Monday, February 11, 2019

Half-Male, Half-Female

An article in the NY Times, A Rare Bird Indeed: A Cardinal That's Half Male, Half Female, discusses the phenomenon of half-male, half-female cardinals. Not much is known about the occurrence, however, the sex split is reported among birds, reptiles, butterflies, and crustaceans. These such creatures are referred to as gynandromorphs. In cardinals, the distinction is more noticeable because the bird appears to be split right down the middle. This is because vertebrates develop in a bilaterally symmetrical manner. As a result, the cardinal resembles a male, scarlet-colored, on the side and a female, taupe-colored, on the other. Technically, each "side" of the bird would be the brother or sister of the other.

Female characteristics

Male characteristics 

Daniel Hooper, an evolutionary biologist at the Cornell University Lab of Ornithology, stated that "gynandromorphs could theoretically be created through the fusion of two developing embryos that were separately fertilized". It is also possible that the female produces an egg that possesses both copies of her sex chromosomes, Z and W, and then is fertilized by two separate sperms, each with a Z chromosome. In the bird species, females are represented by ZW and males by ZZ. However, scientists are still unclear on how an egg yields a progeny with both ZW and ZZ cells.

Additionally, the brain of the gynandromorphic cardinal is half-male, half-female. This lead scientists to wonder how this type of bird is able to learn, evaluate, and produce a bird song. This is because male songbirds have more neural connections than females in their brains in order to sing their complex tunes. Gynandromorphs are thought to be infertile. Some scientists have observed gynandromorphs pairing off with other birds of one distinctive sex. However, not enough research has been accomplished to determine whether the other bird was a mother or father or if the other bird would remain present for mating season. Birds only have functional ovaries on the left side, therefore, if a mixed bird was female on the left half, it could be possible for it to reproduce. Although. Dr. Hooper said that he would expect the offspring to be genetically conventional due to the fact that its egg cells would only have one sex chromosome.

More studies regarding gynandromorphs should be conducted because understanding this phenomenon could yield data to figure out why this occurs. In addition, more research could result in an answer to the question, can these mixed birds reproduce? These half-male, half-female cardinals have a unique appearance that could prove to be beneficial. The taupe color could provide camouflage from predators, while the signature red color could attract the right eyes. Maybe being different is not a bad thing...

1 comment:

  1. This is so neat!. Especially since the bird is showing a laterally divided presence of both male and female phenotypes. If the birds are said to be sterile I wonder when they were observed pairing up with other birds if there was a specific sex that these gyandromorphs were pairing with.