Retention of juvenile pelage into adulthood in black-backed jackal, as part of cooperative breeding?

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Summary:
Cooperative breeding occurs in C. mesomelas, in which young adults defer their own reproductive maturity, in order to help their parents raise the next litter. In such circumstances, is it possible that the helpers delay the full adult colouration, despite approaching mature body size?


I have described the normal colouration of the black-backed jackal (Lupulella mesomelas, https://www.canids.org/species/view/PREKN8360151), in https://www.inaturalist.org/journal/milewski/69677-adaptive-colouration-in-the-black-backed-jackal-lupulella-mesomelas#.

Small juveniles of the black-backed jackal are fairly plain, with a narrow tail (https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-two-cubs-at-the-den-kenya-masai-97237021.html?imageid=A0F723DF-4AB3-40EC-A5BC-B377040567D2&p=1142588&pn=1&searchId=59127445242fbde064768ecd70e333c1&searchtype=0 and http://www.wildlife-pictures-online.com/black-back-jackal_knp-0906.html and https://www.alamy.com/stock-photo-juvenile-black-backed-jackal-canis-mesomelas-watching-something-in-19194484.html?imageid=1C6A6B59-3128-4F09-8688-C77984DE95D4&p=11001&pn=1&searchId=59127445242fbde064768ecd70e333c1&searchtype=0 and https://www.dreamstime.com/two-black-backed-jackal-puppies-play-short-green-grass-to-develop-skills-their-image147640398 and https://www.dreamstime.com/lone-black-backed-jackal-pup-chewing-bone-green-grass-short-image147639672 and https://www.barewalls.com/art-print-poster/lone-black-backed-jackal-pup_bwc69406728.html and https://www.alamy.com/stock-photo-two-black-backed-jackal-puppies-standing-and-lyingin-roadway-124168510.html and https://www.bigstockphoto.com/image-372762946/stock-photo-black-backed-jackal-pup%2C-canis-mesomelas%2C%2C-side-view-masai-mara%2C-kenya and https://l7.alamy.com/zooms/9a0687c40e034b79b8a1144868966570/juvenile-black-backed-jackal-canis-mesomelas-standing-masai-mara-national-bfxx9t.jpg and https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-cubs-in-savannah-kenya-masai-mara-97234403.html and https://www.alamy.com/black-backed-jackal-canis-mesomelas-pup-walking-back-to-its-den-mashatu-game-reserve-tuli-botswana-image357538734.html).

However, this soon changes into adult pelage, with flank-banding and a bushy tail (https://www.inaturalist.org/observations/85339193 and https://www.inaturalist.org/observations/10842757 and https://www.inaturalist.org/observations/121595642). This applies to both subspecies.

This appearance seems consistent, for

  • both sexes,
  • adults of all ages, and
  • juveniles older than those illustrated above.

However, after many years of observing this species, I started to notice something odd (https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-standing-at-a-watercourse-running-58150065.html).

This is that some photos show adults with a combination of

  • no clear development of the flank-banding, and
  • a slender, as opposed to bushy, tail.

Once one forms a search-image for this anomaly, it can be spotted repeatedly, in photos on the Web. What we seem to have here is the colouration and pelage of small juveniles, retained through adolescence and into adulthood.

So, about five years ago, I asked Patricia D. Moehlman, an authority on the black-backed jackal, whether she had noticed this variation. She replied to say that she had not, the implication being that she had lacked a search-image for this.

Because this observation seems to be new, I present a representative sample of images in this Post, and I offer an explanatory hypothesis.

My explanation:

A capacity for cooperative breeding (https://en.wikipedia.org/wiki/Cooperative_breeding) occurs among various genera and species of canids.

This means that the offspring remain with their parents after reaching sexual maturity, instead of leaving to seek new territory for themselves. They help their parents to raise one or more new litters, by contributing to the guarding and provisioning of the infants and juveniles.

The black-backed jackal breeds cooperatively in some situations, despite the tendency for its social unit to be a pair rather than a group.

In all species of mammals and birds that breed cooperatively, it is expected that social maturity is delayed by hormonal means. However, in most such species, the development of the adult pelage/plumage and colouration is not delayed. The status of cooperatively breeding individuals can be detected by behavioural and physiological clues, but usually not by the retention of juvenile pelage/plumage.

In the case of the black-backed jackal, I hypothesise that, for some reason, juvenile pelage and colouration are indeed retained.

If so, this might constitute hormonally-based retardation of ontogenetic development, analogous to (but less extreme than) what is known in e.g. Pongo pygmaeus. (Pongo does not breed cooperatively, but shows extreme ‘suppression’ of secondary sexual features in the male, depending on the social context.)

Under circumstances in which the population is ‘full’, this strategy may buy time and experience for offspring which have little chance of finding a vacant spot in the habitat. The strategy is extremely well-known in many taxa of birds, but does also occur in a few taxa of mammals.

One way to test this idea, at least initially, would be to compare demographically different populations.

Where the black-backed jackal is persecuted on farms, breeding is likely to be at a maximum rate, and I would predict that all adults would show fully mature pelage and colouration.

By contrast, where populations are protected, I would predict that, as part of a reduced rate of reproduction, there should be a noticeable incidence of adults with juvenile pelage and colouration.

The following (https://www.primeugandasafaris.com/blog/black-backed-jackal-animals-uganda-uganda-safari-news.html and https://www.inaturalist.org/observations/8088430 and http://yathin.com/bphoto/2013/0112_00_bb_jackal.jpg and https://thumbs.dreamstime.com/t/black-backed-jackal-pair-grooming-male-being-groomed-female-using-her-long-teeth-to-get-rid-ticks-other-insects-80829547.jpg and https://thumbs.dreamstime.com/t/family-black-backed-jackals-canis-mesomelas-cub-sniffing-mother-serengeti-national-park-tanzania-34366058.jpg and https://www.alamy.com/black-backed-jackal-canis-mesomelas-standing-on-savanna-looking-at-camera-ngorongoro-crater-national-park-tanzania-image209732172.html) establish the early stage of growth by which the flank-banding and the prominence of the tail can appear.

It seems normal for the black-backed jackal that adult pelage and colouration are attained before adolescence.
 
However, adults sometimes lack the flank-banding and tail-fluffing, as if pretending still to be juveniles.
 
The variation in the colouration of adults can be explained in two possible ways:  either there is a colour-polymorphism in this species (i.e. a minor version of the complex colour-polymorphism seen in Vulpes vulpes), or there is an ontogenetic retardation in certain circumstances in which the development of the adult pelage and colouration is delayed owing to social factors.
 
In sparse or heavily predated populations of C. mesomelas, where vacancies continually appear in the territorial network, the hormonal ‘settings’ are such that juveniles promptly develop adult colouration, and then promptly leave their parents to find a territory of their own. In such situations, all full-size individuals will have the full pattern, including banding on the flank.
 
However, by the same hypothesis, where the territories tend to remain occupied because of limited mortality, juveniles experience a hormonal retardation of their maturity, in terms of both appearance and dispersal.

If sexually mature individuals remain with their parents for an additional year or more, retaining the relatively plain juvenile colouration may serve as a kind of 'uniform of appeasement'.

Under these circumstances the mature colouration (https://www.inaturalist.org/observations/98535093 and https://www.inaturalist.org/observations/93188463 and https://www.inaturalist.org/observations/114013895) may only appear at perhaps two years old, when the helpers finally ‘graduate’ to the adventures of dispersal, and go off to attempt to reproduce for themselves.

Has any phenomenon of this sort previously been recorded in any canid?

Wolves can breed cooperatively. However, I have not noticed anything anomalous about the appearance of adult helpers.

And I have certainly not noticed anything like this in Lycaon, which

  • is the most extreme example of all of cooperative breeding in canids, and
  • has no comparable ontogenetic shift in colouration, in the first place.

The following photos illustrate what I take to be ontogenetically retarded pelage and colouration in the black-backed jackal.
   
http://www.interestingfunfacts.com/files/2012/05/jackal.jpg
 
https://i0.wp.com/toonphotosafari.com/wp-content/uploads/2016/10/AMPJ106-Blackbacked-jackal-with-whitebacked-vulture.jpg?resize=900%2C600

http://toonphotosafari.com/?p=3848
 
https://i1.wp.com/www.mammalwatching.com/wp-content/uploads/AAAMammalwatching/Images/African/Namibia/2008-Black-backed-Jackal.jpg?resize=1024%2C725
 
https://cdn.shutterstock.com/shutterstock/videos/14646679/thumb/1.jpg?i10c=img.resize(height:160)
 
https://thumb9.shutterstock.com/display_pic_with_logo/401572/401572,1243090566,2/stock-photo-black-backed-jackal-30749842.jpg

https://thumb9.shutterstock.com/display_pic_with_logo/60660/60660,1219989116,2/stock-photo-alert-black-backed-jackal-canis-mesomelas-kalahari-desert-south-africa-16667041.jpg

https://s-media-cache-ak0.pinimg.com/originals/80/16/cf/8016cf06c8af75e4405c08a917aec2a6.jpg
 
https://thumb1.shutterstock.com/display_pic_with_logo/1190102/194879480/stock-photo-wild-white-backed-vulture-bird-perched-on-an-eland-antelope-carcass-with-a-wild-black-backed-jackal-194879480.jpg
 
http://l450v.alamy.com/450v/c26c2y/stock-photo-of-a-black-backed-jackal-on-the-serengeti-savanna-c26c2y.jpg
  
https://s-media-cache-ak0.pinimg.com/736x/54/2d/c8/542dc83c6a04b9502789780a2c4557ed.jpg
 
http://www.kruger-2-kalahari.com/images/BBJ-DSC_0061.jpg
 
https://upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Black-backed_Jackal_Canis_mesomelas_in_Tanzania_3508_cropped_Nevit.jpg/800px-Black-backed_Jackal_Canis_mesomelas_in_Tanzania_3508_cropped_Nevit.jpg
 
https://visitstothepark.files.wordpress.com/2013/02/kalagadi-290.jpg

https://www.inaturalist.org/observations/41577425

https://www.inaturalist.org/observations/1980968

https://www.inaturalist.org/observations/130392599

https://www.inaturalist.org/observations/104281003

https://www.alamy.com/stock-photo-black-backed-jackal-trotting-canis-mesomelas-40130668.html?imageid=55FC77D5-1F72-42BA-BEB1-C5B510D591F0&p=34420&pn=1&searchId=59127445242fbde064768ecd70e333c1&searchtype=0

https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-tsau-khaeb-sperrgebiet-nationalpark-79497373.html

https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-golden-gate-highlands-national-36809771.html

https://www.alamy.com/black-backed-jackal-canis-mesomelas-kruger-national-park-south-africa-image355242372.html

https://www.alamy.com/black-backed-jackal-canis-mesomelas-kgalagadi-transfrontier-park-south-africa-africa-image179013438.html

https://www.alamy.com/stock-photo-black-backed-jackal-canis-mesomelas-with-dead-impala-masai-mara-park-111494893.html

https://www.alamy.com/a-black-backed-jackal-canis-mesomelas-drinking-water-kalahari-desert-image66899114.html

I can close this Post with two particularly nice photos, which happen to show Parahyaena brunnea together with L. mesomelas.

Adult colouration of L. mesomelas: https://image.jimcdn.com/app/cms/image/transf/dimension=1920x400:format=jpg/path/s42980ac6afc5c05d/image/idd655fdf182e261a/version/1486457893/image.jpg

Hypothetically ontogenetically retarded colouration in L. mesomelas: http://www.stepbystep.com/wp-content/uploads/2013/04/Difference-between-Hyena-and-Jackal.jpg

Posted on Σεπτέμβριος 04, 2022 1136 ΜΜ by milewski milewski

Σχόλια

Thank you for these articles. Very interesting indeed.

Αναρτήθηκε από botswanabugs πάνω από 1 χρόνo πριν

Interesting. May I suggest you also investigate the season in which the differences are recorded. Tails may well be bushier and pelage thicker (which has the effect of softening the patterns) in winter regardless of age or hierarchy?

Αναρτήθηκε από karoopixie πάνω από 1 χρόνo πριν

@karoopixie Many thanks for this helpful suggestion.

Αναρτήθηκε από milewski πάνω από 1 χρόνo πριν

Very interesting, thanks 👍

Αναρτήθηκε από henrydelange πάνω από 1 χρόνo πριν

Haltenorth and Diller (1980) states the following re growth and development in Lupulella mesomelas:

"Suckling period 8-10 weeks, then joins hunt with parents, leaving home finally at 2-2.5 months. Adult coloration at 3 months, fully grown at 8-10 months. Family breaks up at 6 months. SEXUAL MATURITY: at 6-8 months."

Αναρτήθηκε από milewski πάνω από 1 χρόνo πριν

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