The technique of altering a theme to give it a different character is often called:

The right answer is thematic transformation.  

Explanation:

This is a musical technique in which a theme, more specifically a leitmotif, is developed by changing the theme using permutation, augmentations, diminution and fragmentation. It is no connected to the original theme, it is independent of it, and it is usually used to show what the characters have in mind, or demonstrate an important change of the idea, announce something as well.  

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.

all you have to do is look at the pictures to find hope this is the lesson you were also hope this .