分子系統解析から見えてくる動物の「間隙性化」 : シセレ上科貝形虫類を例に(2009年度日本動物分類学会シンポジウム)

抄録

The cytheroid Ostracoda is known as one of the major taxa in interstitial fauna. The evolution from surface dwelling taxa to the interstitial one is defined as "interstitialization" here. In order to resolve how "interstitialization" was achieved in the evolutionary history in Cytheroidea, the phylogenetical positions of the interstitial cytheroids were analyzed by the molecular phylogeny based on the nuclear 18S rDNA region. As a result, it was revealed that the interstitial taxa were independently and frequently derived from various positions in the cytheroid lineage. This result suggests that the dorso-ventrally depressed carapace shared in some interstitial taxa was developed as a result of parallel evolution, and that the "interstitialization" caused the high taxonomical diversification of Cytheroidea. Thus the "interstitialization" is an important change for the adaptive radiation of cytheroid lineage. The viewpoint of frequent "interstitialization" can become a reason why the high diversity of the interstitial fauna.