Rock-dwelling agamids on two continents: Ctenophorus vs Agama, part 3: variation in masculine colouration

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ACKNOWLEDGMENT: I thank Johannes van Rooyen (@johannesvanrooyen ) for educating me about the differences between males and females, in Agama ( The patterns he has pointed out are, in hindsight, now evident to me. However, I was formerly oblivious to them, and field guide-books do not do justice to them, either.

Rock-dwelling agamids in Australia and southern Africa vary extremely in their degree of sexual dimorphism in colouration.

In this respect, they show no evolutionary convergence.

The variation goes along four lines, viz.

  • mature males vary from dull through bright-hued to gaudy, according to the species,
  • females (irrespective of breeding condition) are somewhat bright-hued in Agama planiceps, vs dull in all other spp.,
  • females have bright-hues associated with breeding condition in several spp. of Agama, but no other spp., and
  • mature males of Ctenophorus ornatus, which lack bright hues, differ from females only in the boldness of dark/pale contrast (banding on the tail, plus vertebral stripe).

Further details include the following.

Among mature males, the dullest is Ctenophorus rufescens, whereas the gaudiest are Agama kirkii and A. planiceps. This corresponds, approximately, to a difference between non-gregarious and gregarious, with corresponding polygyny.

Agama anchietae is odd in that it alone

  • among all the spp. studied, has colouration more conspicuous (at least to the human eye) in females than in males, and
  • among the southern African spp., has masculine colouration less conspicuous than that of Australian species (particularly Ctenophorus vadnappa).

This possibly corresponds to A. anchietae being less gregarious than its rock-dwelling congeners in southern Africa, in this way partly resembling the Australian spp. However, the bright hues in females of A. anchietae, in breeding condition, undermine this explanation.

A categorical difference emerging from this study is that females feature conspicuous hues (to the human eye) in no Australian species but all southern African spp. Given that females are the biologically central sex, this degree of intercontinental divergence is surprising indeed.








scroll to third photo in


Fairly typical:

Extensive blue/turquoise:

With prominent pale vertebral stripe:

With yellowish tail and maroon abdomen:



Posted on November 05, 2023 11:02 AM by milewski milewski


@ptexis @johannesvanrooyen @alexander @m_burger @botswanabugs @karoopixie

The following ( nicely illustrate the ambivalence of conspicuous colouration in Agama atra.

The individual shown is adult female, in breeding condition. The hues of feminine advertisement (apart from possible ultraviolet) are blue (slightly iridescent) and yellow, the former shared with mature males but the latter restricted to females.

It makes sense that males should be less risk-averse in their trade-offs between social/sexual advantage and avoidance of predation.

But the point of particular interest is the fine line maintained between social/sexual advertisement on one hand, and anti-predator camouflage on the other. Some concealment is maintained by a combination of a) the bright-hued lichens on the rocks, and b) the limited chroma ( of the hues on the lizard.

This, I suggest, achieves 'the best of both worlds'.

Other relevant photos are and In these cases, the most conspicuous hue on the torso is orange, rather than yellow.

Incidently, the following ( show a mature male individual of the same species.

The colouration still shows some balancing of advertisement and concealment. However, the figure is, overall, unambivalently conspicuous. This is because of a) the rocky surface chosen, b) the pale vertebral stripe, which is incongruous with the background, and c) the retention of disruptive mottling only on the hindquarters (particularly the tail).

Posted by milewski 8 months ago

@milewski one must also remember that agamas can subdue their bright colours within a minute or two. So if they really feel threatened by a potential predator they can take that course of action. The following observations shows this colour change:

Posted by johannesvanrooyen 8 months ago


Many thanks for this valuable comment.

Posted by milewski 8 months ago

The following, of Agama atra, show the subtle distinctions between females and males, when in breeding condition but with the hues 'switched off' in apprehension of the observer.

In females, any yellow that remains is located on the abdomen, just anterior to the hindleg:

In males, the only yellow (restricted to certain individuals) is located on the ventral surface of the tail, and the abdomen just anterior to the hindleg is reddish, never yellowish:

The following ( shows an individual male - which happens to feature yellow on its tail - with the hues 'switched on'.

@johannesvanrooyen Is this correct?

The following ( further illustrates the sexual differences.

Posted by milewski 8 months ago


Which of the following statements is most correct, w.r.t. patterns of colouration (particularly in breeding condition) in Agama atra?

The species
a) consists of subspecies with different colouration,
b) is colour-polymorphic (,
c) is neither subspeciated (w.r.t. bright hues) nor polymorphic, but shows individual variation,
d) shows a predictable sequence of colouration with age (within each sex), after becoming adult.

Posted by milewski 8 months ago

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