The Theory of Evolution How did all of life on Earth come from a few cells? Simpson natural selection

Theory of Evolution Charles Darwin is credited with the development of the theory of evolution, but there were many people that contributed ideas upon which he built his own.

Theory of Evolution Darwin also developed his ideas based on his travels as the ship naturalist on the H.M.S. Beagle. Of particular interest to Darwin were the animals of the Galapagos Islands.

Theory of Evolution In 1859, Darwin and Alfred Wallace jointly proposed that new species could develop by a process of natural selection. The theory can be described as a process:

Hutton and Lyell Hutton- Earth has to be much more than a few thousand years GEOLOGIC FORCES- forces that shape the world ( rocks, mountains, valleys) Lyell Processes that shaped the Earth millions of years earlier continue in present Fossils of marine animals above sea level Influence?: If the Earth could change over time, might life change as well?

Thomas Malthus Essay on the Principal of Population- Malthus predicts that the human population will grow faster than the space and food supplies needed to sustain it What factor/factors determine which ones survive and reproduce, and which do not?

Lamarck's Theory Living things have changed over time 1809- hypothesis (1st to develop) Tendency toward perfection- continually changing and acquiring features that help them live more successfully in their environments Use and disuse- organisms could alter the size or shape of particular organs by using their bodies in new ways Inheritance of acquire traits- pass on traits to offspring Evaluation of hypothesis Did not know how traits are inherited Did not know that behavior has no effect on heritance

Natural Selection Natural Selection Variation of traits within the population leads to different phenotypes. Some variations are better suited to the current conditions of the environment.

Natural Selection Overproduction in populations leads to competition for limited resources (food, for example).

Natural Selection Natural selection favors the best suited phenotype at the time. This does not necessarily mean that those struggling die, but will be in a poorer condition

Natural Selection The survival (or better success) of the best adapted individuals leads to higher reproductive success. The variations will be passed on to the offspring Over time, if the environment does not change, those favorable variations will be seen more frequently in the population because nature has “selected” that trait.

Fill It In … Steps of Natural Selection: 1. 2. 3. 4.

Inherited Variation and Artificial Selection Inherited variation- differences that are passed from parents to offspring Larger fruits on plants; some cows give more milk Artificial selection- selection by humans for breeding of useful traits from the natural variation among different organisms Animal breeders used heritable variation to improve livestock and crops

Evolution Through Natural Selection The struggle for existence More offspring are produced that can survive to maturity Individuals compete for food, living space, and other necessities Some variations increase the change of survival and REPRODUCE

Natural Selection Central to the theory of natural selection is the idea of adaptations. An adaptation is any heritable trait that suits an organism to its natural function in the environment (its niche).

There are 3 basic types of adaptations: Examples of structural adaptations are defensive structures, camouflage, and mimicry. Typically, mimicry occurs when harmless species (mountain king snake) resembles a harmful species (coral snake) using coloration.

There are 3 basic types of adaptations: Examples of behavioral adaptations are herding, schooling, and growling.

There are 3 basic types of adaptations: Examples of physiological adaptations are enzymes, oxygen-binding of hemoglobin, and sight

Decent with Modification Principle that each living species descended with changes, from other species over time Look different from ancestors Implies that all living organisms are related to one another Common descent- principle that all species were derived from common ancestors “Tree of life” links all living things

Fill It In … A body-builder’s large muscles would NOT be an adaptation because …

Check Yourself! Who is credited with developing the theory of natural selection? List the four steps in the process of natural selection. What is an adaptation?

Check Yourself! Who is credited with developing the theory of natural selection? CHARLES DARWIN List the four steps in the process of natural selection. What is an adaptation?

Check Yourself! Who is credited with developing the theory of natural selection? CHARLES DARWIN List the four steps in the process of natural selection. VARIATION, OVERPRODUCTION, BEST SUITED IS FAVORED, & SURVIVAL OF BEST ADAPTED What is an adaptation?

Check Yourself! Who is credited with developing the theory of natural selection? CHARLES DARWIN List the four steps in the process of natural selection. VARIATION, OVERPRODUCTION, BEST SUITED IS FAVORED, & SURVIVAL OF BEST ADAPTED What is an adaptation? ANY HERITABLE TRAIT SUITS AN ORGANISM TO ITS NATURAL FUNCTION IN THE ENVIRONMENT