A test of evolutionary convergence: bush duiker vs gray brocket, part 2

The following show the greatest similarity that can be found in the tails, as well as once again showing the differences in the ears, face and feet: bush duiker https://kmarshall.photoshelter.com/image/I0000anvkMALgQxI vs gray brocket https://commons.m.wikimedia.org/wiki/File:Veado-catingueiro_-_mazama_gouazoubira.jpg and https://www.inaturalist.org/observations/4388740.

The following compare the facial profiles: bush duiker https://www.alamy.com/common-duiker-sylvicapra-grimmia-kruger-national-park-south-africa-africa-image278255132.html vs gray brocket https://www.inaturalist.org/observations/22725310. This shows clearly how different the ears, eyes and mouth are, despite the remarkable reduction of the antlers in the gray brocket. The South American species presents as a generalised ruminant, whereas the African species is distinctively cephalophin in form.

The following compare the frontal view of the face: bush duiker https://www.freeimages.com/photo/grey-duiker-1347170 vs gray brocket https://www.inaturalist.org/observations/60521876. Although this individual of the bush duiker has unusually small ears, a difference remains in the furriness of the front of the ear pinna. The difference in the size of the eyes is once again obvious.

Some individuals of the South American species show an auricular semet, in the form of noticeably pale markings at the base of the ear pinna. This pattern is typical of odocoileine deer (e.g. Odocoileus heinous, https://stock.adobe.com/search?k=mule+deer+family&asset_id=402390444). However, it is hardly evident in cephalophin bovids: gray brocket https://www.inaturalist.org/observations/39813162 and https://www.inaturalist.org/observations/29616490 and https://www.inaturalist.org/observations/59511649.

The African species possesses a buccal semet. By contrast, in the South American species the colouration of the mouth, although nominally similar to other odocoileine deer, is so faint that it does not qualify as a buccal semet: bush duiker https://www.pikist.com/free-photo-srxac vs gray brocket https://www.inaturalist.org/observations/91573682 vs gray brocket https://www.youtube.com/watch?v=ADpnQF-DaEo.

The infants show no convergence whatsoever in colouration. In the African species the adult colouration is already present at birth, whereas in the South American species there is a categorically different, camouflaged pattern: bush duiker https://wildmoz.com/duiker/duiker-mother-and-baby/ and https://www.mosselbayadvertiser.com/news/News/General/86444/Excitement-over-new-baby-buck-in-reserve and https://zululandobserver.co.za/23104/narrow-escape-for-baby-duiker/ and https://www.facebook.com/crow.kzn/photos/meet-dayton-the-baby-grey-duiker-dayton-was-rescued-from-a-man-that-was-trying-t/713394638680888/ and https://twitter.com/sheldricktrust/status/773204220753227776 and https://bushsnob.com/2020/10/22/catalina/ vs gray brocket https://www.inaturalist.org/observations/37914865 and https://www.inaturalist.org/observations/65432134 and https://www.worldlifeexpectancy.com/mammal-life-expectancy-gray-brocket and https://www.inaturalist.org/observations/68830653 and https://www.inaturalist.org/observations/68830286.

In summary: the gray brocket gives the impression of something of a 'living fossil' which has persisted in the relatively protected wooded environments of South America, emerging relatively recently into open vegetation. By contrast the bush duiker has long evolved with the most intense predation, including that imposed by humans and the domestic dog (Canis familiaris) - which it has a remarkable ability to outrun. It is so adapted to these pressures (including having a large brain for a ruminant) that it can actually increase its populations after human settlement has extirpated all other wild ruminants. Whereas the gray brocket looks relatively archaic, the bush duiker looks advanced evolutionarily.

Does this help to explain differences in appearance so great that they would seem to refute the idea of evolutionary convergence?

הועלה ב-אוגוסט 16, 2021 09:50 אחה"צ על ידי milewski