Onthophagus taurus
Onthophagus taurus. Museum specimen
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Scarabaeidae
Genus: Onthophagus
Species:
O. taurus
Binomial name
Onthophagus taurus
(Schreber, 1759)

Onthophagus taurus, the taurus scarab, is a species of dung beetle in the genus Onthophagus and the family Scarabaeidae.[1]

Illustration of a male (left) and a female (right)

Description

Onthophagus taurus can reach a length of 5.5–11 millimetres (0.22–0.43 in). These small beetles are oval shaped, the color is usually black or reddish brown. Sometimes the pronotum has a weak metallic sheen. Males have on the heads a pair of long protrusions or horns (hence the species name) that they use to fight with each other to gain mating rights with females.[2]

Some males do not have horns, and therefore do not come into the fight, but have larger gonads. A similar dimorphism in males have been found in some other species (Ageopsis nigicollis, Podischnus agenor). This adaption reduces direct competition with horned males.[3]

Horns of Onthophagus taurus lack obvious homology to other insect traits. Hence, they are known as an evolutionary novelty, even by the term strictest definition. The evolution and diversification of horns of this species are rooted in an intricate patchwork of extrinsic and intrinsic mechanisms[4] that involves parental effects, developmental plasticity, multiple internal pathways monitored by the doublesex (dsx) gene expression[5][6][7], the hedgehog gene expression[8] as well as the insulin/insulin-growth factor (IGF) pathway,[9] among numerous other elements.

Onthophagus taurus can pull a weight of 1141 times its own body mass and is considered the strongest animal on earth on a body weight to lift ratio.[10]

Distribution

This species is present in Australia, Europe, Morocco, Algeria, Tunisia, Syria, Iraq, Transcaucasia, Asia Minor, Iran, Afghanistan, Central Asia and USA (Texas).[11]

Sexual selection

A prominent feature of the mating system of O taurus is the competition for fertilisation of females by males engaging in trials of strength over the possession of breeding tunnels. Ionizing radiation applied to O. taurus males induced mutations that reduced the expression of such strength-related precopulatory sexual traits.[12] However, sexual selection by females for two generations was sufficient to remove such mutations from progeny.[12]

Economic value

Dung beetles have been utilized in the breakdown of manure on sheep and dairy farms worldwide.[13]

In September 2013 O. taurus was released for the first time in New Zealand, in the Gore District of Southland.[14] These beetles pull the manure into the ground to create their brood balls, which they use as egg chambers.

This increases grazing space for cattle, reduces habitats for flies and bacteria, and reduces the need for chemical fertilizers.[15]

References

  1. ↑ Onthophagus taurus Schreber, 1759. Retrieved through: Interim Register of Marine and Nonmarine Genera on 20 January 2019.
  2. ↑ Emlen, Douglas J.; Marangelo, Jennifer; Ball, Bernard; Cunningham, Clifford W. (2005-05-01). "Diversity in the Weapons of Sexual Selection: Horn Evolution in the Beetle Genus Onthophagus (coleoptera: Scarabaeidae)". Evolution. 59 (5): 1060–1084. CiteSeerX 10.1.1.133.7557. doi:10.1111/j.0014-3820.2005.tb01044.x. ISSN 1558-5646. PMID 16136805. S2CID 221736269.
  3. ↑ Eberhard, W. G. Beetle horn dimorphism: making the best of a bad lot The American Naturalist. — 1982. — Vol. 119, № 3. — P. 420-426.
  4. ↑ Beckers, Oliver M.; Anderson, Wendy; Moczek, Armin P. (March 2015). "A combination of developmental plasticity, parental effects, and genetic differentiation mediates divergences in life history traits between dung beetle populations". Evolution & Development. 17 (2): 148–159. doi:10.1111/ede.12117. ISSN 1525-142X. PMID 25801222. S2CID 30295437.
  5. ↑ Kijimoto, Teiya; Moczek, Armin P.; Andrews, Justen (2012-12-11). "Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns". Proceedings of the National Academy of Sciences of the United States of America. 109 (50): 20526–20531. Bibcode:2012PNAS..10920526K. doi:10.1073/pnas.1118589109. ISSN 1091-6490. PMC 3528601. PMID 23184999.
  6. ↑ Ledón-Rettig, C. C.; Zattara, E. E.; Moczek, A. P. (2017-02-27). "Asymmetric interactions between doublesex and tissue- and sex-specific target genes mediate sexual dimorphism in beetles". Nature Communications. 8: ncomms14593. Bibcode:2017NatCo...814593L. doi:10.1038/ncomms14593. PMC 5333360. PMID 28239147.
  7. ↑ Ito, Yuta; Harigai, Ayane; Nakata, Moe; Hosoya, Tadatsugu; Araya, Kunio; Oba, Yuichi; Ito, Akinori; Ohde, Takahiro; Yaginuma, Toshinobu (June 2013). "The role of doublesex in the evolution of exaggerated horns in the Japanese rhinoceros beetle". EMBO Reports. 14 (6): 561–567. doi:10.1038/embor.2013.50. ISSN 1469-3178. PMC 3674438. PMID 23609854.
  8. ↑ Kijimoto, Teiya; Moczek, Armin P. (2016-05-24). "Hedgehog signaling enables nutrition-responsive inhibition of an alternative morph in a polyphenic beetle". Proceedings of the National Academy of Sciences of the United States of America. 113 (21): 5982–5987. Bibcode:2016PNAS..113.5982K. doi:10.1073/pnas.1601505113. ISSN 0027-8424. PMC 4889385. PMID 27162357.
  9. ↑ Emlen, Douglas J.; Warren, Ian A.; Johns, Annika; Dworkin, Ian; Lavine, Laura Corley (2012-08-17). "A Mechanism of Extreme Growth and Reliable Signaling in Sexually Selected Ornaments and Weapons". Science. 337 (6096): 860–864. Bibcode:2012Sci...337..860E. doi:10.1126/science.1224286. ISSN 0036-8075. PMID 22837386. S2CID 31828080.
  10. ↑ ABC Science
  11. ↑ Catalogue of life
  12. 1 2 Almbro M, Simmons LW. Sexual selection can remove an experimentally induced mutation load. Evolution. 2014 Jan;68(1):295-300. doi: 10.1111/evo.12238. Epub 2013 Sep 6. PMID: 24372608
  13. ↑ Losey, John E.; Vaughan, Mace (2006). "The economic value of ecological services provided by insects". BioScience. 56 (4): 311–323. doi:10.1641/0006-3568(2006)56[311:TEVOES]2.0.CO;2.
  14. ↑ Media Release
  15. ↑ Nelson, Frank (October 21, 2011). "New Zealand imports foreign workers: dung beetles". Pacific Standard. Retrieved December 27, 2012.
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