8D-(14/11/16)Natural selection(decent with modification) by Akarsh Sanjayan https://padlet.com/akarshsanjayan1/ui5h3kug9veh When Darwin visited galapagos islands, he found a species of tortoises, very similar to those found on the mainland. What explanation did he have for this? What does it mean with regard to evolution? en-us 2016-11-14 02:37:59 UTC 2017-02-01 10:11:43 UTC hello@padlet.com Tarasha DarπŸ† https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254861 Darwin thought this was the result of decent with modification, where the different varieties of species have come from one common ancestor. For example, the galapagos tortoise was different from the mainland tortoise, however they were very similar. The differences between the sub-species were made due to the environment difference. For example, one tortoise lived on land where the only nutrition came from cacti, and so they grew longer necks in order to reach the cacti. The other tortoise, who lived in a grassy area lived with a shorter neck as their nutrition came from the grass. 

Decent with modification takes place in on generation, but speciation is the same that takes place over many generations.

The differences were the modification caused.]]> 2016-11-14 02:40:33 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254861 meher https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254870 Darwin believed that the tortoise on the species had adapted to their environment, and had the same common ancestor. He said that even though the tortoises did have the same ancestor, they had all modified and changed so that they could survive in their particular home. This is called Descent with Modification. Even though the two tortoise had similarities and the same beginning (ancestors) , they both were still different, and this helped them survive in their environment. Descent with modification can lead to a helpful trait or a useless trait, but a trait that is useless to one may be helpful to another. An example being the tortoise on the island. He (or she) couldn't reach his (or her) food. They all need food to survive, so they stretched their necks so they could reach the food on the trees. This lead to their children naturally having longer necks. Obviously, the parents of this new long necked being didn't have the same beneficial trait, long necks, and wouldn't be able to survive. Descent with modification helped change this being so it could survive and get the proper resources for its survival in its home. The long necked mainland tortoise went to the island, because it was where it survived the best. The shorter necked tortoise stayed in the mainland because its features helped it survive better there. ]]> 2016-11-14 02:40:39 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254870 Ashna ashna_sehgal https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254871 Darwin found a species of tortoise on the Galapagos Island which were extremely similar to those found on the mainland. Only, these tortoises were completely adapted to all the conditions on the island. Seeing this, he came up with a theory that the mainland tortoises had some how landed on one of these islands and gone through variations and changes to adapt to their new surroundings and survive. But the drastic changes that the tortoise went through, completely changed their appearance and they could no longer be called the same species. This could originally be called descent with modification, but because of the drastic changes, it was almost like a whole new species had been created. This was called speciation.]]> 2016-11-14 02:40:41 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254871 vanshika https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254872 When Darwin visited the galapagos islands, he believed that both the galapagos and the mainland tortoises were results of descent with modification. This means that both the tortoises had the same ancestor, but because the two tortoises had been living in two different conditions, they had adapted to the environment, therefore they look different and have different features, and now are classified as two different species of tortoises. 

For example, some tortoises on the galapagos islands may have originally needed longer necks to reach plants and leaves so they can eat, but others on the mainland or even in the galapagos might not have needed longer necks because they live in areas with lots of grass for them to eat. This then led to the galapagos and the mainland tortoises reproducing children who were naturally born with traits that help them survive in their environment.]]> 2016-11-14 02:40:41 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254872 Gauri https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254881 Darwin's visit to the Galapagos islands brought together the conclusion that species have different variations so that they can adapt to different climates. On the island, he discovered that the same kind of tortoise resides on the mainland, they had a common ancestor. He believed that many years ago a tortoise from the mainland migrated to the island, there the conditions were different so the tortoises there over a period of time evolved into a very large tortoise, who's neck could stretch up to the cacti, so he could eat. Every new generation had slightly different traits. The more desirable traits persisted and undesirable ones died out. This resulted in a very different kind of tortoise living on the island as opposed to the one on the mainland.]]> 2016-11-14 02:40:51 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254881 sharanya https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254883 Darwin found the same species of tortoise on the Galapagos islands and on the mainland. Darwin's theory for this was that the two tortoises came from the same place (ancestor, descent with modification and speciation) but natural conditions made it move from the mainland to the islands, and from there after generations, the tortoises learnt to adapt to the environment they lived in (by adapting and giving the traits to their offspring and so on) 
He found a difference because the two environments were very different and even though the tortoises came from the same species, they learned to adapt, after generations of trying and developing traits to help them survive. 
Eg: there were cacti on the islands and the turtles there eventually got the trait of stretching their necks to grab the cacti from the plant. While on the mainland, there was a lot of grass so the tortoises there did not have to stretch their necks. ]]> 2016-11-14 02:40:52 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254883 Raheema Khan https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254892 When Darwin visited the Galapagos Islands he found a species of tortoise very similar to those on the mainland. Darwin believed that they evolved to adapt to their surroundings but they came from the same place. They have the same ancestors. Both the turtles had similar features but some differed to help it survive. 🐒🐒🐒

Descent with modification in order to survive where they are. The small changes can make a big difference in survival. 

Desirable πŸ‘ and non-desirable πŸ‘Ž traits. 

Examples:
Long Neck: To reach food from high branches. 🌴 
Short Neck: Food on the ground. πŸŒ±

]]> 2016-11-14 02:41:02 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254892 Sanjana https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254896 He realised that both these species of tortoises evolved from one same species, they have one same ancestor. In the past, as the species moved to different habitats, they evolved to have traits that specific to their environment. The tortoises had offsprings which had different, desirable traits, also known as descent with modification. The tortoises with the special traits were able to survive, and the ones that did not died out, creating a completely new species. Therefore, the species in each habitat are similar because they have the same ancestor, but have evolved through common descent to all have that help them survive where they live. ]]> 2016-11-14 02:41:04 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254896 Anjeel https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254909  When Darwin visited the Galapagos Islands and saw similar species of tortoises like those found on the mainland, he constructed a perfect explanation that scientists, humanists, ecologists and biologists now believe.

It was the theory of 'descent with modification' and the theory of 'common decent' , where one type of specie transports to one part of the world and over a few generations, their abilities modify. After the generations, they adapt to their surrounding, and their physical traits change- leading to speciation- when new and distinct species are formed.

Taking the tortoises for example: it is believed that there was one specific kind of tortoise, which somehow moved to the Galapagos Islands from the mainland. There was cacti on the island and after a few generations, the turtles evolved to get longer necks to reach the cacti.
Comparing, the Island Tortoise with the one on the mainland, they now look very different but this example highlights the Darwin's theories of: descent with modification, common descent, natural selection and speciation. Living beings always evolve.]]> 2016-11-14 02:41:11 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254909 Manya https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254942 When Darwin visited Galapagos he saw that the tortoise on the mainland and the tortoise on the island looked very similar. So they both came from the same ancestor but due to the surrounding they live in they adapted which changed them but still showed some similarity from the other island which showed decent with modification. The tortoise on the island had longer necks than the ones on the mainland as they had to reach tall trees to eat food to survive. So his theory is that all the species ascended from one being and then adapted in their own way and changed due to modification in their genes that is how all the species are there. His theory was the common decent. ]]> 2016-11-14 02:41:38 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254942 Vedant https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254945 Darwin observed that the tortoises on the island were similar to the tortoises to the mainland. He found out that the tortoises were fully adapted to the environment they were living in. He then realised that both groups of the tortoises had descended from the same species, but with some "modifications" or differing traits. The likely reason they evolved is because, they had to adapt to the environment they were living in for survival. In conclusion, the tortoises evolved as they needed to "survive" in the environment, therefore descending with modifications. For examples, the tortoises in the island evolved to having long legs so that they could stretch for the cactus. ]]> 2016-11-14 02:41:40 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254945 Shifa https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254969 Darwin was a naturalist and he observed that the tortoise on the Mainland and on another island had very similar traits or resembled each other. There he realised that this was due to decent with modification. He believed that physically one is born a bit vivid looking from their parents bit at the same time one has similar traits to their parents. To his notice he realised that both of the tortoise had the same ancestors. But they did not look completely alike as they were 'modified' a bit. It was evident that when the same type of animals live in the same type of environment they change so much to adapt to the surrounding that they change into something new. The point not to be overlooked is that the evolved so much for their survival that they descended with modification. 

They turtles had a few desirable traits-
The long necked turtles found it easier to grasp food from nearby trees.
The short necked turtles found it easier to find food from the grass growing on the land. 

He believed it was decent with modification, but actually it was common decent. ]]> 2016-11-14 02:41:54 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254969 Aarush https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254974 Upon arriving at the galapagos islands Darwin found a similar species of tortoise found on the mainland and he believed that these tortoise' had evolved from a common ancestor. Years before Darwin observed this the tortoise had moved form the mainland to the islands and thus his traits evolved to survive on that specific habitat. This is also known as decent with modification. He also stated that these changes did not occur immediately but took many generations to develop. These traits subsequent to its developing were convenient for factors such as camouflage for longer survival or longer necks to reach food on tall trees, these are called desirable traits.]]> 2016-11-14 02:41:59 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137254974 Noveera https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255002 When Darwin visited the Galapagos island he found them similar to the tortoises found on the mainland. He beloved that they have evolved from the common ancestor. His theory for this was that a turtle from randomly from the mainlands came to the island. They didn't look alike as they had evolved a bit, but they did have many common traits. His theory for this was that a tortoise randomly from the mainlands came to the Island. The tortoise had to adapt so much to adjust in the new environment, the tortoises there took many years to evolve to make a new specie. So in the new specie the tortoise had traits from both the mainland and the island. This is why Darwin found similarities between the two tortoise.  ]]> 2016-11-14 02:42:20 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255002 Nirav https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255071 After visiting the galapagos islands, Darwin found out that the species of Tortoises on that island were similar to those found on the mainland. According to him, eventually, both the tortoises must have belonged to the same family, but later, when some of the tortoises must have moved from the mainlands to other islands like the galapagos, some of their traits might have evolved to survive in the environment of that particular place, which is known as decent with modification. The tortoises that were successful in physically changing and could adapt were the ones that survived, while the ones which could not survive for that long and eventually died. For example, some tortoises evolved by having a long neck, so that they could stretch and reach heights to get food like cactus, which in turn helped them to survive.]]> 2016-11-14 02:43:12 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255071 David https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255222 Darwin was a Naturalist, and he traveled the world to study animals. He wanted to be the very best like no one ever was, and find out all he could about animals. He quite literally traveled across the land, and searched far and wide to understand animals and their behaviors. His travels then brought him to the Galapagos islands, where he found some tortoise. Surprisingly, these tortoise were very similar to the ones that he found on the mainland. Why? Well, he had an Idea. He stated that the tortoise from the mainland once traveled to the other islands. Because the climate on the other islands differ from the mainland, the turtles changed over a long period of time, and through every generation, a new change was birthed through decent with modification. Some titles died, and some had small changes that helped them survive. Over time, natural selection "selected" out the bad genes and new ones came, generally creating a new species of tortoise. What just happened was Speciation. Over time, each generation was different, changing over the generations to adapt to their environment, and natural selection would slowly pick off the ones who could not survive. Only the ones who's traits adapted to the environment survived.]]> 2016-11-14 02:45:06 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255222 Rhea https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255238 He believed that both, galapagos tortoises and the tortoises on the mainland had different traits but they were both came from the same species [ same ancestor ].  The tortoises living on the island had evolved to grow longer necks in order to reach the food [the cacti plant] whereas, the tortoises living on the the mainland had shorter necks since they feed on grass on the ground. He realised that this was a result of decent with modification. The change in the environment caused them to move to the island and in turn they adapted there. That is why they are found on the mainland and on the island. Basically, this means that there were two of the same species in the same environment and due to modification and attempt to survival thousand years later there were two different species that come from the same ancestor. ]]> 2016-11-14 02:45:25 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/137255238 akarshsanjayan1 https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/150778505 2017-02-01 10:11:43 UTC https://padlet.com/akarshsanjayan1/ui5h3kug9veh/wish/150778505