This is a bit late for Christmas, but I ran across a paper outlining reindeer adaptations and thought it would fit in well with the season. Rudolph may be resting in his stall at this point, but we can still take a look at how his brethren adapted to their Northern habitats.
There are some really interesting adaptations that they were able to trace to specific molecular changes. Some are related to reduced solar radiation at higher latitudes, such as increased efficiency in the enzymes that produce vitamin D and mutations that do away with circadian rhythms induced by day/night cycles since it is either dark or light for most of the day for half the year. They also found a new binding sight for androgen transcription factors upstream of a gene related to antler development explaining why female reindeer have horns instead of just males.
What about the improved version (British readers, mind the difference in American usage):
You know, Jethro, that song about Prancer and Vixen
Sounds mighty fine but the words needed fixin’
Though the tune’s the same,
We changed old Rudolph’s name:
We called him
Randolph the Flat-Nosed Reindeer
Had a funny looking snout;
So Santy cut his nose off
Just to try to smooth it out
And when he sewed it back on,
Santy sewed it upside-down
Now every time it rains out
Poor ol’ Randy nearly drowns.
Then one foggy Christmas Eve,
Santy turned to say:
Randolph, with your nose so flat,
Won’tcha tell me where I’m at;
So Randy took a deep breath,
And he looked so very strange;
“We’re out behind the stock yard;
How I wish the wind would change.”
Randy tried to hitch a ride
One cold December Day:
He hopped on the back of a Chevrolet
And the back-fire took 'is breath away.
Randolph the Flat-Nosed Reindeer
Wished his nose would glow instead;
But it would never light up,
'Cause his batteries were dead!