Pick a science word and write the definition. Chapter 10 Bell work – 3 mins Pick a science word and write the definition. Chapter 10

Title of notes: Evolution p. 35, 36, & 37

I can describe Darwin’s Theory of Evolution. Learning target I can describe Darwin’s Theory of Evolution. Today I am… learning about the evidence that led Darwin to the Theory of Evolution. So that I’ll be able to… understand Darwin’s explanations for why species change over time. I’ll know I’ve got it when… I can write 1-2 sentences describing Darwin’s theory.

What is evolution? Change in species over time by which the process of biological change makes descendants differ from their ancestors.

What is evolution? Evolution is a scientific theory that essentially states species change over time. There are many different ways species change, but most of them are based on the idea of Natural Selection.

Book: The origin of species Charles Darwin (1809 - 1882) Darwin was a British scientist who set the foundations of the theory of evolution. Book: The origin of species

Darwin In 1831 Darwin sets sail on the HMS Beagle. In 1844 he writes his theory on the origin of species. In 1858, Darwin and Wallace publish their theories on evolution. Evolution means change over time.

History of Darwin’s Studies Darwin went on an around- the-world trip on the HMS Beagle and traveled to the Galapagos Islands. He particularly liked and observed the finches. He also observed the tortoises on different islands. He observed each different group had its own niche. He studied 13 different species and saw how they adapted to their environment. Galapagos Finches Video

An Ancient, Changing Earth In 1785 James Hutton proposed the Earth is shaped by geological forces that took place over extremely long periods of time. He estimated the earth is millions, not thousands of years old. Charles Lyell agreed and wrote a book in 1833 the explained the shaping of Earth’s geological features. He gave his book to Darwin before Darwin set sail.

Lamarck’s Evolution of Hypotheses In 1809 Jean-Baptiste Lamarck hypothesized that “simple” organisms emerge spontaneously and evolve to greater “complexity”. Lamarck’s hypothesis about acquired characteristics was disproved by Weisman, who concluded that changes in an individual during a lifetime do not affect its offspring. 3 principles to his theory: Organisms constantly strive to improve themselves. Most used body structures develop and unused waste away. A structure is modified by use or disuse, the modification is inherited to the offspring. (Inheritance of acquired characteristics.)

Origin of Species Darwin’s book, published in 1859, was a quick success. It came from the clear and understandable argument that natural selection and selective breeding of animals was in wide use at the time. There was a massive array of biological and fossil evidence to support the argument. Selective breeding: breeding of organisms to produce certain desired traits in their offspring.

Adaptations The adjustment or changes in behavior, physiology, and structure of an organism to become more suited to an environment.

Darwin relied on the similar anatomies of species to link them. Darwin’s evidence Darwin relied on the similar anatomies of species to link them. He also had some fossil evidence that showed slight changes in the body structure of the species over time, often leading to vestigial structures.

Closely related species diversify to new habitats. Divergent Evolution Closely related species diversify to new habitats.

Convergent Evolution Species of different ancestry begin to share similar traits because of a shared environment.

Parallel Evolution Two species evolve independently of each other, maintaining the same level of similarity.

Natural selection Random genetic mutations occur within an organism's genetic code and beneficial mutations are preserved.

Four Conditions must be met in order for natural selection to occur: 1.  Reproduction 2.  Heredity 3.  Variation in fitness of organisms 4. Variation in individuals and traits

Group discussion – What will happen in the following scenario? In a habitat there are red bugs and green bugs. The birds prefer the taste of the red bugs. What will happen to: Green bugs? Red bugs? , so soon there are many green bugs and few red bugs. The green bugs reproduce and make more green bugs and eventually there are no more red bugs.

Survival of the Fittest Individuals that are best suited to an environment (adaptations that enable fitness) survive and reproduce most successfully. Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species fitness in its environment.

Descent with Modification Over time, natural selection produces organisms that have different structure, establish different niches, or occupy different habitats. As a result, they look different from their ancestors. What do you think the common ancestor to tigers, panthers and cheetahs looked like? Common descent- all living and extinct organisms were derived from a common ancestor.

Structures Homologous Structures- traits that are similar in different species because the species share a common ancestor. Ie. Arm, fin and wing may have evolved from the forelimb of a common vertebrate. Vestigial Structures- inherited, but reduced in size and often unused. example: Pythons have hip and leg bones. Analogous structures- those that are similar in function, but are not inherited from a common ancestor. example: Insect and Bird Wings

Group discussion – What will happen in the following scenario? In an ecosystem, some giraffes have long necks and others have short ones. Over-grazing caused low-lying shrubs to die out. What will happen to: Short-necked giraffes? Long-necked giraffes? , so soon there are many green bugs and few red bugs. The green bugs reproduce and make more green bugs and eventually there are no more red bugs.

Evidence of Evolution 1. Fossil Record- layers of earth 2 Geographical distribution of living species- similar animals in different locations were the product of different lines of evolutionary descent. 3. Homologous structures 4. Similarities in early development (embryology) Darwin argued that living things have been evolving on Earth for millions of years.

Video – What is evolution? (8:52) https://www.youtube.com/watch?v=GhHOjC4oxh8