Earth History GEOL 2110

1. Earth History GEOL 2110 Lecture 5 EVOLUTION Part I

2. Major Concepts • In the late 1700/early 1800’s, a number of natural scientists had proposed that evolution of life was likely, however, without a mechanism to explain evolution, the idea was generally dismissed. • Darwin’s Origin of Species (1859) not only provided multiple lines of evidence for evolution, but moreover, proposed a plausible cause (natural selection). • With the discovery of genetic theory in the early 1900’s providing a mechanism for evolution, it became overwhelmingly accepted as a “fact” of science. • The genetics within isolated, small populations provided the triggers for the “origin” of new species • The mechanisms of evolution are still being figured out, but not the concept of evolution is not in doubt and has achieved the status of a paradigm of science.

3. Early Ideas about Evolution • To the early Greeks and Romans, the notion that nature changes/evolves was well accepted • Christian teachings required that all organisms were created together, at once, and unchanged for all of time • The notion that God would let organisms go extinct (as proposed by Cuvier and Smith) was antithetical to genesis and heretical

4. Early Ideas about Evolution • Georges de Buffon • Histoire Naturelle (1847) • definedthe concept of species (the ability to interbreed) • was the first to emphasize the importance of environment in the changes (evolution) within species • recognized that organism seek to adapt to their environment but did not offer an explanation how this might occur • noted evidence for inheritance of traits, but again did not offer an explanation. • Enough time for Evolution was a major sticking point

5. Early Ideas about Evolution • Erasmus Darwin (1731–1802)Charles’s Grandfather • as an animal breeder, recognized the subtle changes from generation to generation • argued that the fitness of an organism to feed itself, protect itself against predators, and its ability to succeed in mating were important factors controlling its survival and thereby its ability to pass on these characteristics to its offspring. • Still the question remains - how does inheritance work?

6. Early Ideas about Evolution • Defined “biology” as a study of the plant and animal world • Ideas about evolution published in 1809, where he argued that the fundamental course of nature is change and this change was controlled by environment • Did not ascribe to Buffon’s fixed species concept, but rather believed that organism represent a continuum of change. • Did not believe in extinction, but rather the “loss” of an organism was due to it’s changing into or replacement by another form. Jean Baptiste de Monet – Chevalier de LAMARCK (1744–1829)

7. Inheritance of Acquired CharacteristicsLamarck’s Giraffes But again, how are these acquired characteristics passed on?

8. Darwinian Evolution • Born in the year that Lamarck published his ideas about evolution • Embarked on a 5-year voyage (1832-1835) around the world on the HMS Beagle where he was charged with documenting the diversity of flora and fauna in the tropics and Southern hemisphere. • Struck by: • Variety of species • Number and diversity of individuals per species • The importance of competition for food, safety from predators, and shelter Charles Darwin (1809-1882)

9. Darwin’s Epiphany HMS Beagle Captain Fitzroy Ship-side Reading Malthus (1798) Principles of Population Lyell (1830) Principles of Geology Darwin

10. Natural Selection • Natural environments change • Individuals within a population of organisms change • Individual changes that are best fitted (adapted) to the changes in the environment are the most likely to survive • “survival of the fittest”

11. Radiation into Environmental NichesThe Finches of the Galapagos • Only birds on the islands – no competition • 4 different genera • 15 different species • Each adapted a different beak type reflecting their dietary preference

12. On the Origin of Species • First draft completed in 1839, but not published until 1859 • Fearful of backlash from British scholars and clergy • For 20 years, compiled supporting data • Primary goals of the book: • Document evidence for Evolution • Propose a mechanism (Natural Selection)

13. Evidence of EvolutionBranching Organization of Life Early classifications of the animal and plant kingdom show groups within groups within groups based on anatomical features Best portrayed by a branching family tree implies related lineages Today, genetic coding affirms that grouping

14. Evidence of EvolutionHomologous Elements Diverse organisms share similar organs and features For example, the bones of appendages in a variety of vertebrates Green –humerus Red – radius Blue – ulna Tan – wrist and phalanges

15. Evidence of EvolutionVestigal Structures and Imperfections Unnecessary body parts Why would such things be “created”? Humans Tail bones Appendicies

16. Evidence of EvolutionEmbryonic History All vertebrate embryos go through similar early stages of development “Ontogeny recapitulates Phylogeny” Hackel (1866) (i.e. embryonic development repeats evolutionary history)

17. Evidence of EvolutionPaleogeography On unconnected continents, unrelated animals have evolve to occupy similar environmental niches For example – Marsupials of Australia “Ecological Convergence”

18. Next Lecture EVOLUTION II Genetics and the Origin of Species Quiz #2 Chapter 3