Incongruence in molecular species delimitation schemes: what to do when adding more data is difficult.

Using multiple, independent approaches in molecular species delimitation is advocated to accommodate limitations and assumptions of a single approach. Incongruence in delimitation schemes is a potential byproduct of employing multiple methods on the same data, and little attention has been paid to its reconciliation. Instead, a particular scheme is prioritized and/or molecular delimitations are coupled with additional, independent lines of evidence that mitigate incongruence. We advocate that incongruence within a line of evidence should be accounted for before comparing across lines of evidence, that can themselves be incongruent. Additionally, it is not uncommon for empiricists working in non-model systems to be data-limited, generating some concern for the adequacy of available data to address the question of interest. With conservation and management decisions often hinging on the status of species, it seems prudent to understand the capabilities of approaches we use given the data ...