growth rates of lizards

[chrisd]

hi,

Can anyone tell me what affects the growth rate of lizards. Is it purely genetic or can it be the amount of food it receives and/or the size of the enclosure ? I have a v small female exigua which is over 3 years old and still only the size of a small juvenile green. It always looks well fed and is housed in an outside coldframe size enclosure.

Chris

[fluxlizard]

Well, since nobody else jumped in I'll take this one-

The answer is all of the above and in addition temperature and competition.

Temperature is critical for all systems running properly. Too cool and everything slows down, including growth.

Competition- I have hatched many many many lizards over the years. In any given clutch, when clutchmates are reared together, there will be 2 or 3 that are dominant and grow much faster than the others, and usually 2 or 3 that grow much slower than the others. If the fastest growing are removed from the group, within a short time , 2 or 3 more will become dominant and outgrow their fellows in the group that remains.

If the slowest growing are not removed from the group, they will sometimes remain stunted and small, even as adults. So, that would be my first thought- is the slow grower one that has been raised in a group? If so, that is the probable source.

Size of the enclosure only insofar as it limits thermoregulational activity and possibly availability of hides, humidity or dry places- in other words it limits environmental options for the lizard to choose from. Size also determines the lizard's ability to be active. Too small an enclosure can also lead to stress, which in turn can cause the lizard not to thrive and this can also have an effect on growth rate and eventual adult size.

Certainly though genetics and food are important factors.

I would think severely undersized individuals are probably very rare genetically though, and would consider all of the other factors carefully before giving much plausibility of genetics being the cause.

[barb1]

Thanks for your thoughts on that. I guess any really undersized in the wild would not survive. Also in the wild there would be plenty room to wander and find their own food. If Chris's lizard is that small maybe it is a gene problem/hormone problem.

For Chris - is it a miniture adult in colouring and has it bred?

[chrisd]

Thanks for the informative answer fluxlizard,

I don't think that it is the "runt" of the clutch as it seemed to grow at a normal rate until about the 2nd year. Originally it was housed with the rest of the clutch until they were split up around about that time. It did show a slower growth rate than the rest. When I moved I housed it in a coldframe within a greenhouse for the a few months of that year and a few months of the following year until I had settled in. Then it it was placed outside. Whilst it was in the greenhouse it probably didn't receive full sunlight for that period. But it was only for a short period of time. At that time it lost part of its tail and damaged its leg when it made a dash for freedom and was caught under the lid. I only discovered it a little time later.

However, it hasn't grown since it has been housed outside. As it is so small (about 8cm from nose to vent) I haven't moved it to the larger cage with the other adults and have kept it in the cold frame. It seems a stressfull animal within the cage but it hibernates and seems to feed ok. The cage has varied areas as well as plenty of hides and a hibernation chamber. It is a miniature adult but hasn't bred yet as I haven't given it chance as it seems so small.

I have 2 young from last year which are just about the same size as it.

maybe its a number of factors that has affected its growth. The lack of sunlight, the stress of being caught in the lid and a small cage and in a small way, genes ?

[barb1]

I think you have answered that question? A combination of events and if it has passed the age of growing, it will not grow more. Stress situations can cause problems in all animals and if it was in pain over the foot incidence understandable.