Presentation on theme: "PRINCIPLES OF EVOLUTION Chapter 10 Page 278. A. EARLY IDEAS ABOUT EVOLUTION 1. Early Scientists a. Darwin was not the first person to come up with the."— Presentation transcript:
A. EARLY IDEAS ABOUT EVOLUTION 1. Early Scientists a. Darwin was not the first person to come up with the idea b. Evolution – process of biological change by which descendants differ from ancestors c. Carolus Linnaeus – developed classification system for organisms
d. Buffon – proposed that species shared ancestors instead of arising separately e. Lamarck 1) Proposed all organisms evolved toward perfection and complexity 2) Happened b/c changes in the environment
2. Theories of geologic change set the stage for Darwin a. Fossils 1) Traces of organisms that existed in the past 2) Caused from catastrophism – natural disasters happened often in earth’s history b. Gradualism proposed – slow changes over time
c. Charles Lyell 1) Proposed theory of uniformitarianism 2) Uniformitarianism – geologic processes are uniform through time 3) Theory expanded on gradualism and replaced theory of catastrophism 4) Challenged young earth views 5) Ex. Ice melting – if you know the rate, do you have to watch the whole thing melt?
1. Introduction a. Born same day as Abraham Lincoln (1809) b. Went to study medicine c. Hated school and dropped out d. Studied theology 1)“Devote” Christian at this point 2)Graduated w/BA in theology B. DARWIN’S HISTORY AND OBSERVATIONS
e. Had an interest in geology f. Went on a 5 year trip around the world 1) Documented many different species 2) Came up with natural selection
g. Published “The Origin of Species” (1859) 1)Talks about why there is diversity on earth 2)Theory of evolution 3)Didn’t publish right away a)Wanted it perfected b)Wife said no…would have hurt the church 4)When it was published - sold out in one day 5)Huge difference – most scientists used to be trained in the Bible
Origin of species video http://www.youtube.com/watch?v=vfmOaAz371M
2. Darwin observed differences among island species a. Variation – differences in physical traits of an individual from other members of a species 1) Can happen in same species 2) Can happen in different species b. Adaptation 1) Allows an organism to better survive in its environment 2) Can lead to genetic change in a population over time
c. Darwin’s finches (Galapagos islands) 1) Had similar structures but also some variation 2) Beaks for eating insects/nuts 3) Each came from a common ancestor 4) Birds adapted as food source changed 5) If beaks change, why not other structures too?
3. Darwin observed fossil and geologic evidence a. Found animals similar to ones today, meaning there would have to be long periods of time in order to change b. Fossils of marine organisms in the mountains 1) Darwin experienced earthquake 2) Saw land that was underwater move above 3) Geologic processes add up over time
1. Insights to idea of natural selection a. Selection Process 1)Artificial selection a)Process where humans change a species by breeding it for certain traits b)Can give a lot of variation from other organisms c)Breed only animals with that trait C. THEORY OF NATURAL SELECTION
2) Heritability a) Trait can be passed to offspring b) Has to have heritability or natural/ artificial selection wont work
3) Natural selection a) Organisms with beneficial trait have more offspring on average b) Nature is the selecting agent c) Traits are selected by what is beneficial and what is not d) Doesn’t happen perfectly the first time – could take many generations
Moths that blend in don’t get Eaten – selected against NATURAL SELECTION
b. Struggle for Survival 1) Food, water, shelter limit population growth 2) Population – all individuals living in that area 3) W/limited resources what allows one animal to live and another to die?
2. Natural Selection Explains Evolution a. Variation 1) Heritable differences are basis for natural selection 2) Differences b/c of genetics from parents or mutations
b. Overproduction w/offspring 1) Raises chances of survival 2) Increases completion b/w offspring for resources c. Adaptation 1) Allows for some organisms to survive over others 2) Individuals are “naturally selected” to live
d. Descent w/modification 1) Over time a certain trait will stay 2) Offspring will be more likely to have that trait 3) Will cont. as long as environment doesn’t change 4) Ex. – bottom paragraph pg 288 - 289
e. Fitness – measure of the ability to survive and reproduce compared to others in the population
3. Natural selection acts on existing variation a. Acts on phenotypes rather than genotype b. Changing Environments – pg 290 c. Adaptations as compromises – pg 291
1. Fossils a. Look at location, age, and environment of fossil b. Certain fossils are only found in some layers c. Primitive fossils are found deeper in rock D. EVIDENCE OF EVOLUTION
2. Geography a. Provides isolation of populations b. Find similar species in similar rock layers
3. Embryology a. Developing embryos look similar b. Very difficult to tell apart
4. Anatomy a. Homologous structures – similar appearance but different function b. If each of these groups descended from a different ancestor, why would they share these homologous structures?
5. Vestigial Structures a. Remnants of organs or structures that had a function but not any more b. Ostrich wings c. Snakes – pelvic bones and stumplike limbs d. Humans 1) Appendix 2) Tail bone
1. Fossils – a record of evolution a. Paleontology – study of fossils or extinct organisms b. Fossil record is not complete 1)Most living things don’t form fossils 2)Haven’t looked for fossils in every area of the world 3)Missing links – pg 300 E. EVOLUTIONARY BIOLOGY TODAY
2. Molecular and genetic evidence a. Pseudogenes 1) Sequences of DNA nucleotides 2) Similar to vestigial structures b. Homeobox genes 1) Control development of specific structures 2) Found in all organisms 3) Indicate distant common ancestor
c. Protein comparisons 1) Unique set of proteins found in specific cells 2) Cell from different species with similar proteins show common ancestry