Evidence without increases its reliability.
bias
question
repetition
replication

I would say your answer is question, mostly because when your proving something with evidence then you start asking questions (or still have questions) makes it seem like you don't really know. Therefore it's not very reliable.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.