Make a list of some characteristics that birds have that could provide information about their diets

Modern evolutionary theory began when Darwin presented evidence that evolution happens and offered an explanation of how evolution happens Darwin’s experience provided him with evidence of evolution at work Darwin was influenced by ideas from the fields of natural history, economics and geology

Evolution is the process by which species may change over time Modern evolutionary theory began when Darwin presented evidence that evolution happens and offered an explanation of how evolution happens Many scientists since Darwin have tested and added to his ideas. Most of Darwin’s ideas, including his main theory, remain scientifically supported

In Darwin’s time, most people did not think that living things had changed over time. Many doubted that Earth itself had ever changed. Darwin saw evidence of gradual change

The Voyage of the Beagle Darwin’s first evidence: gathered during a global voyage on a ship called the Beagle As a naturalist, Darwin collected natural objects from each place he visited. He also collected fossils and noticed that they were similar to, but not the same as, living things

The Voyage of the Beagle Darwin visited the Galapagos Islands in the Pacific Ocean Collected several different species of birds called finches Each of the finches are very similar, but differences can be seen in the size and shape of the beak Each finch has a beak that seems suited to the finch’s usual food

The Voyage of the Beagle Darwin noticed that many of the islands’ plants and animals were similar, but not identical, to the plants and animals he saw on South America Darwin proposed Galapagos species descended from species that originated in South America

The Voyage of the Beagle He suggested that all of the finch species came from one finch species that migrated from South America The descendant finches were modified over times as different groups survived by eating different types of food Darwin called such change descent with modification

The selective breeding of domesticated plants and animals

Population Growth Darwin simply applied the idea of human overpopulation to all populations A population is all of the individuals of the same species that live in a specific place Darwin saw that all kinds of organisms tend to produce more offspring than can survive. So, all populations must be limited by their environment

Geology and an Ancient Earth In Darwin’s time, scientists had interest in the study of rock landforms, and thus began geology Geologists study fossil and rock layers The fossils in rock layers showed differences in species over time and that many species from the past differed from those of the present

Geology and an Ancient Earth Most scientists and geologists thought that changes in the past occurred suddenly Others thought that geologic processes work gradually and constantly This fit well with Darwin’s observations and showed that Earth's history was long enough for species to have evolved gradually

French scientist Jean Baptiste Lamarck proposed an explanation for how organisms may change over generations Lamarck noticed that each organism was usually well adapted to its environment. He proposed that organisms change over time as they adapt to changing environments

Lamarckian Inheritance Changes due to use or disuse of a characteristic would be passed on to offspring and inherit these changes Lamarck had an incorrect idea about inheritance and this idea was eventually disproved

Modern evolutionary theory began when Darwin presented evidence and explained how evolution could occur Lamarck’s evidence for evolution seemed correct during his time, but it was later disproved

“Nothing in biology makes sense except in the light of evolution” -Theodosius Dobzhansky Journal #2: What do you think this quote means? What is your personal opinion about this quote? (Response must be a minimum of 5 sentences)

What beliefs do you more closely identify with Lamarck or Darwin? Remember responses must be at least 5 sentences. Having trouble? Review your notes, write out the beliefs both Lamarck and Darwin had then support your argument.

Explain how studying fossils can tell you how an organisms lived. Also, are you superstitious?

Darwin’s theory predicts that over time, the number of individuals that carry advantageous traits will increase in a population Darwin presented a unifying explanation for data from multiple fields of study

Every living organism has the potential to produce many offspring, but not all of those offspring are likely to survive and reproduce Darwin formed a key idea: Individuals that have traits that are better suited to their environment are more likely to survive and in turn produce more offspring

Natural selection is the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do Evolution is a change in the inherited characteristics of a population from one generation to the next

Steps in Darwin’s Theory Darwin’s theory predicts that over time, the number of individuals that carry advantageous traits will increase in a population This can be summarized in four logical steps

Steps in Darwin’s Theory Step 1: Overproduction Every population is capable of producing more offspring than can possibly survive Step 2: Variation Variation exists within every population. Much of this variation is in the form of inherited traits

Steps in Darwin’s Theory Step 3: Selection In a given environment, having a particular trait can make individuals more or less likely to survive and have successful offspring. So, some individuals leave more offspring than others do Step 4: Adaptation Over time, those traits that improve survival and reproduction will become more common

Selection and Adaptation Darwin’s theory explains why living things vary in form yet seem to match their environment Each habitat presents unique challenges and opportunities to survive and reproduce Each species evolves because of the “selection” of those individuals that survive the challenges or make best use of the opportunities

Natural selection can alter variation in a population in three ways: Stabilizing selection Favors intermediate phenotypes Directional selection Acts against individuals at one of the phenotypic extremes Disruptive selection Favors individuals at both extremes of the phenotypic range

Selection and Adaptation An adaptation is an inherited trait that is present in a population because the trait helps individuals survive and reproduce in a given environment Darwin's theory explains evolution as a gradual process of adaptation

Darwin’s book On the Origin of Species by Means of Natural Selection presented evidence that evolution happens and offered a logical explanation of how it happens Video

Is natural selection the same as evolution? Why or why not?

Journal #3: What beliefs do you more closely identify with Lamarck or Darwin? Journal #4: Do you think natural selection actually occurs in our world? Do you think it is the means by which organisms evolve?

Think about a dog or cat, compare their way of movement to yours. Compare the bone structure of your arms and legs compared to that of a dog or cat

Biogeography Biogeography is the study of the locations of organisms around the world Sometimes geography separates populations. For example, a group of organisms may become separated into two groups living on two different islands

Biogeography Species tend to be more closely related to other species from the same area than to other species within the same way of life but living in the same area Geologists and biologists have found that the movement of land in Earth’s past helps explain differences in living and fossil organisms

The Fossil Record You can infer past events by looking at fossils, traces of organisms that lived in the past

Anatomy Darwin helped explain differences in organisms through bodily structure, or anatomy Many internal similarities are best explained by evolution and are evidence of how things are related The hypothesis that all vertebrates descended from a common ancestor is widely accepted

Anatomy The forelimbs of many vertebrates are composed of the same basic group of bones

Anatomy This pattern of bones is thought to have originated in a common ancestor The bones are examples of homologous structures, characteristics that are similar in two or more species and that have been inherited from a common ancestor

Many vertebrates have common embryonic structures embryo.html embryo.html

Natural selection favors positive mutation Genes can change by mutation and that such change can make new varieties appear Natural selection may “select against” some varieties and so “favor” others Camouflage adaptations that evolved in different environments

A comparison of DNA shows that some species are more genetically similar than others These comparisons, like anatomy, are evidence of hereditary relationships among the species Gene that encodes leptin in humans, chimps and gorillas. 250 nucelotides, 5 differences

Darwin’s theory of evolution by natural selection predicts that over time, the number of individuals that carry advantageous traits will increase in a population Darwin’s work had three major principles: evidence of evolution, a mechanism for evolution, and the recognition that variation is important

Begin reading news article and answering the following questions: How is TB usually treated? What is TB? How many people does it affect? Why is antibiotic resistant TB so dangerous?

How has Darwin’s theory been updated? At what scales can evolution be studied? Discoveries made since Darwin’s time, especially in genetics, have been added to his theory to explain the evolution of species.

The first major advance beyond Darwin’s ideas was the rediscovery, in 1900, of Mendel’s Laws of Heredity Scientists continued to weave Darwin’s theory together with newer studies of fossils, anatomy, genetics, and more DISCOVERED: long lost fossils from Darwin’s journey around the world (Jan. 16, 2012)

Remaining Questions Can an individual evolve? Darwin correctly inferred that individuals do not evolve. They may respond to outside forces, but individuals do not pass on their responses as heritable traits. Rather, populations evolve when natural selection acts (indirectly) on genes.

Remaining Questions Is evolution the survival of the fittest? Natural selection can act only on the heritable variation that exists in the population. Chance variations do not always provide the best adaptation for a given time and place. So, evolution does not always produce the “fittest” forms, just those that “fit” well enough to leave offspring.

Remaining Questions Is evolution predictable? Evolution sometimes results in larger or more complex forms of life, but this result cannot be predicted. Many forms of life are simple yet successful. Mostly, scientists cannot predict the exact path that evolution will take.

Because it affects every aspect of biology, scientists can study evolution at many scales Microevolution Macroevolution Microevolution refers to evolution as a change in the genes of a population Macroevolution refers to the appearance of new species over time

Five major processes can affect the kinds of genes that will exist in a popualtion (1) Natural selection (2) Migration (3) Mate Choice (4) Mutation (5) Genetic Drift

(1) Coevolution Organisms are part of one another’s environment, so they can affect one another’s evolution (2) Adaptive Radiation Over time, species may split into two or more lines of descendents. As this splitting repeats, one species can give rise to many new species

(3) Extinction If all members of a species die off or simply fail to reproduce, they are said to be extinct

(4) Gradualism Evolution generally occurs uniformly and by the steady and gradual transformation of whole lineages (5) Punctuated Equilibrium Most populations will show little change for most of their geological history, and when evolution does occur, it is localized in rare, rapid events of branching speciation

Discoveries since Darwin’s time, especially in genetics, have been added to his theory to explain the evolution of species Because it affects every aspect of biology, scientists can study evolution at many scales. Generally, these scales range from microevolution to macroevolution, with speciation in between

The evolution of antibiotic resistance in bacteria is a serious public health concern The excessive use of antibiotics is leading to the evolution of antibiotic- resistant bacteria TB research in Russia: ktime/e_s_6.html ktime/e_s_6.html

TB resistance in India: resistant-tuberculosis-india_n_ html resistant-tuberculosis-india_n_ html

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