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Chapter 10: Evolution . Section 10.5 Evolutionary Biology Today . Warm-Up. You have learned that the environment affects how organisms change over generations. How would you explain a species that remains the same for millions of years?. Objectives .
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Chapter 10: Evolution Section 10.5 Evolutionary Biology Today
Warm-Up • You have learned that the environment affects how organisms change over generations. How would you explain a species that remains the same for millions of years?
Objectives • (1) The student will be able to recognize the major sources of evidence for evolution. • (2) The student will be able to examine the patterns of features that reveal the history of a species.
Key Concept • New technology is furthering our understanding of evolution.
Fossils Provide a Record of Evolution • Paleontology: the study of fossils or extinct organisms • Fossils provide us with new information and supports current hypotheses about how evolution occurs. • The fossil record is not complete. Explain why this statement is true.
Fossils Provide a Record of Evolution • Darwin worried about the lack of transitional fossils. • Transitional fossils: an intermediate between a modern species and its ancient ancestor. • Archaeopteryx • Since Darwin’s time transitional forms have been discovered: Basilosaurusisis(pg.316) • In Egypt during 2005 Basilosaurusisiswas discovered. • This mammal had a whale like body but it also had limbs similar to a terrestrial species. • Why is Basilosaurusisisconsidered a transitional fossil?
Molecular and Genetic Evidence Support Fossil and Anatomical Evidence • Different species have similar molecular and genetic mechanisms • DNA or Protein comparisons can be used to show probable evolutionary relationships.
Molecular and Genetic Evidence Support Fossil and Anatomical Evidence • DNA Sequence Analysis: sequences of DNA nucleotides in a gene change overtime due to ________________. The more related the two organisms the more similar their DNA will be. • Pseudogenes: These are like vestigial structures. The presence of pseudogenes reflect a common ancestor.
Molecular and Genetic Evidence Support Fossil and Anatomical Evidence • Homeobox genes: Control the development of specific structures. Homeobox genes show that there is a possible distant common ancestor. • Protein Comparison: Similarities among cell types can be revealed by comparing proteins. This technique is called molecular fingerprinting. • Unique proteins are found in specific cell types. • How can protein comparisons help to determine ancestral relationships between organisms?
Evolution Unites all Fields of Biology • Evolution is used in medicine, geology, geography, chemistry, and ecology. • Scientists from many fields contribute to the basic understanding of evolution. • How can the idea of a common ancestor help us to understand new diseases?
Evidence of Whale Evolution: Vestigial Evidence • Whales have vestigial pelvic and leg bones. • Whales have vestigial nerves that influence their sense of smell. • There are also remnants of small muscles devoted to ears that no longer exist.
Evidence of Whale Evolution: Embryological Evidence • The nostrils in whale embryos are found at the snout but they travel towards the top of the head to form blowholes before birth.
Evidence of Whale Evolution: Molecular Evidence • DNA sequences of milk proteins in ungulates and whales are very similar
Reflection • (1) Summarize different types of evidence that support evolution. • (2) Recognize the importance of evolution in unifying all branches of biological study.