Phylogenetic tree of Syt1. The phylogenetic tree of Syt1 protein was constructed using the neighbor-joining method with MEGA4. Amino acid sequences of Syt1 for these species were downloaded from the protein database of the NCBI. Their corresponding accession numbers are the same as those given in Table 2. The number at the branches denotes the bootstrap majority consensus values on 1000 replicates; the branch lengths represent the relative genetic distances among these species.