Dominant Polled Hereford Mutation

Polled (hornless) herefords originated as a mutation. In the early 1900s, Iowan Warren Gammon exploited the mutation by forming a registry to track this genetic mutation. The polled gene is a dominant trait but horned is recessive.

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Fairfield

Iowa Core Standard

HS-LS3-2

Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors

Driving Question

How could the offspring of the herefords have no horns (polled) if parents are horned?

Probing Questions

Could this gene happen because of something other than dominant or recessive traits?
What type of results does Gammon get when he breeds a polled bull to a polled cow?
What happens when he breeds a horned bull to a polled cow?
Are horns dominant or recessive?

Classroom Suggestions

Students could:

Research possibilities of mutations in a population.
Create a claim for how the offspring became polled.
Devise a working theory of dominant and recessive traits.
Create and explain a Punnett square showing how horned (heterozygous recessive) and polled work

Resources

Oklahoma State Department of Animal Science | Breeds of Livestock, This article explains that polled herefords are a mutation that has been expanded upon for "modern Herefords minus the horns."
The Biographical Dictionary of Iowa - University of Iowa Press Digital Editions: Gammon, Burton Osmond "Bert": Biographical account of Iowan Warren Gammon as the founder of the polled hereford breed.
American Hereford Association } Understanding Horned/Polled and Scurred Traits Explanation of dominant versus recessive traits for horned versus polled in Hereford genetics.
The Concord Consortium | DNA Mutation Simulation: Simulation for modeling mutation of DNA.

Contributors

Submitted by Kala Miller

Pictures Courtesy of Miranda Miller