1. For your homologous traits provide the following information:
(a) I chose the Cat and the Dog as my homologous example because of their paws.
(b) The homologous trait in each of these species is of course, their paws. The cat however comes from the feline species while the dog comes from the canine species. Although it is noted that a big differences in these species is of course their size and bone structure, dogs are usually known to be much larger animals and cats usually always small and petite. Also you will notice that the dogs ears are sometimes bent and slumped over, while the cats never are. When it comes to their paws, cats use their nails to scratch at things and catch prey (i.e. mice, birds, etc) and they are able to climb up trees with ease, while the dog cannot.
(c) The ancestors of cats and dogs is most likely to have been linked to ancient "carnivoraformes" from millions of years ago. Fossils of teeth were discovered *1. (" Dormaalocyon’s teeth places it very close to the carnivoraforms’ evolutionary roots.) as well as samples of their vertebrates concluding it was a tree-hopper.
(d) Cat Paw:
Dog Paw:
Works Cited
*1. Francisco, Mikael Angelo. Cats and dogs had a common ancestor, and here it is. GMA Network. 15 January 2014. Web. 1 May 2014.
ANALOGOUS:
2. For your analogous traits provide the following information:
(a ) I chose the Turtle and the Snail as my analogous example because of their shells.
(b) Both of these animals have a shell that encompasses their bodies. I myself have two red-eared slider turtles and I am always curious as to their ancestor species. Turtles are considered reptiles while the snail is not. Snails seem to maintain a very small shape while the turtles can grow to be up to 200 lbs. Snails are classified as slugs and not reptiles but more on the non-shelled monopod, molluscs and annelids spectrum. The snail shell is secreted by specialized glands while the turtle shell is considered skin-like.
(c) My research has shown that earlier reptiles did not possess the shell, but was considered "Odontochelys semitestac". Turtles ribs have broadened over generations which have evoled from previous anatomicall structures, yet it remains one of the most fascinating things to zoologists. Snails have formed from the annelid worm ancestry. Perhaps the shells weren't evolved back then because the protection wasn't required and their muscles and vertebrates didn't evolve enough.
(d)
My own two red-eared sliders at home in fact:
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Snail Shell:
Hello,
ReplyDeleteI find it amazing that if we trace back millions of years ago we can find that dogs and cats share a common ancestor. This seemed to surprise me as much as discovering that dolphins were once land mammals that evolved into marine mammals. I learned something new by reading your post, I did not know what differentiated shells, in regards to the snail shell being concealed by specialized glands, as compared to the turtle shell is considered skin-like.
Cool turtles by the way!!
I usually recommend that you stay away from domesticated animals in these posts since they are nearly as much a product of artificial selection as they are natural selection. We want to know how nature has shaped organisms, not humans.
ReplyDeleteRemember that homologs do have a common genetic origin (as your example) but they also have distinct difference in structure and function as a result of different environmental pressures. I'm not sure I see them here and I'm inclined to consider the paws of these animals to be shared common traits, different mainly in size, not function or structure.
Claws would have been an interesting option to consider here as homologous traits. Claw structure is very different between dogs and cats due to their different function (primarily climbing in cats). Cats ability to unsheath and retract their claws is also unique.
Very good comparison of analogous traits. Yes, these are similar solutions to a particular selection pressure (needed protection against predation) through parallel evolution. And, yes, we also know that early reptiles did not have this shell. It is a unique derived trait of turtles and tortoises that evolved independently from the snail's development of it's own shell. Well done.