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I've noticed that my captive breed, antless diet horned lizards are experiencing an odd growth rate phenomenon, which I refer to as the Darwin effect. About 1/3 (33%) of my off spring (from 2 DHL clutches and 1 Regal clutch) never really grow. I'm wondering if those of you raising CB hatchlings on ant diets are experiencing the same phenomenon. Checkout my photo. Those are siblings that are just about 1 year old. They eat at the same rate, are cared for in the exact same way. One large female, one large male and one small female. Any comments?

I've seen this with ant diets as well. I've seen it in P. taurus and P. cornutum. Maybe temperment has something to with. I've noticed some individuals are just more outgoing and eat like pigs while the runts are more laid back. Could also have to do with genetics.

Whew...thought it was just me. OK, so with my the clutch I get, I will isolate every animal and see if that makes a difference. Yet another experiment....

BTW...these Solares have gone from ~4g to ~20g on an antless diet just inside of a year. Is that considered below avg, avg, good, etc?

You can see a record of weights for solare from hatchlings tracked for about 8 months. here.
Their growth is not very linear, which I think is largely due to the amount and type of food they can consume at a given size. This is based on nearly 100% ant diet, except for the first few weeks.
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Phrynosoma.Com

Off topic, just a question. See the white dot at the center of their head in my photos. Is this a residual eye, or maybe a heat or light sensor of some type? Anyone know what this is?

What does dwarfism have to due with Darwin? Dwarfs exsist in many different species is apparently a possible gene selection in any brood. Certianly feed and lighting and other factor can play a role, but there are dwarf Collared Lizards and other species from certian locals as well, exact same specie but just smaller. It may have nothing to do with your husbandry in my humble opinion becuase this has been observed in breeding groups of mmany species of lizards, while I think you have nice looking Solares I am still of the opinion that feeding a 80 percent ant eater in nature is not an acceptable husbandry protocol, or at least for the average person, so I am going to recommend ants--but I appreciate you experiment and certianly the proofs in the pudding. Last of all one hast to accept the tenants of Darwinism to tie the two together, don't assume that we all do...... :0) Cheers!!!
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Phrynosoma.org

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signature file edited. [phw 11/14/04]

Yes it is as a matter of fact. It is believed that not only does this aid in defense from overhead predation, but that it may be a type of "sensor" to asssist the lizard in regulating it's UV exposure.

In regard to your feeding and growth rates; with solare I can only say that the juvenile I obtained last year weighed about 10g. On an 80% or better harvester ant diet in the last year, he has put on over 40 grams. And this is after losing 10g over hibernation last year...I think probably due to parasites. I still think he hasn't gained enough, personally.

Good one Lou. I was wondering when someone might jump on that.
I can certainly accept micro-evolution, like a virus or bacteria evolving in some way...but macro-evolution like man from primate, or man from a pool of less complex microorganisms that where somehow mutated into exponentially more complex beings...is just horsepucky!

After all these years Darwin's theory is still just that...a theory. Listening to some people though, they would give you the impression that it's proven fact that should be taught as law!

No offense directed to the original author of the thread.

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"A man that should call everything by it's right name, would hardly pass the streets without being knocked down as a common enemy." The Complete Works of George Savile, First Marquess of Halifax 1912,246