Earth and Life History Chapter 8 MLK Fall 2006 M.Elizabethwww.marric.us/teaching

Chapter 8.1 Change Over Time –Differences Among Organisms –Do Species Change Over Time –Evidence of Evolution: The Fossil Record Fossils Reading the Fossil Record Gaps in the Fossil Record Vestigial Structures –Case Study: Evolution of the Whale –Evidence of Evolution: Comparing Organisms Comparing Skeletal Structures Comparing DNA from Different Species Comparing Embryonic Structures

Changes Over Time Differences between species relate to adaptations. Adaptations – a hereditary characteristic (attribute) that helps an organism survive and reproduce in its environment. –Physical adaptations are heredity. Which means that the organism has no choice about the characteristics. – Emotional, cultural, and behavioral adaptations are choices that humans can make.

It’s all about Species What is a Species? –A population of organisms that can mate with one another produces fertile offspring. Example: Horses, Donkeys, and Mules –Breeding a male donkey to a female horse results in a mule; –Breeding a male horse to a female donkey produces a hinny + = Sterile Mule Horses and Donkeys are separate species

Do Species Change Over Time The Earth is very old – 4.6 Billion Years The Earth was formed approx. 4.6 bya –The oldest rock is 3.5 Billion years Fossil evidence suggests that species have changed over time because younger fossils are different, yet similar to older fossils giving rise to the idea of common ancestor for all life on Earth.

Evolution Evolution is the process by which populations of organisms acquire and pass on unique traits from generation to generation, affecting the overall makeup of the population and potentially leading to new species.

Geologic Time Notations ya – Years Ago mya – Million of years ago bya – Billion years ago Precambrian Paleozoic ERA Mesozoic ERACenozoic ERA

Era word roots Geologist use the clues in some of these words. For example: – zoic refers to animal life – paleo means ancient –meso means middle, –ceno means recent. So the relative order of the three youngest eras, first Paleoozoic, then Mesozoic, then Cenoozoic, is straightforward.

Check for Understanding (T or F) _______ Scientists believe that all living things, including daisies, crocodiles, and humans, share a common ancestor. _______ A great number of species have died out since life first appeared on Earth. _________ The first mammals appeared on Earth at about the same time as the first terrestrial plants. True False

Evidence of Evolution: The Fossil Record Fossils Reading the Fossil Record Gaps in the Fossil Record Vestigial Structures

Fossils Are found in the earth’s crust – the very uppermost part of the earth that is exposed to the surface or lying immediately below the oceans.

The Best Crust for Fossils Sedimentary Rocks are the best crust for fossil formations; Example: The Grand Canyon. Strata = Layers of sediment so its called sedimentary rock

Rocks contain clues to the Earth’s past.

What are Fossils Fossils are the mineralized remains of animals or plants or other traces such as footprints. All of the fossils and their placement in rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology.

What kind of rock is this? Sedimentary Rock

Reading the Fossil Record Law of Superposition: Youngest on Top An undeformed sedimentary rock layer is older than the layers above it and younger than the layers below it A B C D

Law of Superposition A B C D In terms of Relative Age Rock Layer B must be younger than Rock Layer A but Rock Layer B is older than Rock Layers C and D.

Once the order of formation is known, a RELATIVE AGE can be determined for each rock layer

Gaps in the Fossil Record Occur because specific conditions are needed for fossils to form Organisms with hard body parts (skeletons) are more likely to form fossils than organisms with soft body parts. Basic to this is that organisms cannot be completely eaten before fossilization –Why so many are shells and bones Fossils form best without oxygen – why peat bogs and tar pits have great fossils. Burial by sediments reduce oxygen exposure. Freezing also allows fossil formation – Mammoth that Japanese scientists are trying to clone from DNA extracted from frozen Mammoth fossil. Fossils once formed can be destroyed.

Sea shells embedded in marine rock near Santa Cruz Ammonites near Redding

Human Remains

Fossils found in the upper layers of the Earth’s crust are _______than fossils found in the lower layers. (newer or older) There are gaps in the fossil record because a. the conditions needed for fossils to form are rare. b. very few different organisms have lived on Earth. c. many fossils have been destroyed. d. not many people are looking for fossils.

Vestigial Structures Mammals are warm blooded vertebrates Vertebrates are animals with backbones. Vestigial structures are organs that have no apparent function. Examples: –Human appendix – narrow tube attached to the large intestines –Chimpanzee, gorilla, and orangutan appendix is functional and used to help digest tough plant material

Appendix

Whale evolution (terrestrial to aquatic in ~ 8 Myr) 8 million years total

PBS Whale Evolution PBS Whale Evolution One structural remnant (remaining part) of this evolutionary process are hind limb bones. These bones are called vestigial structures.

Evidence of Evolution: Comparing Organisms Comparing Skeletal Structures Comparing DNA from Different Species Comparing Embryonic Structures

Comparing Skeletal Structures Homo logous Structures –Having similar origins and anatom ical patterns (homo - same –Anatomy: study of the structure of biological organisms –Examples – bird wings, human arms, whale flippers, bat wings, cat legs.

Homo logous Structures

Analogous Structures Analogous structures do the same thing – similar function, but different anatomy. –Wings (butterfly external skeleton, bat internal skeleton Analogous structures: wing of an insect, bird, bat and pterosaur

Comparing DNA from Different Species DNA is a biological molecule called deoxyribonucleic acid and is the genetic material of all living things on earth The actual molecular characteristics of DNA is measured and compared to other organisms. There are four different nucleotides in DNA (Adenine, Guanine, Cytosine, and Thymine). Gene sequencing – sections of DNA are sequenced for the order of nucleotide bases (ATCG or ATGC or ACTG, etc).

Looking for Relatedness

Comparing Embryonic Structures Ontogeny: Development of the Individual from conception to maturity. Phylogeny: study of evolutionary relatedness among various groups of organisms (e.g., species, populations) Vertebrate organisms (those having a backbone) have similar stages of life as an embryo

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Check for Understanding All living organisms have the same type of _______________ All ____________look very similar when they are in the embryonic stage. (living things or vertebrates) genetic material

Chapter 8.2 How Does Evolution Occur Charles Darwin –Darwin’s Excellent Adventure –Darwin’s Finches –Darwin Does Some Thinking –Darwin Learned from Farmers and Animal and Plant Breeders –Darwin Learned from Geologists –Darwin Learned from the Work of Thomas Malthaus –Natural Selection –More Evidence of Evolution (DNA Mutation)

Darwin Darwin’s father wanted Darwin to become a Doctor, but Darwin earned a degree in Theology instead. Later, Darwin was the naturalist on the HMS Beagle.

Darwin’s Excellent Adventure HMS Beagle – Galapagos Island Travels Galapagos Islands are part of the country of Ecuador though the islands are about 1,000 kilometers west of the continent of South America in the Pacific Ocean. There are 19 volcanic islands with a land area of 8,000 km 2 in an area of the Pacific Ocean over 60,000 km 2 About Darwin

Darwin’s Finches

Diversity Darwin saw finches that were very different from each other as he traveled to the various islands of the Galapagos. Because of their physiological differences (beak shapes), the finches had very different diets

Darwin Does Some Thinking Darwin wonders how did the finches become so different. He thought maybe there was a storm that separated the original population resulting in geographic isolation (one of the ways that speciation can occur) Darwin’s hypothesis was that the Galápagos finches were descended from an original population of finches that was blown from South America to the Galápagos Islands.

Darwin Learned from Farmers and Animal and Plant Breeders Darwin was very familiar with artificial selection or better known as selective breeding. Certain traits are determined by the breeder to be favorable. If only those organisms with the favorable traits are bred then the trait will occur more often in the population. By isolated certain individuals the differences can grow.

All from an ancestral dog

Darwin Learned from Geologists Darwin learned from Charles Lyell that the Earth was formed over a long period of time by natural process. This idea of geologic time (really really long time ago) helped Darwin to more seriously consider natural processes for changing populations.

Darwin Learned from Thomas Malthus Thomas Malthus was an economist. Malthus reasoned that humans have the potential to reproduce beyond the capacity of their food supply. Malthus recognized that there are some limitations to human population growth: –War (for animals it is predation-predators) –Disease –Starvation

Competition Because there are some limitations to growth, Darwin thought that those survivors must be better equipped (adapted) to their environment allowing them to out-compete other individuals. The offspring of the successful competitors have the same traits so are also more likely to survive in the same kind of environment.

Natural Selection Darwin theorized that evolution occurs through a process he called natural selection 1.Overproduction – Each species produces more offspring that will naturally survive. 2.Genetic Variation – individuals will be slightly different from one another. 3.Survival Struggle – competition for resources Abiotic and Biotic factors 4.Successful Reproduction – fitness (Survival of the fittest)

More Evidence of Evolution Darwin did not know what the mechanism was for how parents passed their traits to their offspring. Gregory Mendel ( ) the Catholic monk studied traits in sweet peas. With Mendel's work and biochemistry we now know that the mechanism is meiosis involving DNA that is subject to mutation.

Mutation Changes to the heredity material- DNA, deoxyribonucleic acid – result in a changed genotype. Some changes that occur are not observed because the change did not significantly affect a function. Changes that affect function result in a different phenotype (what things look or function like).

Natural Selection Darwin theorized that evolution occurs through a process he called natural selection 1.______________ – Each species produces more offspring that will naturally survive. 2.______________ – individuals will be slightly different from one another. 3.____________ – competition for resources Abiotic and Biotic factors 4.___________________ – fitness (Survival of the fittest) Overproduction Genetic Variation Survival Struggle Successful Reproduction

Chapter 8.3 Natural Selection in Action Insecticide Resistance Adaptation to Pollution Formation of New Species Separation Adaptation Division

Insecticide Resistance Insects that cause economic or health damage are becoming more difficult to kill due to insecticide resistances. Insecticides are compounds designed to kill insects (cidal – to kill). Insects that are resistant to a particular insecticide can survive and reproduce while those that do not have the genotype that infers resistance will die and will not reproduce.

Resistance The application of the harmful material (by humans) results in an artificial selection for those insects that are resistance. The same, unfortunately occurs to disease causing bacteria and virus, creating “super bugs” which often times results in incurable situations or death because antibiotics (against life) are no longer effective. This is why it is so important when prescribed an antibiotic to complete the treatment to avoid mutation during treatment of a pathogen creating a resistant pathogen that can survive – generation times of bacteria and virus is measured in minutes.

Adaptation to Pollution Peppered moths are the classic case. Dark moths were low in population because they did not blend well with the environment and so where eaten by predators. The pale moths were high in population because they were camouflaged. Then comes along the Industrial Revolution with coal burning to fuel factory machines and heat homes. The results of burning coal are sooty smoke, acid rain, and mercury contamination.

Well, the sooty smoke coated the vegetation made those pale moths stand out like a sore thumb and the dark moths became camouflaged. So what do you think happened? The population of dark moths increased and the population of pale moths decreased.

Peppered Moths

Match each statement about the peppered moth population (1-4) with the appropriate step in natural selection (a-d). 1. Moths that live to maturity may mate and produce offspring. a. Genetic variation 2. A population of peppered moths contains some light-colored moths and some dark-colored moths. b. Successful reproduction 3. Many moths do not survive because they are eaten by birds. c. Overproduction 4. Peppered moths lay many eggs. d. Struggle to survive B A D C

Formation of New Species Steps: Separation, Adaptation, Division (speciation). Separation allows the gene pool to be come isolated where no mixing of the populations occur. Adaptation are mutations that help the species to be successful in the new environment. Division occurs over time these mutant changes result in a separate species that cannot interbreed, speciation.

Chapter 8 Review One species evolves into another through the process of _____________________. A group of similar organisms that can mate with one another to produce fertile offspring is known as ________________. A(n) __________ helps an organism survive better it its environment. ____________is the process by which populations change over time speciation species adaptation Evolution

In ______________________________, humans select traits that will be passed from one generation to another. A change in a gene at the DNA level is called a __________________. The theory of evolution combines the principles of _________________________ __________________. The fact that all organisms have DNA as their genetic material is evidence that all organisms ______ __________________________. Everything had to start somewhere. Artificial selection Mutation Natural selection and genetic inheritance desended from a common ancestor.