MOLECULAR PHYLOGENY OF SAND DOLLARS (ECHINOIDEA: CLYPEASTEROIDA) WITH NEW DATA EXTRACTED FROM TAIWANESE SPECIES

During the process of documenting the historical collection of extinct and extant echinoids at NTUG started in summer of 2016, a total of 572 syntype specimens of Arachnoides placenta and Sinaechinocyamus mai have been rediscovered and catalogued. Living specimens of A. placenta were found in its natural habitats, and DNA were extracted from sperm cells in November of 2016. Subsequently, individuals of S. mai were successfully captured in July of 2017. Genomic data extracted will be checked with regions of similarity between biological sequences from online database BLAST. Our CO1 and 18S match with many living sand dollar species. The 28S data, however, are similar to species within the Echinodermata but only match to three distantly-related sea urchins. By pulling one of the representative sand dollar 28S data from online source, it turns out to be different regions of 28S gene. Alignment is essential prior to running phylogenetic analyses. This is because that the quality of open-source data varies, thus, selection of useful genomic data and taxa are key for building a phylogenetically meaningful tree for classification. Currently, there are abundant data for comparison under CO1. Upon close examination of aligned data, Clypeaster japonicus is missing relatively more information among closely-related taxa. Thus, it is removed from our analysis. Outgroup taxa include Conolampas sigsbei, Eucidaris metularia, Eucidaris tribuloides, and Strongylocentrotus purpuratus for rooting purposes. Two different computational methods are used: PhyML and TNT. The first one is based on maximum likelihood (ML) and the latter is based on most parsimony (MP). Trees derived from both methods were resampled, and tree branches were kept with Bootstraps Values (BS) that are greater than 50%. The results presented here are derived from the combined data of CO1, 18S and 28S. A total of 27 taxa with 2549 base pairs were studied and the single most parsimonious tree was recovered. Our results show that lunules in keyhole sand dollars may have multiple origins. This is in agreement with study on origins of pedicellariae by others. This work is funded by Ministry of Science and Technology, R.O.C. (MOST 105-2116-M-002-012).