Evolutionary Theory: From Buffon to Darwin, Study notes of Biology

Download Evolutionary Theory: From Buffon to Darwin and more Study notes Biology in PDF only on Docsity! GEN BIO (REVIEWER) GEORGES-LOUIS LECLERC, COMTE DE BUFFON (1707 - 1788) ● A French Mathematician and Naturalist ● Dierent geographical locations have dierent organisms ● All the world’s quadrupeds had developed from an original set of just thirty-eight quadrupeds ● Buon believed that when groups of organisms migrated to new areas, they were gradually altered as a result of adaptation to a somewhat dierent environment. JEAN BAPTISTE-LAMARCK (1744-1829) ● A French Naturalist ● Was one of the first to propose that humans evolved from a lower species through adaptations over time. ● The first scientist who attempted to explain the evolutionary process. ● Principle of Use and Disuse ● Theory of Acquired Characteristics PRINCIPLE OF USE AND DISUSE - If the external environment changed, an animal’s activity patterns would also change to accommodate the new circumstances. This would result in the increase or decreased use of certain body parts, and consequently, those body parts would be modified. THEORY OF ACQUIRED CHARACTERISTICS (THEORY INHERITANCE OF ACQUIRED CHARACTERISTICS) - The alteration would make the animal better suited to its habitat, the new trait would be passed on to its ospring. THOMAS MALTHUS (1766-1834) ● An English economist who is best known for his book “An Essay on the Principle of Population” which was first published in 1789. ● In his book, Malthus argued that the human population was growing exponentially, while the food supply was only growing linearly. This would eventually lead to a “population crisis”, in which there would be too many people and not enough food. ● By reading his book, Darwin and Wallace recognized the important fact that when population size is limited by the availability of resources, there must be constant competition for food and water. JAMES HUTTON (1729-1797) ● Was the first to publish the idea that the same processes that formed the Earth at the very beginning of time were the same that were happening in the present day. These “ancient” processes changed the Earth, but the mechanism never changed. CHARLES LYELL (1797-1875) ● Proposed that gradual geological processes have shaped Earth’s surface. ● Infer that Earth must be far older than most people believed. ● Lyell believed that Earth developed through a series of slow changes that built up over time. ● Lyell theorized that geologic processes that were around at the beginning of time were the same ones that were happening in the present as well and that they worked the same way. HERE ARE SOME SPECIFIC WAYS IN WHICH HUTTON AND LYELL INFLUENCED DARWIN: THE AGE OF THE EARTH - Earth was much older than previously thought, which gave enough time for evolution to have occurred. GRADUALISM - Geological change occurs gradually over time, rather than through sudden catastrophic events. - This idea influenced Darwin’s thinking about how evolution could have occurred, which he also saw as a gradual process. CHARLES DARWIN (1809-1882) ● A British Naturalist and Biologist ● He is known as the “Father of Evolution” ● Published book titled “On the Origin of Species” on 1959 ● Known for his theory of evolution by Natural Selection. ● In 1831, he embarked on a five-year voyage around the world on the HMS Beagle ● Darwin’s most important observations were made on the Galápagos Islands. ● Galápagos Tortoises. Galápagos tortoises have dierently shaped shells depending on which island they inhabit. Tortoises with saddle-shaped shells can reach up to eat plant leaves above their head. Tortoises with dome-shaped shells cannot reach up in this way. These two types of tortoises live on islands with dierent environments and food sources. ● ARTIFICIAL SELECTION: Identification of desirable traits by HUMANS to perpetuate to future generations. THEORY OF EVOLUTION BY NATURAL SELECTION ● Nature selects the variations that are most useful. “Survival of the fittest” - those most suited to their environment are the ones that reproduce most successfully, and are most likely to WHY HOMOLOGOUS STRUCTURES SERVE AS A EVIDENCE OF EVOLUTION? Homologous structures provide evidence of evolution because they suggest that the organisms that possess them share a common ancestor. This is because homologous structures have the same basic structure and origin, but may also have dierent functions. ANALOGOUS STRUCTURES ● Are structures that have similar functions but dierent evolutionary origins. ● They are a result of convergent evolution. Ex: The fins of dolphins, sharks, and ichthyosaurs are not homologous structures. Dolphins are mammals, sharks are fish, and ichthyosaurs were reptiles, this means that they are not closely related and they did not inherit the fins from a common ancestor. Instead, the fins of these three groups of animals evolved independently in response to the need to swim eciently. WHY ANALOGOUS STRUCTURES SERVE AS A EVIDENCE OF EVOLUTION? Analogous structures provide evidence of evolution because they show that similar traits can evolve independently in unrelated species as a result of convergent evolution. VESTIGIAL STRUCTURES ● Are anatomical features of behavior that no longer seem to have a purpose in the current form of an organism of the given species. ● Often, these vestigial structures were organs that performed some important functions in the organism at one point in the past. WHY VESTIGIAL STRUCTURES SERVE AS EVIDENCE OF EVOLUTION? Vestigial structures provide evidence of evolution because they are remnants of structures that were once useful in ancestral species but are no longer needed in the descendant species. This suggests that organisms have changed over time and that new species can arise from existing species. BIOGEOGRAPHY ● The study of the location of organisms around the world and how they are matched to their environment. ● Look at how living organisms are connected to the environment they live in. Ex: The availability of food has influenced the beak shape in finches ● Some organisms that are unrelated have developed similar adaptations to similar environments. WHY BIOGEOGRAPHY SERVE AS EVIDENCE OF EVOLUTION? Because it shows that the distribution of plants and animals around the world can be explained by the process of evolution. EMBRYOLOGICAL EVIDENCE ● It is based on the observation that embryos of dierent species often have similarities, even if the adult organisms do not. ● Human embryos even have a gill slit at some point in their development, even though humans do not have gills. This suggests that humans and fish share a common ancestor that had gills. ● Another example is that all mammal embryos have pharyngeal arches, which are structures that develop into the jaw, throat, and ears in adult mammals. Pharyngeal arches are also present in fish embryos, which suggests that mammals and fish share a common ancestor. EMBRYOLOGY ● Some homologous structures can be seen only in embryos. ● For example, all vertebrate embryos have a tail at some point in their development, even if the adult organism does not have a tail. This suggests that a;l vertebrates share a common ancestor that had a tail. WHY EMBRYOS SERVE AS EVIDENCE OF EVOLUTION? Embryological evidence is a powerful tool for studying evolution because it provides evidence of common ancestry. Embryological evidence suggests common ancestry because it shows that embryos of dierent species often have similarities, even if the adult organisms do not. MOLECULAR HOMOLOGIES Shared features suggest that all living things are descended from a common ancestor. ● The same genetic material (DNA) ● The same, or highly similar, genetic codes ● The same basic process of gene expression (transcription and translation) ● The same molecular building blocks, such as amino acids MOLECULAR HOMOLOGIES ● Are similarities between the DNA and RNA sequences of dierent organisms. ● They are evidence of common ancestry, as they suggest that the organisms that possess them share a common ancestor that also had those sequences. ● For example, humans and chimpanzees share over 98% of their DNA sequences. This suggests that humans and chimpanzees share a common ancestor that lived relatively recently. WHY MOLECULAR HOMOLOGIES SERVE AS EVIDENCE OF EVOLUTION? Molecular homologies provide evidence of evolution because they suggest that organisms share a common ancestor. The fact that dierent organisms have similar DNA and RNA sequences suggests that they share a common ancestor.