Genetics is complicated: mouse edition

Genetics is complicated. I have taken courses to this effect; I have taught the concept in Introductory Biology. Mendel’s peas with their neat logical Punnett squares were a lucky rarity—each trait governed by just one gene, each of those genes on a separate chromosome. The genetic basis of the vast majority of traits is far more complex. If the genes involved aren’t physically linked (called “linkage disequilibrium”) then they are pleiotropic (influencing many different traits at once), or epistatic (modified by other genes), or simply so subtle that their effects disappear in the noise of environmentally-caused trait variation. Relating traits to genes is hard.

I know this; I understand it; but until recently, I had never actually seen it. Then my pet mice decided to give me an object lesson in genetics.

What happens when you think you have all female mice, but you actually have mostly females and one male?

This happens. (Incidentally, doesn't this look like a mouse version of the Canadian flag?)

This happens.
(Unrelatedly: doesn’t this look like a mouse version of the Canadian flag?)

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Blood secrets

Sometimes doing science feels like doing magic. Take a fantastical witch brewing eye of toad and nightshade flower in a cauldron, substitute a 1.5 ml tube for the cauldron, AW1 Buffer for the nightshade flower, and blood of junco for the eye of toad, and that’s me.

(And that “eye of ___” thing happens in science too: a few of my herpetologist colleagues have been talking lately about what you can learn from preserved lizard eyes.)

One of the things I do when I capture a junco is to collect a blood sample. I use a sterile needle, collect very little blood, and don’t let the bird go until I’m sure the bleeding has stopped. The birds usually don’t even flinch. They act much more upset when I blow on their chests to look for brood patches (I think it feels cold to them) than they do when I take blood.

Me collecting blood from GRAY. The blood moves up the tiny capillary tube on its own. Photo by M. LaBarbera.

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A bird in the hand

What happens when we catch a junco:

We band it with the uniquely numbered US Fish & Wildlife band. This is the first priority because once the bird has this on, we can identify it later even if it escapes. Then we add the three colored leg bands so that we can identify it later even from a distance.

GOAL with his leg bands

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