Its Origin and Evolution Levels of Organization Biosphere Ecosystems Communities Populations Organisms Organs and Organ Systems Tissues Cells Organelles Molecules Levels of Organization Biosphere Everywhere within the Earths atmosphere where life exists. Ecosystems The biotic and abiotic factors within an environment Interactions between organisms Interactions between organisms and the environment Cycling of Nutrients Energy flow Community All living organisms in a particular region Population All individuals of a species in a particular area Organism A single living thing Organs & Organ Systems Organ Specialized body parts made of tissues Tissues work together to perform a specific function Organ System Groups of organs that work together to perform specific functions Tissue A group of similar cells Cell Basic unit of: Life Structure and function Contains DNA Organelle Structural component of a cell Molecule Chemical structure consisting of atoms Diversity of Life Domain Bacteria Prokaryotic Domain Archaea Prokaryotic Live under extreme conditions Domain Eukarya Protists (unicellular eukaryotes) Kingdom Plantae (photosynthetic) Kingdom Fungi (decomposers) Kingdom Animalia (ingest others) Evolution On the Origin of Species, Charles Darwin Contemporary species arose from a succession of ancestors descent with modification Natural Selection Mechanism for descent with modification Water vapor CH 4 NH 3 H2H2 Electrode Condenser Cold water Cooled water containing organic molecules Sample for chemical analysis H2OH2O Other Explanations synthesis near submerged volcanoes and deep-sea vents Other Explanations Extraterrestrial Sources Carbon compounds have been found in some meteorites that landed on Earth Millions of years ago Permian mass extinction Extinction rate Cretaceous mass extinction 0 2,500 2,000 1,500 1, Neogene Proterozoic eon CambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogene PaleozoicMesozoic Ceno- zoic Number of families ( ) Extinction rate ( ) Number of taxonomic families Major Events in Biological History Mass extinctions = opportunities for adaptive radiations Permian Killed about 96% of marine animal species and 8 out of 27 orders of insects Cause = volcanic eruptions Cretaceous Killed many marine and terrestrial organisms, notably the dinosaurs Cause = meteor impact Major Events in Biological History Oxygenic photosynthesis - about 3.5 billion years ago (cyanobacteria) Led to oxygen accumulation in atmosphere (about 2.7 billion years ago): Posed a challenge for life Provided opportunity to gain energy from light Allowed organisms to exploit new ecosystems eukaryotic cells evolve (oldest fossils 2.1 billion years) Common ancestor to multicellular eukaryotes dates back 1.5 billion years many animal phyla originated and began to diverge between 1 billion and 700 million years ago (Molecular evidence) Plants, fungi, and animals colonized land about 500 million years ago Plasma membrane Cytoplasm DNA Ancestral prokaryote Endoplasmic reticulum Nuclear envelope Infolding of plasma membrane Engulfing of aerobic heterotrophic prokaryote Nucleus Cell with nucleus and endomembrane system Mitochondrion Engulfing of photosynthetic prokaryote in some cells Plastid Mitochondrion Ancestral heterotrophic eukaryote Ancestral photosynthetic eukaryote Multicellular Eukaryotes Colonies collections of autonomously replicating cells Some cells became specialized for different functions Tree of Life The five kingdom system has been replaced by three domains: Archaea, Bacteria, and Eukarya Each domain has been split into kingdoms Kingdom Phylum Class Order Family Genus Species Chapter 27Chapter 28 ProteobacteriaChlamydiasSpirochetesCyanobacteria Gram-positive bacteriaKorarchaeotes Euryarchaeotes, crenarchaeotes, nanoarchaeotes Diplomonads, parabasalidsEuglenozoans Alveolates (dinoflagellates, apicomplexans, ciliates) Domain Archaea Universal ancestor Domain Bacteria Domain Eukarya Stramenopiles (water molds, diatoms, golden algae, brown algae) Cercozoans, radiolarians Red algae Chlorophytes Charophyceans Chapter 29 Bryophytes (mosses, liverworts, hornworts) Plants Fungi Animals Chapter 30Chapter 28 Seedless vascular plants (ferns)Gymnosperms Angiosperms Amoebozoans (amoebas, slime molds) Chytrids Chapter 31 Zygote fungi Arbuscular mycorrhizal fungi Chapter 32Chapters 33, 34 Sac fungiClub fungi Choanoflagellates Sponges Cnidarians (jellies, coral) Bilaterally symmetrical animals (annelids, arthropods, molluscs, echinoderms, vertebrates) Theories of Evolution Gradualism Hutton & Lyell Lamarck Use and Disuse Darwin On the Origin of Species Descent with Modification Common Ancestors Natural Selection How do environmental changes affect a population? Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. Insect eater. The green warbler finch (Certhidea olivacea) used its narrow, pointed beak to grasp insects. LE A flower mantid in Malaysia A stick mantid in Africa Natural Selection Antibiotic Resistance Insecticide Resistance Ernst Mayer Observation #1: For any species, population sizes would increase exponentially if all individuals that are born reproduced successfully Observation #2: Populations tend to be stable in size, except for seasonal fluctuations Observation #3: Resources are limited Inference #1: Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving Observation #4: Members of a population vary extensively in their characteristics; no two individuals are exactly alike Observation #5: Much of this variation is heritable Inference #2: Survival depends in part on inherited traits; individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals Inference #3: This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations Artificial Selection Cabbage Flower clusters Terminal bud Lateral buds Brussels sprouts Leaves Kale Stem Kohlrabi Wild mustard Broccoli Cauliflower Flowers and stems Evidence for Evolution Homology (homologous structures) LE Human Cat Whale Bat Homologous Plant Structures Evidence for Evolution Comparative Embryology Shows homologies not visible in adult forms LE Chick embryo (LM) Human embryo Pharyngeal pouches Post-anal tail Evidence for Evolution Vestigial Structures Remnants of structures once used in ancestors Evidence for Evolution Molecular Homologies (similar biochemistry) Similarities in protein structure and genes LE Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide 100% 95% 87% 69% 54% 14% Rhesus monkey Species Human Mouse Chicken Frog Lamprey Some Evidence of Evolution Biogeography similar mammals that have adapted to similar environments have evolved independently from different ancestors LE Sugar glider Flying squirrel NORTH AMERICA AUSTRALIA Evidence of Evolution Fossil Record Fossils Formation Sedimentary rocks Low humidity Ice Amber Dating Strata & Index Fossils Relative Dating Radiometric Dating Absolute Dating Paleomagnetism 1 Accumulating daughter isotope Remaining parent isotope Ratio of parent isotope to daughter isotope Time (half-lives) Fossils BenefitsLimitations Preserved remains Previous life Ancestral connections Evolutionary patterns Migration patterns Geographic/environmental history Major changes Exact dates Incomplete Habits Behavior Chemical composition Color Texture Internal anatomy and physiology Phylogeny Phylogeny is the evolutionary history of a species or group of related species Systematics morphological, biochemical, and molecular comparisons to infer evolutionary relationships Cladistics Homology vs. Analogy HOMOLOGYANALOGY Similarity due to shared ancestry Similarity due to coevolution Adaptation to similar environments Binomial Nomenclature LE 25-8 Species Panthera pardus Panthera Genus Family Felidae Carnivora Order Mammalia Class Phylum Chordata Kingdom Animalia Eukarya Domain LE 25-9 Carnivora Panthera pardus (leopard) Mephitis mephitis (striped skunk) Lutra lutra (European otter) Canis familiaris (domestic dog) Canis lupus (wolf) Species Genus Family Order FelidaeMustelidaeCanidae PantheraMephitisLutraCanis Hair Amniotic (shelled) egg Four walking legs Hinged jaws Vertebral column (backbone) Character table CHARACTERS TAXA Lancelet (outgroup) LampreyTunaSalamander TurtleLeopard Turtle Leopard Hair Amniotic egg Four walking legs Hinged jaws Vertebral column Salamander Tuna Lamprey Lancelet (outgroup) Cladogram Kingdoms Eubacteria Archaebacteria Protista Plantae Fungi Animalia DOMAIN EUKARYA DOMAIN ARCHAEA DOMAIN BACTERIA Section 18-3 Cladogram of Six Kingdoms and Three Domains Go to Section: Gene Pools All genes present in a particular population Allele Frequencies The relative frequencies of genes in a population LE 23-3 MAP AREA CANADA ALASKA Beaufort Sea Porcupine herd range NORTHWEST TERRITORIES Fairbanks Fortymile herd range Whitehorse ALASKA YUKON Hardy-Weinberg describes a population that is not evolving Allele frequency constant Genotype constant segregation and recombination of alleles are at work Mendelian inheritance preserves genetic variation LE 23-4 Generation 3 25% C R C R Generation 4 50% C R C W 25% C W C W 50% C W gametes 50% C R come together at random 25% C R C R 50% C R C W 25% C W C W Alleles segregate, and subsequent generations also have three types of flowers in the same proportions gametes Generation 2 Generation 1 CRCRCRCR CWCWCWCW genotype Plants mate All C R C W (all pink flowers) 50% C R 50% C W gametes come together at random X If p and q represent the relative frequencies of the only two possible alleles in a population at a particular locus, then p 2 + 2pq + q 2 = 1 p 2 and q 2 (homozygous genotypes) 2pq (heterozygous genotype) The five conditions for non-evolving populations: Extremely large population size No gene flow No mutations Random mating No natural selection Genetic Drift LE 23-7 CRCRCRCR CRCRCRCR CWCWCWCW CRCRCRCR CRCWCRCW CRCRCRCR CRCWCRCW CWCWCWCW CWCWCWCW CRCWCRCW CRCWCRCW CRCRCRCR CRCWCRCW CRCWCRCW CRCRCRCR CRCRCRCR CRCWCRCW CWCWCWCW CRCWCRCW CRCRCRCR Only 5 of 10 plants leave offspring Only 2 of 10 plants leave offspring CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR CRCRCRCR Generation 2 p = 0.5 q = 0.5 Generation 3 p = 1.0 q = 0.0 Generation 1 p (frequency of C R ) = 0.7 q (frequency of C W ) = 0.3 Bottleneck Effect LE 23-8 Original population Bottlenecking event Surviving population Heterozygote Advantage Sometimes heterozygotes (at a particular locus) have greater fitness than homozygotes Ex. Sickle Cell Natural selection will tend to maintain two or more alleles at that locus LE Frequencies of the sickle-cell allele 02.5% 2.55.0% 5.07.5% 7.510.0% 10.012.5% >12.5% Distribution of malaria caused by Plasmodium falciparum (a protozoan) Types of Selection Sexual Selection Results in sexual dimorphism Intrasexual selection - members of one gender fight against one another for mates of the opposite gender Usually results from picky mates (usu. Females) of Asexual Reproduction Sexual Reproduction ProConPro Con LE Asexual reproduction Female Generation 1 Generation 2 Generation 3 Generation 4 Sexual reproduction Female Male Perfection? Evolution is limited by historical constraints Adaptations are often compromises Chance and natural selection interact Selection can only edit existing variations Speciation - the origin of new species Evolutionary theory explain how new species originate and how populations evolve Microevolution - adaptations that evolve within a population(within one gene pool) Macroevolution - evolutionary change above the species level LE 24-3 Similarity between different species. Diversity within a species. Reproductive isolation - impede two species from producing viable, fertile hybrids prezygotic postzygotic Prezygotic Barriers Impede mating or hinder fertilization if mating does occur: Habitat (geographic) isolation Two species occupy different habitats, even though not isolated by physical barriers Temporal isolation Species breed at different times of the day, different seasons, or different years cannot mix their gametes Ex. orchids Prezygotic Barriers Behavioral isolation Behavioral isolation: Courtship rituals and other behaviors unique to a species are effective barriers Prezygotic Barriers Mechanical isolation Mechanical isolation: Morphological differences can prevent successful mating Prezygotic Barriers Gametic isolation Gametic isolation: Sperm of one species may not be able to fertilize eggs of another species Postzygotic Barriers Postzygotic barriers prevent the hybrid zygote from developing into a viable, fertile adult: Reduced hybrid viability Genes impair development Reduced hybrid fertility sterility Hybrid breakdown Some first-generation hybrids fertile offspring of the next generation are feeble or sterile LE 24-4a Prezygotic barriers impede mating or hinder fertilization if mating does occur Postzygotic barriers prevent a hybrid zygote from developing into a viable, fertile adult REDUCED HYBRID VIABILITY REDUCED HYBRID FERTILITY HYBRID BREAKDOWN HABITAT ISOLATION TEMPORAL ISOLATION BEHAVIORAL ISOLATION MECHANICAL ISOLATION GAMETIC ISOLATION Reduced hybrid viability Fertilization Viable, fertile offspring Reduced hybrid fertility Hybrid breakdown Mating attempt Gametic isolation Fertilization Mechanical isolation Behavioral isolation Temporal isolation Habitat isolation Individuals of different species Speciation AllopatricSympatric gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations One or both populations may undergo evolutionary change during the period of separation takes place in geographically overlapping populations polyploidy LE 24-5 Allopatric speciation Sympatric speciation LE Time Gradualism model Punctuated equilibrium model Patterns of Evolution Adaptive Radiation The process by which a single species or small group of species have evolved into several different forms that live in different ways. Ex. Dinosaurs were the result of adaptive radiation of reptiles. Figure legend: Adaptive Radiation. Diverging from an ancestral form, a group of organisms is suddenly able to exploit a major new range of habitats. Within each smaller habitat, local selection pressures give rise to new gene pools adapted for those conditions. If these groups eventually become reproductively isolated, they may become new species. Adaptive Radiation Patterns of Evolution Convergent Evolution The process by which unrelated organisms come to resemble one another. Ex. Penguins and Dolphins Patterns of Evolution Coevolution The process by which two species evolve in response to changes in each other over time Ex. Hummingbird and some plants with flowers Coevolution