I think this statistic is both fascinating and very informative about the current state of politics. Significantly fewer Republicans now believe in evolution than did in 2009. On the other hand more Democrats now believe in evolution. From Pew Research:
There is not just growing ideological disagreement between the parties about how to solve problems, there is a growing divide about what are the basic facts are. Finding compromise when you don’t even share the same concept of reality becomes very difficult.
I suspect a big driver of this change is that the parties are continuing to sort themselves. We are not just seeing few moderate Republicans in Congress, we are also seeing fewer regular people who see themselves as both moderate and Republican. This is important as partisan primaries are becoming the big election in more districts.