SSD In Chameleons?

[leid]

Sexual Size Dimorphism is a common Reptilia trait. As of current, I am studying SSD in lizards indigenous to the Dominican Republic for my Honors Biology Research class at Avila University. I've noticed male and female chameleons vary in size as well, where females appear to be the smaller set. What are your thoughts on SSD? Why does it occur? I have one running hypothesis:

At the age of maturity, females invest more energy into sexual reproduction (as in the growing of yolked follicles, eggs, and clutches), while males are able to allocate their energy for size. But why? Any thoughts, opinions? My current answer to this question is jaw length/depth/width. I witnessed a chameleon mating session, and noticed the male clamping down on the neck of the female during mating. I'm wondering if this is a typical habit? If this is, it would be simple logic that the stronger and bigger the jaws, the more successful mating as it would hold the female in place, which would lead to more successful fertilization. The genes that would therefore pass on in the young would be for stronger, larger-jawed males..

 

[eisentrauti]

The plus in length and in the weight helps also to rivals far away. And as you said when they are bigger it's easier to rape the females. That's normal for such animals.

 

[Brad Ramsey]

In many species of chameleons the females are significantly larger than the males.

-Brad

 

[leid]

Oh? That's interesting! What are some names of these species? I'd like to read about them.

 

[Eric Adrignola]

It has less to do with the male/female interaction than the male/male interaction. It depends on the behavior. Some species, panthers veileds, etc. have strong dimorphism. Males can be many times the size of females. Some, cristatus, pygmies and others, the females are a bit bigger. Others, melleri, deremensis, some other horned species, the females may be larger, or the same size, but are usually bulkier.

This seems to depend on the habitat in many cases. Animals living in a more open area can defend territories with visual messages - coloration, intimidation, etc. Bigger, brighter males will win a fight, and have a better chance of mating. The biggest ones OR the brightest ones are at an even better advantage - they may not even HAVE to fight. Female size is less dependant on circumstances.

Also - the males probably do not rape the females as a rule, naturally. Females tend to avoid males normally, and when receptive, they make themselves more available. The male also respect the non-receptive/warning coloration.

In species with out such differences - melleri and deremensis I have experience with - things are different. These species tend to territorial, but with a different tolerance than other species. They live in a more dense environment, where color and visual messages might not be as effective. Also, their adaptations might negate any advantage sexual dimprphism has.

Deremensis males are dimorphic, but they're no bigger than females. The males tend to respect females a great deal, and will never(in my experience) rape a non-receptive female. They require a long courtship period, and often, will do nothing unless stimulated by temperatures, rain, food or even territorial disputes.

Melleri are similar - but they are almost impossible to tell apart. Best way to tell is that the one on top is male, the one that lays eggs is female...

they will almost never just "breed". Everything must be well, and the animals usually need to be well-aquainted with each other. Of course, I've heard of stories where they just "do it". In my animals, the courtship has been going on a month or so, and I know she's receptive (she's green, friendy to him, and walks around with her tail curved up (dirty girl).) He's just taking his sweet-**** time with it - which I have been told is not unusual with them. Hes been tenderly licking her tail for God's sake - it's a bit sick if you ask me.

 

[leid]

He's just taking his sweet-**** time with it - which I have been told is not unusual with them. Hes been tenderly licking her tail for God's sake - it's a bit sick if you ask me.

Lol! Maybe she's a 3rd date kind of girl. Thanks for explaining that! I knew that territorial chameleons most likely should be larger male-wise for more successful breeding. The video i saw was on youtube, where the male was taking jabs at the female before they began mating, so I guess I misinterpreted the behavior. I take it since chameleon mating niches are unlike the other reptiles who are more aggressive breeders, size dimorphism isn't necessarily important between males and females. Does it depend (with males and the certain locale) on brightness of their color? I used to breed betas and the females were quite picky about who they mated with. If the male wasn't beautiful she wouldn't even bother with him.

 

[hallenhe]

From what I've read on pygmies (Stump-Tailed Chameleons - Miniature Dragons of the Rainforest), the males of many species will climb onto a (larger) female when they encounter each other, and be carried around on her back at least until evening, when mating takes place. The female may carry the male for a few days. (I have not personally observed this with my 1.2 brevs, which do not appear to be interacting with one another in any fashion.)