Evidence+of+Evolution

Evolution Home 1 Evolution Definitions 2 Evidence of Evolution 3 Charles Darwin 4 Theory of Evolution 5 Study Resources

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=Evidence of Evolution= 1. What evidence do we have that evolution has occured (we discussed 4 items in class...)? The Fossil Record(carbon dating) Geographic Distribution Similarities in Structure Similarities in Development Molecular Biology

=Fossils= 2. What is a Fossil? A fossil is any remains, impression, or trace of a living thing of a former geologic age, as a skeleton, footprint, etc. preserved remains or marking left by an organism that lived in the past.

3. What methods can we use to determine how old a fossil is? Which is most accurate? 1) fossil records- relative= layers and absolute dating=radioactive or carbon dating 2)Compartative embrology- comparing simillarities and differences in embryo's

4. What does the law of superposition state? A basic law of geochronology, stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it.

5. What is a stratum? Stratum is a layer of rock or soil that has internally consistent characteristics that distinguishes from other layers of rock or soil. This is how the scientists determined the age of the fossil.

6. Why is the fossil record so significant? What does it tell us? A term used by paleontologists to refer to the total number of fossils that have been discovered, as well as to the information derived from them. It tells us the different type of species that lived in certain time periods. Also it shows how the evolution of a species has occured over periods of time.

7. What is biogeography? Why is it important to evolution? The study of the geographic distribution of organisms. The scientific study of the geographic distribution of plant and animal life. Factors affecting distribution include the geologic history of a region, its climate and soil composition, and the presence or absence of natural barriers like deserts, oceans, and mountains. Biotic factors such as interactions among competing species, coevolutionary influences, and the reproductive and nutritional requirements of populations and species are also studied.

=Comparative Anatomy= 8. What is a homologous structure? BE ABLE TO IDENTIFY SPECIFIC EXAMPLES! Similar structures found in more than one species that share a common ancestor Example: the Human, the bat, the cat, and the whale all have the same bones in their arms and hands yet are used for different functions.

9. What is a vestigial structure? BE ABLE TO IDENTIFY SPECIFIC EXAMPLES! First of all, a vestige is something that has connotations similar to: burden, bondage, or something unnecessary. A vestigal structure is something that a species has grown and developed to not need. An example of such would be a whale that has a pelvis, because they do not have legs (which would require a pelvis) it does not need that structure. A Vestigial structure used to have a function but is no longer needed. (function in the ancestors) Example: the Human Appendix, the Human Tailbone, or the Whale leg bones

Scientists think that these vestigial structures will grow smaller and smaller until they eventually disappear.

10. What is an analogous structure? BE ABLE TO IDENTIFY SPECIFIC EXAMPLES! Structures that have similar functions but evolved separately ~ such as the fingers of a human vs. a bat or a whale.

11. Why are anatomical structures (homologous, vestigial, and analogous structures....) so significant? What do they tell us?

Homologous structures are one of the best clues to assess how closely organisms are related. The greater the number of homologous structures two species have, the more closely the species are thought to be related. Vestigial structures are part of homologous structures. Vestigial structures are remnants of structures that may have had important functions in an ancesteral species, but have no clear function in modern decendants. Analogous structures have adaptations that result from convergent evolution. For example the wings of an insect and the wings of birds are analogous because they are both flight equipment but evolved independantly, they did not share a common winged ancestor.

=Comparative Embryology= 12. What are the similarities of embryos in the earliest stages of development?

can see differences in early stages
 * Eye socket
 * Ear hole
 * Vertebrae
 * Gills
 * Tail

13. What do the embryos show us about evolution? Embryos show us that we all came from a (LUCA), a last common ancestor. We all developed from something that possesed these similarities, and for the most part, its descendents still have these characteristics.

The embryos show that all life starts off the same and there is a common "blueprint" that all animals and Humans follow

=Biochemical Evidence= 14. What does biochemical evidence (molecular evidence) tell us about evolution This evidence also can tell us how much hemogloben humans have compared to other animals. That all life has the same chemical makeup. It shows the relationship between species.