Alpha male behavior

Question
I recently adopted 2 dogs from the shelter, one is a male mix breed puppy (9 wks) that I adopted 3 weeks ago and a female chihuahua terrier mix, she is 1-2 yrs old, just last week.  The male pup from the beginning has been very dominating (alpha type behavior) not towards me so much but my live-in boyfriend who is not as stern as I am.  He does not like to be disciplined by him, he wags his tail the whole time he is being scolded but at the same time will bark and snap at him.  Now that I have adopted the female just last week, he is constantly trying to mount her, bully her, take her toys, food, etc.  She is not backing down from him, so there are alot of growling and wrestling bouts between the two.  It's almost an even match because she doesn't back down, they have both pinned the other down, but he is very persistant.  Both are being crate trained and do stay in the crate when we are not home, and are supervised when out of the crates, for play time in the house, the yard, and when it is time to eat.  How can I help the two of them, it is mostly the male puppy, stop this behavior?  I appreciate any insight you can provide.  Thank you.

Answer
NO NINE WEEK OLD PUPPY DEMONSTRATES "ALPHA" BEHAVIOR.  What you are seeing is FEAR, and if you persist in attempting to "dominate" this puppy (especially at this age, in the middle of a genetic fear phase) what you will end up with is a FEAR AGGRESSIVE DOG.  His interaction with the other dog is NORMAL "puppy" rank testing and she is standing her ground. Why you would adopt TWO DOGS so close together, especially with a neonate (very young puppy) demonstrating problem behavior, IS BEYOND ME.  You are not equipped to deal with either one of these dogs.

Find a certified applied animal behaviorist.  Call the veterinary college in your geographical area and be sure to obtain referral to someone with an EDUCATION (not a make-believe "title" after their name, a glorified "dog trainer" appointed by some dog training association because he or she pays dues.)

STOP all of your behavior in attempting to "dominate" this very young puppy.  You are scaring him to death and confusing him and giving him all the wrong cues about who you are; further, you are violating the "rules" dogs are born with: LEADERSHIP IS EARNED by offering CALM, CONSISTENT cues; it is not ENFORCED by domination or subjugation.  

Read and learn: John Fisher's "Think Dog", Patricia McConnell Ph.D.'s "For the Love of A Dog"; Karen Pryor's "Don't Shoot the Dog"; go to ClickerTraining.Com and learn about positive reinforcement training, even a 9 week old baby can learn in VERY SHORT SESSIONS (no more than three to five minutes);  Dogs TRUST and FOLLOW by acquiescence, NOT overt dominance and fear.