Dillon Flint 14 Sept 2014
Topic: What caused the platypus to continue to lay eggs, develop a venomous component (and its purpose), and continue to survive today?
Warren, Wesley, et al. “Genome Analysis of the platypus reveals unique signatures of evolution.” Nature 453 (8 May 2008): 175-183. Web. 14 September 2014. <doi:10.1038/nature06936>
The platypus has always been known as an interesting animal due to its unique body structure. However, scientists have been attempting to classify for years. The animal lays eggs like a reptile, yet still has mammary glands for the underdeveloped young (175). Also, the monotreme has a venom delivery system unique to any types of mammals and sexually selective to males (175). Lactation has improved contrary to previous egg production, meaning milk has increased its nutrient benefit toward offspring (much different from just egg-laying animals) (178).
Whittington, Camilla, et al. ”Defensins and the convergent evolution of platypus and reptile venom genes.” Genome Research 18 (7 May 2008): 986-994. Web. 14 September 2014. <doi:10.1101/gr.7149808>
The platypus has been seen as a myth or made up animal differing from any other animal on earth. It has the capability to lay eggs and lactate. One special feature on this animal is its venom spur. Most people would see this as a defensive weapon, however, it has been observed most likely to serve as an offensive weapon to convey dominance during breeding season (987). Injection of venom has immediate pain and discomfort in humans and is not easily alleviated from most anesthetics (987). Platypus venom has independently evolved from reptile venom (991).
Veyrunes, Frédéric, et al. “Bird-like sex chromosomes of platypus imply recent origin of a mammal sex chromosomes.” Genome Research 18 (7 May 2008): 965-973. Web. 13 September 2014. <doi:10.1101/gr.7101908>
Monotremes have an extremely complex sex-determining gene complex dealing with 10 (5 X and 5 Y chromosomes). This has shown that their homology is more like a birds genetic mapping unlike previously reported to be like mammals (966). This means the divergence occurred 166 million years ago.
Ordoñez, Gonzalo, et al. “Loss of gene implicated in gastric function during platypus evolution.” Genome Biology 9: (15 May 2008): 1-11. Web. 14 September 2014. <genomebiology.com/2998/9/4/R81>
The absence of pepsinogen and gene encoding gastrin have been observed within the platypus genome which is similar to fish, therians, and chickens. Many things seem to distinguish the platypus from mammals and make it a mixture of many other species. One hypothesis is that the loss of the gastric genes have had an advantage against pathogens (which rely on high pH levels) (6). How could this be to bring them to higher survival rates. These small mammals have a mixture of species yet have selective advantage through some evolutionary traits.
Retief, Jacques, et al. “Evolution of the Monotremes.” Department of Medical Biochemistry 218 (7 September 1993): 457-461. Web. 14 September 2014. http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1993.tb18396.x/pdf
Much of the evolution of monotremes resembles closeness to birds. The sperm has grown in length much like birds and so do their reproductive characteristics. However, their soft fur and ability to lactate to feed the young resemble mammals, much of its reproduction is similar to birds. The protamine P1 genes have unique similarities and allow for the relationships between eutherian mammals, marsupials, and birds to be observed.
Suggestions, Citations, and Edit
Edit plus citation https://en.wikipedia.org/wiki/Platypus_venom "which secrete venom that is only seasonally active to breeding season, supporting the theory that the use of venom is for competition of mates only, not protection. While the spur remains out of breeding season, the platypus's venom gland lacks secretion" </ref>Whittington, Camilla, et al. ”Defensins and the convergent evolution of platypus and reptile venom genes.” Genome Research 18 (7 May 2008): 986-994. Web. 14 September 2014. <doi:10.1101/gr.7149808></ref>
And my 3 suggestion occurred on the main page: https://en.wikipedia.org/wiki/Talk:Platypus Mating and Venom[edit] Could anyone further explain how the venom actually affects platypus to platypus contact? I realize it states that venom production increases during mating season but how does the venom affect each other apart from other small animals?
How is reproduction achieved? I have read up on the echidna, and they have four penises for reproduction (only two ejaculate on opposing sides while alternating during mating).[1] Since monotremes are one break away from echidna, how does the platypus mate?
Mating season seems to be concrete; however, I have found an article where individual adult females breed randomly throughout the mating season. Would this be able to enlighten reproductive success?
Flint.39 (talk) 16:33, 1 October 2014 (UTC)Dillon Flint Over the past couple of weeks, I have been hoping for a response or some sort of suggestion to the questions I posted and the change that I have made but nothing seems to be catching anyone's attention. I don't know what else I should do. Just providing some feedback upon waiting for something to happen. Flint.39 (talk) 01:16, 13 October 2014 (UTC)Dillon Flint
My additions to the platypus talk page can be seen here https://en.wikipedia.org/wiki/Talk:Platypus Flint.39 (talk) 01:35, 17 November 2014 (UTC)Dillon Flint