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: Basilosaurus isis (pg.316) In Egypt during 2005 Basilosaurus isis was discovered. This mammal had a whale like body but it also had

limbs similar to a terrestrial species. Why is Basilosaurus isis considered 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 Evidence1. 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.

2. Pseudogenes: These are like vestigial structures. The presence of pseudogenes reflect a common ancestor.

Molecular and Genetic Evidence Support Fossil and

Anatomical Evidence3. Homeobox genes: Control the development of specific structures. Homeobox genes show that there is a possible distant common ancestor.

4. 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.

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:

Embryological Evidence

Evidence of Whale Evolution: Molecular

Evidence DNA sequences of milk proteins in

ungulates and whales are very similar

Evidence of Whale Evolution: Fossil

Evidence

Reflection (1) Summarize different types of

evidence that support evolution. (2) Recognize the importance of

evolution in unifying all branches of biological study.