Sofia Messier- Biology Notebook 05.01: Evolution

What is continental drift?

A theory that explains the formation, alteration, and extremely slow movement of the continents across the Earth's crust. The continents are thought to have been formed from one large landmass that split, drifted apart, and in places collided again.

Uniformitarianism

A theory, built upon gradualism, proposing that the rates of geological processes that form the Earth are uniform, or constant, throughout history.

Botany

Botany is a field of science that studies plants. Botanists are the scientists that work in this field of study.

List some of the fields that provide support and evidence for evolution.

1. Fossils 2. Comparative Anatomy 3. Comparative Embryology 4. Biogeography 5. Molecular Biology

Naturalist

A naturalist is an expert in the study of the natural history of the Earth.

1880-1930

Alfred Wegener was a German astronomer who made contributions in many fields of science. He proposed and published the geological theory of continental drift. This theory claims that the Earth's continents once formed a single mass that split apart, with the pieces moving away from each other ever since. Wegener was not the first to suggest that the continents had once been connected, but he was the first to provide extensive geological and fossil evidence to support to the theory. This theory provides for evolutionary relationships between fossils now found on different continents.

What does molecular evidence support?

All living organisms share the same early ancestor.

What are vertebrates?

Animals with backbones, have the same basic bone structure in their limbs. These bones are examples of homologous structures.

Astronomy

Astronomy is the field of science that studies outer space, including the position, distribution, dimensions, motion, composition, and energy of planets, stars, and other celestial bodies.

A scientist looked at a group of embryos. Upon examination she observed that species A and B diverged closer to fertilization. She also observed that species C and D diverged closer to birth. Which of the following statements is true?

B. Species C and D are more closely related than species A and B.

1707-1778

Carolus Linnaeus was a Swedish physician and botanist who worked in the field of taxonomy, the branch of biology concerned with naming and classifying the various forms of life on Earth. He developed the two part naming system for organisms, using the genus and species, known as scientific naming. Although he did not believe in the evolution of organisms, Linnaeus's classification scheme presented possible kinship relationships for other scientists to investigate.

Catastrophism

Catastrophism is a theory about the earth's history that says major changes in the earth's crust result from catastrophes rather than from slow, gradual processes.

1809-1882

Charles Darwin is credited with proposing the theory of evolution. As we have seen in this brief timeline, Darwin did not invent the idea and he did not observe and collect all of the supporting evidence on his own. However, he carried out the research necessary to document that evolution has occurred, proposed a plausible mechanism (natural selection) to explain why and how it occurs, and then published the theory and evidence in order to make it available to other scientists and to the general public. Unlike Lamarck's idea that individuals alter their traits based on the environment, Darwin proposed that variations already existed within a population and those individuals with the more favorable, or useful, traits survive to reproduce. These traits then become more common in the population, leading the population to evolve slowly over time.

1797-1875

Charles Lyell was an Englishman who studied under many catastrophists at Oxford to become the leading geologist of his time. He eventually turned away from catastrophism, building upon James Hutton's gradualism principles to develop a theory known as uniformitarianism. This theory proposes that the rates of geological processes that form the Earth are uniform, or constant, throughout history.

What is the universal genetic code?

DNA and RNA

Define embryonic.

Early developing stage of a multicellular organism

1731-1802

Erasmus Darwin was an English physician, natural philosopher, botanist, and poet. He was also grandfather to the famous naturalist Charles Darwin. Erasmus Darwin presented one of the first formal theories on evolution in his publication Zoonomia, or, The Laws of Organic Life (1794-1796). In these writings he discussed how life may have evolved from a single common ancestor and wrestled with the question of how one species could evolve into another. Darwin also wrote about how competition and sexual selection could cause changes in species. His grandson Charles Darwin commented on these writings and expanded on many of these ideas in his own studies.

Describe how scientists can use comparative embryology to explain evolution from a common ancestor.

Even as early as the 1800s, scientists noticed that the embryonic development of many vertebrates looks similar. As technologies improved, scientists were able to determine that closely related organisms go through equivalent stages of embryonic development. For example, in all vertebrate embryos, cells in the same location develop in a precise order and identical pattern to produce the organism's tissues and organs. In addition, all vertebrate embryos have gill slits during early development. Later in development, the embryos' characteristics differentiate depending on the species. The slits develop into true gills in fish, but the same slits develop into the tubes that connect the inner ear to the throat in humans.

Give an example of vestigial structure.

For example, many marine mammals have hip bones that they do not need or use. The movements of a whale do not require hip bones, but these bones remain as evidence that whales likely evolved from ancestors that were land mammals. The whale's hip bones are examples of a vestigial structure, a structure in an organism that no longer serves its original function due to natural selection.

What are some examples of homologous structures in animals?

For example, the front limbs of birds are more similar to those of reptiles than those of mammals. This similarity, as well as other structural similarities, indicates that birds and reptiles share a common ancestor more recently than the common ancestor of birds and mammals.

Geology

Geology is the field of science that investigates the earth's physical structure, its history, and the processes that act upon it.

1769-1832

Georges Cuvier was a French anatomist largely responsible for developing the field of paleontology, the study of fossils. Greatly influenced by the writings of Buffon, Cuvier found that layers, or strata, in the Earth's rock each represent a different period in the Earth's history. Each of these strata layers contains a unique collection of fossils. The deeper (older) the layer, the more dissimilar the plants and animals are from the current organisms on Earth. Cuvier speculated that the strata layers corresponded to catastrophic events on Earth such as floods or drought that destroyed many of the organisms living at the time, causing the differences in the fossils found in each strata layer. This view of Earth's history is called catastrophism.

1707-1788

Georges-Louis Leclerc, Comte de Buffon was a French aristocrat who studied law and medicine, but then became a naturalist and author. He published thirty-six volumes of his Histoire naturelle (Natural History) during his lifetime. In his writings, he noted that different regions of the world have distinct plants and animals, even when they have similar environments. This is considered to be the first principle of biogeography. Buffon also suggested that species may have improved and degenerated since creation, and that the Earth is probably much older than the 6,000 years widely accepted at the time.

Gradualism

Gradualism is a theory about the earth's history that says slow but continual processes can result in large, dramatic changes.

1822-1884

Gregor Mendel, an Austrian monk, provided the first experimental findings that began to explain heredity and genetics. The scientific community at the time, including Charles Darwin, did not recognize the importance of these findings. It was more than 15 years after Mendel's death before scientists recognized the importance of his work. Today, scientists have applied their knowledge of genetics to the theory of evolution.

1953

James D. Watson and Francis Crick used various data and observations, including x-ray diffraction data from female scientist Rosalind Franklin, to propose the double helix structure of the DNA molecule. In the years that followed, Watson, Crick, and other researchers learned the basics of how DNA works. Today, scientists are able to compare the genetic codes of various species in order to compare how closely they are related.

1726-1797

James Hutton was a Scottish geologist who proposed a different idea of the earth's geological history. He applied the principle of gradualism, which theorizes that slow but continual processes can result in large, dramatic changes on the Earth. For example, canyons are formed by rivers over long periods of time instead of by a sudden catastrophic event. This meant that Hutton proposed that the Earth was very old, because gradualism would take much more time to develop the current conditions of the Earth than the sudden, catastrophic events theorized by Cuvier and other scientists of the time.

1744-1829

Jean Baptiste Lamarck of France was one of the first scientists to develop a model attempting to explain how life evolved. He compared fossils to current species and found what he felt were several lines of descent from older fossils to younger fossils to modern species. He proposed that evolution responded to an organism's inner drive toward complexity and perfection; parts of an organism's body that were commonly used would grow and develop, while parts that were not used would eventually deteriorate. He also proposed that the modifications made to an organism during its lifetime can be passed on to its offspring, which has since been disproven. Although Lamarck's theories are not well supported today, he served as an important influence on Charles Darwin and other scientists who followed.

What is the theory of evolution built upon?

Like many other scientific theories, the theory of evolution is built on observations, scientific analysis, and evidence discovered by many different scientists working in several different fields.

What are vestigial structures?

Many living organisms have structures that no longer serve their original purpose due to evolutionary changes. They are called vestigial structures. Vestigial: visible evidence of something that is no longer in existence, such as the remaining columns of an ancient temple

What does evolution describe?

Refers to the processes that transform life on Earth from its earliest forms to the vast diversity on Earth today. These changes are based primarily on the interactions of organism populations and their environments.

What are homologous structures?

Scientists believe that animals with similar structures evolved from a common ancestor. These similar structures, called homologous structures, are shared by related species.

How can scientist determine that evolution occurred?

Scientists use a variety of evidence left by living organisms to develop and support the theory of how life evolved on Earth.

Explain how fossils provide evidence for evolution.

Some fossil findings show the link between dinosaurs and birds, between fish and land animals, and between ancient land mammals and whales. As the fossil record grows, it continues to make connections in the evolutionary timeline. The age of the fossils found, as well as their location within the layers of earth, indicates the order in which they evolved. Single-celled prokaryotes are the oldest known fossils, followed by invertebrates, amphibians, reptiles, mammals, and birds. This order coincides with the evolutionary timeline indicated by other fields of science. Advances in technology have helped scientists learn more about the fossil timeline. Some of the oldest known rock samples date back 3.5 billion years and contain fossils of microscopic organisms. Using technology such as lasers to identify organic material, we can compare them to organisms that live today.

Evolution by Natural Selection

Some individuals within a population have traits that better enable them to survive and reproduce in a given environment, while others may not survive to reproduce. This process is called natural selection, and it can lead to the evolution of a population over many generations.

How are DNA sequences used to determine ancestry in molecular biology?

Species with very similar DNA sequences share close ancestors. With advances in technology and a growing understanding of genetics, scientists have uncovered evidence of evolutionary relationships in DNA and proteins. Scientists have found that all living things on Earth share the same universal code in DNA and RNA molecules, which indicates that they share a common ancestor. In addition, the more nucleotide sequences two species' DNA molecules have in common, the more closely related they appear to be on the evolutionary timeline. Biologists believe that all living organisms share the same early ancestor, and molecular evidence supports that theory. Even single-celled bacteria and humans share some of the same proteins and amino acid sequences.

1941-2002

Stephen Gould was an American paleontologist, science historian, and evolutionary biologist who spent most of his career teaching at Harvard University and working at the American Museum of Natural History in New York. One of his greatest contributions to science is the theory of punctuated equilibrium, developed with Niles Eldredge in 1972 after careful and detailed examination of fossils. This theory proposes that evolution happens in rare instances of rapid branching evolutionary change in between long periods of stability. This is in contrast to the theory of evolutionary gradualism.

1823-1913

The British biologist Alfred Russel Wallace independently developed a theory of evolution, based on natural selection that prompted Darwin to publish his own similar theory. Wallace developed his theories on evolution while studying the wildlife of South America and Asia. He was the 19th century's leading expert on the geographical distribution of animal species. Wallace corresponded at times with Darwin, even supplying Darwin with birds for his studies. He sent his theory of evolution to Darwin in 1858, and they were surprised to learn how similar it was to the theories that Darwin was working on.

Anatomy

The field of anatomy is concerned with the bodily structures of humans, animals, and other organisms. Anatomists use dissection as just one of the ways in which they study body structures.

Biogeography

The field of biogeography studies where on the planet species live now and where their ancestors lived in the past.

What is biogeography?

The field of biogeography studies where species live now and where their ancestors lived in the past. Similar environments in different parts of the planet may be inhabited by very different plants and animals. For example, organisms in the tropics of South America appear to be more closely related to those in South American deserts than to organisms in the tropics of Australia. Scientists have found that most species on the same continent are more closely related to each other than to organisms on other continents, due to the evolution that occurred after the continents split apart through continental drift. Some similar features can also be seen in organisms living in similar climates on different continents. This shows that even though they are only distantly related, similar environmental conditions result in the evolutionary success of similar adaptations.

Paleontology

The field of paleontology is concerned with the study of fossilized plants and animals. Paleontologists are the scientists who work in this field.

Describe how scientists can use comparative anatomy to explain evolution from a common ancestor.

The similarities and differences between the homologous structures of two species determine how recently they shared a common ancestor.

Punctuated Equilibrium

The theory of punctuated equilibrium proposes that evolution happens in rare instances of rapid branching evolutionary change in between long periods of stability. This is in contrast to the theory of evolutionary gradualism.

Briefly describe the following fields of study:

nothing

Describe the events that helped to shape the theory of evolution in these years:

nothing