Verb (used with object), : The French they speak is mongrelized.    From Dictionary.com. 

Could the Galicians be assimilated or would their presence mongrelize the nation?.    From Wordnik.com.  [what i'm reading] Reference

In the South, Democrats who understood nothing about the candidate as a man, nothing at all, castigated him as a symbol of “Black Republicanism”–a “sooty and scoundrelly” abolitionist who wanted to free the slaves and mongrelize the white race.    From Wordnik.com.  [Happy Birthday Abe - Reading Local: Portland] Reference

3) White Supremacists -- Obama will mongrelize America and subjugate White Americans.    From Wordnik.com.  [Chip Berlet: The Obama Assassination Plot In Context] Reference