Phasianus

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Phasianus
Temporal range: miocene-Recent, 5.4–0 Ma
Pheasant.jpg
Mongolian ringneck-type common pheasant (P. colchicus) cock
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Subfamily: Phasianinae
Genus: Phasianus
Linnaeus, 1758
Type species
Phasianus colchicus
Linnaeus, 1758
Species

One or two, see text

The "typical" pheasant genus Phasianus in the family Phasianidae consists of at least one species. The genus name comes from Latin phasianinus "pheasant-like" (from phasianus, "pheasant").[1] Both Phasianus and "pheasant" originally come from the Greek word phāsiānos, meaning "(bird) of the Phasis".[2] Phasis is the ancient name of the main river of western Georgia, currently called the Rioni.

The common pheasant (P. colchicus) has about thirty recognised subspecies forming 5 or 6 distinct groups; one is only found on the island of Taiwan off the southern coast of continental China, and the rest on the Asian mainland, reaching west to the Caucasus. Some subspecies have been introduced to Europe, North America and elsewhere, where they have hybridized and become well established.

The three subspecies on the Japanese islands are usually treated as a distinct species, the green pheasant (P. versicolor), but some consider the Japanese birds to be part of the common pheasant complex, making thirty-three subspecies in total.

Fossil remains of a Phasianus pheasant have been found in Late Miocene rocks in China. Thus, like many other phasianid genera this lineage dates back more than 5 million years.

Sexual Selection[edit]

Phasianus pheasants are a harem polygynous species that are a highly sexually dimorphic genus, where males are large and elaborately ornamented with brightly coloured plumage, ear tufts, wattles, spurs, and long tails, compared to females that are non-ornamented with a dull cryptic plumage.[3][4][5] They have a polygynous mating system that is based upon males defending mating territories during breeding season in the early spring to control access to females with higher quality resources and defence against predation.[3][6][7] Females are free to move between different male territories, allowing them to benefit from indirect or direct benefits by choosing high quality mates and areas with better resources for her offspring.[7] Phanianus chicks are precocial so males provide no parental care for their young.[3][6][7]

A male's ornaments and weaponry are a symbol of status that allow females and rivals to examine a male's fitness and fighting ability.[3] During breeding season, males court females or challenge males by enlarging their sexual traits, sloping their body towards their opponent or mate while spreading their tail and plumage, inflating the wattle and raising their ear tufts.[7]. Older males usually have more exaggerated ornaments and weaponry than younger males, and are more likely to mate and control larger territories.[8] Submissive or juvenile males will conceal their wattle display from bigger males, reducing their chance of mating but minimizing their risk of injury by avoiding physical conflict with a more dominant male.[7] The general brightness of the plumage may also be used to identify healthy males from unhealthy males.[3] Only in cases where males exhibit similar characteristics, do males attack one another.[9]

To display these traits throughout breeding season entails a physiological cost, leading to an endurance rivalry between males, were only males that can afford to display these breeding rituals will pass over their offspring.[7][9] An example of this can be seen in the length of a male's spur and the wattle display that is enlarged during sexual displays, both are considered costly as they are highly dependent on nutrition and testosterone levels.[4][5][10][11][12] Females generally prefer brighter wattles and longer spurs.[4] The brightness in the wattle comes from storing a carotenoid pigment known as astaxanthin in their diet that is inhibited by an infestation of parasites.[4] Only healthy individuals in good physical condition can afford to fully express bigger and brighter wattles, which may also be associated with disease resistance.[4][12] Spurs function not only as weapons in combat between males but also as an important cue in female choice as the length of the spur signifies the males phenotypic condition (age, weight, size) and viability.[6][10] Studies have found that longer spurs resulted in bigger harem sizes compared to males with shorter spurs.[11]

Females will benefit from choosing males with higher expressed ornaments, as her offspring will also inherit these genes, increasing their survival and chance for reproduction (sexy son hypothesis).[7]

References[edit]

  1. ^ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 302. ISBN 978-1-4081-2501-4. 
  2. ^ Online Etymology Dictionary
  3. ^ a b c d e Mateos, C., & Carranza, J. (1997). Signals in intra-sexual competition between ring-necked pheasant males. Animal Behaviour, 53(3), 471–485. doi:10.1006/anbe.1996.0297.
  4. ^ a b c d e Ohlsson, T., Smith, H. G., Raberg, L., & Hasselquist, D. (2002). Pheasant sexual ornaments reflect nutritional conditions during early growth. Proceedings of the Royal Society B: Biological Sciences, 269(1486), 21–27. doi:10.1098/rspb.2001.1848. JSTOR 3068165.
  5. ^ a b Briganti, F., Papeschi, A., Mugnai, T., & Dessì-Fulgheri, F. (1999). Effect of testosterone on male traits and behaviour in juvenile pheasants. Ethology Ecology and Evolution, 11(2), 171–178. doi:10.1080/08927014.1999.9522834.
  6. ^ a b c Goransson, G., Von Schantz, T., Groberg, I., Helgee, A., & Wittzell, H. (1990). Male characteristics, viability and harem size in the pheasant, Phasianus colchicus. Animal Behaviour, 40(1), 89–104. doi:10.1016/S0003-3472(05)80668-2.
  7. ^ a b c d e f g Mateos, C. (1998). Sexual selection in the ring-necked pheasant: A review. Ethology Ecology and Evolution, 10(4), 313–332. doi:10.1080/08927014.1998.9522846.
  8. ^ Grahn M., & Von Schantz, T. (1994). Fashion and age in pheasants: Age differences in mate choice. Proceedings: Biological Sciences, 255(1344), 237–241. doi:10.1098/rspb.1994.0034. JSTOR 49943.
  9. ^ a b Mateos, C., Carranza, J. (1999). Effects of male dominance and courtship display on female choice in the ring-necked pheasant. Behavioral Ecology and Sociobiology, 45(3/4), 235–244. doi:10.1007/s002650050558. JSTOR 4601599.
  10. ^ a b von Schantz, T., Göransson, G., Andersson, G., Fröberg, I., Grahn, M., Helgée, A., & Wittzell, H. (1989). Female choice selects for a viability-based male trait in pheasants. Nature. doi:10.1038/337166a0. PMID 2911350.
  11. ^ a b Mateos, C., & Carranza, J. (1996). On the intersexual selection for spurs in the ring-necked pheasant. Behavioral Ecology, 7(3), 362–369. doi:10.1093/beheco/7.3.362.
  12. ^ a b Papeschi, A., & Dessì-Fulgheri, F. (2003). Multiple ornaments are positively related to male survival in the common pheasant. Animal Behaviour, 65(1), 143–147. doi:10.1006/anbe.2002.2013.