| Summary: | 博士 === 國立臺灣大學 === 漁業科學研究所 === 106 === For this study, nine species of gall crabs belonging to nine genera were collected from scleractinian corals by SCUBA diving from offshore surrounding Taiwan. They were Cryptochirus coralliodytes, Dacryomaia edmonsoni, Hapalocarcinus marsupialis, Hiroia krempfi, Lithoscaptus paradoxus, Neotroglocarcinus hongkongensis, Pseudocryptochirus viridis, Opecarcinus crescentus and Utinomiella dimorpha. In order to understand the evolutions of the morphologic (gall crabs themselves), and ecological diversity (their host relationships, and the construction of their gall/pit) of gall crabs. The phylogenetic tree of Maximum parsimony tree and Neighbor-joining tree (combined partial mt. COI and 16S) illustrated that they belonged to a monophyletic group and subdivided into 9 groups. In addition, host coral species of gall crabs include Faviidae, Fungiidae, Pocilloporidae, Dendrophylliidae and Agariciidae, a total of 5 families and 18 species. A variety of crab host coral species and species vary (ranging from 1-5 species), each gall crab species showed a host-specificity in a Family taxonomic level of their host corals. This might also imply that the members of each gall crab species derived from a common ancestor.
A gall polymorphism, incl. irregular, circular, elliptical, semicircular, spheres by two valves, crescent and high degree of conservation of gall shapes was observed in relation to the gall crabs’ phylogeny. In addition, a significant relationship between the crab size (carapace width) and its gall/pit opening size (p < 0.01) demonstrated that the crabs have an ability to shape the gall/pit which suits to their own size. Thus, the galls/pit morphology might be considered as an extension of the crabs’ phenotypes.
The Neighbor-joining tree and Bayesian inference tree topology (combined partial mt. COI and 16S) of gall crab H. marsupialis collected from 5 different host corals showed that the significant genetic variation and clearly divided into four clades (support >90%), the genetic diversity of each clade ranged from 2.2% to 7.2%. The phylogeny tree reveals that the genetic divergence of H. marsupialis is strongly related to differences among host corals, rather than the geographical distribution of H. marsupialis. The molecular data had revealed a genetic differentiation as a result of the host shift of H. marsupialis.
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