Descent with modification Evolution Descent with modification

I. Biological Evolution = observable fact A. Change in species over time B. Change in gene frequencies from generation to generation C. A Process of change

II. Proposed Mechanism for evolution A. Natural Selection – Requires 1. Genetic diversity 2. differential reproduction by individuals with the most fit genes 3. Increase in those genes within population

III. Pre-Darwin Ideas A. Carolus Linnaeus (1707-1778) 1. Binomial Nomenclature Genus species 2. nested groupings into increasingly specific categories based on morphology 3. K P C O F G S 4. Kingdom, phylum, class, order, family, genus, species 5. now we have added Domains

B. Stratification – 1. rock laid down in layers 2. oldest at bottom 3. fossils in strata show when organisms lived order of appearance (now isotopic dating) 4. Older fossils more dissimilar to modern 5. species appear and disappear 6. Cuvier (1769-1832) catastrophism a. catastrophes destroyed species in an area new species moved in

C. Lamarck (1744-1829) 1. one of many to propose that life evolves as environments change 2. first to propose mechanism 3. compared fossils showing lines of descent a. chronological fossils show gradual change b. leading to modern species c. use and disuse d. inheritance of acquired characteristics

III. Darwin’s Contemporaries A. Charles Lyell ( 1797 – 1875) 1. Geologist 2. Theory of Uniformity 3. Natural processes observed today are the same as processes acting in the past 4. The rate of processes today mirror those of the past 5. contradicted young earth theory

B. Thomas Malthus: economist 1. war and famine result from human overpopulation 2. Other organisms also produce more individuals than can survive

C. Alfred Wallace (1823-1913) 1. first to publish Natural Selection as a mechanism for evolution 2. ideas nearly identical to Darwin’s D. Charles Darwin ( 1809 – 1882) 1. Origin of Species 2. extensive evidence of natural selection 3. Lylle, Darwin & Wallace convinced most scientists with in 10 years

Origin of Species Three Main Ideas 1) Unity of Life: shared characteristics attributed to shared common ancestor 2) Diversity of Life: due to descent with modification 3) Match between organisms and environments: due to adaptation

IV. Darwin’s main observations/Inferences Observations in blue Followed by associated Inference Inferences in yellow

A. Artificial selection: selective breeding can produce visible change over a life-time A. If artificial selection can produce rapid change….then natural selection could produce dramatic change given enough time * Lyell suggested a time line of millions of years

B. Organisms produce more offspring than can survive (Malthus) B. Survival most likely for those best fit to their environment.

C. members of a population vary in Inherited traits C. If only some organisms can survive then those with best traits are more likely to survive So good genes accumulate in population… Genetic make-up of population ∆ over time = Evolution!

(morphological evidence note) Mammal neck bones =7 Bird neck bones 13-25 Giraffe neck vertebrae are each elongated… No new bones added Birds with short neck have curve in neck vertebrae… not fewer vertebrae

VI. Natural Selection Vocab. A. Fitness: ability to pass on its genes 1. survive 2. mate 3. fertile offspring live to reproduce B. Adaptation: inherited traits that improve fitness in a given environment 1. individuals can NOT adapt its genetic!! 2. only populations adapt over generations

VII. Theory of Evolution A. speciation – one species branches into 2 new species (ancestral species gone) B. Adaptive radiation –1 species gives rise to many species (common after mass extinctions) 1. individuals disperse to new environments 2. adapting to new environment causes them to change

C. Universal Common Ancestor – all started from some single celled organisms 1. ‘the unity of life’ 2. universal genetic code DNA, RNA 3. shared genes (homeotic genes) 4. Semiconservative replication 5. transcription/translation (Met) 6. shared proteins(DNA and RNA polymerase)

VIII. Main Branches of Evidence A. Direct observation – species change over time 1. Bacteria develop antibiotic resistance

2. Weeds develop resistance to roundup Figure 1. Number of weed species with glyphosate resistant populations and number of states with glyphosate-resistant weed populations. Source: Heap, 2009.

3. Grant’s finch research a. recorded beak depth of all finches on an island over 30 years

B. Homology: similarities resulting from common ancestor 1. Homologous Structures a. anatomical features b. same underlying structure c. may have adapted to different function

d. embryo homology may be lost in adult 1. pharyngeal arches – all chordates 2. post anal tail – all chordates

e. Chordate limbs : same bones just different shape due to different function of appendage

2. Vestigial Structures : inherited from ancestor but no longer used a. explains presence of useless structures b. pelvic girdle & femur in whale & snake

C. Human vestigial structures

3. molecular homologies: same DNA/ protein a. all organisms homologous DNA structure b. Many homologous DNA genes 1. some have developed a new function 2. some still same function a. genes for ribosome subunits homologous between humans and bacteria 3. some genes vestigial

C. Fossil Record A. document formation of new species by sequential fossils

D. Biogeography 1. Geographic distribution of species 2. endemic species : a. ancestor from mainland b. adaptive radiation c. island species all share 1. homologous structures 2. homologous DNA/proteins d. homologies shared with a mainland species 3. Similar species from different continents not genetically similar (convergent evolution)