Evolution I History of Life on Earth I

Evolution

I. History of Life on Earth

I. History of Life A. Early History of Earth I. Early earth was inhospitable • • • hot, with many volcanoes little free oxygen and lots of carbon dioxide other gases present: nitrogen, methane, ammonia, hydrogen and water vapor

I. History of Life B. History in Rocks • Fossils are clues to the past • • • Any trace of a species that once lived can infer the structure of the organisms, what they ate, what ate them, and the environment that they lived in Paleontologists- detectives to the past • scientists who collect, study and classify fossils

I. History of Life • Fossils occur in sedimentary rock • sedimentary rock is formed when exposure to rain, heat, wind and cold breaks down existing rock into small particles of sand, silt and clay. • The particles are carried by streams and rivers into lakes or seas where they eventually settle to the bottom. • As layers of sediment build up over time, dead organism may also sink to the bottom and become buried. • The weight of layers of sediment gradually compresses the lower layers and along with chemical activity, turns into rock

I. History of Life • Non-rock fossils • Fossils can be found in ice • Ex. Woolly Mammoth preserved in ice • Fossils can be found in amber • Organisms preserved in amber • Amber is a form of tree resin—exuded as a protective mechanism against disease and insect infestation—that has hardened and been preserved in the earth’s crust for millions of years

I. History of Life C. Age of a fossil • Relative Dating • oldest fossils are in deepest layers • paleontologists can compare fossils with that of older fossils

I. History of Life C. Age of a Fossil • Radiometric Dating • Use of radioactive isotopes in rocks to date fossils • The technology of radiometric dating provides evidence that the earth is at least 4. 5 billion years old • Certain elements convert to other elements at known rates, which can be measured, thus revealing the age of the specimen • One half Potassium 40 decays to Argon 40 in about 1. 3 billion years • Carbon 14 decays to half of its original amount in 5730 years

Common Isotopes used to date Geologic Materials Parent Daughter T (1/2) Useful range Type of material >10 millions Igneous & sometimes metamorphic rocks and minerals 238 U 206 Pb 4. 47 b. y 235 U 207 Pb 707 m. y 232 Th 208 Pb 14 b. y 40 K 40 Ar & 40 Ca 1. 28 b. y >10, 000 years 87 Rb 87 Sr 48 b. y >10 million years 147 Sm 143 Nd 106 b. y 14 C 14 N 5, 730 y 100 -70, 000 years Organic material

Bacteria were the earliest life Formed colonies called stromatolites (age 3. 5 billion years old) Best colonies in Australia

Era Period Precambrian Paleozoic Mesozoic Cenozoic Million Years Ago Major Events 3500 Life evolves Major Life Forms Photosynthetic bacteria 3000 Prokaryotes 2000 Eukaryotes Cambrian 540 Invertebrates Ordovician 510 First Invertebrates Silurian 439 First land plants Devonian 408 First Amphibians Carbonifero us 362 First reptile Permian 290 Conifers dominant Triassic 245 First dinosaurs First mammals Jurassic 208 First birds First flowering plants Cretaceous 146 Tertiary 66 Quaternary 1. 8 Dominant flowering plants Humans

II. Origins of Life

II. Origins of Life A. Origins: The Early Ideas • • Spontaneous generation—non-living material can produce life Disproved by Redi experiment meat and maggots

II. Origins of Life • Disproved by Pasteur—S flask experiment • • boils broth in S flask broth is free of microorganisms for a year removes curved neck broth is “teeming” with microorganisms • Biogenesis—living comes from living things.

II. Origins of Life B. Modern Ideas • Oparin—suggested sun, lightning, and molecules such as water vapor, carbon dioxide, nitrogen, methane and ammonia formed a “primordial soup” that was the beginning of simple organic molecules

II. Origins of Life • Miller and Urey— 1953 -1954 • Tried to answer the question by simulating conditions on the early Earth • Filled flask with hydrogen, ammonia, methane, and water = atmosphere • They passed electric sparks through the mixture to simulate lightning • Within a few days amino acids were present—the building blocks of protein

II. Origins of Life

II. Origins of Life • Sidney Fox—showed how sort chains of amino acids could cluster to form protocells • Experiments like Miller and Urey’s are currently studied at major universities (i. e. Georgia Tech, U Michigan

II. Origins of Life C. Evolution of Cells (based on fossil record) • First true cells—were probably prokaryotic, heterotrophic and anaerobic • • • single celled—no nucleus consumed food for energy did not need oxygen to survive Then came chemosynthetic organisms Then autotrophs—were probably archaebacteria that live in harsh environments Next came photosynthetic prokaryotes— releases oxygen into atmosphere

II. Origins of Life • Endosymbiotic theory • Proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms—Lynn Margulis of Boston University

II. Origins of Life Endosymbiotic Theory Explained: • Mitochondria and chloroplasts contain DNA similar to bacterial DNA. • Mitochondria and chloroplasts have ribosomes whose size and structure resemble those of bacteria • Like bacteria, mitochondria and chloroplasts reproduce through binary fission • Eukaryotic cells evolved from prokaryotic cells

Endosymbiotic Theory ENDO = Into Symbiosis = relationship of two organisms living close together According to theory of endosymbiosis eukaryotic cells evolved when aerobic eubacteria either infected or were engulfed by a larger host cell and later established a symbiotic relationship

III. Natural Selection and Evidence for Evolution

History of the Theory of Evolution Darwin’s Role http: //evolution. berkeley. ed u/evosite/history/index. sht ml

III. Natural Selection and Evidence for Evolution A. Charles Darwin—credited with the Theory of Evolution • Scientists, including Darwin, used fossils to explain that organisms have changed over time Darwin and HMS Beagle • • • At age 22, Darwin sailed around the world, trip took 5 years Ship’s naturalist—he collected specimens and note of the diversity he saw

Galapagos Islands

III. Natural Selection and Evidence for Evolution • Darwin in the Galapagos • Group of islands off the coast of South America • Noted that the animals were unique but similar to the species he had seen elsewhere • Giant tortoises had differences in shell depending on which island they inhabited • Marine iguanas could swim and eat algae • Finches had many different size beaks depending on the type of food they ate

III. Natural Selection and Evidence for Evolution • Darwin Continues his Studies • Lamarck proposed a theory about evolution in the year Darwin was born called Use and Disuse Theory • Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime • These acquired traits then could be passed on to their offspring

III. Natural Selection and Evidence for Evolution How do we know Lamarck’s explanation is false?

3/10/2016 Review • What element was missing in early atmosphere? • What is the difference between relative and radiometric dating? • What is spontaneous generation? • What is biogenesis? • What does Lamark’s Use and Disuse Theory state?

III. Natural Selection and Evidence for Evolution • Darwin continued to look for explanations to evolution for the next 22 years • He read about Thomas Malthus’ study which stated that the human population grows faster than the earth’s food supply—Darwin applied this idea to all of life

III. Natural Selection and Evidence for Evolution • Darwin also gained insight by breeding pigeons using artificial selection • Breeders determine which individuals to use for breeding based on the natural variation • Are able to produce a wide range of plants and animals that looked very different from their ancestors

III. Natural Selection and Evidence for Evolution • Darwin Explains Natural Selection • Natural selection is a mechanism that occurs when organisms with certain variations survive, reproduce and pass on their variations to the next generation • At this time, Wallace also reached similar conclusion

III. Natural Selection and Evidence for Evolution • Darwin wrote a book, “On the Origin of Species” which today is still a unifying theme of biology • There is variation among population • There is an overproduction of offspring • There is a struggle for survival, competition for food and shelter • The fittest survive and reproduce • Heritable variations are passed onto offspring • Giving way to “decent with modification”

III. Natural Selection and Evidence for Evolution • Interpreting Evidence After Darwin • Modern biologists define evolution as any change in the gene pool of a population • gene pool is the combined genetic information of all the members of a population

III. Natural Selection and Evidence for Evolution B. Three Types of Natural Selection • Directional Selection • Favors individuals possessing extreme values of a trait, which causes the population to move in a particular direction • If a climate becomes colder, a population may evolve in a consistent direction in response—thicker fur

Directional Selection # of Individuals Phenotypic Range Shift towards ONE extreme

III. Natural Selection and Evidence for Evolution • Stabilizing Selection • Acts against individuals who deviate too far from the average, favors the average • Sizes in lizards: large lizards may be subject to predation; small lizards may have a hard time defending territories, natural selection favors the average

Stabilizing Selection # of Individuals Phenotypic Range Shift towards middle

III. Natural Selection and Evidence for Evolution • Disruptive Selection • Adapts individuals in a population to different habitats. • Similar to directional selection—but it favors either extreme • May occur in an area that provides very different resources

III. Natural Selection and Evidence for Evolution • Galapagos finches had a variety of food choices: smaller birds fed on small seeds, larger birds feed on large seeds. Natural selection favors both but not the average who would compete for both resources.

Disruptive Selection # of Individuals Phenotypic Range Shift towards both extremes

Practice • http: //wps. pearsoncustom. com/wps/ media/objects/3014/3087289/Web_Tu torials/17_A 02. swf • Plus More Practice • Check Tomorrow

Review 3. 11. 16 • What is a gene pool? • Sketch the graph of directional selection. • Sketch the graph of disruptive selection. • Sketch the graph of stabilizing selection.

III. Natural Selection and Evidence for Evolution C. EVIDENCE FOR EVOLUTION

III. Natural Selection and Evidence for Evolution • Fossil evidence • • • Not all species existed at the same time Fossil record is fully consistent with the prediction that more “derived” groups should appear over time in the fossil record There has not been a single case of a species out of order—no mammals mixed in the rock with early fish

III. Natural Selection and Evidence for Evolution

III. Natural Selection and Evidence for Evolution • Fossil evidence • Life began in the sea. The oldest fossils are marine

Burgess Shale: 505 Million Year Old Coral Reef

III. Natural Selection and Evidence for Evolution • Fossil Evidence • Transitions between major groups (classes) of species • Fish amphibians (transition from ray-finned fish to tetrapods (vertebrate with 4 limbs)). • Reptiles birds (Archaeopteryx) • Reptiles mammals (synapsid reptiles (therapsids) have very mammalian characteristics

The London Specimen and a reconstruction of Archaeopteryx (from Levin, 1996)

III. Natural Selection and Evidence for Evolution • Fossil Evidence • Transitions between classes (ex. Orders of mammals) Gradual loss of legs

Leg bones become smaller and smaller in more recent whales Modern whales have remnants of their ancestral hind legs

III. Natural Selection and Evidence for Evolution • Fossil Evidence • Well preserved family groups (horse family)

III. Natural Selection and Evidence for Evolution • Fossil Evidence • Well preserved communities of species that no longer exist but resemble modern species. (Rancha Le. Brea Tar Pits, Los Angeles 25, 000 years ago)

III. Natural Selection and Evidence for Evolution • Biogeographical • Species that existed in the past are fossilized in areas where species that resemble them are living now • Geographic Distribution • organisms that live under similar ecological conditions are exposed to similar pressures of natural selection • Because of similar selection pressures, different animals end up evolving certain striking features in common

III. Natural Selection and Evidence for Evolution • Adaptations: gradual change in an organism that enables it to survive in a particular environment. • Types • Structural • Behavioral • Physiological

III. Natural Selection and Evidence for Evolution • Structural adaptations are physical features of an organism like the bill on a bird, the fur on a bear, stinging cells of jellyfish or sticky tongue of an anteater

III. Natural Selection and Evidence for Evolution Structural adaptations • homologous structures (HSS) • structures that have different mature forms in different organisms but develop from the same embryonic tissue • exist among related groups, providing support for having a common ancestor

Highly complex anatomical structures have evolved from simple structures that served the same purpose: ex: different kinds of eyes

III. Natural Selection and Evidence for Evolution Structural Adaptations: • analogous structures (ASF) • outwardly similar structures

Comparison Chart

III. Natural Selection and Evidence for Evolution Structural Adaptations: • vestigial structures (NF) structure that serves no useful function in an organism (A) Whales have pelvic bones floating in their abdominal cavity

Vestigial Structures (B) Pelvic bones in pythons are unused remnants from their common ancestor shared with lizards We would not expect to see these structures if snakes had an origin separate from other vertebrate animals. (c) Blind salamanders have eyes with retinas and lenses, yet the eyelids grow over the eye, sealing them from outside light

Vestigial Structures (D) Flightless Cormorant Wings: Cormoront lives on Galapagos Islands, & has wings too small for flight (E) Legless Skinks a type of lizard. In some species the legs have become vestigial. (so reduced that they no longer function)

Human Vestigial Structures • Humans have > 100 vestigial structures. • 90% develop wisdom teeth (molars used for chewing & grinding plant material) which usually don’t erupt from gums, can be malformed and cause pain. • Tailbone (Coccyx) fused vertebrae that in other vertebrates are tails. It serves no purpose. • Ear muscles used in other vertebrates for twitching • Appendix part of digestive tract used to digest tough plant material is so reduced in humans that it is dysfunctional

III. Natural Selection and Evidence for Evolution • Adaptations • Behavioral adaptations are things organisms do to survive. For example, bird calls and migration are behavioral adaptations.

III. Natural Selection and Evidence for Evolution Adaptations • Physiological • A metabolic adjustment within the cell, or tissues of an organism in response to an environmental stimulus, resulting in the improved ability of that organism to cope with its changing environment. • Physiological adaptations can develop rapidly • digestive enzymes • hemoglobin • bioluminescence

III. Natural Selection and Evidence for Evolution • Embryological Evidence • during the early stages of development many animals with backbones are so similar that they can be hard to tell apart • embryonic development shows that the same group of embryonic cells develop in the same order and in similar patterns to produce tissues and organs of all vertebrates

III. Natural Selection and Evidence for Evolution • Molecular/biochemical evidence • • • Fields unknown during Darwin’s time support predictions made from his theory and provide independent evidence that is congruent with the fossil record All organisms share the same genetic code which code for amino acids that make up proteins Ex. DNA, ATP, proteins

III. Natural Selection and Evidence for Evolution • Molecular/biochemical evidence • Mutations that help an organism survive its environment are passed on to the next generation. • Species that diverged longer ago have more differences in their corresponding proteins. (just like comparing how closely related two humans are, one can compare how related different species are.

• Flagella- • http: //www. millerandlevine. com/km/e vol/design 2/article. html

Review 3. 14. 2016 • What type of adaptation is this? Leaf-cutter ants raise fungi for food, their own type of agriculture. Mosquitoes inject an anti-clotting chemical when they bite animals. The beak of the hummingbird allows it to get nectar deep within flowers. The black widow spider injects a deadly poison into its prey. The walking stick is an insect that looks just like a stick…great camouflage.

Continue Review • Which type of evidence is most reliable? • Which of the following terms describes Homologous structures and Analogous Structures? Same Basic Structure that Services a Different Function Different Basic Structure that Services a Similar Function Due to Similar Environmental Pressures.

IV. Mechanisms of Evolution

IV. Mechanisms of Evolution • A. Population Genetics • POPULATIONS, not individuals, EVOLVE • Gene pool—all of alleles of population’s genes • Allelic (gene) frequency--% of specific allele in gene pool • Genetic equilibrium—gene frequency remains constant over many generations (not evolving)

IV. Mechanisms of Evolution Changes in Genetic Equilibrium • Mechanisms for genetic change 1. Mutation—environmental factors or chance 2. Sexual reproduction 3. Gene flow —when individuals enter or leave a population Immigration -individuals moving INTO a population Emmigration -individuals moving OUT of a population 4. Natural selection is the most significant factor to cause change in a gene pool

IV. Mechanisms of Evolution Example of Gene Flow Genetic drift —occurs in small populations that become isolated like animals in the Galapagos • In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. • The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better” individuals. • It happens to ALL populations—there’s no avoiding the vagaries of chance.

IV. Mechanisms of Evolution • Genetic drift can cause big losses of genetic variation for small populations. • Examples: Bottleneck Populations and Founder Effect Population bottlenecks occur when a population’s size is reduced for at least one generation.

• Reduced genetic variation means that the population may not be able to adapt to new selection pressures, such as climatic change or a shift in available resources, because the genetic variation that selection would act on may have already drifted out of the population.

An example of a bottleneck • Northern elephant seals have reduced genetic variation probably because of a population bottleneck humans inflicted on them in the 1890 s. • Hunting reduced their population size to as few as 20 individuals at the end of the 19 th century. • Their population has since rebounded to over 30, 000—but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.

IV. Mechanisms of Evolution Founder effect • A founder effect occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have: • reduced genetic variation from the original population. • a non-random sample of the genes in the original population.

Example of Founder Effect • For example, the Afrikaner population of Dutch settlers in South Africa is descended mainly from a few colonists. • Today, the Afrikaner population has an unusually high frequency of the gene that causes Huntington’s disease, because those original Dutch colonists just happened to carry that gene with unusually high frequency. • This effect is easy to recognize in genetic diseases, but of course, the frequencies of all sorts of genes are affected by founder events.

V. Evolution of Species--Speciation

V. Evolution of Species--Speciation Add this! Species: a group of organisms with a common gene pool that is reproductively isolated from other organisms Isolating mechanism: factors that restrict gene flow between species and sometimes different populations within a species

V. Evolution of Species--Speciation A. Allopatric Speciation • geographic barrier physically isolates populations of a species which blocks gene flow • once isolated allopatric populations (living in different places) accumulate genetic differences due to natural selection, genetic drift, and new mutations • removing the geographic barrier---the following could happen: 1. meld together by allele flow and 2. recombination once again to form a single species; 3. remain reproductively isolated—pre-mating or post-mating isolating mechanisms-different types of reproductive isolation

Example of Allopatric Speciation • island chains frequently produce new species; • provide geographic barriers that facilitate invasion and re-invasion by different species; • this is the probable mechanisms for the proliferation of Darwin's finches on the Galapagos Islands; • Hawaiian Islands once supported thousands of speices of Drosophilia flies that probably evolved by a similar mechanism

V. Evolution of Species--Speciation B. Sympatric speciation (does not involve a geographic barrier) • results from intrinsic factors such as chromosomal changes and non-random mating • become genetically isolated even though their ranges overlap ex. polyploidy, non-random mating • change in Chromosome Numbers and Speciation Ex. Polyploidy—more than a normal set of chromosomes.

V. Evolution of Species--Speciation C. Reproductive Isolation—interbreeding organisms can no longer mate and produce fertile offspring • Genetic material very different so fertilization doesn’t occur • Behavioral—mating at different times of day/month/year • Different pheromones • Mechanical—physical differences prevent mating between species

VII. Pacing of Evolution

VII. Pacing of Evolution Gradualism—fossil evidence shows this • Explanation that evolution involves a slow and steady accumulation of changes over a period of time Punctuated equilibrium —occurs relatively quickly, in rapid bursts, with long periods of genetic equilibrium in between • Pattern of long, stable periods of stasis (no change) interrupted by brief periods of rapid evolution

VIII. Patterns of Evolution

VIII. Patterns of Evolution A. Convergent Evolution • • Two different species develop similar adaptations because they live in similar environments For example—ability to move through the water rapidly—shark (fish), penguin (bird), and dolphin (mammal)

• Species evolve to fill niches • Mutations occur randomly in geographically distinct populations • Natural selection allows the mutations that “work” to become adaptations

VIII. Patterns of Evolution B. Divergent Evolution • Occurs when a population becomes isolated from the rest of the species and begins to follow a different evolutionary course • often results in adaptive radiation • associated with the opening up of a new biological frontier • For example—Darwin’s finches which had different beak lengths

Examples of Divergent Evolution

Example of Adaptive Radiation (divergence into an abundance of available niches)

VIII. Patterns of Evolution C. Coevolution • Two different species evolved at the same time because of a beneficial relationship between the two groups

IX. Primate Adaptation and Evolution • Primate—a group of mammals that include lemurs, monkeys, apes and humans • • • Most are arboreal (live in trees) Binocular vision Opposable thumbs Flexible joints Fossils indicate that they appeared on earth 60 -70 million years ago • Major trends—increasing brain size and walking upright

X. Human Ancestry • Earliest Hominids • • Australopithecine fossils from Africa 5 -8 million years ago Bipedal and climbed trees Brain and body size increased and jaws and teeth decreased in size Stone Tools and genus homo • • Appeared 2 million years ago Use of fire, language, and culture developed

Embryological development matches the progression of fossils in the fossil record Fossil Record Vertebrates not only repeat the development of ancestral vertebrate but they have similar bone structure and unused remnants of their structures Anatomical Embryological Present & past distribution of continents explains the distribution of fossils Mutations exhibited in bacteria provide concrete evidence for the changes that lead to the branching of species observed in the fossil record Amino acid sequences are more similar in species with more similar bone structures. Biogeography Molecular

Mistakes during cause DNA REPLICATION MUTATIONS h ic wh Add variations to GENE POOL NATURAL SELECTION ADAPTATIONS

Direct Evidence (microevolution) Evolution Before Our Very Eyes 1. Selective Breeding 2. Industrial melanism. 3. Antibiotic resistant bacteria 4. Herbicide resistant weeds. 5. Annual changes in influenza viruses 6. Pesticide Resistant Insects 7. Resistance to anti viral medicines (HIV)