C h a n g e s i n S p e c i e s O v e r T i m e 1

Age of Earth Scientist believe that the Earth is 4.6 Billion years old. Evidence: Rock data, environmental changes 2 CLIP

Natural Selection Also know as “survival of the fittest. Only certain members of the population will survive and reproduce. Ones that are most suited to the environment. 3

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. 4

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. 5

Example: Peppered Moth  Two versions of the moth-  Black and peppered  During the industrial revolution on England  Population of moths changed 6

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Decent with modifications Overtime natural selection produces organisms that have different structures, established different niches, or occupy different habitats. Organisms that were once the same have now grown “apart” and have become different organisms. 8 These changes increase a species’ fitness in their environment.

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History James Hutton Propsed that he Earth is millions of years old. Thomas Malthus proposed that populations outgrew their food supplies, causing competition between organisms and a struggle for one species to survive against another Jean-Baptiste Lamark 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. 11

Lylle proposed that 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 emphasis was based on the idea of competition for resources as the main force in natural selection Charles Darwin Publishes “On the Origin of Species” 12

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" 13

From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world. In South America Darwin found fossils of extinct animals that were similar to modern species. On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America. 14 CLIP

15 Humans select and breed for certain traits. Examples: The largest hog, the cow that gives the most milk, or fastest horse. Artificial selection provides a model that helps us understand natural selection. People have been artificially selecting domesticated plants and animals for thousands of years. These activities have amounted to large, long-term, practical experiments that clearly demonstrate that species can change dramatically through selective breeding. Broccoli and brussels sprouts bear little superficial resemblance to their wild mustard relatives (left).

Evidence for Change Over Time Fossil Record –Fossils that show how the same organism looked millions of years ago. –Paleontology –Use rock layers –Isotope dating 16

17 Relative Dating

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Homologous structures Structures that have different mature forms in different organisms but have developed from the same type of tissue. 19

Homologous structures 20

21 Embryology –Early development of the organism

Stages of development p385 22

Vestigial organs –Organs or structures that do not seem to be used by the organism any longer. –They are usually reduced in size. 23

Vestigial Organs c 24

25 Genetics DNA sequences in organisms are close Sources of genetic variation in species: 1.Mutations 2.Gene Shuffling 3.Crossing over during meiosis

Speciation is the evolution of a new species that occurs when interbreeding happens, or when the production of fertile offspring is prevented. In the physical world, natural barriers form and cause the breakup of populations to form smaller populations. Volcanoes, sea-level changes, and earthquakes are a few examples of natural occurrences that affect populations26

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 year27

28 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. 29

Divergent Evolution Divergent evolution is the process of two or more related species becoming 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. 30

Convergent Evolution Convergent evolution is the emergence of biological structures or species that exhibit similar function and appearance but that evolved through widely different evolutionary pathways. examples include the multiple origins of wings (bats, birds) and eyes. 31

Coevolution Predators and their prey Parasites and their hosts Plant-eating animals and the plants upon which they feed 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. 32

 Evolution at the species level is called microevolution.  It results from genetic variation and natural selection within a population of organisms.  Macroevolution is evolution that occurs between different species. 33

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Evolution is the change in a species over time. 35

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Rates of Evolution 39

Gradualism & Punctuated Equilibrium Two ways in which the evolution of a species can occur. A species can evolve by only one of these, or by both. CLIP40 Species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.

41Gradualism Very gradually, over a long time... Over a short period of time it is hard to notice. 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. Change is slow, constant, and consistent. Punctuated equilibrium 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.

Resistance in Bacteria42 Read page p403.

Two main sources of genetic variation 1.Mutations 2.Genetic Shuffling 43

EOCT- It is important that you are able to explain how the concepts of genetics provide the basis for explaining natural selection and evolution. This will help you answer questions like this: What is the end result of natural selection? A increased number of offspring of a given phenotype that survive B changes in the frequency of alleles in a population C fossil formation through extinction D environmental changes of a habitat 44

Although the Arctic fox and the kit fox are closely related, they look very different because the individuals A acquired traits during their lifetimes that contributed to survival B with traits most suited to their environments reproduced most successfully C migrated long distances to environments that most suited their traits D passed on to their offspring acquired behaviors that were helpful 45

Fossils of Archeopteryx show that this animal had feathers, like a bird. It also had a bony tail, teeth, and claws on its wings, like a reptile. This fossil is evidence that supports the idea that A birds and reptiles have a common ancestor B birds have changed very little over 150 million years C reptile species are more advanced than bird species D reptiles are warm-blooded like birds 46

Horses and tapirs have a common ancestor, but now look very different. Horses now are grassland animals adapted for grazing on grass and shrubs. Tapirs are jungle animals that live in dense forests and eat fruit, leaves and aquatic vegetation. Which of the following led to the development of such differences in the two species? A selective breeding B convergent evolution C DNA hybridization D natural selection 47

Review CLIP48 Adaptation is the key concept in natural selection.

Adaptation is a key concept in natural selection. Natural selection can change the inherited characteristics in a population and possibly even result in a new species.

The environment affects the evolution of living things. House sparrows arrived in North America from Europe in the nineteenth century. Since then, genetic variation within the population, and selection in various habitats, have allowed them to inhabit most of the continent. House sparrows in the north are larger and darker colored than those in the south. Darker colors absorb sunlight better than light colors and larger size allows less surface area per unit volume, thus reducing heat loss—both advantages in a cold climate. This is an example of natural selection acting upon a population, producing micro-evolution on a continental scale.

Proposed by Charles Darwin, natural selection is the process by which organisms that are best suited to their environment survive and pass their genetic traits on to their offspring.