Showing posts with label sexual dimorphism. Show all posts
Showing posts with label sexual dimorphism. Show all posts

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...

Sunday, December 11, 2016

Dimorphism of Orchid Mantis

Often times the female in a species of an insect or spider tends to be larger than the male. This difference is attributed to the connection that the larger the female the more eggs it can produce. The orchid mantis is no exception to this difference in size between sexes, however the reason behind this difference might be the result of something other than an increase in the amount of eggs one can lay. It was discovered by Dr. Cleveland and some of his colleagues, who were looking at studies on mantis shape, DNA, and size of praying in order to revise their species classification and evolutionary history, that the orchid mantis was quite different from their close relatives. Instead of being small and camouflaged, the female orchid mantis was large and exhibited colors causing it stand out.


 This was later attributed to the fact that these early relatives evolved so that they could blend in with flowers and then prey on any pollinators who came over, eventually leading individuals to evolve to flat out mimic the flowers, so they could attract pollinators directly to themselves. The females continued to evolve in this way, getting bigger and exhibiting colors that made them stand out, while males evolved differently, favoring a small size and a color scheme that enhanced camouflage. It is interesting to see how certain organisms differ depending on the sex of the individual. I especially enjoy that the differences between male and female orchid mantises don’t stop on appearance alone. They also live completely different lives. The females on one hand act as more effective predators, while the male move around eating whatever they can catch while looking for a female.