Evolution & Turtles

            Charles Darwin provided scientific evidence in the mid 1800’s about how different species evolved over time. Darwin's theory of evolution fundamentally changed the direction of future scientific thought, though it was built on a growing body of thought that began to question prior ideas about the natural world. The core of Darwin's theory is natural selection, a process that occurs over successive generations and is defined as the differential reproduction of genotypes. Darwin’s theory of natural selection was based on a process in which more desirable traits are systematically favored for reproduction. Natural selection focuses on the struggles of survival and reproduction. Natural selection requires heritable variation in a given trait, and differential survival and reproduction associated with possession of that trait. Only some of the organisms manage to survive, which allows for the more favorable traits to remain and the less favorable traits to disappear. Over time, through natural selection of the most desirable traits, the species begin to evolve. Evolution occurs as inherited traits change from one generation to the next. From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world. In South America Darwin found fossils of extinct animals that were similar to modern species. On the Galapagos Islands in the Pacific Ocean he noticed many differences among plants and animals of the same general type as those in South America. The expedition visited places around the world, and Darwin studied plants and animals everywhere he went, collecting samples for study. On his return to England in 1836, Darwin tried to solve the puzzle of how species evolved. He proposed a theory of evolution occurring by the process of natural selection. The animals or plants best suited to their environment are more likely to survive and reproduce, passing on the characteristics that helped them survive to their offspring. Gradually, the species changes over time. In 1859 Darwin published 'On the Origin of Species by Means of Natural Selection'. This book was a success immediately and helped to promote Darwin’s new theory, though it was met with some criticism

In our class we studied several different types of turtles. These turtles were the red-footed tortoise, box turtle, russian tortoise, yellow-footed tortoise, and mud turtle. Turtles are often referred to as turtles and tortoises with the difference being, that turtle refers to all the species, where tortoise is defined as any land-dwelling species. The box turtle has a domed shell, with yellow lines, and 3 claws on each hand. Also box turtles have a hinged plastron that can be shut completely to hide from predators. Mud turtles tend to have dull shell colors to help them blend into their habitat of damp and muddy dwellings. These turtles sometimes go into swamps or ponds, but rarely go in the water. Their diet consists of fish, worms, and insects. The Russian tortoise has sharp long digging claws and a dark shell with black spots. The red-footed tortoise has a dark skin with red scales and its shell is a dark color with some yellow spots. Their shells are also high domed and narrow to allow the turtles to move about in narrow openings in the forests. And the red-footed has no beak, just a short snout to eat grass. The yellow-footed tortoise is a close relative to the red-footed. The yellow-footed has dark skin with yellow scales and a wood colored shell. It also has nails for digging on dry land. These tortoises have large and strong shells to protect it from predators.