Sunday, February 5, 2012

Evolutionary Background



The platypus is a semi-aquatic animal found uniquely in Australia and Tasmania. Although it is classified as a mammal, it is deemed a monotrome, which refers to a mammal that lays eggs. Its family is Ornithorhynchidae and its genus is Ornithorhynchus; both of which the platypus is the only member, meaning that there are no other representatives in the platypus family or genus! In fact, up until 2008, the platypus genome remained largely a mystery to the scientific community. The platypus, which possesses both reptilian and mammalian features, is officially classified as a mammal. Scientists have been very interested in decoding this particular mammal’s genome and discovering its evolutionary history because it is able to give us a unique insight into how mammals could have potentially come to develop their particular traits.

Fortunately a study published in the journal Nature was able to unravel some of the mystery surrounding this unique mammal’s genome.  The study’s analysis found that the platypus evolved into the first “offshoot of the mammalian family tree.” (National Geographic News) This means that the platypus’ genes possess unique information about the period of time when reptiles evolved into mammals. One of the interesting discoveries made in this study is that the platypus actually possesses the genes responsible for lactation even though they do not give live birth, but rather lay eggs. The implication of this discovery is in fact quite large because it tells us that lactation actually evolved long before giving live birth did!

While the platypus is completely unique in its family and doesn’t have any close relatives persay, there are four species of Echidnas (Spiny Anteaters) that are also monotremes and could therefore be considered a close relative to the Platypus because of their unique characteristic of laying eggs while still being classified as mammals.


FUN PLATYPUS VIDEO OF THE WEEK!!: http://www.youtube.com/watch?v=2PA_3zRIS54




2 comments:

  1. It is quite amazing to see an almost "evolution in process" species that is relevant to the gradual evolution in the mammalian class. The platypus being an organism that can adapt to both aquatic and land environments provides an excellent example for a multidimensional animal that demonstrates both reptilian and mammalian characteristics. In relevance to the questions in class regarding our human uniqueness, this animal is truly one of the most unique in the animal kingdom.
    An article I found in the New York TImes (http://www.nytimes.com/2008/05/08/science/08platypus.html) explained how the platypus lineage diverged approximately 166 million years ago. Also, contributing to the previous post, although these animals contain mammalian characteristics such as lactation they do not possess nipples. They instead nurse from the abdominal skin. What I found particularly interesting (and so did the author) was that the Platypus contains highly advanced odor sensory receptors, which they believed were beneficial in mating and navigation for hunting in aquatic environments. I liked the video and enjoyed the post!! The platypus is truly an amazing animal. Keep it up.

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  2. This animal really is fascinating. It is like many different types of animals all rolled into one. I wonder if somewhere down the line the species will evolve (like the rest of today's mammals) to give live birth since it is already beginning to develop certain characteristics of mammals such as lactation. I like Mike's classification of the platypus as an "evolution in process". I think that's very accurate! This animal will be interesting to study for many years to come.

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