@tonyrebelo @jeremygilmore @botswanabugs @paradoxornithidae @matthewinabinett @capracornelius @tandala
...continued from https://www.inaturalist.org/journal/milewski/57747-the-bambis-part-6-a-selection-of-the-most-revealing-photos-of-klipspringers#
Tropical organisms often seem more colourful than organisms from the non-tropical latitudes (https://tomwhite.io/docs/dalrymple_et_al_2015_life_isnt_more_colourful_in_tropics.pdf). Think of coral reefs and Amazonian parrots.
We would not expect this trend to apply to ungulates, because neither the hoofed mammals nor the carnivores that hunt them can see hues such as red and green. For these animals, even browns may be effectively just shades of grey.
In the visual systems of ungulates and carnivores, the main sensitivity is to movement, not colour. And hues would be indiscernible at night anyway - even to the most light-sensitive eyes of nocturnal mammals.
So it is puzzling that two types of small antelopes in Africa seem more colourful in the tropical than in the non-tropical parts of their ranges, and that the patterns are convergent.
Bush duikers (Sylvicapra, https://wildlifesafari.info/duiker_common.htm) and klipspringers (Oreotragus, https://www.mindenpictures.com/stock-photo-klipspringer-oreotragus-oreotragus-adult-male-standing-on-rock-naturephotography-image80072538.html) are not particularly closely related to each other, but both range widely across sub-Saharan Africa. In both cases the fur is uniformly brownish at high latitudes in southern Africa, but differentiated into yellowish/reddish hues vs greyish in the tropics.
And in both cases the richer hues occur on the forequarters, whereas the greyish occurs on the hindquarters.
Sylvicapra:
https://www.inaturalist.org/observations/127329788
https://www.inaturalist.org/observations/95528820
https://www.inaturalist.org/observations/17353514
https://www.inaturalist.org/observations/86593063
Oreotragus:
https://www.alamy.com/stock-photo-klipspringer-on-rock-serengeti-tanzania-africa-103618837.html
Not only have Sylvicapra and Oreotragus converged with each other in this differentiation, but both have converged somewhat with a third, unrelated genus, namely Madoqua, which is restricted to the tropics.
Madoqua:
https://upload.wikimedia.org/wikipedia/commons/7/75/Damara_Dik-Dik.JPG
The hues seen in these antelopes are dull compared with other tropical organisms, but raise a puzzle nonetheless.
In all three genera, the overall colouration is adaptively inconspicuous, allowing the figures to blend into their environments.
In which ways does differentiation of reddish at the anterior of the figure vs greyish at the posterior of the figure help to disguise small antelopes - particularly in the bright light of the tropics?
One possibility is that certain birds - which see all the hues - are important predators for bambis.
I refer in particular to the martial eagle (Polemaetus bellicosus, https://en.wikipedia.org/wiki/Martial_eagle#Mammals).
See https://www.youtube.com/watch?v=ZwS-yGOc8UY and https://www.reddit.com/r/HardcoreNature/comments/hdl261/juvenile_martial_eagle_feeding_on_a_klipspringer/ and http://wildernessdiary.squarespace.com/eagles-kenya/martial-eagle-on-dik-dik-kill-09-10-october-2007/908168 and https://i.redd.it/d9sjsm1mtyw41.jpg and https://i.redd.it/ahfpga61lf851.jpg and https://africageographic.com/martial-eagle-with-impala-kill-2/ and https://www.flickr.com/photos/david_o/4036136915 and https://i.redd.it/975n8t4uqy141.jpg and https://www.youtube.com/watch?v=c1Mzko2wUuU and https://www.eveshamphoto.net/photo2017/authors/veronica_rice.htm and https://www.alamy.com/stock-photo-martial-eagle-polemaetus-bellicosus-with-killed-young-of-a-thomsons-59310018.html and https://www.kruger-2-kalahari.com/martial-eagle-takes-bushbuck.html and https://www.mediastorehouse.com/ardea-wildlife-pets-environment/dec2014/2/martial-eagle-impala-kill-10493024.html#openModal and https://www.classicafrica.com/News/newsView.asp?NewsId=40968592&CategoryID=49).
My hypothesis is that the patchwork of hues shown above acts as an element of disruptive colouration, reducing the conspicuousness of bambis to eagles.
to be continued in https://www.inaturalist.org/journal/milewski/70250-the-bambis-part-8-adaptive-colouration-in-grysboks-raphicerus-melanotis-and-raphicerus-sharpei#...
Comentarios
https://www.alamy.com/stock-photo-klipspringer-standing-on-a-rock-with-a-massive-baobab-tree-towering-119488728.html?pv=1&stamp=2&imageid=95C40148-F534-4FB1-94FA-D4327EC66934&p=220803&n=157&orientation=0&pn=1&searchtype=0&IsFromSearch=1&srch=foo%3Dbar%26st%3D0%26sortby%3D2%26qt%3DOreotragus%26qt_raw%3DOreotragus%26qn%3D%26lic%3D3%26edrf%3D0%26mr%3D0%26pr%3D0%26aoa%3D1%26creative%3D%26videos%3D%26nu%3D%26ccc%3D%26bespoke%3D%26apalib%3D%26ag%3D0%26hc%3D0%26et%3D0x000000000000000000000%26vp%3D0%26loc%3D0%26ot%3D0%26imgt%3D0%26dtfr%3D%26dtto%3D%26size%3D0xFF%26blackwhite%3D%26cutout%3D%26archive%3D1%26name%3D%26groupid%3D%26pseudoid%3D%26userid%3D%26id%3D%26a%3D%26xstx%3D0%26cbstore%3D0%26resultview%3DsortbyPopular%26lightbox%3D%26gname%3D%26gtype%3D%26apalic%3D%26tbar%3D1%26pc%3D%26simid%3D%26cap%3D1%26customgeoip%3D%26vd%3D0%26cid%3D%26pe%3D%26so%3D%26lb%3D%26pl%3D0%26plno%3D%26fi%3D0%26langcode%3Den%26upl%3D0%26cufr%3D%26cuto%3D%26howler%3D%26cvrem%3D0%26cvtype%3D0%26cvloc%3D0%26cl%3D0%26upfr%3D%26upto%3D%26primcat%3D%26seccat%3D%26cvcategory%3D*%26restriction%3D%26random%3D%26ispremium%3D1%26flip%3D0%26contributorqt%3D%26plgalleryno%3D%26plpublic%3D0%26viewaspublic%3D0%26isplcurate%3D0%26imageurl%3D%26saveQry%3D%26editorial%3D1%26t%3D0%26filters%3D0
A tendency for tropical forms to have hue-differentiation is also evident in hares (Lepus) in North America.
Lepus alleni, which occurs mainly in Mexico (https://upload.wikimedia.org/wikipedia/commons/6/68/Antelope_Jackrabbit_area.png), has patches of reddish, brownish, and greyish pelage (https://www.inaturalist.org/observations/9218510 and https://www.inaturalist.org/observations/9083061 and https://www.inaturalist.org/observations/24747561 and https://www.inaturalist.org/observations/36509677 and https://www.shutterstock.com/nb/image-photo/antelope-jackrabbit-biggest-all-north-american-1477694501 and https://www.alamy.com/stock-photo-an-antelope-jackrabbit-lepus-alleni-alert-for-danger-139269054.html).
Furthermore, the subspecies (Lepus alleni palitans) extending into the tropics is brighter-hued than the more northerly subspecies.
For comparison, see the plain colouration of Lepus townsendii (http://animal.memozee.com/view.php?tid=3&did=7293), which replaces L. alleni in the northern part of the USA (https://upload.wikimedia.org/wikipedia/commons/0/0e/White-tailed_Jackrabbit_area.png).
Please note that, as in the case of the bambis described above, the reddish hue occurs on the forequarters whereas the greyish occurs on the hindquarters.
Lepus in tropical East Africa:
https://www.inaturalist.org/observations/5183240
https://www.inaturalist.org/observations/19540140
https://www.alamy.com/stock-photo-close-up-view-from-side-of-african-hare-sitting-crouching-on-grass-59635760.html
https://www.alamy.com/close-up-view-from-side-of-african-hare-sitting-upright-on-grass-masai-image60125683.html
https://www.superstock.com/asset/african-hare-cape-hare-brown-hare-lepus-capensis-serengeti-national/1890-98636
https://www.inaturalist.org/observations/153489838
https://www.inaturalist.org/observations/153298862
https://www.inaturalist.org/observations/96045265
https://www.inaturalist.org/observations/108988695
https://www.inaturalist.org/observations/86703116
https://www.inaturalist.org/observations/75297147
https://www.inaturalist.org/observations/68922166
https://www.inaturalist.org/observations/35207312
https://www.inaturalist.org/observations/33834605
https://www.inaturalist.org/observations/9790788
https://www.inaturalist.org/observations/19225610
Lepus in South Africa:
https://www.inaturalist.org/observations/20367006
https://www.dreamstime.com/scrub-hare-natural-habitat-scrub-hare-lepus-saxatilis-sitting-natural-habitat-south-africa-image109094710
https://www.shutterstock.com/it/image-photo/scrub-hare-resting-shade-kgalagadi-transfrontier-2230142817
https://www.inaturalist.org/observations/162126892
https://www.inaturalist.org/observations/161458429
https://www.inaturalist.org/observations/156615460
https://www.inaturalist.org/observations/146451072
https://www.inaturalist.org/observations/142618351
https://www.inaturalist.org/observations/141964746
https://www.inaturalist.org/observations/140861707
https://www.inaturalist.org/observations/130518120
https://www.inaturalist.org/observations/126235713
https://www.inaturalist.org/observations/104017514
https://www.inaturalist.org/observations/93273216
https://www.inaturalist.org/observations/87319808
https://www.inaturalist.org/observations/79973212
https://www.inaturalist.org/observations/78188020
https://www.inaturalist.org/observations/71211493
https://www.inaturalist.org/observations/71241030
https://www.inaturalist.org/observations/65029120
https://www.inaturalist.org/observations/49330365
https://www.inaturalist.org/observations/35846952
https://www.inaturalist.org/observations/30850543
https://www.inaturalist.org/observations/19407001
https://www.inaturalist.org/observations/11080636
https://www.inaturalist.org/observations/10964330
Agregar un comentario