BIOL 1308 Chapter 13-15 Study Guide PDF

Chapter 13, 14, 15 - Evidence of Evolution, Speciation and Extinction, The Origin and History of Life Key Terms allopatric analogous structures aneuploidy biogeography convergent evolution endosymbiosis evolution fossil record fossils geologic time scale homologous structures macroevolution microe...

Chapter 13, 14, 15 - Evidence of Evolution, Speciation and Extinction, The Origin and History of Life Key Terms allopatric analogous structures aneuploidy biogeography convergent evolution endosymbiosis evolution fossil record fossils geologic time scale homologous structures macroevolution microevolution paleoanthropology paleontologist pangea parapatric polyploid population prezygotic primates postzygotic speciation sympatric theropod vestigial structures Word Roots allo- = other analogous = proportionate aneu- = without; -ploid = fold anthro- = human; -oid = likeness (anthropoid: a member of the primate group including apes and monkeys, all of which resemble humans in certain characteristics) bio- = life; geo- = the Earth (biogeography: the study of the past and present distribution of organisms) converge = inclining together endo- = inner, within (endospore: a thick-coated protective cell produced within a bacterial cell that can become dormant to survive harsh environmental conditions; endotoxin: a poisonous component of the outer membrane of gram-negative bacteria, released only when the bacteria die) homo- = like, resembling (homologous structures: structures in different species that are similar because of common ancestry; homology: similarity in characteristics resulting from a shared ancestry) macro- = large micro- = small paleo- = ancient (paleontologist: a scientist who studies fossils); anthrop- = man; -ology = the science of (paleoanthropology: the study of human origins and evolution) pan- = across; -gea = the Earth para- = along poly- = many post- = after pre- = before; zygot- = a fertilized egg sym- = same, with, together; -bios = life (symbiosis: a close association between organisms of two or more species) ther- = wild beast, beast of prey; -pod = foot vestigi- = trace (vestigial organs: a structure of marginal or no importance to an organism that is the historical remnant of structures that had important functions in ancestors) Lecture Outline Introduction Are Birds reptiles? Yes. An amazing amount of evidence has been discovered linking birds to a group of small, fleet-footed dinosaurs called Theropods. Before the last mass extinction event, 65 million years ago, there were no birds, only dinosaurs with modern bird-like features. Then, after the last mass extinction took place, 30 living Orders of Birds appear in the Fossil Record signifying a quick diversification of avian reptiles due to their ease of mobility to find food, water, shelter, etc. over larger areas than terrestrial reptiles could traverse. Archaeopteryx lithographica had feathers and was the first bird- like reptile discovered. This led to several other genera of avian reptiles to be found and linked to early groups of birds. 13.1 Clues to Evolution Lie in the Earth, body Structures, and Molecules 1. Darwin’s ideas about evolution also relied on the Fossil Record, the sequence in which fossils appear within Strata (layers) of sedimentary rocks. 2. Paleontology is the study of Fossils which are the imprints or remains of organisms that lived in the past. 3. The Earth is about 4.6 Billion years old and life has been on Earth for about 3.5 Bil- lion years. Early organisms didn’t fossilize very well but there is ample evidence of their existence. It wasn’t until plants and animals arose in great numbers about 543 million years ago that we have had a diversity of fossils to study. 13.2 Fossils Record Evolution 1. Paleontologists are scientists who study Fossils. They have found many categories: 2  a. A Petrified Fossil occurs due to the mineralization of organic materials. Slowly, over long periods of time, minerals replace organic material in a dead organism (usually its’ harder tissues such as bones or shells since soft tissues usually disinte- grate quickly) leaving a rock in the same shape as the original organic matter. b. A Cast Fossil is usually a shell (or other hard structure) which fills in with sedi- ments, the sediments harden or solidify, and the original hard structure disinte- grates leaving and impression of the inside of the deceased organism (think of a cast leftover from a broken arm). c. A Trace Fossil is the imprint of where an organism used to be. Think of a foot- print in the mud after the mud has dried. d. An Organic Fossil still retains organic matter within the fossil. e. Amber is an example of fossilized Resin or tree sap which dries and hardens, sometimes encasing insects, small birds, and rodents. f. Ice has been known to fossilize or preserve ancient organisms. g. Peat Bogs are watery, low-lying areas where primitive plants called Bryophytes or “True-Mosses” grow, live, and die. Water leaches acids out of their structures leaving the “bog” very acidic which prevents bacteria and fungi from decomposing organisms that get “trapped’ in the bog. 13.3 Biogeography Considers Species’ Geographical Locations 1. The Theory of Plate Tectonics states the the Earth’s surface is composed of several large crustal plates which move around due to interior forces, forming deep trenches when one plate subducts under another plate, large mountains when two plates push against each other, and earthquakes when two plates moves towards, away from, and past each other. 2. About 280 Million Years Ago (MYA), all continents were merged together into one super-continent named Pangea. And slowly, continents have been moving around the Earth’s surface forming the seven great continents we see today. 3. When the continents were merged together, it was easier for species to share the same reproductive populations. However, as they drifted apart, populations became iso- lated from each other leading to Speciation or the forming of new Species, unique types of life on Earth. 4. Biogeography is the study of the distribution of organisms around the globe. 13.4 Anatomical Comparisons May Reveal Common Descent 1. Organisms with Homologous structures share a common evolutionary origin such as arm of a Human, the front leg of a cat, and the wings of a bat, all Mammals. 2. Vestigial Structures are structures which used to have a specific function in an organ- ism but has lost that ability or is no longer needed such as the Human appendix, our eyebrows, and male nipples. 3. Analogous structures are structures which have similarity in function of unrelated groups of organisms such as the winds on a pine seed, the wings on an insect, the wings on a bird, and the wings on a bat. 4. Convergent Evolution is the formation of these Analogous structures among unre- lated species into to gain some type of ecological advantage such as the wings of an 3  insect and the wings of a bird or the barrel-shape of some cacti on different conti- nents. 14.1 What is a Species? 1. The word Species is from the Latin for “kind” or “appearance.” 2. Although the basic idea of species as distinct life-forms seems intuitive, devising a more formal definition is not easy and raises questions. a. How similar are members of the same species? b. What keeps one species distinct from others? 3. Microevolution is a change in the relative frequencies of alleles (how often alleles are ex-pressed) in a Gene Pool over time but Speciation, or the formation of a new species, does not occur. An example would be pesticide resistance in crop insects. 4. Macroevolution is the change in large characteristics of a group of organisms leading to novel traits, new species, and unique new groups of organisms. Examples include feathers on birds or flowers on plants. 5. The Biological Species Concept defines a Species as a group of populations, whose members have the potential to interbreed in nature, and produce fertile, viable off- spring. Therefore, members of a species are similar because they can reproduce with each other. 6. Speciation is the process by which one species evolves into two or more species. a. Every time speciation occurs, the diversity of life increases. b. The many millions of species on Earth have all arisen from an ancestral life form that lived around 3.5 billion years ago. 7. The Biological Species Concept can be problematic. Some pairs of clearly distinct species occasionally interbreed and produce Hybrids. a. For example, grizzly bears and polar bears may interbreed and produce hybrids called Grolar Bears. b. Melting sea ice may bring these two bear species together more frequently and pro- duce more hybrids in the wild. c. The mating of a Horse to a Donkey produces a Mule, a sterile hybrid. 14.2 Reproductive Barriers Cause Species to Diverge 1. Reproductive Isolation is the inability of two populations to interbreed. This pre- vents members of different species from mating with each other, prevents gene flow between species, and maintains separate species. 2. Therefore, species are distinct from each other because they do not share the same Gene Pool (set of genes of an interbreeding population). 3. Reproductive isolation cannot usually be determined for extinct organisms known only from fossils. 4. Reproductive isolation does not apply to prokaryotes or other organisms that repro- duce only asexually. 5. Two Types: a. Prezygotic Barrier is a barrier to reproduction before the act of reproduction takes place. This could be due to Ecological (place) Isolation, Temporal (time) Isolation, Behavioral Isolation, Mechanical Isolation (incompatable reproductive organs), Gametic Isolation (Sperm and Egg don’t recognize each other), etc. 4  b. Postzygotic Barrier is a barrier to reproduction after zygote formation and could be due to a weakened individual, sterility, etc. This could be due to Hybrid Invia- bility (embryo death before maturity), Hybrid Infertility (infertility), Hybrid Break- down (infertile offspring), etc. 14.3 Spatial Patterns Define Three Types of Speciation 1. In Allopatric (“other-homeland”) Speciation, populations of the same species are ge- ographically separated, isolating their gene pools. 2. Isolated populations will no longer share changes in allele frequencies. 3. Gene flow between populations is initially prevented by a geographic barrier. For example the Grand Canyon and Colorado River separate two species of antelope squirrels and the Northern Spotted Owl is separated from the Mexican Spotted Owl by distance and climate. 4. Allopatric Speciation is dependent upon the type of animal, the type of barrier, and distance. What may be a barrier to a ground squirrel, such as a river, may not a bar- rier to a flying insect or bird, etc. 5. Sometimes when a few members of a species inhabit a new area, some members find various new niches in which they fill their role in the environment. This leads to Adaptive Radiation or the formation of several new species from one ancestral stock. 6. The Galápagos Islands a. are located about 900 km (560 miles) west of Ecuador, b. are one of the world’s great showcases of Adaptive Radiation, c. was formed devoid of life from underwater volcanoes, d. was colonized gradually from other islands and the South America mainland, and e. has many species of plants and animals found nowhere else in the world. 7. The Galápagos Islands currently have 14 species of closely related finches, called Darwin’s finches, because Darwin collected them during his around-the-world voy- age on the HMS Beagle. 8. These finches share many finch-like traits, differ in their feeding habits and their beaks, specialized for what they eat, and arose through Adaptive Radiation. 9. In Parapatric (“along-side”) Speciation, the ranges of two populations overlap and those individuals at the borders of each population interbreed. 10. These interbreeding groups form their own unique characteristics. 11. Sympatric (“same-homeland”) Speciation occurs when a new species arises within the same geographic area as a parent species. 12. Many organisms, such as plants, can survive having too many or too few chromo- somes and this is called Aneuploidy. This condition can lead to some genes being repeated and expressed in the offspring making them “bigger”, “faster”, “more drought tolerant”, etc. 13. Many plant species have evolved by Polyploidy in which cells have more than two complete sets of chromosomes. 14.5 Extinction Marks the End of the Line 1. Extinction is the loss of a species from Earth. This may occur gradually over time or in rapid bursts. 5  2. The Background Extinction Rate is the rate at which species are gradually lost over a long period of time due to normal evolutionary processes. 3. A Mass Extinction event is a relatively short period of time in which at least 50% (or more) of all species are lost. 4. There have been five major Mass Extinction events over the past 500 million years (or so). Scientists believe we are in the “sixth” Mass Extinction today due to the Hu- man Population Explosion we are going through right now. As of Fall 2022, the Earth now has 8 Billion people. We added the last one billion people in only 11 years. 14.6 Biological Classification Systems Are Based on Common Descent 1. Taxonomy is the Science of naming and classifying organisms based upon common, morphological (body-form) characteristics. 2. Taxonomy as a Science was invented by a Swedish physician named Carolus Lin- naeus in the 1700s. 3. At the time, science believed that all life consisted of only Plants and Animals. He placed all life into two major taxons or categories of like characteristics he called Kingdoms; Kingdom Plantae and Kingdom Animalia. 4. Since then, science has added four more kingdoms creating the Six Kingdom Sys- tem: a. Kingdom Archaea - unicellular, prokaryotic, ancient, extreme-living bacteria. b. Kingdom Bacteria - unicellular, prokaryotic, common bacteria. c. Kingdom Protista - unicellular or multicellular, eukaryotic animal-like Protozoans, plant-like Algae, and fungus-like Molds. d. Kingdom Fungi - unicellular or multicellular, eukaryotic, saprophytic or parasitic. e. Kingdom Plantae - multicellular, eukaryotic, autotrophic, non-motile. f. Kingdom Animalia - multicellular, eukaryotic, heterotrophic, motile. 5. And in 1990, it was proposed that the highest taxon should be called a Domain and thus the Three Domain System was coined with each Kingdom directly underneath a Domain: a. Domain Bacteriae – unicellular, prokaryotic, common bacteria. b. Domain Archaea – unicellular, prokaryotic, bacteria which live in extreme envi- ronments (very hot, very cold, very salty, very acidic, etc.). c. Domain Eukarya – unicellular or multicellular, eukaryotic, Protistans, Fungi, Plants, and Animals. 15.1 Life’s Origin Remains Mysterious The origin and history of life is described using the geologic time scale o It is a way to divide time and visualize major geological and biological events Conditions in Earth were very harsh and hostile, yet somehow an entity that is capa- ble of surviving, thriving, and reproducing arose Regardless, it is thought that life began when the first organic molecules came to- gether o Some suggest amino acids (that form proteins) were the first molecules that were formed o Others suggest that RNA must have been the first informational molecule 6  Some say that the first cells were formed during this time period… but we will never know 15.2 Complex Cells and Multicellularity Arise over a Billion Years Ago A. Endosymbiosis Explains the Origin of Mitochondria and Chloroplasts 1. The Endosymbiont Theory explains the origin of Mitochondria and Chloro- plasts. a. It states that Eukaryotic cells evolved when prokaryotes established residence within other, larger prokaryotes. They became Endosymbi- onts or organisms living inside of other organisms. b. This theory is supported by present-day Mitochondria and Chloro- plasts that have structural and molecular similarities to prokaryotic cells and replicate using their own DNA (mDNA = Mitochondrial DNA or cDNA = Chloroplast DNA), separate from the DNA inside of the Nucleus of the host cell. 2. Secondary Endosymbiosis is the process in which an autotrophic Protist be- came endosymbiotic inside of a heterotrophic Protist. B. Multicellularity May Also Have Its Origin in Cooperation 1. Earliest fossils of multicellular life are from red algae that lived about 1.25 billion years ago 2. Some multicellular organisms resemble single-celled protists 3. Multicellularity made specialized cells a possibility, which allowed for new features and functions to arise in living organisms 15.3 Life’s Diversity Exploded in the Past 500 Million Years The Precambrian Period was when life was thought to have originated and di- versified o Highlights include  Accumulation of O2 in the Earth’s atmosphere made photosynthe- sis possible  Appearance of eukaryotic cells, as well as multicellular algae and animals The Paleozoic Era is known as a period of diversification in living organisms o Highlights include  Appearance of major phyla of animals (both invertebrates and ver- tebrates) in marine environments  Appearance of plants (including vascular plants) and fungi in land o Later in this era, the appearance of first terrestrial animals (amphibians and reptiles) as well as seed plants were noted The Mesozoic Era is known as the “Age of Reptiles” o Highlights include  Dinosaurs dominating and roaming most of the lands 7   Appearance of the first mammals  Appearance and diversification of flowering plants The Cenozoic Era is known as the “Age of Mammals” and continues today o Highlights include  Diversification of mammals  Emergence of primates  Appearance of Homo sapiens 15.4 Fossils and DNA Tell the Human Evolution Story Primates include monkeys, apes, and humans and share similar physical charac- teristics like o Grasping hands with opposable thumbs o Flat nails instead of claws o Grasping hands and feet o Binocular vision with excellent depth perception o Large brains Molecular evidence suggest that humans are a species of great ape o Chimpanzees (a type of Ape) and Humans diverged in evolution about 6 million years ago and differ in DNA by about 1%. Fossilized remains are used by paleoanthropologists to compare physical features of hominin species, species that are more closely related to Humans than to Chimpanzees o Paleoanthropology is the study of human origins and evolution, the brief history since the divergence of human and chimpanzee lineages. o Paleoanthropologists or scientists who study Human origins, have un- earthed about 20 species of extinct Hominins 8