### Clue: House doctor's 6 11 (4)
### Answer: HOMO 
 ### Explanation: Definition: 6 11
 HO(abbrev. for "house") + MO(abbrev. for "medical officer", a doctor, especially in the military).
Answer: The genus that includes the various species of homonids, including homo sapiens, the most successful invasive species so far, having spread out from its origins in Africa. There is some debate as to whether it's invasive or not, but I don't see why it shouldn't be considered so.
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