Ch. 19 Warm-Up 1. What do you remember about Charles Darwin and his scientific ideas? 2. According to Campbell, what is the definition of evolution? Chapter 19
Descent with Modification Part A: Darwin & Natural Selection What you must know: Several examples of evidence for evolution from different scientific disciplines and how each supports change
of populations over time. The difference between structures that are homologous and those that are analogous, and how this relates to evolution. The role of adaptations, variation, time, reproductive success, and heritability in evolution. Descent with Modification
Theme: Evolutionary change is based on the interactions between populations & their environment which results in adaptations (inherited characteristics) to increase fitness Define: Evolution 1. Descent with modification (Darwin) 2. Change over time in the genetic composition of a population from
Aristotle Species are fixed (unchanging) Scala naturae: life-forms arranged on ladder of increasing complexity Aristotle 384-322 BCE
Old Testament (Creationism) Earth ~6000 years old Perfect species individually designed by God for particular purpose Carolus Linnaeus = founder of taxonomy binomial nomenclature: Carolus Linnaeus
1707-1778 genus, species Domain Kingdom Phylum Class Order Family Genus Species Dear King Philip Came Over For Good Spaghetti Classification based on anatomy & morphology
Cuvier: Paleontologist studied fossils Deeper strata (rock layers): very different fossils from current life Opposed idea of evolution Boundaries between strata= many living
species destroyed by catastrophic event, then repopulated by immigrant species George Cuvier (1769-1832) Formation of sedimentary strata with fossils
Hutton: geologic change results from slow & gradual, continuous process Lyell: Earths processes same rate in past & present therefore Earth is very old Slow & subtle changes in organisms big change James Hutton 1726-1797 Charles Lyell
1797-1875 Jean-Baptiste de Lamarck 1744-1829 Lamarck Published theory of evolution (1809) Use and Disuse: parts of body used bigger, stronger (eg. giraffes neck)
Inheritance of Acquired Characteristics: modifications can be passed on Importance: Recognized that species evolve, although explanation was flawed Malthus: More babies born than deaths
Consequences of overproducing within environment = war, famine, disease (limits of human pop.) Struggle for existence Thomas Malthus (1766-1834) Charles Darwin (1809-1882) English naturalist
1831: joined the HMS Beagle for a 5-year research voyage around the world Collected and studied plant and animal specimens, bones, fossils Notable stop: Galapagos Islands
HMS Beagle (1831-1836) Galapagos Islands 14 15 Darwins Finch Collection
The birds were all about the same size, but the shape and size of the beaks of each species were Darwin waited 30 years before publishing
his ideas on evolution Alfred Russell Wallace published paper on natural selection first (1858) Charles Darwin (1859): On the Origin of Species by Means of Natural Selection Mechanism for evolution is Natural Selection Darwin didnt use evolution, but rather descent with modification
17 Descent With Modification Organisms descended from an ancestor that lived in the remote past I think (Darwins sketch) Natural Selection
Adaptations enhance an organisms ability to survive and reproduce in specific environments Eg. Desert fox - large ears, arctic fox small ears Natural Selection Artificial Selection Nature decides
Man decides Works on individual Selective breeding Inbreeding occurs eg. beaks
eg. dalmations Therefore, if humans can create substantial change over short time, nature can over long time. Key Ideas of Natural Selection: Competition for limited resources results in differential survival.
Evolutionary Fitness: Individuals with more favorable adaptations are more likely to survive and produce more offspring, and pass traits to future generations If environment changes or individuals move to new environment, new adaptations and new species may arise. Populations evolve, not individuals. Discovery Video: Charles Darwin
PBS: What Darwin Never Knew Video Clip: 20:18 31:27
