Evolution and the Meaning of Change PDF

Timeline of Earth  What do you wonder about the new unit? Things to think about…. ⚫ How has the Earth changed over time? ⚫ Do organisms change? How? In what ways? ⚫ Are changes in organisms passed on from generation to generation? The history of the world in 4 minutes https://www.youtube.c...

Timeline of Earth  What do you wonder about the new unit? Things to think about…. ⚫ How has the Earth changed over time? ⚫ Do organisms change? How? In what ways? ⚫ Are changes in organisms passed on from generation to generation? The history of the world in 4 minutes https://www.youtube.com/watch?v=hryoONc4Pgo What inferences can you make?  What is Evolution? ⚫ Biological evolution is: ⚫ the scientific theory that states that living things have diverged from shared ancestors ⚫ the idea that the universe has a history and that change over time has taken place ⚫ Scientists have questions, and often disagree about the patterns and processes of evolution (ie. “how” evolution occurs), but do not call into question “whether” evolution has occurred What is Evolution - https://www.youtube.com/watch?v=GhHOjC4oxh8 4 billion years of evolution in 6 minutes https://www.youtube.com/watch?v=XyTcINLKq4c Science Career https://www.youtube.com/watch?v=OUMPG_hWrek&feat ure=emb_logo  Changes during a lifetime Development: are physical changes that occur during an individual’s lifetime 🡪 they result from ‘growth’ or the natural ‘aging’ process 🡪 cosmetic alterations and accidental scars are non-inheritable changes Newborn Adult Advanced Age Adaptations ⚫ There are 3 processes that help an organism survive and reproduce 1. Structural 2. Behavioural 3. Physiological Let’s look at penguins!! Where do penguins live? Structural Adaptations: 🡪 A feature of an organism’s body that helps it to survive and reproduce Penguins have a short, stiff tail so they can lean backwards and balance on their heels and tail. This reduces heat loss from their feet to the ground. How is their colouring (black back, white belly) a structural adaptation?? Behavioural Adaptations: 🡪 they are part of the ‘learning’ process; to survive and/or live in comfort 🡪 memory is non-inheritable, that is why every newborn has to be ‘educated’ Penguins huddle together during the winter. This helps them avoid heat loss and survive until spring. They breed during the winter so that their offspring reach independence in summer when there is more food. https://www.youtub e.com/watch?v=6AiC IZ9wM1o  Other behavioural adaptations swinging exploring or using (commuting) grooming or tool socializing examining unfamiliar food source caring for offsprings washing food Physiological process Adaptations: 🡪 A body process that helps an organism to survive and reproduce Male penguins can go without food for about 100 days! This allows them to survive during winter when food is scarce. A penguin’s resting heart rate can slow down during a dive so that it can conserve oxygen underwater and spend more time finding food. How do these adaptations arise in a population?  What is the original source of Genetic Variation? ⚫ Mutations!! ⚫ Mutations create new versions of genes (alleles) that provide a continual supply of new genetic information ⚫ Mutations have an immediate and direct effect on individuals and have the potential to influence future generations when mutations are inherited  Changes between generations Evolutionary Change: when inheritable traits of a species population are different 🡪 i.e. When an individual obtain a derived (new) trait due to random mutation AND this trait is favourable for it survival. Because this trait is favourable, the individual survives and reproduces. The trait therefore gets passed down to the next generation and next. This results in more individuals of the same species having this trait. So when you compare the before-having-the-trait & after-having-the-trait populations of this species, they are different! Original Flower population flower population generations after Trait helps pollinate faster  Types of Mutations ⚫ NEUTRAL: mutation does not benefit or harm the individual’s chance of survival or reproduction ⚫ Lactase is an enzyme that helps infants break down lactose, a sugar in milk. Normally the gene that codes for lactase is active in babies and then turned off at about age four. When people who don't make lactase consume milk, they experience gas, nausea, and discomfort. But some people have a mutation in a genetic switch that keeps the lactase gene active. This variation caused by a mutation is called "lactase persistence," and people who have it can keep milk in their diets even as adults. http://learn.genetics.utah.edu/content/variation/mutation/ ⚫ HARMFUL: reduces the reproductive success of an organism ⚫ Mutation of HHT gene (provides instructions for making protein that plays a role in nerve cells) can cause Huntington’s Disease ⚫ BENEFICIAL: increases the reproductive success of an organism (give individuals an advantage) ⚫ Sickle cell allele gives carriers resistance to malaria and enhances chances of survival in regions where malaria is endemic  Changes between generations Evolutionary Adaptation: when a mutation is favoured by the environment 🡪 Mutations produce heritable changes in individuals, called derived (new) trait. 1. This trait can be harmful to the individual in a given environment leading to the loss of trait within the species population (gene pool) Trait colour cannot be recognized, so no pollination 2. This trait can be neutral to the individual in a given environment leading to a sustenance of the trait within the species population, but with low frequency (a low number has it) Infrequent pollination 3. This trait can be favourable to the individual in a given environment leading to a spreading of the trait via reproduction within the species population (high frequency) Trait colour attracts bees effectively so lots of pollination Mutations and the Environment ⚫ The impact of a mutation also depends on the environment in which it is expressed ⚫ The same mutation can be harmful in one environment, neutral in another, and beneficial in still another ⚫ Example: ⚫ A mutation in the gene that codes for one part of the hemoglobin molecule can cause considerable damage and discomfort at extremely high altitudes, but cause no problems at all at sea level. ⚫ Other mutations may not become harmful to an individual unless he or she is exposed to a toxic chemical, carcinogen, allergen, or a specific environmental agent that acts on a genetic susceptibility. ⚫ Beneficial mutations include those that have allowed our species to acquire new, adaptive structures and functions during evolutionary history (e.g. opposable thumbs, binocular vision). There would be no evolution in any species without the genetic variation produced, in part, by mutations! Adapted from: http://www.nchpeg.org/dentistry/index.php?option=com_content&view=article&id=22&Itemid=55&limitstart=3  Life after Chernobyl Life after Chernobyl ⚫ On morning of April 26, 1986 reactor # 4 steam explosion due to flawed design and inexperienced workers ⚫ 237 people suffered acute radiation sickness (ARS) ⚫ 28 deaths within 4 months from high exposure; 7000 cases thyroid cancer ⚫ Radiation is most damaging to actively dividing cells (skin, hair follicles, bone marrow, gastrointestinal tract) so vomiting, hair loss common symptoms of ARS Natural Selection at work - https://www.youtube.com/watch?v=YCd5XUeTglQ