Evolution of submarine cave molluscs

海底洞穴软体动物的进化

基本信息

批准号：
04454032
负责人：
HAYAMI Itaru
金额：
$ 2.88万
依托单位：
Faculty of Science, Kanagawa University (1994)The University of Tokyo (1992-1993)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

The present study has been continued since 1992 in order to clarify the characteristics of diversity and life history of cryptic molluscs in submarine caves around coral reefs as well as their evolutionary signifcance. With assistance of skillful divers we surveyed the biota of many caves in Okinawa, Miyako, Yonaguni and Bonin Islands. Materials from the Philippines, Palau and various localities of Japan are also compared.As the result the following common features are found in cavernicolous bivalves : 1) Most bivalves are very small in size, 2) Many species are defenseless against predators (ecologically primitive) ; some species can be regarded as "living fossils", 3) Cave bivalves are mostly undescribed and include many species referable to deep-water genera, 4) Many species show paedomorphosis (progenesis), 5) Non-planktotrophic species is unusually common like deep-water and arctic bivalves, 6) Many species are characterized by huge prodissoconch I,suggesting large egg size and K-strategy, 7) Some species may be endemic to particular caves, but widely distributed species in the western Pacific are common in spite of their non-planktotrophic larvae.These features are interpreted as due to the adaptation to low predation pressure and poor nutrition in such caves. We already published the systematic description of bivalves from Ryukyu and some discussion about their evolutionary significance.

本研究从1992年开始继续进行，旨在阐明珊瑚礁周围海底洞穴中隐秘软体动物的多样性特征和生活史及其进化意义。在熟练潜水员的帮助下，我们调查了冲绳岛、宫古岛、与那国岛和小笠原岛的许多洞穴的生物群。还对来自菲律宾、帕劳和日本各地的材料进行了比较。结果发现海绵状双壳类动物具有以下共同特征：1）大多数双壳类动物体型很小，2）许多物种对捕食者毫无防御能力（生态原始） ;有些物种可以被视为“活化石”，3) 洞穴双壳类大多未被描述，包括许多涉及深水属的物种，4) 许多物种表现出幼体发育（生殖），5) 非浮游营养物种非常常见，如深水物种-水和北极双壳类，6) 许多物种的特征是巨大的 prodissoconch I，表明卵尺寸和 K 策略较大，7) 某些物种可能是为特定洞穴所特有，但在西太平洋广泛分布的物种尽管有非浮游营养幼虫，但也很常见。这些特征被解释为由于适应了此类洞穴中的低捕食压力和营养不良。我们已经发表了对琉球双壳类动物的系统描述以及对其进化意义的一些讨论。