Chapter 21 The Evidence For Evolution

The "clear air acts" passed in both America and England aimed to reduce pollution levels in previously polluted areas. As a result, the air quality improved, leading to a decrease in pollution. This decrease in pollution likely caused a decrease in the ratio of dark to light moths in Biston populations. This is because dark moths, which were better camouflaged in polluted environments, had a higher survival rate compared to light moths. However, with the reduction in pollution, the advantage of dark moths decreased, resulting in a decrease in their population ratio.

Fossils are the preserved remains, tracks, or traces of once-living organisms. They provide valuable evidence of past life on Earth and offer insights into the evolution and biodiversity of different species. Fossils can include bones, shells, imprints, or even preserved soft tissues. Through the study of fossils, scientists can reconstruct ancient ecosystems, understand the history of life on our planet, and make connections between different species and their ancestors. Fossils are essential for understanding the geological and biological history of Earth and are often found in sedimentary rocks or preserved in amber or ice.

Natural selection is a process in which certain traits or characteristics become more or less common in a population over time due to their impact on survival and reproduction. This process leads to changes in the genetic makeup of a population, resulting in the gradual evolution of species. The historical record of these changes is called evolution.

Industrial melanism is a term used to describe an evolutionary event in which darker individuals come to predominate over lighter individuals as a result of increased air pollution and the process of natural selection by predators. This phenomenon occurs when industrial pollution, such as soot and smoke, darkens the environment, making lighter individuals more visible to predators. As a result, darker individuals, which are better camouflaged in the polluted environment, have a higher chance of survival and reproduction, leading to an increase in their population. This process is an example of natural selection favoring individuals with traits that provide a survival advantage in a changing environment.

The "clear air acts" passed in both America and England aimed to reduce pollution levels, particularly in unpolluted areas. As a result, the ratio of dark to light moths in Biston populations would not be affected and would remain the same. These acts did not have a direct impact on the coloration of moths, so the proportion of dark to light moths would not change.

Corn is the correct answer because it has undergone significant artificial selection by humans. Through selective breeding, humans have modified corn plants to have larger and more nutritious kernels. This process of artificial selection is a form of evolution, as it involves the deliberate manipulation of genetic traits over generations. The dramatic changes observed in corn plants provide strong evidence for the power of evolution and the impact that human agriculture can have on the evolution of species.

Natural selection is the process by which certain traits become more or less common in a population over time. In the case of Darwin's finches, the shape of their beaks varies in response to the available food supply. This means that individuals with beaks that are better suited for obtaining and consuming the available food sources have a higher chance of survival and reproduction. Over generations, this leads to a population with a higher proportion of individuals with beaks that are well adapted to the specific food resources in their environment.

Darwin concluded that evolution was at work by studying the shapes of beaks of finches. This is because he observed that different species of finches on the Galapagos Islands had distinct beak shapes that were adapted to different food sources. This variation in beak shape and function demonstrated to Darwin that natural selection was acting on the finch populations, favoring those individuals with beaks that were best suited to their specific environments and food sources. This observation provided strong evidence for the process of evolution and the adaptive nature of species.

The progressive changes in fossils of different ages provide evidence for evolution. Fossils show a gradual transition from simpler to more complex organisms over time, indicating that species have changed and evolved over millions of years. This supports the theory of evolution, which states that all living organisms share a common ancestor and have diversified through natural selection and genetic variation. Extinction, coevolution, adaptation, and mutation are all related to the process of evolution but do not specifically address the evidence provided by the progressive changes in fossils.

Convergence refers to the evolution of similar forms in different lineages when they are exposed to the same selective pressures. This means that unrelated organisms develop similar traits or characteristics due to similar environmental conditions or adaptations. It is a result of convergent evolution, where different species independently evolve similar traits to adapt to similar environments or lifestyles.

The evidence for evolution is supported by various factors such as the fossil record, which provides physical evidence of past life forms. Homologous structures, which are similar body parts found in different species, indicate a common ancestry. The molecular record, which examines DNA and genetic similarities, also supports the idea of evolution. Vestigial structures, which are remnants of organs or structures with no apparent function, provide further evidence. However, intelligent design, which suggests that life is the result of a purposeful creator, is not considered as evidence for evolution.

Radioactive isotope decay is a technique used in dating rocks and can also be applied to accurately predict the age of fossils occurring in those rocks. Radioactive isotopes, such as carbon-14, decay at a known rate over time. By measuring the amount of remaining radioactive isotopes in a fossil or rock sample, scientists can determine its age. This technique is based on the principle that radioactive isotopes decay at a constant and predictable rate, making it a reliable method for dating geological materials and fossils.

The correct answer is structures of animals that have difference appearances and functions but seem to have evolved from the same body part in a common ancestor. This is because homologous structures are similar structures found in different species that indicate a common ancestry. These structures may have different functions and appearances in different species, but they share a similar underlying structure, suggesting a shared evolutionary history.

The fossil record can be dated reasonably well using a variety of radioactive isotopes with known half-lives. This means that scientists can determine the age of fossils by measuring the amount of radioactive isotopes present in the fossil and comparing it to the known decay rate of that isotope. By doing so, they can estimate the age of the fossil relative to other fossils and geological layers. This method allows for a reasonably accurate estimation of the age of fossils, although it does not provide precise dates to within a single year.

Fingers are not considered a vestigial trait in humans because they serve a functional purpose in daily activities such as gripping, grasping, and manipulating objects. Vestigial traits are remnants of evolutionary adaptations that no longer serve a purpose or have lost their original function. In contrast, fingers are essential for various tasks and are actively used by humans in their everyday lives.

The process of natural selection involves the differential survival and reproduction of individuals with traits that are better adapted to their environment. In the case of Darwin's finches, the shape of their beaks varied depending on the type of food available on the different islands they inhabited. Finches with beaks better suited for cracking hard seeds had a higher chance of survival and passing on their genes, leading to an evolutionary change in the population over time. Industrial melanism refers to the increase in dark-colored moths in polluted areas, as they had a better chance of blending in and avoiding predation. Sickle-cell disease is an example of natural selection as carriers of the sickle-cell trait have a higher resistance to malaria, providing a survival advantage in regions where the disease is prevalent.

The wings of birds and butterflies are examples of structures that resemble each other and have similar function, but they have evolved independently in separate lineages. This means that they are not inherited from a common ancestor, but rather have evolved separately to serve a similar purpose. Therefore, these structures are called analogous structures.

Today's Australian marsupials and placental mammals have undergone convergent evolution. Convergent evolution occurs when unrelated species develop similar characteristics or adaptations due to similar environmental pressures. In this case, both marsupials and placental mammals in Australia have evolved similar traits, such as pouches for carrying their young, due to similar ecological niches and selective pressures. This is an example of convergent evolution because these species are not closely related, but have independently evolved similar features.

During dry years, the environment on the Galápagos island Daphne major becomes more arid and food sources may become scarce. Birds with large beaks have an advantage during these times as they are better equipped to crack open and access the limited food resources available. This allows them to survive and reproduce more successfully compared to birds with smaller beaks. Therefore, birds with large beaks are favored during dry years.

Vestigial structures are organs or structures in organisms that have lost or reduced their original function through evolution. These structures may have been functional in ancestral species but are no longer necessary in the current organism. They serve as remnants of evolutionary history and provide evidence of common ancestry between different species. Therefore, the presence of structures with no apparent function but resembling those of presumed ancestors is a characteristic of vestigial structures.

Homologous structures are derived from the same body part in a common ancestor but may have different appearances and functions. This means that despite their differences, these structures share a common evolutionary origin. Analogous structures, on the other hand, have similar functions but do not share a common ancestor. Vestigial structures are remnants of structures that were functional in ancestors but are now reduced or non-functional. Embryonic structures refer to the similarities observed in the early stages of development of different organisms. Homozygous structures is not a valid term in biology.

The biologist would think that evolution is a theory that is supported with a tremendous amount of evidence because the term "theory" in scientific context does not mean a guess or speculation, but rather a well-substantiated explanation for a phenomenon that is based on a large body of evidence. In the case of evolution, there is a vast amount of evidence from various scientific disciplines such as paleontology, genetics, and comparative anatomy that support the theory of evolution. Therefore, the biologist would understand that evolution is not just a random collection of facts, but a comprehensive and well-supported scientific theory.

The side toes of a horse, the pelvis of the whale, and the human appendix are all examples of vestigial structures. Vestigial structures are anatomical features that have lost their original function in the course of evolution. These structures were once useful in the ancestors of these organisms but have become reduced or obsolete in the present-day organisms. The side toes of a horse were once used for running, but now they are remnants of an ancestor's fully developed toes. The pelvis of the whale is a vestige of their terrestrial ancestors who had hind limbs. The human appendix, although it may have had a digestive function in the past, is now considered a vestigial organ with no clear purpose.

The correct answer is Kettlewell. Kettlewell conducted field tests that provided evidence for industrial melanism being due to an increase in the dark allele.

Australian marsupials and placental mammals of other continents is an example of convergent evolution. Convergent evolution occurs when unrelated species develop similar traits or characteristics due to similar environmental pressures. In this case, Australian marsupials and placental mammals have independently evolved similar features, such as pouches for carrying their young, in response to similar ecological niches and selective pressures.

The most precise method of obtaining estimates of the absolute ages of geological deposits is to measure the ratios of various radioactive isotopes in the deposits. Radioactive isotopes decay at a known rate, and by measuring the ratio of parent isotopes to daughter isotopes, scientists can determine how much time has passed since the rock formed. This method is highly accurate and reliable for determining the absolute age of geological deposits.

The molecular record refers to the study of DNA sequences and how they have changed over time. The suggestion that a series of evolutionary changes is tied to a progressive accumulation of alterations of DNA sequences means that as species evolve, their DNA sequences also change. These alterations can be caused by various factors such as mutations, genetic recombination, or genetic drift. This answer implies that the changes in DNA sequences play a significant role in driving evolution and the accumulation of these alterations is linked to the overall evolutionary process.

The correct answer is "shows they evolved from a land mammal with hooves." The explanation for this answer is that the fossil record of toothed whales provides evidence that they evolved from a land mammal with hooves. This is supported by the discovery of transitional fossil species such as Pakicetus and Ambulocetus, which had features of both land mammals and early whales. These fossils show a gradual transition from a terrestrial lifestyle to an aquatic one, indicating the evolutionary process of toothed whales from a land-dwelling ancestor.

The correct answer is that the marsupials are very similar to placental mammals in the ways they have adapted to similar ecological niches. This suggests that despite evolving earlier, marsupials have been able to fill similar ecological roles as placental mammals, indicating convergent evolution. This similarity in adaptation implies that both groups have faced similar selective pressures and have independently evolved similar traits to survive in their respective environments.

The half-life of carbon-14 is 5,600 years, which means that after 5,600 years, half of the carbon-14 in the rock will have decayed. Therefore, after the first half-life, the amount of carbon-14 in the rock will be reduced to 9 mg. After the second half-life, it will be reduced to 4.5 mg, and after the third half-life, it will be reduced to less than 4 mg. Therefore, it will take 3 half-lives, which is equal to 16,800 years, for the carbon-14 in the rock to decay to less than 4 mg.

Feathers are a clear feature of Archaeopteryx that demonstrates its place on the evolutionary line from dinosaurs to birds. Feathers are a unique characteristic of birds and are not found in any other group of animals. The presence of feathers in Archaeopteryx suggests that it had evolved from a dinosaur ancestor and was in the process of developing bird-like characteristics. This is supported by other anatomical features of Archaeopteryx, such as its skeletal structure, which shows both dinosaur and bird-like traits.

The multiple toes of ancient horses are not an adaptation for living on open grasslands. This is because having multiple toes is actually a primitive trait that ancient horses inherited from their ancestors. Over time, as horses evolved and adapted to living on open grasslands, they gradually lost their extra toes and developed a single toe with a hoof, which is a more specialized adaptation for running on grassy terrain. Therefore, the presence of multiple toes in ancient horses is not related to their ability to live on open grasslands.

Convergent evolution refers to the process in which two species living in different areas develop similar traits or characteristics due to natural selection. This happens because both species are exposed to similar environmental pressures and therefore evolve in a similar way to adapt to their respective habitats. This concept does not involve reproductive isolation or competition for resources, but rather focuses on the independent evolution of similar traits in unrelated species.

Different structures evolving in similar ways when subjected to the same selective pressures does not illustrate shared ancestry by anatomical comparison studies. This scenario suggests convergent evolution, where unrelated organisms independently evolve similar traits in response to similar environmental pressures. Shared ancestry is typically inferred when structures are found to be homologous, meaning they share a common evolutionary origin. Other options, such as the same structure evolving to carry out different functions or a structure becoming vestigial, can also indicate shared ancestry through the process of divergent evolution.

Convergent evolution refers to the phenomenon where different geographical areas have similar-looking plant and animal communities, even though the individual species are not closely related. This similarity in appearance is a result of similar environmental pressures and selective forces acting on different species, leading to the development of similar adaptations and traits independently. The fossil record is a separate concept that refers to the preserved remains of past organisms. Homology refers to shared traits due to common ancestry, while divergent evolution is the process where closely related species evolve different traits. Adaptation refers to the process of species adjusting to their environment.

This study of Drosophila suggests that there can be significant variation within a population, but it may not be easily observable unless there is strong selection pressure. This implies that while the variation exists, it may not be readily apparent or visible unless certain environmental factors or selective pressures are present. Therefore, it highlights the importance of considering the role of selection in studying and understanding evolutionary changes in populations.

The domestication of dogs has resulted in a variety of phenotypes. This is because humans selectively bred dogs for specific traits, such as size, coat color, and behavior, leading to the development of different breeds with distinct physical and behavioral characteristics. These phenotypic variations are the result of genetic variations within the dog population, which have been shaped by artificial selection over thousands of years.

In nonpolluted forests, the dark forms of the peppered moths are selected against. This means that they are less likely to survive and reproduce compared to the light forms. This could be due to factors such as camouflage, where the dark forms are more easily spotted by predators in nonpolluted environments. As a result, the proportion of dark forms in the population decreases over time.

The abundance of lichens on trees seems to be least important in understanding the basis for industrial melanism because lichens do not directly affect the coloration of moths. Industrial melanism refers to the phenomenon where dark-colored moths become more prevalent in polluted areas due to their increased camouflage on darkened bark surfaces. The greater crypticity of the dark moths in polluted woodlands and the light moths in unpolluted woodlands, as well as the darkening of bark surfaces by pollutants, are all factors that contribute to the understanding of industrial melanism. Additionally, differential predation by birds plays a role in the selection of moth coloration.

Radioactive dating techniques measure the degree of radioactive decay in a material to determine its age. The statement that is true is that it uses a technique in which the degree of radioactive decay is measured, and the older the rock, the more radioactive decay has occurred. This is because radioactive isotopes decay at a constant rate over time, so the more decay that has occurred, the older the material is. This technique is commonly used to date materials from the distant past.

An alternate hypothesis that could explain industrial melanism is that dark moths are more resistant to the toxic effects of pollution than light moths. This suggests that the dark coloration of the moths may provide some sort of protection against the harmful effects of pollution, allowing them to survive and reproduce better in polluted environments compared to light moths. This hypothesis implies that natural selection may favor dark moths in polluted areas, leading to an increase in their population over time.

The correct answer is that the light forms were favored because they are more cryptic. This means that the light-colored moths were better camouflaged and harder for predators to spot on lighter trees, giving them a survival advantage. As pollution abated and the trees became cleaner, the dark form of the peppered moth became more visible to predators, causing a shift in favor of the lighter form.

Divergence refers to the process in which different forms or traits evolve within the same lineage due to exposure to different selective pressures. This results in the development of distinct characteristics and adaptations, leading to the divergence of species from a common ancestor. Convergence, on the other hand, refers to the development of similar traits or forms in unrelated species due to similar selective pressures. Homology refers to the presence of similar traits in different species due to a shared ancestry. Phylogeny is the study of the evolutionary history and relationships between different species. Analogy refers to the development of similar traits in unrelated species due to similar functions, but not due to a shared ancestry.

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The half-life of carbon-14 is the amount of time it takes for half of the carbon-14 to decay into carbon-12. Since the fossil has one-eighth the normal proportion of carbon-14 to carbon-12, it means that seven-eighths of the carbon-14 has decayed. If the half-life is 5,600 years, then it would take three half-lives (5,600 x 3 = 16,800) for seven-eighths of the carbon-14 to decay. Therefore, the fossil is likely 16,800 years old.

The opposable thumb is the correct answer because it is a unique feature of humans that sets them apart from other vertebrates. While other vertebrates may have limb bones and even a long bony tail during development, the opposable thumb is a specialized adaptation that allows humans to grasp and manipulate objects with precision. This feature is not found in other vertebrates and therefore does not provide evidence for human evolution from them.

The convergence in form seen in sharks, tuna, and dolphins can be best explained by the physical properties of water. These animals have evolved similar streamlined bodies, fins, and tails to efficiently move through water. The physical properties of water, such as its density and viscosity, create resistance and drag, which these animals have adapted to overcome. This convergence in form is a result of natural selection favoring traits that enhance their ability to swim and navigate in their aquatic environment. It is not related to a recent shared common ancestor, dissimilar selection pressures, or intelligent design.

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After 35 generations of artificial selection, the researchers found that there was a significant and opposite change in the number of bristles in the two populations. The population selected for high numbers of bristles (S) showed a huge increase in bristle numbers, while the population selected for low numbers of bristles (R) showed a huge decrease. Additionally, there was no overlap in the bristle numbers between the two populations, indicating a clear divergence in the selected trait. This suggests that the artificial selection process was successful in causing a significant change in the bristle numbers of the fruit flies.

Species that show convergent evolution do not necessarily have to be found in the same biogeographical region. Convergent evolution refers to the process in which different species independently evolve similar traits or characteristics in response to similar selection pressures, even if they do not share a recent common ancestor. Therefore, it is possible for species exhibiting convergent evolution to be found in different biogeographical regions. The other statements are true about species that show convergent evolution, as they do share similar selection pressures, have similar phenotypes, and can share homologous structures.