Name Date Period Evolution and the History of Life, MLK 2005

Transcription

1 Evolution and the History of Life, MLK 2005 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 Embryonic Structures Differences between species relate to. Adaptations a hereditary characteristic (attribute) that helps an organism survive and reproduce in its environment. Physical adaptations are hereditary. Which means that the organism has no choice about the characteristics. Emotional, cultural, and behavioral adaptations are choices that humans can make. 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 which is not fertile. Breeding a male horse to a female donkey produces a hinny which is not fertile. - Horses and Donkeys are separate species. 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. 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. ya bya mya Precambrian Paleozoic ERA Mesozoic ERA Cenozoic ERA

2 Geologist use the clues in some of these words. For example: zoic refers to paleo means meso means ceno means So the relative order of the three youngest eras, first Paleoozoic, then Mesozoic, then Cenoozoic, is straightforward. Fossils Reading the Fossil Record Gaps in the Fossil Record Vestigial Structures 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. Sedimentary Rocks are the best crust for fossil formations; 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. The study of fossils is called An undeformed sedimentary rock layer is older than the layers above it and younger than the layers below it 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. Evolution and Life History 2 Structured Notes Part 1

3 Once the order of formation is known, a can be determined for each rock layer. 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. Find shells and bones Fossils form best without oxygen why peat bogs and tar pits have great fossils. Burial by sediments reduce oxygen exposure and UV light Freezing also allows fossil formation Mammoth that Japanese scientists are trying to clone from DNA extracted from frozen Mammoth fossil. Besides not having the right conditions, organisms can be eaten or fossils destroyed Mammals are warm blooded vertebrates 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 26 Comparing Skeletal Structures Comparing Embryonic Structures Homologous Structures Having similar origins and patterns o Examples bird wings, human arms, whale flippers, bat wings, cat legs. 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 Evolution and Life History 3 Structured Notes Part 1

4 The actual molecular characteristics of DNA is measured and compared to other organisms. There are four different nucleotides in DNA 1. A= Adenine, 2. G = Guanine, 3. C= Cytosine, 4. T = Thymine). Gene sequencing sections of DNA are sequenced for the order of nucleotide bases (ATCG or ATGC or ACTG, etc). Ontogeny: Development of the Individual. Phylogeny: Development of the Species. Vertebrate organisms (those having a backbone) have similar stages of life as an embryo 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) HMS Beagle Galapagos Island Travels (HMS Beagle is a ) Galapagos Islands are part of the country of Ecuador though the islands are about 1,000 kilometers west of the continent of South America. 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 Darwin saw finches that were very different from each other as he traveled to the various islands of the Galapagos. Because of their differences (beak shapes), the finches had very different diets Darwin wonders how did the finches become so different. He thought maybe there was a storm that separated the original population 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 breed then the trait will occur more often in the population. By isolated certain individuals the differences can grow. Evolution and Life History 4 Structured Notes Part 1

5 All from an ancestral dog 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. 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: o o o War (for animals it is predation-predators) 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. 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 4. fitness (Survival of the fittest) 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 which is mutated over time. Mutation: Evolution and Life History 5 Structured Notes Part 1