Evolution Chapters 21-24

Evolution (chapter 22) Change over time in the genetic composition of a population Descent with modification

Evolution History American RevolutionFrench RevolutionU.S. Civil War – The Origin of Species is published. Wallace sends his hypothesis to Darwin. Darwin begins his notebooks. Darwin writes essay on descent with modification. Darwin travels around the world on HMS Beagle. Malthus publishes “Essay on the Principle of Population.” Lyell publishes Principles of Geology. Lamarck publishes his hypothesis of evolution. Hutton proposes his theory of gradualism. Linnaeus (classification) Cuvier (fossils, extinction) Malthus (population limits) Lamarck (species can change) Hutton (gradual geologic change) Lyell (modern geology) Darwin (evolution, natural selection) Wallace (evolution, natural selection)

Evolution History Aristotle “Scala naturae” Each form of life was permanent

Linnaeus Taxonomy Naming & classifying organisms Binomial system (Genus & species) Grouping similar species in general categories

Georges Cuvier Paleontology Study of fossils Noted species in some layers of rocks Catastrophism: Events in the past occurred suddenly Different from present day Each layer in rocks represents a catastrophe

Hutton Gradualism: Change can take place through cumulative effect Slow but continuous processes Valleys formed from rivers eroding away rocks over time

Hutton Marine fossils had been carried by rivers to the sea Fossils placed in sedimentary rock

Lyell Uniformitarianism Mechanism of change are constant over time Geological processes are happening now as they were in the past

Lamacrk Two principles 1. Use and disuse Parts of the body used became stronger Those not used deteriorate

Lamacrk 2. Inheritance of acquired characteristics Giraffes stretched necks to reach the leaves Pass on the stretched neck

Charles Darwin

Darwin’s voyage

Observed adaptations of many species Collected fossils Resembled animals living in S. America Collected different species of birds from Galapagos Islands Species on the island were similar to the species only on SA mainland

Finches

Darwin’s voyage Conclusion Birds adapted to environment to survive Adapted to food source that is available

Darwin Adaptation Accumulation of inherited characteristics Enhance an organism’s ability to survive Reproduce in specific environment Result of natural selection

Wallace Developed a theory of natural selection similar to Darwin’s Forced Darwin to publish his writings

Charles Darwin November 24, 1859 Origin of Species Focused on diversity of animals Origins & relationships Similarities & differences Geographic distribution Adaptations to surroundings

Adaptation

Fig a (a) A flower mantid in Malaysia

Fig b (b) A stick mantid in Africa

Darwin Descent with modification “ through time species accumulate differences; As a result: When new species are formed Descendent species differ from its ancestor”

Descent with Modification All organisms are related Descent from an ancestor that lived awhile ago Descendants were in various habitats Diverse modifications or adaptations Specific ways of life

Origin of Species 1. Present species on earth are decendents of ancestral species 2. Natural Selection Mechanism for evolution Organisms with specific heritable traits Produce more offspring with the traits Population grows with more offspring with advantageous traits

Descent with Modification History of life as a tree Trunk is the common ancestor Branches represent an ancestor of all the lines that evolve from that point Recent divergence--closely related species Many branches dead end Many species are extinct

Fig Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Moeritherium Barytherium Deinotherium Mammut Elephas maximus (Asia) Stegodon Mammuthus Loxodonta africana (Africa) Loxodonta cyclotis (Africa) Millions of years ago Years ago Platybelodon

Artificial selection Modification of crops Modification of animals for desired trait Domesticated foxes Choosing most docile in the offspring Mating them Over time produced a fox very similar to domesticated dogs

Variation Variation in the population Leads to differences in individuals in survival & reproduction Variation among individuals must be genetically transmitted

Fig

Variation

Natural selection 1. Selects the organism that will survive better Reproduce at a high rate 2. Selection depends on environment Over time, organisms adapt to environment 3. Change in environment causes change in adaptation Can lead to new species

Natural selection 1. Populations evolve not individuals 2. Affects inheritable traits 3. Environment greatly influences selection of traits Trait favorable in one environment Detrimental in another

Evolution Evidence 1. Direct Observations 2. Paleontology 3. Homology Anatomy Embryology Molecular biology 4. Biogeography

1. Direct Observations Industrial Melanism Peppered moth Variation of traits Increased industrial use caused blackened trees Favored darker moth 1956 restrictions on pollution Favored lighter colored moth

Industrial Melanism

Bacterial antibiotic resistance

HIV Drug resistance 3TC drug affects HIV reverse transcriptase Enzyme makes DNA from RNA genome Virus DNA inserted into host DNA 3TC Is similar to cytosine Resistant HIV carry a different reverse transcriptase (enzyme0 Prevents drug from working

Guppies Wild Dull colors less attractive to predators Bright colors more attractive to mates Ponds increased predators dull Ponds decreased predators brighter

2. Fossils Show change over time Fossils of extinct whales Supports idea whales came from a species that was a land animal Fossil evidence that birds came from dinosaurs

Fig (a) Pakicetus (terrestrial) (b) Rhodocetus (predominantly aquatic) (c) Dorudon (fully aquatic) Pelvis and hind limb Pelvis and hind limb (d) Balaena (recent whale ancestor)

3. Anatomy Homologous structures Structures with different appearances & function Derived from a common ancestor Forelimbs in humans, cats, whale & bats Show same arrangement of bones but different uses

Homologous structures

Fig Humerus Radius Ulna Carpals Metacarpals Phalanges HumanWhale Cat Bat

Embryology Study of early development Shows evidence of structures that do not develop into adult structures Tail Gills/ears and throat

Fig Human embryoChick embryo (LM) Pharyngeal pouches Post-anal tail

Vestigial organs Remnants of organs Do not serve any function now Resemble structures of their ancestors Appendix in humans Pelvis/leg bones in snakes

Molecular biology DNA RNA Similar in organisms Organisms that are very different share a common code Genes have different functions

Molecular biology Compare aa sequence for human hemoglobin Animals closely related to humans Have a higher percent of similar aa than those not as closely related Rhesus monkey has 95% identical aa Frog has 54% identical aa

Evolutionary tree Diagram that shows evolutionary relationships Descent from common ancestor

Fig Hawks and other birds Ostriches Crocodiles Lizards and snakes Amphibians Mammals Lungfishes Tetrapod limbs Amnion Feathers Homologous characteristic Branch point (common ancestor) Tetrapods Amniotes Birds

Convergent evolution Independent development of similar structures in organisms Not directly related Found in organisms that live in similar environment Sugar glider (Australia) (marsupial) Flying squirrel (Europe) (placental)

Fig Sugar glider Flying squirrel AUSTRALIA NORTH AMERICA

Convergent evolution Analogous structures Evolve independently Not common ancestor Adapted to similar environments

4. Biogeography Geographic distribution of species Closely related species live in the same geographic region Distant regions are occupied by very different species

Biogeography Australia Home to marsupials Embryo develops in a pouch Isolated by geography Placental mammals Embryo develops in uterus