Limericks for confusing terms in Evolutionary Biology
Post date: May 18, 2016 7:54:10 PM
Purifying and background selection (by Alan Downey-Wall)
When the environment has an objection
To your allelic imperfections…
Try not to cry
Although you might just die…
…that’s negative selection
If upon close inspection
You find you have a strong connection
To a harmful allele
That’s kind of a big deal
You might find yourself removed through the process of background selection
Directional Selection (by Courtney Dunphy)
The most common type of artificial selection
Allele frequency shifts towards a new direction
The extreme phenotype chosen
Puts the shift in motion
Playing a major role in speciation
Negative frequency-dependent selection (by ?)
There was a novel strain of the flu
It spread from Hong Kong to Peru
But the infection’s existence
Selected for host resistance
And these days it infects very few
Positive frequency-dependent selection (by ?)
There once was a poisonous snake
Who’s patterning was due to a coding mistake
The snakes’ fitness depends
On matching his friends
The poor bird that ate him had a belly-ache
Hard and Soft Sweeps (by Micah Dean)
Conquering the genome like a Viking
The loss of variation is striking
This mutation is adaptive
And its neighbors are captive
They come along as if hitchhiking
It's advantage is undisputed
Other alleles were ill-suited
The adjacent basepairs
Wanted to share
In the fun of being substituted
It all starts with a mutation
Selection leads to fixation
Let's call it a sweep
If neighbors follow like sheep
The type depends on the variation
Were there multiple mutations?
Or, just standing variation?
While it can be assured
A soft sweep has occurred
We just don't know the causation
Soft selection (by Sara Schaal)
Does your fitness make you look like a clown,
when your superior competitors are around?
If this is true,
there is nothing you can do.
Soft selection you are bound.
Reinforcement selection (by ?)
Two populations diverged due to a barrier
Now they’re back together all the merrier
But their hybrids have low fitness
So low sex-drive they witness
And Reinforcement wins out superior
Diversifying selection (by Diana Townsend)
Diversifying selection favors the extreme
And intermediate traits become unseen
Observed in Darwin’s finches
By the size of their beaks in inches
And can create two new species by eliminating the in-betweens
Stabilizing selection (by Diana Townsend)
Diversity decreases with stabilizing selection
While extreme alleles receive rejection
It works on polygenic traits,
May be the most common form of updates
And studying it involves difficult detection
Bonus limericks (by Micah Dean)
"Be a poet!" says Katie
"Your knowledge will increase greatly!"
But I'm having a time
Finding a good rhyme
I keep ending with words like 'Kuwaiti'
Katie wants us to be poetic
With words both obscure and genetic
Let's not be obscene
Please, stay in your genes
As for puns, we're unapologetic