1. Thinking About Darwinian Evolution: What is evolution?? And what is this finch doing?!?

2. CHARLES DARWIN. We owe much of our understanding of EVOLUTION to CHARLES DARWIN. Darwin’s Origin of Species (1859): 1. Descent with Modification (Evolution) 2. Natural Selection as a mode of Evolution Remember: Mendel publishes in 1866…

3. Darwin’s Natural Selection: Observation #1: Individual Variation Observation #2: Struggle for Existence Inference: Differential Reproductive Success or Natural Selection

4. ADAPTATIONS ADAPTATIONS are the result of natural selection.

5. Darwin also proposed that natural selection, over time, could produce new species from ancestral species. This was his explanation for the 14 unique species of finches he observed on the Galapagos Islands.

7. Darwin’s Historical Context: The Philosophy of the Time Plato (427-347 BC): two worlds: a real (ideal) world, and an illusory world (imperfect) that we perceive with our senses. Aristotle (384-322 BC): all living forms can be arranged on a scale or ladder or increasing complexity. (All rungs taken!) Judeo-Christian Context: Biology in Europe and America dominated by natural theology- classifying species in order to reveal the steps of the scale of life God created.

8. The Historical Context "Those who which to succeed must ask the right preliminary questions." - Aristotle

9. FOSSILS: Paleontology (the study of fossils) is developed by Cuvier (1769-1832). He documents the succession of fossil species in the Paris Basin. He advocates catastrophism rather than evolution. Darwin’s Historical Context: The Philosophy of the Time

10. GEOLOGICAL THEORIES: Hutton (1726-1797) proposes gradualism (profound change is the result of slow continuous processes). Lyell (1797-1875) expands to uniformitarianism (geologic processes have not changed throughout the Earth’s long history). Darwin’s Historical Context: The Philosophy of the Time

11. Other Scientists had suggested EVOLUTION, but none had proposed a MECHANISM! First Mechanism: Jean Baptiste Lamarck Lamarck observes several lines of descent in fossils. Suggests that use and disuse results in change in morphology. He suggests that these acquired characteristics (adaptations!) could be inherited. This is wrong, but visionary!

12. Malthus contends that much of human suffering is the unavoidable consequence of the potential for the human population to increase faster than food supplies and other resources. Darwin is heavily influenced by Thomas Malthus’ writings on human population (1798)

13. Darwin’s MECHANISM = NATURAL SELECTION Natural selection is differential success in reproduction Natural selection occurs through an interaction between the environment and the variability inherent among the individual organisms making up a population The product of natural selection is the adaptation of populations of organisms to their environment.

14. Darwin’s ideas remain unpublished until another scientist, Alfred Wallace, independently develops the same theory of Natural Selection. Darwin publishes second, but in much more detail.

15. Darwin illustrates his mechanism with examples from ARTIFICIAL SELECTION, the breeding of domesticated plants and animals If artificial selection can change so much in a relatively short time, argues Darwin, then natural selection should be capable of considerable modifications.

16. Examples of Natural Selection: Insecticide-Resistant Insects Antibiotic-Resistant Bacteria Drug-Resistance in HIV

17. Homology Other Evidence of Evolution: Homology Similarity in characteristics resulting from common ancestry is known as HOMOLOGY. Homology can be: 1. Anatomical (Homologous Structures) 2. Molecular (esp. DNA) 3. Embryological- developmental structures and processes.

18. Anatomical Homology:

19. FISH REPTILEFISHCHICKENHUMAN Developmental Homology:

21. MOLECULAR HOMOLOGY:

22. Some HOMOLOGIES are MISLEADING… as they result from CONVERGENT EVOLUTION.

23. BIOGEOGRAPHY BIOGEOGRAPHY, or the geographic distribution of species, provides many clues about their evolution. Islands are especially good for studying biogeography as they contain many isolated, endemic species.

24. The FOSSIL RECORD provides the last major line of evidence in support of Darwin’s ideas. The Darwinian view of life predicts the existence of evolutionary transitions. Bailosaurus

25. Thus Darwin’s views are supported by multiple, independent lines of evidence. Homology Biogeography Fossil Record Evolutionary patterns of Homology that match patterns in space (Biogeography) and time (the Fossil Record).