Evolution Group 7: Kyle, John, Sydney, and Jeff Quarter 2, Period 3, 2011

Scientific Theory An explanation of natural events that have support from scientific evidence that has been investigated thoroughly.

Evolution  Evolution: A gradual change in a species throughout time by means of adaptation.  Adaptation: A trait that increase an organism’s chances of survival.

Charles Darwin  Was the first to propose the theory of natural selection based on his travels to the Galapagos Islands aboard the HMS Beagle.  Natural Selection (Survival of the Fittest): Those better suited to the environment will survive longer than those less suited. Creates change in a population.

Genetic Variation  Mutations create a varied genetic code which ensures a species’ survival and helps create new and better traits.

Three Types of Natural Selection  Stabilizing: Favors average. Reduces variation.  Directional: Favors one extreme. Leads to rapid evolution.  Disruptive: Favors both extremes. Leads to 2 new species. Stabilizing Selection…….Directional Selection………Disruptive Selection

Speciation  The process of one species changing into two separate ones.  The resulting species will no longer be able to interbreed.

Evidence for Evolution  Fossils: Pieces or imprints of organisms left behind that prove changes in species  Vestigial Structures: Structures of the body that serve no purpose but once did  Homologous Structures: Structures that share a common ancestor and act or appear similarly.  Embryology: Similarities of the embryos of different species  Homologies: DNA, amino acids, mitochondrial DNA, photosynthetic plant cells, etc. Comparing these things in different species show similarities.

Carbon Dating  Amounts of carbon-14 in fossils show when the fossil was created. This helps to “date” when the species of the fossils existed.

Homologous Structures vs. Analogous Structures  Homologous structures: are derived from a common ancestral  Analogous structures: are similar in function but not in structure

Biochemistry  Is the comparison of DNA and RNA

Dating fossils, rocks, and other materials  Radiometric dating: the decay of radioactive elements, can allow scientists to date rocks and materials directly  Stratiography: A sequence of events from which dates can be extrapolated  Molecular clocks: The divergence of genetics over time between organisms to estimate dates

DNA and Amino Acid Homology  The comparison of strips of DNA  Used to find how similar organisms are  You can chart the similarities through cladograms

Species  Species- members of a group/population that are able to interbreed and create fertile offspring

Causes of Speciation  Geographic isolation- species that are able to reproduce are unable to do so due to different geographic locations  Reproductive isolation- species may appear similar but are unable to reproduce or species may appear different but are able to reproduce  Differences in chromosome numbers- Polyploid species are created from nondisjunction during the processes of meiosis or mitosis

Pre- and Postzygotic Barriers  Pre-: –Temporal, habitat, or behavioral isolation  Post-: –Hybrid inviability/sterility (mules)

Rates of Speciation  Polyploid speciation- occurs through one generation.  Gradualism- the idea that species change over many generations at a slow rate until speciation eventually may occur.  Punctuated equilibrium- the idea that speciation occurs quickly with long periods of generic equilibrium in between.

Patterns of Evolution  Divergent- Once-similar species diverge.  Adaptive radiation- One species evolves into many different species.  Convergent- Unrelated species evolve similar characteristics.

Web Resources deos.html deos.html

Questions Q1-3: What is each type of natural selection based on? Stabilizing?Disruptive?Directional? A. Favors both of the extremes and produces 2 new species B. Favors the average of the species and reduces Genetic Variation C. Favors some of both extremes and produces no new species D. Favors one extreme of a population and produces a new species Q4: What are fossils? A. Pieces of evidence of an organism B. Only pieces of an organism C. An organisms preserved DNA Q5: What are Vestigial structures? A. Structures that are useful and similar to another organisms B. Structures that are no longer useful to an organism but once were C. Organs that are vital for survival

Q6: What do Vestigial structures prove? They help prove A. That organisms were created similarly B. That Embryology is a successful stuff C. 2 Organisms had a common ancestor Q7: What is one type of Evidence of Evolution? A. Embryology B. Stabilizing selection C. Similar Organs D. All of the above Q8: What are other types of Evolution Evidence? A. Biochemistry only B. Comparing DNA and RNA only C. Only Embryology D. All the above Q9: What are Molecular clocks: A.The divergence of genetics over time between organisms to estimate dates OR B. the process of using an unstable Isotope of Carbon Q10: What Is the compliment of the nucleotide Adenine (A)? A. G (Guanine) B. C (Cytosine) C. T (Thymine)

True or False (Q’s 11-17): ______: Homologous structures are useless structure ______: Radiometric dating is the process of the decay of radioactive elements ______: Analogous Structures are similar in Function but not in structure ______: Speciation is the formation of 1 new species ______: Stratiography is a sequence of events from which dates can be extrapolated ______: Punctuated equilibrium argues that species are always changing ______: Convergent evolution is where 2 not similar like species develop similar characteristics What are the 3 causes of Speciation and what are they (Q17-20): Geographic Isolation: Reproductive Isolation: Change in chromosome number: A. During a reproductive defect in an organism has an abnormal amount of chromosomes making them sterile B. Species may appear similar but are different C.Geographic barriers separate a species forming 2 species

1 B 2 A 3 D 4 A 5 B 6 C 7 D 8 D 9 A 10 C 11 F 12 T 13 T 14 F 15 T 16 F 17 T 18 C 19 B 20 A Answers