bio 2 chapter 19 book notes

Three examples of beak variation in Galápagos finches (see pic)

(see pic) their beaks are adapted for specific diets

just read 1) Overall, summarize Darwin's 2 observations/inferences based on artifical selection but in nature 2) As these two inferences suggest, Darwin saw an important connection between _____ and _____ 3) He began to make this connection after ______

1) Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than do other individuals. Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations. 2) As these two inferences suggest, Darwin saw an important connection between natural selection and the capacity of organisms to "overreproduce." 3) He began to make this connection after reading an essay by economist Thomas Malthus, who contended that much of human suffering—disease, famine, and war—resulted from the human population's potential to increase faster than food supplies and other resources. Similarly, Darwin realized that the capacity to overreproduce was characteristic of all species. Of the many eggs laid, young born, and seeds spread, only a tiny fraction complete their development and leave offspring of their own. The rest are eaten, starved, diseased, unmated, or unable to tolerate physical conditions of the environment such as salinity or temperature.

A fourth type of evidence for evolution comes from the field of ______ 1) define 2) read the rest

1) A fourth type of evidence for evolution comes from the field of biogeography, the scientific study of the geographic distributions of species. 2) (read all the rest of this) The geographic distributions of organisms are influenced by many factors, including continental drift, the slow movement of Earth's continents over time. About 250 million years ago, these movements united all of Earth's landmasses into a single large continent called Pangaea. Roughly 200 million years ago, Pangaea began to break apart; by 20 million years ago, the continents we know today were within a few hundred kilometers of their present locations. We can use our understanding of evolution and continental drift to predict where fossils of different groups of organisms might be found. For example, scientists have constructed evolutionary trees for horses based on anatomical data. These trees and the ages of fossils of horse ancestors suggest that the genus that includes present-day horses (Equus) originated 5 million years ago in North America. Geologic evidence indicates that at that time, North and South America were not yet connected, making it difficult for horses to travel between them. Thus, we would predict that the oldest Equus fossils should be found only on the continent on which the group originated—North America. This prediction and others like it for different groups of organisms have been upheld, providing more evidence for evolution.

heritable traits (read each time, just define it) 1) define 2) An organism's heritable traits can influence not only _____, but also ____. For example, ______ 3) When such advantages _______. 4) Thus, over time, _______.

1) A trait that can be passed on genetically from parent to offspring. 2) An organism's heritable traits can influence not only its own performance, but also how well its offspring cope with environmental challenges. For example, an organism might have a trait that gives its offspring an advantage in escaping predators, obtaining food, or tolerating physical conditions. 3) When such advantages increase the number of offspring that survive and reproduce, the traits that are favored will likely appear at a greater frequency in the next generation. 4) Thus, over time, natural selection resulting from factors such as predators, lack of food, or adverse physical conditions can lead to an increase in the proportion of favorable traits in a population.

convergent evolution 1) although _____ share ____ because of _____, ____ can resemble one another _____ 2) define 3) example (just read)

1) Although organisms that are closely related share characteristics because of common descent, distantly related organisms can resemble one another for a different reason: convergent evolution 2) the independent evolution of similar features in different lineages 3) Consider marsupial mammals, many of which live in Australia. Marsupials are distinct from another group of mammals—the eutherians, or placental mammals—few of which live in Australia. (Eutherians complete their embryonic development in the uterus, whereas marsupials are born as embryos and complete their development while nursing, often in an external pouch.) Some Australian marsupials have eutherian look-alikes with superficially similar adaptations. For instance, as shown in Figure 19.18, the sugar glider, a forest-dwelling Australian marsupial, looks very similar to flying squirrels, gliding eutherians that live in North American forests. But the sugar glider has many other characteristics that make it a marsupial, much more closely related to kangaroos and other Australian marsupials than to flying squirrels or other eutherians. Once again, our understanding of evolution can explain these observations. Although they evolved independently from different ancestors, these two mammals have adapted to similar environments in similar ways. In such examples in which species share features because of convergent evolution, the resemblance is said to be analogous, not homologous. pic explanation: The ability to glide through the air evolved independently in these two distantly related mammals.

Darwin's Focus on Adaptation 1) adaptation in relation to darwin + define it 2) explain finches on galapagos 3) natural selection + define it

1) During the voyage of the Beagle, Darwin observed many examples of adaptations - inherited characteristics of organisms that enhance their survival and reproduction in specific environments. 2) Later, as he reassessed his observations, he began to perceive adaptation to the environment and the origin of new species as closely related processes. Could a new species arise from an ancestral form by the gradual accumulation of adaptations to a different environment? From studies made years after Darwin's voyage, biologists have concluded that this is indeed what happened to a diverse group of finches found on the Galápagos Islands. The finches' various beaks and behaviors are adapted to the specific foods available on their home islands. Darwin realized that explaining such adaptations was essential to understanding evolution. 3) His explanation of how adaptations arise centered on natural selection, a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits.

The S. aureus and soapberry bug examples highlight three key points about natural selection.

1) First, natural selection is a process of editing, not a creative mechanism. A drug does not create resistant pathogens; it selects for resistant individuals that are already present in the population. 2) Second, in species that produce new generations in short periods of time, evolution by natural selection can occur rapidly—in just a few years (S. aureus) or decades (soapberry bugs). 3) Third, natural selection depends on time and place. It favors those characteristics in a genetically variable population that provide an advantage in the current, local environment. What is beneficial in one situation may be useless or even harmful in another. Beak lengths suitable for the size of the typical fruit eaten by members of a particular soapberry bug population are favored by natural selection. However, a beak length suitable for fruit of one size can be disadvantageous when the bug is feeding on fruit of another size.

vestigial structures 1) type of 2) they concern ___ 3) define 4) example (read)

1) another type of homology 2) concern "left-over" structures of marginal or little importance to the organism 3) vestigial structures are remnants of features that served a function in the organism's ancestors. 4) For instance, snakes arose from ancestors with legs, and the skeletons of some snakes retain vestiges of the pelvis and leg bones of their ancestors. Likewise, blind species of cave fishes descended from ancestors with eyes—which explains why these blind fishes have eye remnants buried under their scales. We would not expect to see these vestigial structures if snakes and blind cave fishes had origins separate from those of other vertebrate animals.

molecular homology 1) define (2 ish definitions) 2) a gene organisms may have + define it

1) similar DNA (amino acid sequences) among different species from a common ancestor; a shared genetic code across all forms of life 2) It is also common for organisms to have genes that have lost their function, even though the homologous genes in related species may be fully functional. Like vestigial structures, it appears that such inactive "pseudogenes" may be present simply because a common ancestor had them. PSUEDOGENES DEFINITION FROM QUIZLET (NOT THE BOOK) - former genes that have accumulated mutations and are nonfunctional

the other scientist whose ideas were consistent with the old testament 1) name him/general time he lived/who he was 2) important thing he did 3) his version of classifying species (WHAT'S THIS CALLED) 4) how did he classify species

1) summary: Linnaean system - HE GROUPED SIMILAR SPECIES INTO INCREASINGLY GENERAL CATEGORIES. For example, similar species are grouped in the same genus, similar genera (plural of genus) are grouped in the same family, and so on 2) he developed the binomial system 3) his ideas are also consistent with the Old Testament These ideas were generally consistent with the Old Testament account of creation, which holds that species were individually designed by God and therefore perfect. In the 1700s, many scientists interpreted the often remarkable ways in which organisms are well suited for life in their environment as evidence that the Creator had designed each species for a particular purpose. Carolus Linnaeus 1) (1707-1778). a Swedish physician and botanist who sought to classify life's diversity, in his words, "for the greater glory of God." 3) In the 1750s, Linnaeus developed the two-part, or binomial, format for naming species (such as Homo sapiens for humans) that is still used today. 4) summary: Linnaean system - HE GROUPED SIMILAR SPECIES INTO INCREASINGLY GENERAL CATEGORIES. In contrast to the linear hierarchy of the scala naturae, Linnaeus adopted a nested classification system, grouping similar species into increasingly general categories. For example, similar species are grouped in the same genus, similar genera (plural of genus) are grouped in the same family, and so on 5) Linnaeus did not ascribe the resemblances among species to evolutionary kinship, but rather to the pattern of their creation. A century later, however, Darwin argued that classification should be based on evolutionary relationships. He also noted that scientists using the Linnaean system often grouped organisms in ways that reflected those relationships.

Paleontology 1) define 2) developed by 3) explain

1) the study of fossils 2) was developed in large part by French scientist Georges Cuvier (1769-1832). 3) summary: observed strata, saw that the older the stratum, the more dissimilar its fossils were to current life-forms. saw species disappear from one layer to next. opposed evolution. said there were extinctions he reasoned organisms were later repopulated by different species immigrating from other areas. In examining strata near Paris, Cuvier noted that the older the stratum, the more dissimilar its fossils were to current life-forms. He also observed that from one layer to the next, some new species appeared while others disappeared. He inferred that extinctions must have been a common occurrence, but he staunchly opposed the idea of evolution. Cuvier speculated that each boundary between strata represented a sudden catastrophic event, such as a flood, that had destroyed many of the species living in that area. Such regions, he reasoned, were later repopulated by different species immigrating from other areas.

Ideas from The Origin of Species: In his book, Darwin amassed evidence that descent with modification by natural selection explains three broad observations about nature:

1) the unity of life 2) the diversity of life 3) the striking ways in which organisms are suited for life in their environments

Formation of sedimentary strata with fossils (2) tbh just read and view the picture

1. rivers carry sediment into aquatic habitats such as seas and swamps. overtime sedimentary rock layers (strata) form under water. some strata contain fossils. 2. as water levels change and geological activity pushes layers of rock upward, the strata and their fossils are exposed.

Homology (just define -- text in bold)

A second type of evidence for evolution comes from analyzing similarities among different organisms. As we've discussed, evolution is a process of descent with modification: Characteristics present in an ancestral organism are altered (by natural selection) in its descendants over time as they face different environmental conditions. As a result, related species can have characteristics that have an underlying similarity yet function differently. Similarity resulting from common ancestry is known as homology. As we'll describe in this section, an understanding of homology can be used to make testable predictions and explain observations that are otherwise puzzling.

The Evolution of Drug-Resistant Bacteria 1) An example of ongoing natural selection that dramatically affects humans is ______

An example of ongoing natural selection that dramatically affects humans is the evolution of drug-resistant pathogens (disease-causing organisms and viruses). This is a particular problem with bacteria and viruses because they can produce new generations in a short period of time; as a result, resistant strains of these pathogens can proliferate very quickly. Consider the evolution of drug resistance in the bacterium Staphylococcus aureus. About one in three people harbor this species on their skin or in their nasal passages with no negative effects. However, certain genetic varieties (strains) of this species, known as methicillin-resistant S. aureus (MRSA), are formidable pathogens. Most MRSA infections are caused by recently appearing strains such as clone USA300, which can cause "flesh-eating disease" and potentially fatal infections

Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life (just read)

As the 19th century dawned, it was generally thought that species had remained unchanged since their creation. A few clouds of doubt about the permanence of species were beginning to gather, but no one could have forecast the thundering storm just beyond the horizon. How did Charles Darwin become the lightning rod for a revolutionary view of life?

read abt darwin publishing on the origin of species

By the early 1840s, Darwin had worked out the major features of his hypothesis. He set these ideas on paper in 1844, when he wrote a long essay on descent with modification and its underlying mechanism, natural selection. Yet he was still reluctant to publish his ideas, in part because he anticipated the uproar they would cause. During this time, Darwin continued to compile evidence in support of his hypothesis. By the mid-1850s, he had described his ideas to Lyell and a few others. Lyell, who was not yet convinced of evolution, nevertheless urged Darwin to publish on the subject before someone else came to the same conclusions and published first. In June 1858, Lyell's prediction came true. Darwin received a manuscript from Alfred Russel Wallace (1823-1913), a British naturalist working in the South Pacific islands of the Malay Archipelago (Figure 19.7). Wallace had developed a hypothesis of natural selection nearly identical to Darwin's. He asked Darwin to evaluate his paper and forward it to Lyell if it merited publication. Darwin complied, writing to Lyell: "Your words have come true with a vengeance. . . . I never saw a more striking coincidence . . . so all my originality, whatever it may amount to, will be smashed." On July 1, 1858, Lyell and a colleague presented Wallace's paper, along with extracts from Darwin's unpublished 1844 essay, to the Linnean Society of London. Darwin quickly finished his book, titled On the Origin of Species by Means of Natural Selection (commonly referred to as The Origin of Species), and published it the next year. Although Wallace had submitted his ideas for publication first, he admired Darwin and thought that Darwin had developed and tested the idea of natural selection so extensively that he should be known as its main architect.

Darwin's Research (read)

Charles Darwin (1809-1882) was born in Shrewsbury, England. He had a consuming interest in nature—reading nature books, fishing, hunting, and collecting insects. Darwin's father, a physician, could see no future for his son as a naturalist and sent him to medical school in Edinburgh. But Charles found medicine boring and surgery before the days of anesthesia horrifying. He quit medical school and enrolled at Cambridge University, intending to become a clergyman. (At that time many scholars of science belonged to the clergy.) At Cambridge, Darwin became the protégé of John Henslow, a botany professor. Soon after Darwin graduated, Henslow recommended him to Captain Robert FitzRoy, who was preparing the survey ship HMS Beagle for a long voyage around the world. FitzRoy, who was himself an accomplished scientist, accepted Darwin because he was a skilled naturalist and because they were of similar age and social class.

Comparing early stages of development in different animal species reveals additional anatomical homologies not visible in adult organisms.

Comparing early stages of development in different animal species reveals additional anatomical homologies not visible in adult organisms. For example, at some point in their development, all vertebrate embryos have a tail located posterior to (behind) the anus, as well as structures called pharyngeal (throat) arches (Figure 19.17). These homologous throat arches ultimately develop into structures with very different functions, such as gills in fishes and parts of the ears and throat in humans and other mammals. see pic read: At some stage in their embryonic development, all vertebrates have a tail located posterior to the anus (referred to as a post-anal tail), as well as pharyngeal (throat) arches. Descent from a common ancestor can explain such similarities.

In contrast to ____ emphasis on sudden events, other scientists suggested that profound change could take place through the cumulative effect of slow but continuous processes. 1) scientist #1 2) scientist #2 3) explain these two scientists effects

Cuvier's 1) James Hutton says geologic feautures could be explained by gradual mechanisms, such as valleys being formed by rivers wearing through rocks. In 1795, Scottish geologist James Hutton (1726-1797) proposed that Earth's geologic features could be explained by gradual mechanisms, such as valleys being formed by rivers wearing through rocks. 2) The leading geologist of Darwin's time, Charles Lyell (1797-1875), incorporated Hutton's thinking into his proposal that the same geologic processes are operating today as in the past, and at the same rate. 3) Hutton's and Lyell's ideas strongly influenced Darwin's thinking. Darwin agreed that if geologic change results from slow, continuous actions rather than from sudden events, then Earth must be much older than the widely accepted age of a few thousand years. It would, for example, take a very long time for a river to carve a canyon by erosion. He later reasoned that perhaps similarly slow and subtle processes could produce substantial biological change. However, Darwin was not the first to apply the idea of gradual change to biological evolution.

What impelled Darwin to challenge the prevailing views about Earth and its life? skip

Darwin developed his revolutionary proposal over time, influenced by the work of others and by his travels. As we'll see, his ideas also had deep historical roots.

The Voyage of the Beagle (read)

Darwin embarked from England on the Beagle in December 1831. The primary mission of the voyage was to chart poorly known stretches of the South American coastline. Darwin, however, spent most of his time on shore, observing and collecting thousands of plants and animals. He described features of organisms that made them well suited to such diverse environments as Brazil's humid jungles, Argentina's broad grasslands, and the Andes' towering peaks. Darwin observed that the plants and animals in temperate regions of South America more closely resembled species living in the South American tropics than species living in temperate regions of Europe. Furthermore, the fossils he found, though clearly different from living species, distinctly resembled the living organisms of South America. Darwin also read Lyell's Principles of Geology during the voyage. He experienced geologic change firsthand when a violent earthquake shook the coast of Chile, and he observed afterward that rocks along the coast had been thrust upward by several meters. Finding fossils of ocean organisms high in the Andes, Darwin inferred that the rocks containing the fossils must have been raised there by many similar earthquakes. These observations reinforced what he had learned from Lyell: Physical evidence did not support the traditional view that Earth was only a few thousand years old.

read -- How rapidly do such changes (favorable traits that are heritable/natural selection) occur?

Darwin reasoned that if artificial selection can bring about dramatic change in a relatively short period of time, then natural selection should be capable of substantial modification of species over many hundreds of generations. Even if the advantages of some heritable traits over others are slight, the advantageous variations will gradually accumulate in the population, and less favorable variations will diminish. Over time, this process will increase the frequency of individuals with favorable adaptations, hence increasing the degree to which organisms are well suited for life in their environment.

Darwin's drawing (see pic)

Darwin reasoned that over a long period of time, descent with modification eventually led to the rich diversity of life we see today. He viewed the history of life as a tree, with multiple branchings from a common trunk out to the tips of the youngest twigs (Figure 19.8). In his diagram, the tips of the twigs that are labeled A through D represent several groups of organisms living in the present day, while the unlabeled branches represent groups that are extinct. Each fork of the tree represents the most recent common ancestor of all the lines of evolution that subsequently branch from that point. Darwin reasoned that such a branching process, along with past extinction events, could explain the large morphological gaps (differences in form) that sometimes exist between related groups of organisms.

Beagle's stop at the Galápagos (December 1831-October 1836)

Darwin's interest in the species (or fossils) found in an area was further stimulated by the Beagle's stop at the Galápagos, a group of volcanic islands located near the equator about 900 km west of South America. Darwin was fascinated by the unusual organisms there. The birds he collected included several kinds of mockingbirds. These mockingbirds, though similar to each other, seemed to be different species. Some were unique to individual islands, while others lived on two or more adjacent islands. Furthermore, although the animals on the Galápagos resembled species living on the South American mainland, most of the Galápagos species were not known from anywhere else in the world. Darwin hypothesized that the Galápagos had been colonized by organisms that had strayed from South America and then diversified, giving rise to new species on the various islands.

Natural Selection in Response to Introduced Species (read)

Herbivores, animals that eat plants, often have adaptations that help them feed efficiently on their primary food sources. What happens when herbivores switch to a new food source with different characteristics? An opportunity to study this question in nature is provided by soapberry bugs, which use their "beak," a hollow, needlelike mouthpart, to feed on seeds located within the fruits of various plants. In southern Florida, the soapberry bug (Jadera haematoloma) feeds on the seeds of a native plant, the balloon vine (Cardiospermum corindum). In central Florida, however, balloon vines have become rare. Instead, soapberry bugs in that region now feed on seeds of the goldenrain tree (Koelreuteria elegans), a species recently introduced from Asia. Soapberry bugs feed most effectively when the length of their beak is similar to the depth at which seeds are found within the fruit. Goldenrain tree fruit consists of three flat lobes, and its seeds are much closer to the fruit surface than are the seeds of the plump, round fruit of the native balloon vine. These differences led researchers to predict that in populations that feed on goldenrain tree, natural selection would result in beaks that are shorter than those in populations that feed on balloon vine (Figure 19.14). Indeed, beak lengths are shorter in the populations that feed on goldenrain tree. Can a change in a population's food source result in evolution by natural selection? Field Study Soapberry bugs feed most effectively when the length of their "beak" is similar to the depth of the seeds within the fruit. Scott Carroll and his colleagues measured beak lengths in soapberry bug populations feeding on the native balloon vine. They also measured beak lengths in populations feeding on the introduced goldenrain tree. The researchers then compared the measurements with those of museum specimens collected in the two areas before the goldenrain tree was introduced. Results: Beak lengths were shorter in populations feeding on the introduced species than in populations feeding on the native species, in which the seeds are buried more deeply. The average beak length in museum specimens from each population (indicated by red arrows) was similar to beak lengths in populations feeding on native species. Conclusion: Museum specimens and contemporary data suggest that a change in the size of the soapberry bug's food source can result in evolution by natural selection for a corresponding change in beak size.

read -- Let's now summarize some of the main ideas of natural selection: (2 points)

Natural selection is a process in which individuals that have certain heritable traits survive and reproduce at a higher rate than do other individuals because of those traits. Over time, natural selection can increase the frequency of adaptations that are favorable in a given environment

Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. what is observation #1? + see pic

Observation #1: Members of a population often vary in their inherited traits (SEE PIC + EXPLANATION OF PIC) pic expanation: Individuals in this population of Asian ladybird beetles vary in color and spot pattern. Natural selection may act on these variations only if (1) they are heritable and (2) they affect the beetles' ability to survive and reproduce.

Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. what is observation #2? + see pic

Observation #2: All species can produce more offspring than their environment can support (Figure 19.12), and many of these offspring fail to survive and reproduce. pic explanation: A single puffball fungus can produce billions of spores that give rise to offspring. If all of these offspring and their descendants survived to maturity, they would carpet the surrounding land surface.

In the first edition of The Origin of Species, Darwin never used the word evolution (although the final word of the book is "evolved"

Rather, he discussed descent with modification - unity of life comes from organisms havving common ancestors. the descendants of those ancestors lived in various habitats so overtime they accumulate modifications aka adaptations. Rather, he discussed descent with modification, a phrase that summarized his view of life. Organisms share many characteristics, leading Darwin to perceive unity in life. He attributed the unity of life to the descent of all organisms from an ancestor that lived in the remote past. He also thought that as the descendants of that ancestral organism lived in various habitats, they gradually accumulated diverse modifications, or adaptations, that fit them to specific ways of life. Thus, Darwin thought of evolution as a process in which both descent (shared ancestry, resulting in shared characteristics) and modification (the accumulation of differences) can be observed.

What Is Theoretical About Darwin's View of Life? (just read)

Some people dismiss Darwin's ideas as "just a theory." However, as we have seen, the pattern of evolution—the observation that life has evolved over time—has been documented directly and is supported by a great deal of evidence. In addition, Darwin's explanation of the process of evolution—that natural selection is the primary cause of the observed pattern of evolutionary change—makes sense of massive amounts of data. The effects of natural selection also can be observed and tested in nature. What, then, is theoretical about evolution? Keep in mind that the scientific meaning of the term theory is very different from its meaning in everyday use. The colloquial use of the word theory comes close to what scientists mean by a hypothesis. In science, a theory is much more comprehensive than a hypothesis. A theory, such as the theory of evolution by natural selection, accounts for many observations and explains and integrates a great variety of phenomena. Such a unifying theory does not become widely accepted unless its predictions stand up to thorough and continual testing by experiment and additional observation (see Concept 1.3 ). As the rest of this unit demonstrates, this has certainly been the case with the theory of evolution by natural selection. The skepticism of scientists as they continue to test theories prevents these ideas from becoming dogma. For example, although Darwin thought that evolution was a very slow process, we now know that this isn't always true. Populations can evolve rapidly, and new species can form in relatively short periods of time—a few thousand years or less. Furthermore, evolutionary biologists now recognize that natural selection is not the only mechanism responsible for evolution. Indeed, the study of evolution today is livelier than ever as scientists use a wide range of experimental approaches and genetic analyses to test predictions based on natural selection and other evolutionary mechanisms.

What else can fossils tell us about cetacean origins? read

The earliest cetaceans lived 50-60 million years ago. The fossil record indicates that prior to that time, most mammals were terrestrial. Although scientists had long realized that whales and other cetaceans originated from land mammals, few fossils had been found that revealed how cetacean limb structure had changed over time, leading eventually to the loss of hind limbs and the development of flukes (the lobes on a whale's tail) and flippers. In the past few decades, however, a series of remarkable fossils have been discovered in Pakistan, Egypt, and North America. These fossils document steps in the transition from life on land to life in the sea, filling in some of the gaps between ancestral and living cetaceans. pic explanation: Multiple lines of evidence support the hypothesis that cetaceans (highlighted in yellow) evolved from terrestrial mammals. Fossils document the reduction over time in the pelvis and hind limb bones of extinct cetacean ancestors, including Pakicetus, Rodhocetus, and Dorudon. DNA sequence data support the hypothesis that cetaceans are most closely related to hippopotamuses.

read

The story begins in 1943, when penicillin became the first widely used antibiotic. Since then, penicillin and other antibiotics have saved millions of lives. However, by 1945, over 20% of the S. aureus strains seen in hospitals were resistant to penicillin. These bacteria had an enzyme, penicillinase, that could destroy penicillin. Researchers responded by developing antibiotics that were not destroyed by penicillinase, but resistance to each new drug was observed in some S. aureus populations within a few years. Then, in 1959, doctors began using a promising new antibiotic, methicillin. But within two years, methicillin-resistant strains of S. aureus were observed. How did these resistant strains emerge? Methicillin works by deactivating an enzyme that bacteria use to synthesize their cell walls. However, some S. aureus populations included individuals that were able to synthesize their cell walls using a different enzyme that was not affected by methicillin. These individuals survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common, leading to the spread of MRSA. Initially, MRSA could be controlled by antibiotics that work differently from the way methicillin works. But this has become less effective because some MRSA strains are resistant to multiple antibiotics—probably because bacteria can exchange genes with members of their own and other species (see Figures 24.16 and 24.18). Thus, the multidrug-resistant strains of today may have emerged over time as MRSA strains that were resistant to different antibiotics exchanged genes.

Anatomical and Molecular Homologies + define homologous structures. (read)

The view of evolution as a remodeling process leads to the prediction that closely related species should share similar features—and they do. Of course, closely related species share the features used to determine their relationship, but they also share many other features. Some of these shared features make little sense except in the context of evolution. For example, the forelimbs of all mammals, including humans, cats, whales, and bats, show the same arrangement of bones from the shoulder to the tips of the digits, even though the appendages have very different functions: lifting, walking, swimming, and flying. Such striking anatomical resemblances would be highly unlikely if these structures had arisen anew in each species. Rather, the underlying skeletons of the arms, forelegs, flippers, and wings of different mammals are homologous structures that represent variations on a structural theme that was present in their common ancestor. (see pic) READ THIS PART: Even though they have become adapted for different functions, the forelimbs of all mammals are constructed from the same basic skeletal elements: one large bone (purple), attached to two smaller bones (orange and tan), attached to several small bones (gold), attached to several metacarpals (green), attached to approximately five digits, each of which is composed of multiple phalanges (blue).

read again don't skip

We can also use our understanding of evolution to explain biogeographic data. For example, islands generally have many plant and animal species that are endemic. Yet, as Darwin described in The Origin of Species, most island species are closely related to species from the nearest mainland or a neighboring island. He explained this observation by suggesting that islands are colonized by species from the nearest mainland. These colonists eventually give rise to new species as they adapt to their new environments. Such a process also explains why two islands with similar environments in distant parts of the world tend to be populated not by species that are closely related to each other, but rather by species related to those of the nearest mainland, where the environment is often quite different.

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Within a decade, Darwin's book and its proponents had convinced most scientists that life's diversity is the product of evolution. Darwin succeeded where previous evolutionists had failed, mainly by presenting a plausible scientific mechanism with immaculate logic and an avalanche of supporting evidence.

However it is defined, we can view evolution in two related but different ways:

as a pattern and as a process. summary: the pattern is revealed by data via biology, geology, physics, etc. this data is facts--they're observations about the natural world that show that life has evolved over time. The pattern of evolutionary change is revealed by data from many scientific disciplines, including biology, geology, physics, and chemistry. These data are facts—they are observations about the natural world—and these observations show that life has evolved over time. summary: the process of evolution includes the mechanisms that cause the observed pattern of change The process of evolution consists of the mechanisms that cause the observed pattern of change. These mechanisms represent natural causes of the natural phenomena we observe. Indeed, the power of evolution as a unifying theory is its ability to explain and connect a vast array of observations about the living world.

four types of data that document the pattern of evolution and illuminate how it occurs

direct observations, homology, the fossil record, and biogeography.

A third type of evidence for evolution comes from _____. 1) the ____ record does what? read this stuff 2) show what? + example 3) can shed light on _____ + example

fossils (The Fossil Record) 1) documents the pattern of evolution, showing that past organisms differed from present-day organisms and that many species have become extinct. 2) show the evolutionary changes that have occurred in various groups of organisms. for example: , researchers found that over several thousand years, the pelvic bone in fossil stickleback fish became greatly reduced in size. The consistent nature of this change over time suggests that the reduction in the size of the pelvic bone may have been driven by natural selection. 3) Fossils can also shed light on the origins of new groups of organisms. An example is the fossil record of cetaceans, the mammalian order that includes whales, dolphins, and porpoises. As shown in Figure 19.19, some of these fossils provided strong support for a hypothesis based on DNA sequence data: that cetaceans are closely related to even-toed ungulates, a group that includes hippopotamuses, pigs, deer, and cows. pic explanation: Comparing fossils and present-day examples of the astragalus (a type of ankle bone) indicates that cetaceans are closely related to even-toed ungulates. (a) In most mammals, the astragalus is shaped like that of a dog, with a double hump on one end (indicated by the red arrows) but not at the opposite end (blue arrow). (b) Fossils show that the early cetacean Pakicetus had an astragalus with double humps at both ends, a shape otherwise found only in (c) pigs, (d) deer, and all other even-toed ungulates.

Among other sources of information, Darwin drew from the work of scientists studying ______ + define (just read)

fossils - the remains or traces of organisms from the past

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four types of data/evidence that document the pattern of evolution and illuminate how it occurs: direct observations, homology, the fossil record, and biogeography. In The Origin of Species, Darwin marshaled a broad range of evidence to support the concept of descent with modification. Still—as he readily acknowledged—there were instances in which key evidence was lacking. For example, Darwin referred to the origin of flowering plants as an "abominable mystery," and he lamented the lack of fossils showing how earlier groups of organisms gave rise to new groups. In the last 150 years, new discoveries have filled many of the gaps that Darwin identified. The origin of flowering plants, for example, is much better understood (see Concept 26.4 ), and many fossils have been discovered that signify the origin of new groups of organisms (see Concept 23.1 ). In this section, we'll consider four types of data that document the pattern of evolution and illuminate how it occurs: direct observations, homology, the fossil record, and biogeography.

Although natural selection occurs through ______, _____

interactions between individual organisms and their environment, individuals do not evolve. Rather, it is the population that evolves over time.

endemic

native or confined to a particular region or people; characteristic of or prevalent in a field; found nowhere else in the world

natural selection can _____ or _____. Thus, even if a trait is _____, if all the _____, _____.

natural selection can amplify or diminish only those heritable traits that differ among the individuals in a population. Thus, even if a trait is heritable, if all the individuals in a population are genetically identical for that trait, evolution by natural selection cannot occur

analogous structures/features (define) vs. homologous structures

share similar function, but not common ancestry, while homologous features share common ancestry, but not necessarily similar function. pic explanation: The ability to glide through the air evolved independently in these two distantly related mammals.

1) where are many fossils found? 2) how is strata formed 3) explain this term further

summary: 1. Many fossils are found in sedimentary rocks 2. sediment covers old layers and compress into layers called strata (singular, stratum) 3. erosion can carve thru young strata and reveal older strata that was buried 1) Many fossils are found in sedimentary rocks formed from the sand and mud that settle to the bottom of seas, lakes, and swamps (Figure 19.3). 2) New layers of sediment cover older ones and compress them into layers of rock called strata (singular, stratum). 3) The fossils in a particular stratum provide a glimpse of some of the organisms that populated Earth at the time that layer formed. Later, erosion may carve through upper (younger) strata, revealing deeper (older) strata that had been buried.

Lamarck's Hypothesis of Evolution (3 things)

summary: 1. proposed principle of use and disuse: the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate. Among many examples, he cited a giraffe stretching its neck to reach leaves on high branches. 2. The second principle, inheritance of acquired characteristics, stated that an organism could pass these modifications to its offspring 3. Lamarck also thought that evolution happens because organisms have an innate drive to become more complex 1) Although some 18th-century naturalists suggested that life evolves as environments change, only one proposed a mechanism for how life changes over time: French biologist Jean-Baptiste de Lamarck (1744-1829). Alas, Lamarck is primarily remembered today not for his visionary recognition that evolutionary change explains patterns in fossils and how organisms are well suited for life in their environments, but for the incorrect mechanism he proposed. 2) Lamarck published his hypothesis in 1809, the year Darwin was born. By comparing living species with fossil forms, Lamarck had found what appeared to be several lines of descent, each a chronological series of older to younger fossils leading to a living species. 3) He explained his findings using two principles that were widely accepted at the time. The first was use and disuse, the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate. Among many examples, he cited a giraffe stretching its neck to reach leaves on high branches. 4) The second principle, inheritance of acquired characteristics, stated that an organism could pass these modifications to its offspring. Lamarck reasoned that the long, muscular neck of the living giraffe had evolved over many generations as giraffes stretched their necks ever higher. 5) Lamarck also thought that evolution happens because organisms have an innate drive to become more complex. Darwin rejected this idea, but he, too, thought that variation was introduced into the evolutionary process in part through inheritance of acquired characteristics. Today, however, our understanding of genetics refutes this mechanism: Experiments show that traits acquired by use during an individual's life are not inherited in the way proposed by Lamarck

Scala Naturae

summary: ancient greek philosopher Aristotle viewed species as fixed (unchanging). Through his observations of nature, Aristotle recognized certain similar characteristics among organisms. he arranged organisms on the scala naturae aka scale of nature. each form of life, perfect and permanent, had its specific rung on the ladder. this was consistent with the old testament account of creation saying that species were individually designed by God and therefore perfect. These ideas were generally consistent with the Old Testament account of creation Long before Darwin was born, several Greek philosophers suggested that life might have changed gradually over time. But one philosopher who greatly influenced early Western science, Aristotle (384-322 bce), viewed species as fixed (unchanging). Through his observations of nature, Aristotle recognized certain "affinities" among organisms. He concluded that life-forms could be arranged on a ladder, or scale, of increasing complexity, later called the scala naturae ("scale of nature"). Each form of life, perfect and permanent, had its allotted rung on this ladder. These ideas were generally consistent with the Old Testament account of creation, which holds that species were individually designed by God and therefore perfect. In the 1700s, many scientists interpreted the often remarkable ways in which organisms are well suited for life in their environment as evidence that the Creator had designed each species for a particular purpose.

artificial selection + explain the background behind it and define it

summary: artificial selection: Humans have modified species over many generations by selecting and breeding individuals that possess desired traits for example crops livestock and pets look very diff to their wild ancestors Darwin proposed the mechanism of natural selection to explain the observable patterns of evolution. He crafted his argument carefully, hoping to persuade even the most skeptical readers. First he discussed familiar examples of selective breeding of domesticated plants and animals. Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits, a process called artificial selection (Figure 19.10). As a result of artificial selection, crops, livestock animals, and pets often bear little resemblance to their wild ancestors. Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. description of picture: These different vegetables have all been selected from one species of wild mustard. By selecting variations in different parts of the plant, breeders have obtained these divergent results.

overall the fossil record shows ______

that over time, descent with modification produced increasingly large differences among related groups of organisms, ultimately resulting in the diversity of life we see today.