai was found. Morphological differences were also recognized among four areas which may be related to genetic differences. They are also thought to be associated with the phenotypic plasticity in response to different environmental factors in each area. B. tsubai inhabits the the upper portion of the Sea of Japan Proper Water (UJSPW); and in the UJSPW of the Yamato Basin, nutrients are comparatively abundant and the dissolved oxygen content is low. Such environmental differences may be related to morphological differences among the four areas.

Plasticity in shell morphology and growth among deep-sea protobranch bivalves of the genus Yoldiella (Yoldiidae) from contrasting Southern Ocean regions

“…Vermeij, 1973;Nolan, 1991;Trussell, 2000;Bayne, 2004;Sousa et al, 2007) where adapting to different environmental conditions may increase their chances of survival and successful dispersal. In the deep sea, morphological analysis has been focussed on gastropods where species identification is often more reliable Rex and Etter, 1990;Iguchi et al, 2005). However, the deep-sea protobranch bivalves make a good model group to examine morphological plasticity due to their large geographical ranges.…”

A review of genetic intra- and interspecific relationships of deep-sea Buccinum and Neptunea species around Japan (with special reference to the Sea of Japan)

“…Subsequently, we found the morphological differences among subpopulations of B. tsubai ( Fig. 2; Iguchi et al 2005). So far, many Buccinum species have been described mainly by morphological characteristics (Golikov 1980), but some subpopulations within species may be described as species in the previous taxonomy.…”

“…Comparative analysis of genetic population structures among several taxa would provide general understanding on how paleoenvironmental changes during the glacial periods influenced on the formation of populations of marine organisms in the Sea of Japan. About interspecies relationships among Buccinum species, as described above, the wide range of morphological variation within and between species is noteworthy (Iguchi et al 2005, Shirai et al 2010). For species delimitaion of Buccinum species, sympatry and genetic distances based on some molecular markers including nuclear DNA should be considered by using enough samples per species.…”

“…Considering no overlapping of geographic distribution of the subpopulations of B. tsubai and the morphological differences among the subpopulations (Fig. 2, Iguchi et al 2005), these subpopulations may correspond to subspecies. Considering that the average genetic distance within the clade of Aniawabai group is almost equal to that of Tsubai group, the Aniwabai group may include some subspecies.…”

Three predominant species groups of deep-sea whelks (Gastropoda: Buccinidae) in the Sea of Japan: their molecular taxonomy and geographic distribution

“…In the Sea of Japan, Iguchi et al (2004Iguchi et al ( , 2005Iguchi et al ( , 2007a have examined the systematics, population biology, and biogeography of buccinid molluscs. In these studies, for example, B. tsubai in the Sea of Japan including the area of western Hokkaido, has been found to be composed of four genetically separate populations based on mitochondrial DNA (mtDNA) polymorphisms, and each population has been found to have unique morphological features (Iguchi et al 2005).…”