Altruism is when someone is selflessly concerned for the well-being of others.
In the first photo, Mr Fredrickson lets go of his dream to have his house on top of the waterfall, to save Kevin and Russell. This shows that he values the others more than his past.
Another time altruism was shown was when Russell decides to save Kevin. This shows that he cares for the bird more than his life, because he goes into the aircraft knowing that Charles is capable of hurting/killing him.
When Carl got his house to fly and didn't realise that Russell was hanging on to it, Carl forgot about saving his house and helped Russell get inside.