Tag Archives: evo devo

The difference between homeobox and Hox genes

This is a big pet peeve. Let’s get straight to business: the terms “homeobox” and “Hox” are not interchangeable. They do mean different things. I’m correct in saying that Amphioxus (Branchiostoma lanceolatum) has 15 Hox genes. I’m also correct in pointing out that it has over 130 homeobox genes.

Gene names can be very confusing and difficult to remember, so there are many abbreviations in biology. For example, the gene insulin-like growth factor 1 is abbreviated to Igf1. Does that make it easier to remember? Who knows. But I believe the use of abbreviations is partly responsible for the incredible confusion over homeobox and Hox genes. And I do mean incredible. It’s very obviously a confusing topic for students, or anyone new to evo-devo, developmental genetics, or gene regulation… but it’s so much worse than that. Professional publications make the mistake, academics make the mistake, and they do it often. I think the reason it keeps happening is that the word “Hox” appears to be a shortened “Homeobox”. All over the internet you will see the terms used interchangeably, and sometimes with the apparently shortened version in brackets. “Homeobox (Hox)”. This otherwise decent glossary for Epigenesys manages to dump the terms homeotic, homeobox, and Hox into one single paragraph and glossary entry, which is of little help to a confused student seeking clarity. So let’s clear this up, and I’ll keep it quick.  Continue reading The difference between homeobox and Hox genes

Evo-Devo summary

I love this guy’s enthusiasm and light-heartedness. There are mistakes though. Please be cautious with “homeobox genes” and “Hox genes”. The problem here is that all Hox genes are homeobox genes, but not all homeobox genes are Hox genes. This guy makes the extremely common mistake of treating “Hox” as a shortened version of the word “homeobox”. Be cautious if you ever see “Hox” in brackets after “homeobox”.

The Monday Quote #3

This week’s quote is another relating to evolutionary developmental biology, but with less creationism-bashing this time. Most biologists are aware of the abandoned idea that ontogeny recapitulates phylogeny. Now we realise that phylogenetic change in morphology reflects transformation in ontogeny. Or as Garstang said in 1922, “Ontogeny does not recapitulate phylogeny, it creates it”. This week’s quote argues the same point.


“All that we call phylogeny is today, and ever has been, ontogeny itself. Ontogeny is, then, the primary, the secondary, the universal fact. It is ontogeny from which we depart and ontogeny to which we return. Phylogeny is but a name for the lineal sequences of ontogeny, viewed from the historical standpoint.”

– C.O. Whitman, Posthumous Works of Charles Otis Whitman, 1919, p.178.

c o WhitmanontogenyphylogenyThe Monday Quote