Charles Darwin is, for some reason, a controversial character among evangelical protestants. His theories of Natural Selection essentially stated that species change over time. While that theory may arguably have been followed too far with the proposal of a Last Universal Common Ancestor, it's not all that controversial (or at least it shouldn't be) to say that things change.

Exhibit A in Darwin's time was a species of finch which he studied during his visit to the various islands of the Pacific where he made his analytic observations. The finches, he theorized, must have developed their unique beak shapes over the course of several centuries of breeding which favored birds with the ability to adequately feed on the various plants and insects which were on each island. While the animals that couldn't feed weren't necessarily doomed, the ones that could feed more effectively would inevitably become stronger, and a stronger mate is always more appealing than a weaker one.

Here's a drawing of the same species of finch as observed by Darwin on different islands:

For starters, watch this speech by Jimmy Johnson, a three-time Super Bowl winning football coach.

"And let us not be weary in well doing: for in due season we shall reap, if we faint not."
-Galatians 6:9