Gynandromorphism is the phenomenon that occurs when an individual organism possesses both male and femalephenotypes due to genetic chimera of sex chromosomes in cells across the body and is most easily recognized in species that display sexual dimorphism.[1] An individual who displays this characteristic is called a gynandromorph. The term comes from the Greek γυνή (gynē) 'female', ἀνήρ (anēr) 'male', and μορφή (morphē) 'form', and is most commonly documented the field of entomology.[1] The definition of “gynandromorphism” is distinct from both intersexuality and hermaphroditism, although they are sometimes used interchangeably.[2]
Pattern of distribution of male and female tissues in a single organism
Several patterns of tissue distribution occur amongst observed gynandromorphs. Patch-like patterns may arise, but commonly the phenotype presents in a symmetrical pattern, of which there are three main types: bilateral, oblique, and transverse.[2] Bilateral describes an organism that is split laterally with one side possessing female characteristics and the other having male characteristics. Oblique refers to a diagonal line across the sagittal plane that separates the male and female phenotypes. Lastly, transverse is a separation of male and female phenotypes along an axis that intersects with what would be considered the primary axis for the body of a given organism.[2]
A notable example in birds is the zebra finch. These birds have lateralized brain structures in the face of a common steroid signal, providing strong evidence for a non-hormonal primary sex mechanism regulating brain differentiation.[28]
The exact cause for gynandromorphism is unknown, and appears to vary by species.[1] One proposed cause for the phenotype in birds is a disruption that occurs in meiosis in female birds -- who possess ZW chromosomes -- in which polar bodies are not forced out of the cell.[29] This is then followed with fertilization by two Z-bearing sperm cells which creates cells in the embryo containing both ZZ and ZW chromosomes.[29] The same phenomenon can be seen in other species, such as Drosophila melanogaster, and creates a genetic mosaic which gives rise to the mixed phenotype.
As a research tool
Gynandromorphs occasionally afford a powerful tool in genetic, developmental, and behavioral analyses. In Drosophila melanogaster, for instance, they provided evidence that male courtship behavior originates in the brain,[30] that males can distinguish conspecific females from males by the scent or some other characteristic of the posterior, dorsal, integument of females,[31][32] that the germ cells originate in the posterior-most region of the blastoderm,[33] and that somatic components of the gonads originate in the mesodermal region of the fourth and fifth abdominal segment.[34]
↑ Labruna, M. B.; Ribeiro, A. F.; Cruz, M. V.; Camargo, L. M A.; Camargo, E. P. (August 2002). "Gynandromorphism in Amblyomma cajennense and Rhipicephalus sanguineus (Acari: Ixodidae)". Journal of Parasitology. 88 (4): 810–811. doi:10.1645/0022-3395(2002)088[0810:GIACAR]2.0.CO;2. PMID12197141. S2CID26299983.
↑ Morgan, T. H. (1 June 1914). "Mosaics and gynandromorphs in Drosophila". Experimental Biology and Medicine. 11 (6): 171–172. doi:10.3181/00379727-11-105. S2CID87401593.
↑ Maeno, Koutaro; Tanaka, Seiji (September 2007). "Morphological and behavioural characteristics of a gynandromorph of the desert locust, Schistocerca gregaria". Physiological Entomology. 32 (3): 294–299. doi:10.1111/j.1365-3032.2007.00573.x. S2CID85317122.
↑ Taniyama, Katsuya; Onodera, Kaori; Tanaka, Kazuhiro (December 2018). "Sexual identity and sexual attractiveness of a gynandromorph of the lawn ground cricket, Polionemobius mikado (Orthoptera: Trigonidiidae): Gynandromorph of Polionemobius mikado". Entomological Science. 21 (4): 423–427. doi:10.1111/ens.12321. S2CID91381517.
↑ Mitchell, Joseph C.; Fouquette, M. J. (10 February 1978). "A Gynandromorphic Whiptail Lizard, Cnemidophorus inornatus, from Arizona". Copeia. 1978 (1): 156. doi:10.2307/1443840. JSTOR1443840.
↑ Krohmer, Randolph W. (27 December 1989). "Reproductive Physiology and Behavior of a Gynandromorph Redsided Garter Snake, Thamnophis sirtalis parietalis, from Central Manitoba, Canada". Copeia. 1989 (4): 1064–1068. doi:10.2307/1446001. JSTOR1446001.
↑ Hollander, W. F.; Gowen, John W.; Stadler, Janice (February 1956). "A study of 25 gynandromorphic mice of the Bagg albino strain". The Anatomical Record. 124 (2): 223–243. doi:10.1002/ar.1091240207. PMID13302819. S2CID21938150.
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