1 / 35

Fundamentals of Evolution

Fundamentals of Evolution. A Summary of Evolution. Fundamentals of Evolution. A Summary of Evolution. Nothing in Biology Makes Sense Except in the Light of Evolution. EVOLUTION:.

gagan
Download Presentation

Fundamentals of Evolution

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fundamentals of Evolution A Summary of Evolution

  2. Fundamentals of Evolution A Summary of Evolution Nothing in Biology Makes Sense Except in the Light of Evolution

  3. EVOLUTION: • The frequency of an allele in a gene pool of a population depends on many factors and may be stable or unstable over time. As a basis for understanding this concept: • Students know why natural selection acts on the phenotype rather than the genotype of an organism. • Students know why alleles that are lethal in a homozygous individual may be carried in a heterozygote and thus maintained in a gene pool. • Students know new mutations are constantly being generated in a gene pool. • Students know variation within a species increases the likelihood that at least some members of a species will survive under changed environmental conditions. • Evolution is the result of genetic changes that occur in constantly changing environments. As a basis for understanding this concept: • Students know how natural selection determines the differential survival of groups of organisms. • Students know a great diversity of species increases the chance that at least some organisms survive major changes in the environment. • Students know the effects of genetic drift on the diversity of organisms in a population. • Students know reproductive or geographic isolation affects speciation. • Students know how to analyze fossil evidence with regard to biological diversity, episodic speciation, and mass extinction. • Students know how to use comparative embryology, DNA or protein sequence comparisons, and other independent sources of data to create a branching diagram (cladogram) that shows probable evolutionary relationships.

  4. Evolution • Definition: A change in a population of a species over time • Organisms evolve to adapt better to their environment • According to Evolution, all living things (organisms) on the planet are related and have a common ancestor A unicellular prokaryote (bacteria) that lived near hydrothermal vents where the temperature is near 200 degrees Fahrenheit amidst poisonous hydrogen sulfide and deadly sulfuric acid

  5. Formation of EARTH • First need to talk about formation of earth: 4.6 billions yrs ago! • How do we know this stuff: RADIOACTIVE DATING- • Not relative dating- • Solar system in beginning (~5 billion yrs ago) was a swirling mass of gas and dust that collapsed inward leaving some debris outside (planets)

  6. Formation of Earth and water

  7. FORMATION OF LIFE(First organic molecules) • Scientists believed early earth had perfect conditions: ammonia (NH3), Water vapor, hydrogen gas, and methane gas (containing Carbon) • Perfect boiling temperatures lead to first organic compounds amino acids • Earth cooled and water vapor turned to liquid (oceans) • Then complex reactions with UV light and lightning lead to more complex organic compounds that did not contain any genetic info (no DNA nor RNA)

  8. First replicating molecules • RNA was the first genetic material to self-duplicate. • DNA was the second and the one that most organisms use today

  9. First Prokaryotes(the early cells that are still around today aka bacteria) • Since no oxygen on earth before 1.7 bya, first cells must have been anaerobic-- • Most likely heterotrophs that depended on organic molecules. After consuming all organic molecules, there was a need for some organisms to evolve into autotrophs • These first autotrophs resembled archaebacteria (aka extremophiles)-- • These early archaebacteria obtained their energy by chemosynthesis--

  10. Effects of Oxygen • Oxygen began being produced about 1.7 billion yrs ago by photosynthetic organisms that resemble modern cyanobacteria (like simple unicellular green algae). • Oxygen was probably deadly to most early organisms • As O2 levels rose (for another 1billion years), ultraviolet radiation by the sun converted O2 to O3 ozone (poisonous to life) so life could still not exist on land yet • Life continued to exist only in the ocean

  11. First cells by endosymbiosis Then many of these cells began sticking together, first in colonies, then permanently attached; first multicellular organisms: early invertebrates (look at timeline Handout in summer reading packet) Then after more oxygen was released by early plant forms and algae, multicellular organisms diversified rapidly (Cambrian explosion)

  12. EVIDENCE FOR EVOLUTION • MACROMOLECULAR EVIDENCE: #1 (Comparing the DNA, proteins and other molecules of life of other organisms) • FOSSIL EVIDENCE: #2 • BIOGEOGRAPHY • EMBRYOLOGY • COMPARATIVE ANATOMY • VESTIGIAL STRUCTURES • HOMOLOGOUS STRUCTURES • ANALOGOUS STRUCTURES • CLASSIFICATION

  13. 1. FOSSIL EVIDENCE • Allow scientists to see how organisms changed over time • Shows when different forms of organisms appeared, lasted for periods of time, then disappeared only to be found by newer forms of life.

  14. Another look at sedimentary layers Absolute age: measuring radioactivity in certain rocks Relative age: by comparing layers

  15. 2. Macromolecular (Molecular biology) Evidence Since all organisms on the planet contain DNA, we can compare their DNA to see which organisms are more related and then construct a phylogenic tree or a cladogram DNA EVIDENCE-

  16. DNA evidence Here is the GENOTYPE (genetic information of an organism). This Genotype will eventually lead to an organisms’ PHENOTYPE (organism’s physical or behavioral appearance)

  17. 2. Macromolecular (Molecular biology) Evidence (continued) • Amino acid evidence; the building blocks of proteins!

  18. 3. BIOGEOGRAPHY: • Study of Geographical distribution of fossils • Same fossils on West Coast of Africa and East Coast of South America. HOW??--- • Scientists see a trend. Life forms arise in the same areas where similar, older forms once existed

  19. Homologous Structures -Structures from different organisms that look similar because the organisms descended from common ancestors. These structures have evolved to perform different functions

  20. ANALOGOUS STRUCTURES Structures that are similar in form and function but evolved independently. Although a bird and insect are not recently related, they are distantly related but for whatever reason, they happened to evolve wings for flight.

  21. EMBRYOLOGICAL EVIDENCE Embryos look similar ___________ ____________ but look different __ ____________________________ This suggests that all these vertebrates have a _____________ ______________. The fact that they end up looking different, is a result of evolution. Each organism’s DNA (instructions) has evolved a new message – to become a different type of organism

  22. VESTIGIAL STRUCTURES • Definition- • Examples-

  23. LAMARCK vs DARWIN • Acquired traits (Lamarck)- • Use and disuse • Acquired Traits are passed down to offspring. NOT!- no genetic change only a phenotypic change

  24. DARWIN’S THEORY • OVERPRODUCTION: some must die because of ____________ • VARIATION: increases the likelihood that at least some members of a species will survive under changed environmental conditions • NATURAL SELECTION “survival of the fittest (according to the environment!)” not everyone survives the same! • INHERITED (passed down): Successful individuals pass down these fit traits

  25. Genes and evolution: Natural selection acts on (tests) the phenotype

  26. PATTERNS OF EVOLUTION • Co-evolution: Hummingbird’s beak and a long thin flower • Convergent evolution: similar environments push development of similar features –anteater’s tongue • Divergent evolution: • Adaptive radiation - ___________ • Artificial selection- ____________

  27. SO HOW DO WE GET A NEW SPECIES???? • Called Speciation: The formation of a new species occurs when members of a species are isolated reproductively (they can’t reproduce with each other and so they adapt to their environment on their own) • Two ways: Geographic isolation Reproductive isolation

  28. FORMATION OF A NEW SPECIES (Branching on the tree of life) • BIOLOGICAL SPECIES CONCEPT:Proposed by Ernst Mayr: a species is a – ____________________________________ • Limitations in this concept • Extinct organisms? • Asexual organisms?

  29. Population Genetics • The smallest unit of evolution is the population. • Population: Collection of individuals from a single species that routinely interbreed. • There is variation in a population (humans, fish, every life form) A bell curve shows the variations on a population and how they average out in the center. Extremes at either end.

  30. The gene pool: • Gene pool= all the genetic differences in a population Let’s pretend our classroom represents the gene pool with all the differences in our population

  31. Things that can affect the gene pool • Mutations: add more variety to the gene pool • Migration: immigration (+) and emigration (-): both cause gene flow: • Genetic Drift: When a random event causes your gene pool to change: genetic drift is more dramatic in small populations not large • Non random mating: choosing to mate with organisms with similar characteristics; not random but controlled

  32. Types of Natural Selection

  33. RATE OF SPECIATION • GRADUAL VS PUNCTUATED

  34. Can organisms plan their evolution? • Did giraffe’s grow longer necks on purpose to reach the trees? • Did ancient primates decide to walk upright to become humans? • If the world gets covered in water like in the movie “Waterworld”, will some of us grow gills? • Will we look like aliens in the future?

  35. Evolution is random!!! • Not something planned or on purpose • Mutations and sexual reproduction create variation- if these variations happen to help you live in your environment– then good for you!  • You’ll get to survive better, reproduce more successfully, and pass those “fit” traits to others • But what if the environment changes again? Well, we don’t know if those traits will keep on helping you. Maybe they will, maybe they won’t • Just keep hoping that we keep creating variations- this will increase our chances of adapting • What about the future of earth and global warming?

More Related