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It has been wonder me, in spite of so-many variations in color-patterns in dogs; these 2 dots (1 on each eyebrow) remains frequently occurring.

Dog-1 Dog-1 Dog-1 in close-up Dog-1 close up.

this one has a white dot. photographed from Kolkata.

Dog 2 this one is from Uttarakhand, Western Himalayas. Also has white dots. I've seen brown dots too, which I have not photographed, so I cite an example from internet (wikimedia: From web)


Now, my question is; why are these 2 dots are so conserved? Is it associated with some conserved region of a chromosome? or maybe it has/ had served any purpose or advantage (such as recognition or nonverbal communication or to mislead their prey since if the prey think of them as eyes; then they would miss the gazing direction of actual eye) so that it was selected by nature? Some sort of wolves too have similar paired-spots, so could I guess that once upon a time certain ancestor of all dogs and wolves contained these paired dots?

PS. I've not found helpful discussion about that dots. From this webpage it seems to me, it is being called false-white black and tan atat genotype. Don't know have i understood correct or not...

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  • $\begingroup$ I am not sure if this is relevant but surely a very striking photograph. (reddit link) $\endgroup$ – user1136 Sep 9 at 19:43
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I suspect but can't prove that these markings are not adaptive, but are accidents or epiphenomena of the general genetic system that determines coat colour.

On the one hand, an Australian Broadcasting Corporation documentary claims that canid eyebrows are adapted for social interaction: they have specialized muscles (which are not present in other carnivorous mammals such as cats), and ...

One study showed foxes who hunt alone had about half the facial expressions of wolves who work in packs. In fact, in wolves and dingoes, the eyebrows are often even a different colour, exaggerating the movement.

(they don't give any primary references).

On the other hand (supporting my guess) a lot of the evolution of these colour patterns seems to have occurred after domestication. These markings (not the eyebrow spots in particular) seem to be called tan points:

Red (tan) appears as pips above the eyes, on the sides of the muzzle extending to the cheeks, as pips on the cheeks, on the front of the neck just below the head, as two triangular patches on the front of the chest, on the lower legs and feet (and inside of the legs), and as a patch underneath the tail (and sometimes along the bottom edge of the tail too).

(I don't know whether eyebrow contrast in animals that aren't strictly brown/black is caused by the same genes ...)

A PhD thesis by Dayna Dreger (some material published in Journal of Heredity 2013:104(3):399–406 doi:10.1093/jhered/est012)

The black-and-tan phenotype, associated with the at allele, is a predominantly eumelanistic phenotype, with phaeomelanin restricted to distinct regions on the lower limbs, cheeks, eyebrows, chest, and around the anus. (p. 7)

Genome wide association study analysis, fine mapping, and sequence analysis identified a 16 bp tandem duplication in intron 5 of the hnRNP-Associated with Lethal Yellow (RALY) gene that segregates with the black-and-tan phenotype, versus saddle tan, in Basset Hounds and Pembroke Welsh Corgis. In breeds that never have the saddle tan phenotype, but frequently have the black-and-tan phenotype, the RALY duplication does not segregate with black-and-tan. This, together with further genotype analysis, suggests a gene interaction of ASIP, MC1R, DEFB103, RALY, and an additional modifier gene is required for expression of saddle tan or black-and-tan. (p. ii)

Neither the coyote nor 9 of the 10 wolves had the RALY duplication and the tenth atypical wolf was heterozygous (+/dup) (Table 5.1), suggesting that the lack of the duplication is the ancestral or wild-type allele (+). It follows then that the saddle tan phenotype is ancestral to the black-and-tan phenotype, despite the relatively limited number of breeds that currently express the saddle tan phenotype, making black-and-tan a modification of the saddle tan phenotype. The popularity of the black-and-tan phenotype across breeds and breed types is likely explained by artificial selection for the striking black-and-tan phenotype over that of saddle tan. Since the saddle tan pattern is found primarily in terriers, scent hounds, and a small number of herding breeds, this finding may also shed light on the development and relation of modern dog breeds, hinting at common ancestors between breed types.

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I can't attest to the purpose of these "eye spots". But they do seem to be rather atavistic in nature. My last dog had them even though neither of his parents sported eye spots. I've seen them on other mixed breeds, completely unrelated to the breeds my dog derived from, whose owners reported none in the parents. This suggest an early origin and a possible selective advantage.

There are "eye spots" on the wings of some butterflies and moths. Textbook explanations state these deter predators by giving them the impression they are looking at a larger, possibly predatory, animal. Not that that exactly applies here. If the spots were more largely separated than the eyes, it might be an argument for making the dog appear larger which might minimize conflicts with other predators. Maybe this idea still works if the eyespots look like larger eyes and convey a perception of a larger animal.

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  • $\begingroup$ I thought previously about such purpose to mislead prey; because: 1. When I was 5 or 6 yrs kid I thought ('get misleaded') as actual eyes. 2. In our school when I played map-map with friends (where I have to choose a obscure place's name and friends have to find it from map), they tried to 'cheat' me by following my eyes but every time I cheated them by telling the name of selected place but gazing at the name of someother place. $\endgroup$ – Always Confused Oct 20 '16 at 16:56
  • $\begingroup$ I didn't mean dogs currently use them; but may be (hypothetically) some of their ancestors used them. As well it seems to me some wolves and wild dogs too have them and in much more conformed way than domesticated ones. $\endgroup$ – Always Confused Oct 20 '16 at 16:59
  • $\begingroup$ @ bpedit I could not make sense of the 1st paragraph (sorry if it is I'm non-fluent in English)... You told about certain breeding result and then conclude to a selective advantage. How you conclude from some man-made breeding-experiment result, into presence of selective advantage? $\endgroup$ – Always Confused Oct 20 '16 at 17:42
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    $\begingroup$ Atavistic means a reversion to ancestral traits. So the eye spots seem, from the experiences I mentioned, to go way back in dog lineages. Perhaps this suggests a selective advantage way back when. No guarantees over what that might be. No proof there was a selective advantage. I chimed in because I've seen this appear in dogs where it is not characteristic of the breed. $\endgroup$ – bpedit Oct 20 '16 at 23:05
  • $\begingroup$ (p.s. I didn't downvoted it myself. It was helpful (some helpful information was there)) $\endgroup$ – Always Confused Oct 21 '16 at 3:20
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Dogs are actually not prey animals and are pretty high up on the food chain, so the theory that the eye dots are "decoy eyes" doesn't make a whole lot of sense. Realistically speaking, dogs are pack animals, and use several parts of their body to interact and 'converse' with other dogs. One of these body parts are the eyes. Like humans, dogs can widen and narrow their eyes to show emotion. The eye dots simply accentuate these movements, aiding greatly in pack conversation while hunting. Besides that, they're just plain cute.

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  • $\begingroup$ dogs are not usually prey but are commonly predator animals. Btw imrove your answer by backing them up with supporting references. Wlcome to biology SE and thank you :) $\endgroup$ – Always Confused May 17 '17 at 20:20
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enter image description hereeyespots on sleeping bloodhound. I believe these serve the purpose of making the dog appear alert even when it isn’t.

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I agree with Steve above. The eye spots serve no function when the dog is awake and alert, but they successfully mimic eyes for the sleeping dog, who is less likely to be attacked while sleeping if he appears to be alert.

I use an image of a sleeping dog as my blog header for a composition course that encourages students to look beyond the obvious.

https://rowancounterintuitive.com/

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When a dog fights with a cat, the cat would be disoriented to scratch the dog’s two brown dots as the fake eyes. So the two dot fake eyes help protect injuries to the real eyes during a fight with cats. This is just my guessed hypothesis that needs to be proven by a scientist. : )

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    $\begingroup$ Welcome to Biology.SE! It isn't clear that this is adding anything to the already existing answers. In addition, answers are much more likely to receive a favorable response if they include supporting references (primary literature is best). ——— You may also wish to take the tour and then consult the help pages for additional advice on How to Answer effectively. Thanks! 😊 $\endgroup$ – tyersome Sep 8 at 20:36
  • $\begingroup$ see also the "opinion-based" link also given in a comment to another answer: biology.meta.stackexchange.com/questions/3179/… $\endgroup$ – Ben Bolker Sep 8 at 23:38

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