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