Use of colouration on lower legs as flag or anti-flag, within genus Equus

 Here is a subtle but simple principle of adaptive colouration in animals.

I use the genus Equus to exemplify the principle that a given feature of colouration (in this case, striping) can function in 'opposite' ways, within a single taxon, depending on how it is presented..

In Equus, some taxa use the lower legs as a ‘flag’, enhancing overall conspicuousness, whereas others hide the legs, the antithesis of flagging.
 
The best example of leg-flagging is Equus przewalski, in which the markings on the lower legs are so obviously conspicuous that there is no rationale for their serving in any way to enhance crypsis or camouflage. This species has a pedal flag on each of the four legs.

The best example of leg-hiding is Equus africanus somaliensis - which is also the best example within Equus of a taxon in which only the lower legs are striped.
 
I have chosen one photo of each of these taxa below, to illustrate this basic distinction.
 
This comparison seems all the more meaningful given that, in at least some individuals, E. przewalskii resembles E. a. somaliensis in retaining striped lower legs/carpals/hocks.

In Equus przewalskii, the leg striping has been ‘co-opted’ into a conspicuous overall darkness of the lower legs.

This means that the adaptive function of striping on the lower legs is categorically different between these two taxa, even in those individuals showing similar incidence of striping on the lower legs.
  
Equus africanus somaliensis:
 
https://www.dreamstime.com/stock-photography-african-wild-ass-image10430092
https://pt.dreamstime.com/fotografia-de-stock-burro-selvagem-africano-image10430092
 
Equus przewalskii:
 
http://c8.alamy.com/comp/D91Y9T/przewalskis-horses-showing-the-zebra-striped-legs-D91Y9T.jpg

Publicado el julio 22, 2022 04:13 MAÑANA por milewski