Transcript Evolution
Theory of Evolution • Life on Earth, as well as the shape of Earth’s surface, has a history of change that is called evolution. • The evidence that organisms and landforms change over time is scientifically described using the following: 1. Theory of Plate Tectonics 2. Law of Superposition 3. Theory of Evolution Theory of Evolution • States that species change over time and that living things change in response to their environment. • The change results from a change in the genetic material of an organism and is passed from one generation to the next. Theory of Evolution • Charles Darwin is known as “The Father of Evolution” • His theory is the widely held notion that all life is related and has descended from a common ancestor. Darwin’s Finches • Darwin spent some time in the Navy and traveled to many places. • One of the places he traveled to was the Galapagos Islands where he observed several traits about the finches that lived there. • He observed finches with heavy, short beaks (good for pecking trees or seeds) and others with small thin beaks (good for capturing insects). Darwin’s Finches • These observations caused Darwin to wonder whether if the birds had evolved from similar species. • He eventually developed a hypothesis that accounted for the diversity he observed called natural selection. Natural Selection • In natural selection, members of a species that are best suited to their environment survive and reproduce at a higher rate than other members of a species. • 1. 2. 3. 4. Darwin based this idea on the following: Overproduction Variation Adaptation Selection Overproduction • When a species makes more than the environment can handle so that a good number have a chance of survival. Variation • Variation exists in the phenotypes (body structures and characteristics-physical traits) of the individuals within every population. • Phenotype can influence its ability to find, obtain and use resources (food, shelter, water) and might also affect its ability to reproduce. Adaptation • Any inherited trait that gives an organism an advantage in its particular environment. • Ex. A slight change in the shape of a tail fin might help a fish’s chance of survival by helping it to swim faster and avoid predators. Selection • Over time, more of the fish will have tails that are shaped differently and will survive to reproduce. • As a result, they will make up a larger part of the group. Changes in Environmental Conditions • Changes in an environment can affect the survival of individual organisms as well as entire species. • Organisms with characteristics that are well suited to the new environment are more likely to survive and reproduce at higher rates. Changes in Environmental Conditions • The alleles (genes) associated with favorable phenotypes (physical traits) increase in frequency and become more common and increase the chances of survival of the species. • Those trails will be passed on to their offspring. Diversity and Survival • Within a species, there is a variability of phenotypic traits leading to diversity among the organisms of the species. • The greater the diversity, the greater the chances are for that species to survive during environmental changes. Evidence Supporting Evolution • Evidence supporting evolution can be observed by looking at the following: 1. Vestigial Organs (organs that were fully developed and used by ancestors, but are smaller and unused in current species) Evidence Supporting Evolution • Similar Structures with Different Functions: many species have similar organs, but they have a different purpose in each species (ex. Bone structure in lizards, bats and manatees) • This similarity indicates that they shared a common ancestor at some point. Biological Classification • Biological classification is a system which is used to organize and codify all life on Earth (also called “taxonomy”) • This allows scientists to examine relationships between various organisms as well as the relationship between current and historical organisms.