A new explanation for the hypercursoriality of the pronghorn (Antilocapra americana): selenium as a crucial micronutrient

The pronghorn (Antilocapridae: Antilocapra americana) is renowned for its extreme speed and endurance when running (https://www.youtube.com/watch?v=jR18k9c3MsE).

It is widely accepted that no animal on Earth exceeds the pronghorn in this combination.

Skeptical readers may perhaps suspect that the performance of the pronghorn my perhaps have been exaggerated.

However, the claims of speed and endurance are consistent with several other exceptional/extreme features, viz.

  • a consistent habit of opening the mouth while galloping,
  • long-range visual vigilance,
  • long-distance signalling by means of 'semaphoric' pale patches on the pelage, and
  • a lack - relative to other forms of 'plains game' - of displays of individual fitness to scanning predators.

All of the above add up to a syndrome of apparent 'hypercursoriality' in the pronghorn.

This syndrome seems incongruous, because the predatory regime in which the pronghorn lives is less, not more, intense than that pertaining to 'plains game' in Africa and Eurasia.

https://www.perplexity.ai/search/Compare-the-maximum-RVcPX3W1Q5GD5EbGMHJ5Vw

The long-range visual vigilance of the pronghorn is indicated partly by fully lateral placement of the eyes on the head, permitting the pronghorn to scan the horizon behind it as well as in front and to the sides.

However, this in itself hardly differs from 'plains game' in Africa and Eurasia.

What distinguishes the pronghorn are

  • extremely large eyeballs, both absolutely for a mammal and relative to body size, and
  • bony orbits that protrude from the skull laterally, to a degree possibly exceeding that in any other ungulate.

The long-distance signalling of the pronghorn is indicated partly by a conspicuously pale patch on the hindquarters (https://www.inaturalist.org/observations/211220855 and https://www.flickr.com/photos/189038430@N06/53350736417/in/faves-58287925@N05/ and https://pngtree.com/freebackground/pronghorn-antelope-buck-antlers-hunting-pronghorn-nature-photo_4107882.html).

However, various other forms of 'plains game' have comparable features of colouration.

What is extreme in the case of the pronghorn is

The limited incidence of displays of individual fitness in the pronghorn is not categorically different from various 'plains game' in Africa. For example, Damaliscus spp. tend not to stot, despite being extremely cursorial among Bovidae.

However, what is odd in the case of the pronghorn is that

  • stotting, to the extent that it occurs among adults, is displayed mainly sociosexually, rather than to potential predators,
  • 'style-trotting' is rather poorly-developed, and
  • neither stotting nor proud-trotting occur in juveniles, even while playing.

This raises the question:

Selenium:

https://www.horizons-mag.ch/2017/04/03/the-world-map-of-a-trace-element/

https://www.researchgate.net/figure/Selenium-distribution-and-availability-in-regions-of-the-continental-United-Sates-Panel_fig3_228832815

https://extension.uga.edu/publications/detail.html?number=B1390&title=selenium-in-georgia-soils-and-forages-importance-in-the-livestock-industry

https://drkhorsesense.wordpress.com/2021/03/11/lose-your-fear-of-selenium/

https://poisonousplants.ansci.cornell.edu/toxicagents/selenium_map.html

https://pubs.usgs.gov/publication/70006713

https://meridian.allenpress.com/jwd/article/32/1/9/121989/TOXICOLOGIC-EVALUATION-OF-A-HIGH-SELENIUM-HAY-DIET

https://customequinenutrition.com/blogs/nutrients/selenium-101

https://www.researchgate.net/figure/Indicators-of-environmental-selenium-status-for-the-USA-Selenium-rich-environments_fig2_40455792

https://bioone.org/journals/journal-of-zoo-and-wildlife-medicine/volume-32/issue-3/1042-7260_2001_032_0373_PCDIHR_2.0.CO_2/PRESUMPTIVE-COPPER-DEFICIENCY-IN-HAND-REARED-CAPTIVE-PRONGHORN-ANTILOCAPRA-AMERICANA/10.1638/1042-7260(2001)032[0373:PCDIHR]2.0.CO;2.short

https://link.springer.com/article/10.1007/s10344-012-0645-z

https://www.pharmanord.com/history-of-selenium-research

Posted on April 23, 2024 03:45 AM by milewski milewski

Comments

The white panel on the flanks of the pronghorn is less conspicuous than the acetabulo-ischiopygal bleeze when the figure is standing.

However, the converse is true when the figure is lying, in sternal procumbency.

https://www.inaturalist.org/observations/210624355

https://www.inaturalist.org/observations/211132956

https://www.inaturalist.org/observations/206866146

Posted by milewski 3 months ago

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