Simic Ascendancy's second ability will trigger whenever a creature is given one or more +1/+1 counters as it enters the battlefield under your control, not just if an effect that says to "put" one or more +1/+1 counters on a creature you control gives it those counters (C.R. 121.6). See also this thread. In general, a counter is "put" on a permanent if the effect says "put ... counter[s]", "move ... counter[s]" (C.R. 121.5), or "enter[s]" or "put ... onto" or "return ... to" "the battlefield ... with ... counter[s]" (C.R. 121.6).
Rule 121.6: Some spells and abilities refer to counters being put on an object. This refers to putting counters on that object while it’s on the battlefield and also to an object that’s given counters as it enters the battlefield.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules