I think it’d be helpful for observations to be taggable as native or introduced and have those data reflected in the map icons. For example, this map for the Yellow Tang shows an outlier in the Mediterranean Sea. An observation like that could be tagged as “waif” with a correspondingly different icon (a yellow circle, a purple triangle, etc). For established populations (like, say, Pterois in the West Atlantic), a separate “introduced” tag could be applied with its own corresponding icon. And perhaps another icon for plant cultivars. etc etc etc.
[edit: this was meant for the Feature Request forum]