Interesting "Bradypodion thamnobates"

[melanocephalum]

There is some interesting stuff happening in these pictures, below are what is said to be "variations" of Bradypodion thamnobates from the Howick area 30km's away from the terra tyical distribution of the species.

The Specimens from Howick Kwa Zulu Natal are much smaller , with reduced gular crests and smaller casque's also lacking the vibrant colours.
The Howick individuals seem to have some Bradypodion melanocephalum - http://farm3.static.flickr.com/2696/4239234189_19ed56a336_b.jpg characteristics on them.

My feelings are indeed this is yet another species which needs work or al the very least a sub species elevation.

At the moment all the chameleons pictured below are the same species.

Female Howick - Typical

Male Howick - Typical

This is a Male from Nottingham Road some 30km's away inland
Juvenile From Nottingham Road Temperature were averaging between 8 -12 Degrees Celsius.

Male Nottingham Road.

Typical Nottingham Road Male. Pretty Specimen.

 

[Motherlode Chameleon]

Great pictures and interesting taxonomy subject.

 

[eisentrauti]

Amazing pics ! Are you sure about the id of the Howick Bradypodions ? I don't have the distribution map of Br.caffer in my head but they look very similar to the ones of Howick

 

[Chris Anderson]

Tyrone,

Are you certain these are not subadult animals that have not yet developed into their full adult characteristics? Bd. thamnobates and Bd. melanocephalum have been shown to be extremely closely related with very limited genetic divergence. There is mounting evidence of gene flow between them and they could actually represent ecomorphs of the same species with different locales experiencing strong but differential selection associated with their different habitats. Based on the close relatedness of these two species, I'd be hesitant to agree that this locale represents a distinct species or subspecies but rather may represent an intermediate form between Bd. thamnobates and Bd. melanocephalum along a cline of closely related but morphologically variable populations/ecomorphs extending from the coast up into the Drakensberg mountains.

Chris

 

[eisentrauti]

Hi Chris,

do you have some papers about the genflow between melanocephalum and thamnobates ? They may have close genetics but when we come to their phenotype I cant imagine that there can appear mixed forms. I mean melanocephalum reaches max 13 cm in length, thamnobates 22 cm. Length isnt everything but other characteristics as casque size, gular crest length and the scalation are very different too

Best regards
Benny

 

[laurie]

It will be interesting to follow and see if they are determined to be a subspecies. I could see it remaining as is if they are just juveniles.

 

[Chris Anderson]

Benny,

Phenotype and morphological variation are not always good indicators of relatedness. I'm sure you are familiar with the ecomorphs of Bd. pumilum and the morphological variation seen between these ecomorphs. These morphs look very different and would easily be classified as their own species based on morphological variation alone, however they are all Bd. pumilum. There are a number of examples in lizards showing strong selection on phenotype despite limited genetic variation. A lot of the microsat genetics work for these species is still in progress although some of it has been published (i.e. Tolley et al., 2004, Mol. Phylogenet. Evol.; Tolley et al., 2008, J. Biogeogr., etc.).

Chris

 

[eisentrauti]

It will be interesting to follow and see if they are determined to be a subspecies. I could see it remaining as is if they are just juveniles.

They have much to do in SA with other undescribed populations

 

[Chris Anderson]

They have much to do in SA with other undescribed populations

Some of these undescribed populations appear to also fall into this cline of potential ecomorphs so it'll be interesting to see if some of them are actually described as distinct species or not as well.

Chris

 

[eisentrauti]

Benny,

Phenotype and morphological variation are not always good indicators of relatedness. I'm sure you are familiar with the ecomorphs of Bd. pumilum and the morphological variation seen between these ecomorphs. These morphs look very different and would easily be classified as their own species based on morphological variation alone, however they are all Bd. pumilum. There are a number of examples in lizards showing strong selection on phenotype despite limited genetic variation. A lot of the microsat genetics work for these species is still in progress although some of it has been published (i.e. Tolley et al., 2004, Mol. Phylogenet. Evol.; Tolley et al., 2008, J. Biogeogr., etc.).

Chris

Of course I know this example, but I think the differences are here even bigger than between the fynbos form of pumilum and the typical form. But thats just my impression. All in all, the chameleons of SA have still much potential for new species, whether based on genetics in the labs or on classical field work

 

[melanocephalum]

Amazing pics ! Are you sure about the id of the Howick Bradypodions ? I don't have the distribution map of Br.caffer in my head but they look very similar to the ones of Howick

Thanks,
They are not Bradyoidion caffer i am familair with those as well as distribution is about 350 km South East of Howick.

 

[melanocephalum]

Tyrone,

Are you certain these are not subadult animals that have not yet developed into their full adult characteristics? Bd. thamnobates and Bd. melanocephalum have been shown to be extremely closely related with very limited genetic divergence. There is mounting evidence of gene flow between them and they could actually represent ecomorphs of the same species with different locales experiencing strong but differential selection associated with their different habitats. Based on the close relatedness of these two species, I'd be hesitant to agree that this locale represents a distinct species or subspecies but rather may represent an intermediate form between Bd. thamnobates and Bd. melanocephalum along a cline of closely related but morphologically variable populations/ecomorphs extending from the coast up into the Drakensberg mountains.

Chris

Chris,

They certainly are, it is not the first time i have been to the population and photographed the animals , we collected tissue for the exact purpose. The adults found at Howick are much smaller then Typical animals found in Nottingham road and Mooi River in the Midlands.

melanocephalum have an extremely limited distribution they do not overlap with thnobates nor the animals from Howick, even the mirco habitat of these animals differs greatly. Sure, it's much harder to make a decision purely on photographs, when you see the animals in hand it's quite evident there is something going on. A possible inter grade is suspected but this is interesting because of the lack of distribution over lap between thamnobates and melanocephalum. As i mentioned tissue and samples were collected for further work and as we know that takes time.

Regards.

 

[Chris Anderson]

Tyrone,

Interesting. I would caution, however, that a lack of current distribution overlap does not mean a lack of historic distribution overlap. Many of the habitats inhabited by Bradypodion are remnant habitats that were once interconnected. Evolution and diversification is a slow process and these populations likely may have been better connected at a point in time that is relevant to their genetic similarity. Similarly, habitat specialization does not necessarily mean that historic distributions were not abutting such that they could interbreed or even that said habitat specialization is relatively recent in evolutionary time. I think a more complete picture of these two species will become more clear in the coming years.

Chris