Chapter 1

1. Chapter 1 Exploring Life: Evolution, Taxonomy, and Classification

2. Background information: So, what is the Origin of Life on Earth??? Many ideas... Some of the hypotheses: • Intelligent Design, or Special Creation • Panspermia -  Cosmic Origins (from outer space) • Chemosynthesis (chemical reaction produced organic compounds, possibly cells, on young planet earth) • How long has there been LIFE on Earth? Let’s go back! • Formation of the Earth: • prob. about 4.6 bya Evidence of this? Scientific data? Life? • Evidence of 1st life forms (microfossils) about 3.5 bya

3. One of the strongest hypotheses is "Chemosynthesis", or chemical evolution of the first cells on the ancient earth, put forth by Alexander Oparin (1920's) • On early earth ---> • volatile atmospheric gases (H2, H2O, CH4, NH3...) • warm seas • energy from volcanoes, lightning, UV • 1st organic compounds formed as a result of this chemical reaction, much like in a test tube.  • When the seas washed onto shore and the puddles evaporated, the organic molecules were condensed into "packets" which were able to sustain themselves; "cells" • This idea was initially NOT popular in the scientific community; it sounds an awful lot like spontaneous generation!

4. Let’s Review: Abiogenesis –vs- Abiogenesis Abiogenesis:  aka “spontaneous generation” of life; used to be generally believed to be the way that some new life formed... ...when actually BIOGENESIS was proven using the scientific method by (among others) • Francesco REDI- (17th century)  "Does life really arise from rotting meat?“ • Lazzaro SPALLANZANI- (18th c) "Does life arise from materials in soup broth?" (microbes) • Louis PASTEUR- (19th c) "Does life arise from materials in the air?"

5. Oparin’s Hypothesis revisited: ...an experiment was tried out in a lab by Stanley Miller and Harold Urey (1953) who were NOT able to make cells, but did manage to cook up some organic molecules necessary for cells (amino acids, nucleotides, ATP) Since then, modification of this experiment have been explored and some labs have been able to come up with some self-sustaining cell-like things (coacervates, microspheres)...who knows?  If given a billion years or so...???

6. So, now that we have 1st cells, what happens next? Microfossil evidence suggests:1st forms of life:  • 1st prokaryotes:   unicellular, simple, anaerobic, heterotrophic • competition..---> chemotrophic autotrophs ---> photosynthetic autotrophs brought about changes on earth...helped to add oxygen to the air......atmosphere forming, cloud cover, ozone (protection) ---> first eukaryotes...unicellular, about 1.5 bya; membrane-bound nucleus and organelles... “Endosymbiont Hypothesis" -->first multicellular organisms about 750 million yrs ago (fossils) -fairly "recent"!

7. Figure 1.17 Evolution is the Unifying Principle of Biology Evolution accounts for life’s unity and diversity • The history of life • Is a saga of a changing Earth billions of years old

8. Figure 1.18 • The evolutionary view of life • Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection

9. Darwin based his idea on the understanding of human-influenced selective breeding of domestic animals

10. Figure 1.19 Darwin’s basic suppositions in “On the Origin of Species…” • Variation (due to?) • Competition (for?) • Natural selection (the environment decides…) • “the cruelty of nature” • “the struggle for existence” • differential reproduction • “survival of the fittest” (Herbert Spencer)

11. Population of organisms Overproduction and struggle for existence Hereditary variations Differences in reproductive success Evolution of adaptations in the population Figure 1.20 Natural Selection • Darwin proposed natural selection as the mechanism for evolutionary adaptation of populations to their environments Define “adaptation”?

12. 1 Populations with varied inherited traits 2 Elimination of individuals with certain traits. 3 Reproduction of survivors. Figure 1.21 4 Increasing frequency of traits that enhance survival and reproductive success. • Natural selection is the evolutionary process that occurs • When a population’s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others

13. Each species is on twig of a branching tree of life (phylogeny) • Extending back in time through ancestral species more and more remote • All of life • Is connected through its long evolutionary history

14. Figure 1.22 • The products of natural selection are often exquisite adaptations of organisms to the special circumstances of their way of life and their environment

15. Caution: common features don’t always mean common ancestry! Convergent evolution: shaped by the environment, rather than shared common ancestry Clues: look for homologousvsanalogous features

16. Convergence http://www.all-about-reptiles.com/convergent-evolution.html

17. Flower fly(non-stinging) Honeybee (stinging) Figure 1.26 A Case Study in Natural Selection: Mimicry • In mimicry • A harmless species resembles a harmful species

18. Evolutionary Divergence http://whyevolutionistrue.wordpress.com/2012/07/24/a-new-study-of-polar-bears-underlines-the-dangers-of-reconstructing-evolution-from-mitochondrial-dna/

19. Large ground finch Large tree finch Smallground finch Large cactus ground finch Camarhynchuspsitacula Greenwarbler finch Graywarbler finch Geospiza magnirostris Geospizafuliginosa Mediumtree finch Sharp-beaked ground finch Woodpecker finch Mediumground finch Geospiza conirostris Certhideaolivacea Certhideafusca Geospiza difficilis Camarhynchuspauper Cactusground finch Cactospizapallida Mangrovefinch Geospiza fortis Small tree finch Geospizascandens Camarhynchusparvulus Cactospiza heliobates Vegetarianfinch Cactus flowereater Seed eater Seed eater Platyspizacrassirostris Insect eaters Bud eater Ground finches Tree finches Warbler finches Common ancestor fromSouth American mainland Figure 1.23 • Darwin proposed that natural selection • Could enable an ancestral species to “split” into two or more descendant species, resulting in a “tree of life” Ex: Allopatric speciation

20. 15 µm 1.0 µm Cilia of Paramecium.The cilia of Parameciumpropel the cell throughpond water. 5 µm Cross section of cilium, as viewed with an electron microscope Cilia of windpipe cells. The cells that line the human windpipe are equipped with cilia that help keep the lungs clean by moving a film of debris-trapping mucus upward. Figure 1.16 Unity in the Diversity of Life • As diverse as life is • There is also evidence of remarkable unity

21. The Tree of Life • Many related organisms • Have very similar anatomical features, adapted for their specific ways of life • Such examples of kinship • Connect life’s “unity in diversity” to Darwin’s concept of “descent with modification”

22. Drawing evolutionary trees Cladistics bases classification of a group of species solely on their most recent common ancestor. Cladistics uses shared derived characters. The phenetic approach is popular with molecular evolutionists because it relies heavily on character data - such as sequences - and requires relatively few assumptions.In this approach, a tree is constructed by considering the phenotypic similarities of the species without trying to understand the evolutionary history that brought the species to their current phenotypes. Animation “How to build a cladogram” YouTube lesson on how to make a cladogram (10 min) Evolutionary trees (Berkeley) Practice worksheet

23. Figure 1.13 • Concept 1.3: Biologists explore life across its great diversity of species • Diversity is a hallmark of life

24. Classification of Living Things • Over a million species named (so far) • More identified every day • 2-20 Million left to find? • Why? Need to organize information • Taxonomy = science of identifying and classifying organisms

25. Species Genus Family Order Class Phylum Kingdom Domain Ursusameri- canus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya Figure 1.14 Classifying life • Taxonomy • Is the branch of biology that names and classifies species according to a system of broader and broader groups

26. The Three Domains of Life • Distinguished based on biochemical evidence (differences in rRNA, genes) • Domains Archaea and Bacteria are unicellular organisms lacking membrane-bound organelles like nuclei (Prokaryotes) • Domain Eukarya is organisms whose cells have nuclei (Plants, Animals, Fungi and Protists)

27. Classification of Living Things • 3 Domains • Kingdom • Phylum (Division for plants) • Class • Order • Family • Genus • Species

28. Domain Archae • Prokaryotes • Single celled • Complex metabolic ability • Kingdom Archaebacteria • Found in extreme environments • Environments similar to those of early earth • First organisms similar to Archaea?

29. Domain Bacteria • Kingdom Eubacteria • Found almost everywhere • More of them than any other living thing • Some are parasites, causing diseases • Most are harmless and many are vital to human well being • Decompose our wastes • Make vitamins in our guts • Producing certain products that we use (yogurt, cheese)

30. Domain Eukarya • Protista- one celled organisms- producers or consumers (or both) • Fungi- molds, mushrooms; mostly decomposers • Plantae- multicellular plants; mostly producers • Animalia - multicellular animals from sponges to humans; consumers

31. Classification of Living Things • Within Kingdoms, organisms are sorted into Phylum, Class etc. • At species level organisms so closely related they can interbreed • Scientific name = Genus and species names (binomial nomenclatureex. Felis catus, Drosophila melanogaster, Homo sapiens • Genus includes other similar species ex. F. leo and F. tigris or Quercus rubra, Quercus alba • Genus ALWAYS starts with cap, species lower case • Genus and species names are always either underlinedoritalicized

32. Example: How are humans related to other animals? Human House cat DomainEukaryaEukarya KingdomAnimaliaAnimalia PhylumChordataChordata ClassMammaliaMammalia Order Primates Carnivora FamilyHominidaeFelidae GenusHomo Felis Speciessapiens catus