The Input Data Format dialog is displayed if MEGA does not find enough information about the type of data included in the input file.
Data Type
This displays the list of data types that MEGA is able to analyze. Highlight the current data type by clicking on it. Depending on the type of data selected, you may need to provide information about the following additional items.
For Sequence Data
Missing Data
Character used to show missing data in the data file; it should be set to a question mark (?).
Alignment Gap
Character used to represent gaps inserted in the multiple sequence alignment; it is set to a dash (-) by default.
Identical Symbol
Character used to represent identity with the first sequence in the data files; it is set to a dot (.) by default.
For Pairwise Distance Data
Missing Data
Character used to show missing data in the data file; it should be set to a question mark (?).
Matrix Format
Choose the lower-left or upper-right distance matrix for the pairwise distance data type.
Note: To avoid having to answer these questions every time you read your data file, save the data by exporting it in MEGA format.