E v o l u t i o n i s : C h a n g e s i n O r g a n i s m s O v e r T i m e

Age of Earth Scientist believe that the Earth is 4.6 Billion years old. Evidence: Rock data, environmental changes “Isn’t Evolution Just A Theory? Clip

How did the theory of Evolution come about? James Hutton Earth is millions of years old. Thomas Malthus populations outgrew their food supplies, causing competition between organisms and a struggle for one species to survive against another Jean-Baptiste Lamarck believed that all life forms evolved and that the driving force of evolution was the inheritance of acquired characteristics. He believed that organisms changed due to the demands of their environment.

1831: Charles Darwin – voyage to the Galapagos Islands Lyell plant and animal species had arisen, developed variations, and then became extinct over time. He also believed that the Earth’s physical landscape changed over a long period of time. Alfred Russel Wallace competition for resources is the main force in natural selection Charles Darwin Publishes “On the Origin of Species”

Charles Darwin British Naturalist “I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection.” —Charles Darwin from "The Origin of Species"

CHARLES DARWIN *served as a naturalist on the HMS Beagle from 1831 to 1836 *found fossils of extinct animals that looked like modern animals *did most of his work on the Galapagos Islands CLIP

On the Galapagos Islands Darwin noticed many variations among plants and animals of the same general type as those in South America. clipclip Finches - noticed different shapes and sizes of beaks which fit the type of food each bird eats Tortoises - noticed different shaped shells which allowed for different neck movement based on the environment

Natural Selection Only the ones that are most suited for the environment will survive and reproduce and pass on their genes. Video Clip

If an organism reproduces, then the traits of that organism are passed to the next generation. Traits that are favorable for a certain environment become more prevalent within that population.

What if the environment changes? The organisms must adapt to the environment. Those that don’t adapt-die. This is a very slow process….does not occur over night…many generations must past before any change in the population can be seen.

Example: Peppered Moth *Two versions of the moth- 1.Black 2.Peppered During the Industrial Revolution pollution covered trees Population of moths changed

When the trees were normal, the black moths were easily seen by the birds, so there were more peppered moths that survived. When the trees were black, the peppered moths were easily seen by the birds, so there were more black moths that survived.

Decent with modifications Overtime natural selection produces organisms that have different structures, different niches, or different habitats. Organisms that were once the same have now grown “apart” and have become different organisms. These changes increase a species’ fitness in their environment.

Examples: The largest hog, the cow that gives the most milk, fastest horse, domesticated dogs. Darwin compared the processes of nature to … Artificial selection – aka- selective breeding Humans select and breed for most desirable traits. WOLF HUSKY Crab Clip

Evidence for Change Over Time 1. Fossil Record –Fossils that show how an organism looked millions of years ago. 2. Geographic Distribution 3. Comparative Anatomy and Embryology 4. Genetics & Molecular Biology How do we know evolution is happening? Clip

Relative Dating of fossils helps us to know how old organisms are and when they lived…

Homologous structures Structures that have different mature forms in different organisms but have developed from the same type of tissue.

Homologous structures

Embryology- study of early stages of development This may show that organisms had a common ancestor.

Vestigial organs –Organs or structures that are no longer used by an organism. –They are usually reduced in size.

Vestigial Organs c

Sources of Genetic Diversity DNA sequences in organisms are close Sources of genetic variation in species: 1.Mutations 2.Gene Shuffling (Ex.immigration & emigration) 3.Crossing over during meiosis

Speciation the evolution of a new species when the genes in a population changes

Overtime they can change so much that they become unable to breed as they adapt to their environment. Speciation Mechanisms Behavioral Isolation –Populations are capable of interbreeding, but have different courtship rituals or other type of behavior. Geographic Isolation –Separated by bodies of water or mountains. Temporal Isolation –Reproduction takes place at different times of the year

Gene Pool Combined genetic information of a particular population. All the genes present with in a population Can change!

Changes in allele frequency with in a population Genetic drift Random changes in allele frequency that occurs in small populations Also know as the “founder effect” Populations may move into a new area and the alleles that carry with them will be passed on to their offspring.

Divergent Evolution when two or more related species become more and more dissimilar. The red fox and the kit fox provide and example of two species that have undergone divergent evolution. As they adapted to different environments, the appearance of the two species diverged. Example…Adaptive Radiation

Convergent Evolution Convergent evolution is when organisms have similar functions and appearance but that evolved through widely different evolutionary paths. EX: multiple origins of wings (bats, birds) and eyes.

Coevolution Predators and their prey Parasites and their hosts One example of coevolution is between plants and the animals that pollinate them. Coevolution is the joint change of two or more species in close interaction.

 Microevolution-Evolution at the species level  It results from genetic variation and natural selection within a population of organisms.  Macroevolution is evolution that occurs between different species.

Evolution is the ______ in a species over _____. REMEMBER!!!!!!!

Structural Adaptation Change in physical structure or anatomy EX: wings of a seagull TYPES OF ADAPTATIONS Physiological Adaptation Change in internal function or chemistry EX: having the proper enzyme to digest carbs Behavioral Adaptation Change in behavior that responds to environment EX: lay eggs in nests

Rates of Evolution

Gradualism Very gradually change, over a long time... Change is slow, constant, and consistent. Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. CLIP

38 change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals. Punctuated Equilibrium

LABEL each as gradualism or punctuated equilibrium GRADUALISMPUNCTUATED EQ GRADUALISM

Resistance in Bacteria39 Read page p403.

40